Basics of Blood Management - part 5 ppsx

Key points rAlgorithm for preparation of a patient for surgery 1 Take a thorough history and perform a physical exami-nation, paying special attention to obstacles to transfusion avoida

Melagatgran Ximelagatran Abciximab Eptifibatide Tirofiban Ticlopidine Clopidogrel Dipyridamole Aspirin Flurbiprofen

Direct

thrombin

inhibitor

Direct thrombin inhibitor

Blocks GPIIb/IIIa receptor of platelets

GPIIb/IIIa inhibitor

GPIIb/IIIa inhibitor

Irreversible blockage of platelet ADP receptor

Irreversible blockage of platelet ADP receptor

ane inhibition

Thrombox-Thromboxane inhibition

May be not

needed

May be not needed

Hemodyne analysis, modified TEG

Specific platelet function tests (aggregometry or platelet count ratio) using ADP

as an activator, platelet count

Platelet function assay

Chromogenic substrate (Chromozym), FEIBA, rFVIIa

Desmopressin Dialysis, possibly

desmopressin

or rFVIIa, fibrinogen/

cryo-ppt

pressin, fibrinogen/

Desmo-cryo-ppt

Aprotinin, desmopressin, rFVIIa, plasmapherese

Desmopressin, Aprotinin

value is not yet fully understood If the surgeon plans treating an anticoagulated patient, please refer to the literature for indication and dosages of the proposed agents.

full-dose heparin instead of vitamin K antagonists This

permits emergency reversal with protamine if bleeding

occurs

Another common anticoagulant is aspirin, an

an-tiplatelet agent It has been documented as a reason

for an increased risk of perisurgical bleeding and

in-creased use of transfusion [56], although this effect has

not been demonstrated in other studies The antiplatelet

effect of aspirin is pronounced if the patient has taken

other anticoagulants, has a preexisting problem with

hemostasis, or if alcohol is taken concurrently [53] Since

aspirin irreversibly inhibits thromboxane synthesis in

platelets, it is best stopped several days before surgery

and the surgeon should wait until functional platelets are

produced

Nowadays many other anticoagulants are used in

clini-cal practice Table 11.5 provides an overview of the existing

drugs and potential reversal methods if such become

nec-essary [58–79]

Avoid pharmacologic coagulopathies Many drugs are not

used for anticoagulation but nevertheless affect

hemosta-sis (Table 11.6) [53, 80, 81] Whether all such drug effects

translate into increased perioperative bleeding has not yet

been determined However, if at all possible, such

phar-macologically induced coagulopathies should be avoided

Often it is possible to switch from one drug to another or

to stop the drug altogether Drug-induced coagulopathies

can be antidoted occasionally

cardiopulmonary and general condition

In coronary artery disease, the ability to increase thecardiac output is impaired, thus limiting the patient’sability to tolerate anemia It is important to avoid car-diac ischemia Perioperative analgesia, anxiolytic medica-tions, normothermia, judicious beta-blockade, and closemonitoring for cardiac events are recommended [82] If

Table 11.6 Examples of drugs and herbs that can cause

coagu-lopathies and may increase perioperative blood loss

Nonsteroidal anti-inflammatory drugsPenicillin

Some cephalosporins such as cefotaxime, moxalactamQuinidine

AlteplaseProtamineNifedipineNitroglycerineParoxetine, fluvoxamine (vitamin C)High-dose vitamin C

Valproate

St John’s wortGingerGarlicCertain hydroxyethyl starches (desmopressin)Propofol

Note : The agents in parenthesis may be used to counteract

pharmaco-logical coagulopathies.

the patient has had beta-blockers before surgery, such

should be continued to prevent withdrawal, which may

otherwise cause ischemia The perioperative risk for

is-chemia can also be reduced by preoperative coronary

revascularization

There are several measures available to optimize

pa-tients’ pulmonary function prior to surgery Smokers

should stop smoking at least 8 weeks before surgery

In-centive spirometry before and after surgery should be

en-couraged in patients with pulmonary problems Medical

therapy is at times indicated, such as bronchodilators for

wheezing, and beta-agonists and atropine analogs in

pa-tients with asthma and chronic obstructive pulmonary

disease

A number of conditions can adversely affect anemia

tolerance and counteract efforts to lower the patient’s use

of donor blood Efforts should be taken to optimize the

patient’s condition preoperatively

Optimizing the surgical field

In certain situations it seems prudent to optimize the

sur-gical field There are several methods for reducing the

surgical field, for example, reducing the size of a tumor by

preoperative chemotherapy or radiation The vascularity

of the surgical field can also be reduced Preoperative

em-bolization for primary tumors and metastases as well as

for whole organs can reduce perfusion and thus blood loss

[83–85] Pharmacological therapy may be equally effective

in selected cases For instance, finasteride given before

be-nign prostate hyperplasia operations reduces angiogenesis

in the prostate and reduces bleeding and transfusions in

patients [86–88]

Patient education

By definition, blood management is patient centered This

means that at all times the patient is the center of all

efforts It is crucial, therefore, to actively include him

in the preparations for surgery or any other treatment

This is essential for a good patient–doctor relationship

and improves patient compliance The patient can do

much to reduce exposure to donor blood All patients

should be advised not to take drugs on their own

initia-tive Help patients understand that a single aspirin for a

headache or menstrual discomfort can increase blood loss

Sound habits such as healthy nutrition, sufficient sleep,

and abstinence of noxae are very basic but improve

pa-tients’ general condition Moderate physical exercise may

improve not only the overall condition of the patientbut may also treat anemia [89] An information book-let may be handed to the patient detailing the plannedblood management procedures It may also include a sum-mary of what the patient can do during the treatment andperisurgical period Such a booklet may remind the pa-tient of the need to adhere to the prescribed schedule oftherapy

Prepare the equipment

Hours before the battle of Waterloo, Napoleon Bonapartetold his generals: “This affair will be no more serious thaneating one’s breakfast.” Shortly thereafter, however, he wasproven wrong It was raining The raindrops rendered theweapons useless, made the roads muddy and impassablefor war wagons, blocked the vision of the combatants, andleft the soldiers soaked to the skin The battle at Water-loo was lost, at least in part, because proper, water-proofequipment was lacking Something as insignificant as rain-drops stopped Napoleon Experience gained in years ofcampaigning was rendered useless due to the presence ofrain This drives home an important point The most so-phisticated equipment is of little use if it is damaged orunavailable Therefore, make sure all devices and drugsare handy before surgery When it starts pouring and vi-sion is obscured, equipment must be readily available tomaster the situation Always prepare the equipment andhave the needed drugs available to ensure the patient doesnot meet his Waterloo

Preparation should not only involve getting ready forthe intended procedure Emergency equipment shouldalso be made ready One suggestion is to prepare an emer-gency tray with all that is needed to treat sudden massivebleeding [90] The contents of such a tray can be tailored

to the specialty and skills of the surgeon It may containtourniquets, tamponade materials, catheters to block ves-sels, special clamps, glues, mashes, balloons, etc It mayalso contain copies of algorithms that guide through themanagement of emergent or heavy bleeding [91] Havingsuch a tray ready saves time in an emergency and mayreduce the total blood loss

Be prepared

The duration of a surgical procedure influences the degree

of blood loss Independent of other factors, long operationtimes increase blood loss However, speeding up a proce-dure at the expense of quality does not reduce blood loss

either Rehearsing the procedure before going to the

oper-ating theater is wise, because this helps the surgeon have

the steps of the planned procedure fresh in mind This

may not only shorten the duration of the procedure but

also improve the quality of the operation, both of which

reduce blood loss

Key points

rAlgorithm for preparation of a patient for surgery

1 Take a thorough history and perform a physical

exami-nation, paying special attention to obstacles to transfusion

avoidance and matters pertaining to blood management;

Review test results already available

2 Order labs and other tests if such are clearly indicated

but beware of iatrogenic blood loss

3 Based on the findings of #1 and #2, calculate the

allow-able blood loss, blood volumes, and determine the lowest

tolerable hematocrit

4 Formulate a plan of care (with a timetable) It should

include the allowable blood loss and the expected blood

loss Record:

◦How the patient’s medical problems will be treated, e.g.,

coagulation problems

◦How to optimize the hemoglobin level

◦What surgery is to be done and what preparations are

necessary

◦What measures will be taken to reduce blood loss

◦What emergencies can be expected and how such will

be dealt with

Further, list all additional personnel, items, and drugs

required

5 Prepare the patient and the equipment, and make

personal preparation in accord with the plan of

care

Questions for review

rWhich steps are vital to prepare a patient for surgery in

a blood management program?

rHow do drugs influence the blood management of

patients?

rWhat measures need to be taken to work up a patient

with anemia and with a coagulopathy?

rWhat preparations are required for surgery in a blood

management program?

Suggestions for further research

Compile a list of drugs that have an impact on surgicalblood loss

List laboratory tests of coagulation and evaluate their value

as predictors for surgical blood loss

Exercises and practice cases

Answer the following questions:

rA patient does not complain of any signs of a bleeding

disorder During the physical examination petechiae and

a splenomegaly are found Which laboratory tests should

be ordered for the patient?

rLast week, a patient presented with a Quick of 28 He

was treated with appropriate doses of vitamin K Today,

he presents with a Quick of 35 What needs to be done?

rA female patient complains of heavy menstrual bleeding

although no obvious anatomic pathology is found in agynecologic exam Otherwise, she is healthy Her Quick is114%, her aPTT is 24 seconds, her platelet count is 250,and her hematocrit is 28 What tests should be ordered?

rA male patient presents for elective hip replacement He

is scheduled for surgery in 3 weeks On questioning, hestates that he usually takes up to 2.5 g of aspirin per dayabout once a week for tension headache Otherwise he ishealthy What tests should be ordered?

Introduce Miss B to a colleague Discuss in a ciplinary fashion how her treatment should be continuedand write a plan of care for Miss B

multidis-Miss B is 70 years old; she has been sent by her familydoctor for bilateral hip replacement She suffers from along-standing arthrosis She has never had an operationbefore

Miss B lives alone on the third floor of an apartmentbuilding and has increasing difficulty climbing stairs Herfriend Millie used to have the same trouble Once she gotartificial joints, the patient says, she was again able to gofor extended walks in the park Miss B wants to join herfriend and asks for the same procedure

Among other information the letter from Miss B’s tor contains the following:

doc-Her height is 1.60 m and weight 55 kgMiss B takes the following drugs:

rCordarone tablets 200 mg per os 1-0-0-0

rCoumarin tablets 3 mg per os depending on the INR

rIbuprofen tablets 400 mg per os 1-1-1-1

Current laboratory test results:

Table 11.7 Proposal for emergency hemorrhage equipment used in obstetrics and gynecology.

Plastinated emergencyinformation

Tranexamic acid, desmopressin,

conjugated estrogens, aprotinin,

oxytocin, ergot derivative,

prostaglandin analogues

(Carboprost, Misoprostol),

anticoagulant for cell salvage

(heparin, citrate), vasopressin

and glues for enhancement of

packing, other topical

hemostatics (gelatin, collagen,

etc.)

packing (5-yard roll), balloondevice for uterine tamponade(Foley, Sengstaken- Blakemore),straight (10 cm) eyed-needlesand large curved eyed-needlesfor use with No 1 suture, 3Heaney vaginal retractors, 4sponge forceps, container andsuction for cell salvage

diagrams+ instructions for thevarious types of compressionsutures and tamponadetechniques; Algorithm fornonblood management ofpostpartum hemorrhage, phonenumber of radiology dept

(embolization), pharmacy(rhFVIIa), dosage andindications for mentioned drugs

Determine storagetime, sterilization,responsiblepersons, intervals

of checks, training

Hematocrit 0.30; hemoglobin 10 g/dL (red cell

in-dices: mean corpuscular volume and mean

corpuscu-lar hemoglobin content decreased); leukocytes 8000;

platelets 250000; electrolyte profile, liver, and kidney

panel unremarkable

Experience shows that implanting a single artificial hip

joint causes the loss of 1000 mL of whole blood

What is the allowable blood loss for patients with the

fol-lowing characteristics:

r66 kg male with a minimum tolerable hematocrit of

20 and a current hematocrit of 45

r100 kg male with a minimum tolerable hematocrit of

30 and a current hematocrit of 33

r40 kg female with a minimum tolerable hematocrit

of 25 and a current hematocrit of 37

Homework

Take a focused history of three surgical patients in the

hospital; be sure to get all the data needed for the patients’

blood management

Go to the hospital laboratory and find out whether

platelet function tests are available If so, obtain more

in-formation on them

Find out what the three most common congenital and

three most common acquired bleeding disorders are in

your field of practice

Following the example of Table 11.7, draw up a list

of contents for an emergency hemorrhage tray or chart

for at least one of the following departments:

Emer-gency department (acute trauma care), gastroenterology,

urology, operating room for unexpected major bleeding,pediatrics, ENT, any other you prefer

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12 Iatrogenic blood loss

A number of patients are transfused after they developed

anemia or a coagulopathy, due to surgery or trauma with

major blood loss or due to an underlying medical

con-dition However, there is another group of patients who,

although not belonging to the above, are transfused

any-way Many of these patients lost blood as a result of

medi-cal interventions A series of small iatrogenic blood losses

can add up resulting in patients becoming anemic This

chapter will address seven of the major causes of such

ia-trogenic blood loss and describe methods that minimize

these losses

Objectives of this chapter

1 List different ways in which a medical caregiver causes

blood loss

2 Describe methods how iatrogenic blood loss is

minimized

3 Explain the vital role of minimizing iatrogenic blood

loss in a comprehensive blood management program

Definitions

Iatrogenic blood loss : The word “iatrogenic” stems from the

word “iatros” which is Greek and means “physician,” and

“genesis,” which means “origin” or “cause.” “Iatrogenic”

therefore means “caused by a physician.” All blood losses

that are, directly or indirectly, caused by a physician’s

in-tervention are summarized under the phrase “iatrogenic

blood loss.” Actually, iatrogenic blood loss is not caused

by physicians only Every member of the care team can

cause blood loss In turn, every member of the medical

care team can also help to reduce iatrogenic blood loss

Causes of iatrogenic blood loss

You may ask: “How can a physician (or any medical

care-giver) be the culprit?” and, “What ways are there to cause

iatrogenic blood loss?” Well, almost everything a medicalteam does has the potential to cause blood loss Not onlyhave the surgeons caused blood loss by their operation No,every specialty can cause blood loss—directly or indirectly.Blood loss may be caused simply by the fact that a patienthas to see a physician The patient may be so stressed bythe very thought of seeing a doctor that he develops astress ulcer and bleeds internally Patients prescribed bedrest soon show a lowered red cell count Many diagnos-tic procedures cause blood loss Some of them to such anextent that physicians are moved to transfuse Also, manytherapeutic interventions cause blood loss This holds truefor drug therapy as well as for more invasive approaches,such as dialysis and other forms of extracorporeal circu-lation (ECC) Nevertheless, all of these interventions can

be adapted so that iatrogenic blood loss is minimized

Problem 1: phlebotomy—laboratory testing causes blood loss

Blood loss by phlebotomy is not a new phenomenon Forages, phlebotomy in the form of blood letting was a le-gitimate “cure” for all kinds of ailments, including ane-mia While beneficial in selected cases, phlebotomy to theextent of blood letting more often than not harmed thepatient, even resulting in his death Blood losses by to-day’s phlebotomists are more subtle, yet clearly detectable

as well They have a great impact on patient care and also

on transfusion practice Since laboratory results are animportant tool to achieve a diagnosis and to guide med-ical care, a certain amount of blood usually is required

to get the needed information However, a great quantity

of blood drawn for laboratory testing is drawn needlessly.One major problem is that laboratories are drawn with-out good reason, drawn too often, or drawn despite notbeing indicated Some members of the care team orderingblood tests are not aware of the significance of the resultsobtained Often, laboratory results do not influence pa-tient’s care at all So, what is the point of obtaining them?

160

Table 12.1 Average phlebotomy-induced blood loss in critically

ill patients

Average

United States Cardiothoracic ICU Avg 377 mL/day

United States General surgical ICU Avg 240 mL/ day

United States Medical surgical ICU Avg 41.5 mL/day

Great Britain First day in ICU Avg 85.3 mL/day

Great Britain Following days Avg 66.1 mL/day

Europe Medical ICUs Avg 41.1 mL/day

ICU, intensive care unit; Avg., average.

Another problem with phlebotomy is that excessive blood

volumes are drawn A study in a neonatal intensive care

unit (ICU), for instance, indicated that almost 20% of the

blood drawn was not needed in the laboratory to perform

the requested tests [1]

When blood is drawn from indwelling arterial or venous

lines, a certain amount of blood (“dead space volume”) is

withdrawn to clear the line, before the actual phlebotomy

volume is drawn This is done in order to reduce the

mix-ing of the catheter flushmix-ing solution with the blood

sam-ple The drawn dead space volume is usually discarded

Depending on local custom, the discarded volume differs

between 2 and 10 mL per blood draw [2]

The total daily amount of blood drawn for laboratory

tests differs, depending on the pathology and the length

of stay Sicker patients experience more blood loss than

those less sick, placing the sicker patients at higher risk

for anemia Table 12.1 demonstrates how substantial the

total daily amounts of blood drawn from one patient can

be [2]

Possible solution: reduction of

phlebotomy-induced blood loss

Strategies to reduce phlebotomy-induced blood loss exist

and are usually employed in patients at high risk for

ane-mia, such as neonates, pediatric patients, the critically ill,

and patients for whom transfusions are not an option

Reduction of the amount of phlebotomy

Reducing the amount of blood for phlebotomy starts with

the plain avoidance of unnecessary phlebotomy

Thought-less ordering of a variety of parameters does not contribute

to your value as a caregiver, nor does it help your patient.Ask yourself: What would change in the care of the patient

if I do or do not have the result? If there is no clear cation for a blood test, it is most probably not indicatedand a waste of blood and money Standing orders (“Mr.Miller is going to have his liver function test every otherday, no matter what”) should be reconsidered and in manyinstances eliminated

indi-When you know what laboratory values are needed,think whether batching the requests is possible One spec-imen is often sufficient to obtain several values at a time.Then, make sure that you know how much blood is needed

to perform the requested tests Phlebotomy overdraw can

be substantial Especially in small children, small amounts

of blood, drawn unnecessarily, matter Collection tubeswith fill lines should help in this regard [1] Drawing theblood up to the fill line prevents overdraw, either caused

by drawing too much blood for one sample or by ing blood for the same test twice The latter may be thecase when insufficient blood is drawn into the containerresulting in a wrong mixing ratio of blood and the addi-tive provided in the container (e.g., anticoagulant) In thiscase, blood has to be drawn again, resulting in unnecessaryblood loss

draw-Patients at high risk for anemia will probably fit from further means to reduce blood draws The use

bene-of neonatal tubes, with a smaller fill volume, reducesblood loss and at the same time provides the needed re-sults (Table 12.2) A switch from adult to pediatric-sizedtubes may reduce the diagnostic blood loss by over 40%[3] A more blood-saving method is microsampling Onlyfew microliters of blood are needed to obtain requiredinformation, e.g., 150 μL for blood gases, electrolytes,hemoglobin and hematocrit, and the blood sugar De-vices for point-of-care testing [4] often require only smallblood volumes Some point-of-care devices are even able

Table 12.2 Phlebotomy volumes of commercially available blood

tubes

Neonatal/Regular Pediatric microsamplingHematology 3.5–9 mL 2.6–3.0

Serology 4.9–10 mL 2–2.7 mL 250μL–1 mLCoagulation 4–10 mL 2.9–3.0 mL

Blood sugar 2.6–3.0 mL 20–50μL (or less)Sedimentation

to return the drawn blood directly back to the patient after

it has been analyzed [5] In areas where rather expensive

point-of-care devices are not available, color scales may

help to obtain fairly accurate laboratory results, using only

one drop of the patient’s blood [6, 7]

Keeping track of the amount of phlebotomy of

indi-vidual patients is especially helpful in high-risk patients

(neonates, severely anemic) It sensitizes the members of

the personnel (physicians, nurses, phlebotomists,

labo-ratory technicians) to take greatest care in their efforts

of blood conservation Therefore, it may be beneficial to

mark such high-risk patients, to alert personnel to be

es-pecially careful Having every member of the care team

who orders or executes phlebotomy sign a special sheet

may also be of help, especially in the initial phase of

estab-lishing blood saving techniques

Practice tip

Place a sheet of paper next to all patients in the ICU and

have all persons who draw blood list the total volume of

blood drawn After the patient leaves the unit, add all

losses up and present them to the health-care team for

discussion.

Reduction and elimination of discard volume

Dead space volume drawn before obtaining the blood

sample is usually discarded It was shown that a volume

of only twice the catheter dead space is sufficient to gain

the required accuracy of the drawn laboratory values [8]

Whatever goes beyond this volume is a wasted resource

To avoid discard volume as a source of iatrogenic blood

loss altogether, several methods are used The simplest

one is probably just to return the sterile dead space

vol-ume once the blood sample is drawn Discard volvol-ume is

completely eliminated when a passive extracorporeal

ar-teriovenous backflow is used [9] For this technique, a

double-stopcock-system connects the central line and the

arterial line When the appropriate stopcocks are opened,

blood from the arterial line flows back, through the

tub-ing, toward the venous line The blood is allowed to flow a

certain distance (which equals the usual discard volume)

past a sampling port Then, the blood sample is drawn

through the sampling port and the blood is directed back

to the patient

Additionally, special systems, using a reservoir that is

meant to be included in an arterial line, are available for the

withdrawal of dead space volume and subsequent

retrans-fusion Adapting arterial blood draws, by using a closedsystem, reduces the blood loss by about 50% [10]

Replacement of phlebotomy

by “bloodless” monitoring

Another way to eliminate the need for blood draws is theuse of methods that deliver the needed information with-out a blood draw Some values (e.g., pH, partial pressure ofcarbon dioxide (PCO2), partial pressure of oxygen (PO2),arterial oxygen saturation (SaO2), bicarbonate, base ex-cess) can be obtained, with satisfying accuracy, using in-dwelling measuring catheters with photochemical sensors[11] The catheter can either be inserted into an ECC [11]

or directly into the vascular system [12] Photochemicalsensors can be placed intravascular for continuous mea-surement, or extravascular for on-demand-measurement

To obtain some blood values, direct contact between bloodand a measuring device is not always necessary Skin sen-sors may be placed on patients who are at high risk for ia-trogenic blood loss The sensors measure the partial pres-sures of carbon dioxide and oxygen in the blood and theblood glucose level through the skin, obviating the needfor serial blood draws

Education

Educating members of the team on techniques for ing unnecessary blood loss, e.g., ordering only essentialblood tests, exercising the greatest care in infants, prac-ticing drawing blood samples into syringes, etc., may alsohelp While studies to evaluate the effect of education onthe appropriate use of phlebotomy did not show a signif-icant change in practice, the introduction of mandatorypolicies and guidelines for laboratory use did

reduc-Problem 2: resting patients lose blood

Even patients who do nothing at all may lose blood Onereason for this is that inactivity and bed rest elicit physio-logical responses that lead to anemia [13] Another prob-lem of bed-resting patients may be the development of de-cubital ulcers, leading to so-called “pressure sore anemia”[14] Anemia due to decubital ulcers is characterized bymild to moderate anemia with low serum iron and normal

or increased ferritin in combination with mia and hypoalbuminemia Anemia probably developsbecause of the chronic inflammatory state caused by thepresence of pressure ulcers

hypoproteine-Possible solution: keep them moving

Since the blood count of resting patients may gradually

decrease, unnecessary bed rest in hospitalized patients

should be avoided There is no evidence that

ambula-tion of patients decreases their transfusion exposure, but

there is some evidence that it reduces postoperative

pneu-monia, length of stay in the hospital, and

psychologi-cal changes [15] Moderate physipsychologi-cal training has been

shown to reduce anemia [16–18] The reasons for this

phenomenon are not clear One hypothesis is that

ex-ercise increases hormones that stimulate erythropoiesis

and leucopoiesis Growth hormones, granulocyte

colony-stimulating factor (G-CSF), and a variety of other

cy-tokines are produced during exercise Besides, cycy-tokines,

which are typically produced in an inflammatory state and

inhibit hematopoiesis (e.g., interleukin 6), seem to

dimin-ish during exercise [19, 20]

Whatever the reason, exercise may ameliorate anemia,

and you can use this effect to the good of your patient

Educate the patient and his family that moderate exercise

is very beneficial Also, you may be able to prescribe a

regimen of physical therapy This may be especially

ben-eficial for patients with chronic anemia (such as dialysis

patients) These patients should be advised to exercise

reg-ularly If you see a dialysis patient, in order to plan elective

surgery, this may be a good time to start him on an

ex-ercise program Certain types of anemia react very well

to exercise Through an exercise routine, the blood levels

of preoperative anemia patients can be optimized Thirty

minutes per day of interval training, on a stationary

er-gometer, for 3 weeks, may be sufficient for a substantial

improvement of the patient’s blood count Patients who

experience prolonged periods of chemotherapy-induced

anemia may start with moderate exercise immediately

af-ter chemotherapy If it is not possible for the patient to

get out of bed, exercise in the supine position, using a

“bed bike” or cycling in the air, may be recommended

Most of your medical and surgical patients will benefit

from being mobilized as early as possible Adequate pain

management, nutrition, and a schedule for mobilization

and exercise may support the patient compliance to your

prescribed program [16–19]

Pressure ulcers, which can develop during bed rest,

con-tribute to anemia as well Diligent nursing staff know how

to avoid the development of such sores If they are already

present, appropriate therapy is warranted Pressure sore

anemia needs to be taken seriously Iron therapy is said

to be useless Instead, it has been recommended to treat

serum protein alterations, prescribing a diet rich in

pro-tein and calories [21] Both anemia and hypopropro-teinemiadisappear after the pressure ulcers heal

Problem 3: stressed patients lose blood

Not only resting patients suffer from iatrogenic blood lossand anemia Stressed patients share the same fate, but due

to completely different underlying mechanisms Criticallyill patients regularly (40–100%) develop alterations in themucosa of the gastrointestinal tract This may contribute

to the development of stress “ulcers” in the gastrointestinaltract Up to 90% of ventilated patients admitted to an ICUsuffer from stress ulcers on the 3rd day of their stay [22,23] These may lead to occult gastrointestinal hemorrhage.About 1–2% of the patients even experience severe hem-orrhage, leading to blood transfusion [24] Such bloodloss is aggravated by anticoagulant use and the presence

of coagulation disturbances

While all pediatric and adult patients may develop stressulcers, there are a variety of conditions that obviously pre-dispose patients to stress ulcers The classical conditionsare head and brain trauma, major burns, emergency ormajor surgery, major trauma, shock, coagulopathies, me-chanical ventilation for more than 2 days, therapy withdrugs that may cause ulcers, and a history of gastrointesti-nal ulcers

Possible solution: ulcus prophylaxis

Stress ulcer prophylaxis is an integral part of a strategy toavoid iatrogenic blood loss The first and most importantmethod is to attempt to maintain adequate mucosal perfu-sion Unfortunately, specific measures to do so are limited.Maintaining sufficient cardiac output and giving sufficientamounts of oxygen enhance the mucosal integrity, form-ing the basis for ulcer prophylaxis

A simple measure, yet often overlooked, to protect theintegrity of the mucosal lining in the gastrointestinal tract

is enteral feeding This is thought to be due to the izing effect on the acid in the stomach as well as the nu-tritional effect of the food on the mucosa Patients should

neutral-be asked to eat If this is not possible, tuneutral-be feeding has thesame effect

If enteral feeding is not possible, or the patient is athigh risk of developing stress ulcers, medical prophylaxis isindicated Histamine-2-receptor antagonist therapy aims

at reducing the gastric acid levels in the stomach It wasshown to decrease incidences of gastrointestinal hemor-rhage There is a trend toward decreased hemorrhage when

antacids are used for the same purpose (compared with

no therapy) Sucralfate may be as effective in reducing

hemorrhage as gastric pH-altering drugs Advantages of

sucralfate include a lower rate of pneumonia and

mortal-ity, as well as lower costs [25] Proton pump inhibitors

may be even more effective than

Histamine-2-receptor-2-antagonists They reduce transfusions in patients with

ulcer hemorrhage and effectively decrease rebleeding [26]

Problem 4: diagnostic interventions cause

blood loss

Diagnostic and therapeutic interventions, at times, cause

blood loss Among them are the placement of arterial and

central lines as well as interventions such as tracheostomy

[27] and angiography

The impact of blood loss caused by the insertion of

a central line is obvious when an untrained individual

performs the insertion Often, blood flows back freely,

pouring out on to the drapes and is lost Quantifying such

blood losses is difficult One study on iatrogenic blood

loss mentioned the insertion of arterial and central venous

catheters as source of blood loss, but did not determine

the amount of blood lost [28] Though the magnitude of

blood loss is not clearly defined, obtaining vascular access

and a variety of other procedures doubtless cause blood

loss

Also, the presence of arterial lines causes blood loss

This happens when blood is drawn freely using this easy

access to the patient’s blood [29]

Possible solution: practice

A certain amount of skill is needed to obtain vascular

access It seems that unskilled health-care providers, such

as beginners, lose, on average, more blood than skilled

persons In patients at high risk of anemia, a skilled

health-care provider may be more appropriate for the placement

of the lines than a beginner

Also, the choice of technique to obtain vascular access

may influence the amount of blood lost during the

pro-cedure Inserting an arterial line in open Seldinger’s

tech-nique causes more blood loss than the same procedure

per-formed in modified Seldinger’s technique (closed system)

or by direct cannulation Slight changes in the method

of using the guide wire also promise to reduce blood loss

One article describes this as follows [30]: “The method

en-tails inserting the guide wire through a previously created

side hole in a standard 5 ml plastic syringe The problems

of needle dislodgement, air embolism and blood loss arevirtually eliminated with this technique.” The use of valves

in the introducer sheaths for large vascular catheters mayhelp reduce blood loss as well [31]

Another way to minimize blood loss that is associatedwith placed arterial or central venous lines is to removethem soon as possible This will also reduce access to thepatient’s blood [29]

The method with which some interventions are formed can result in more or less average blood loss.Tracheostomy, for instance, can be performed as a con-ventional surgical procedure or as a percutaneous dilata-tional tracheostomy The latter was shown to have a lowerperi- and postoperative blood loss than the conventionalapproach The reason may be that “following percuta-neous placement, the stoma fits snugly around the tra-cheostomy tube This lack of dead space conceivably serves

per-to tamponade bleeding vessels” [27] There are also ferent methods for the insertion of a permanent pace-maker, some of which cause less blood loss than others[32]

dif-Problem 5: medications may cause blood loss

Medications may cause blood loss by many differentmechanisms Over-anticoagulation may contribute to theblood loss, as well as side effects of medications given dur-ing hospitalization Commonly encountered mechanismsthat increase iatrogenic blood loss include the following,

iatro-if possible

If anticoagulation is required, judicious use of thedrugs is warranted For several anticoagulants, monitor-ing is prudent, and should be employed to prevent over-anticoagulation, which may lead to undue blood loss.When a patient is at high risk of hemorrhage, for instance,when he has a very low platelet count, anticoagulationmay not be the wisest choice Thrombosis prophylaxismay be more appropriate using nondrug methods such

Table 12.3 Drug effects that may increase iatrogenic blood loss.

Aspirin and other nonsteroidal

antirheumatic drugs,

glucocorticoids

(Occult)gastrointestinalhemorrhageHeparin, aspirin, heart glycosides,

other chemotherapeutics, gold

derivatives, neuroleptics,

pyrimethamine

Blunted hematopoiesis

Some cephalosporins Toxic changes in the

blood count, e.g.,leucopenia,thrombocytopeniaAjamlin, l-asparaginase,

carbamazepine, rifampicin,

thiazides, rapid infusion of

hypotonic solutions

Hemolysis

High-dose penicillins, aspirin,

valproic acid, serotonin

antagonists

Impairment ofcoagulation

as inflatable pressure stockings or, in selected cases, the

placement of a Greenfield filter

Other drug regimens, which may alter the patient’s

blood, may also be amendable for adaptation

Chemother-apy can be varied to reduce the impact it has on

hematopoiesis Antibiotics can be chosen so as not to

unnecessarily aggravate coagulopathy Hemolysis, due to

hypotonic solutions and other medications is also

pre-ventable It goes beyond the scope of this chapter to engage

in an in-depth discussion of all possible effects of drugs on

blood loss Just a little hint: a short look into a reference

book is often tremendously helpful

Problem 6: blood loss caused by ECC

Patients with end-stage renal failure, patients undergoing

open heart surgery, patients with potentially reversible

heart or lung failure all have something in common:

they have a good chance of needing therapy that includes

an ECC, such as hemodialysis, cardiopulmonary bypass,

ventricular assist devices, or extracorporeal membrane

oxygenation The basic principle of an ECC is the same,

regardless of the specific purpose of the device All thesedevices have the potential to cause iatrogenic blood loss.Additionally, other devices being introduced in the bloodstream of a patient (such as intra-aortic balloon pumps,ventricular assist devices, and prosthetic heart valves) maycause iatrogenic hemolysis [33]

ECC is a nonphysiological approach to blood lation that takes its toll on the blood The blood in theECC comes into contact with air and foreign surfaces, andthe shear stress within the blood increases Furthermore,the flow pattern in the circulation changes from a pul-satile to a nonpulsatile flow All of this leads to alterations

circu-of the corpuscular elements circu-of the blood, the activation

of coagulation and complement cascade, and the tion and adherence of a variety of other blood proteins

activa-As a result, red cells hemolyze, platelets are activated andchange in number, shape, and functionality, the clottingability is disturbed, and blood proteins are reduced in thecirculation

Anticoagulation is needed for the successful use of ECC.However, it contributes to blood losses and allogeneictransfusions Over-, as well as under-anticoagulation maylead to intra- and postoperative coagulopathies and un-necessary blood loss If the patient is exposed to excessamounts of an anticoagulant, he may hemorrhage due tothe action of the anticoagulant If he is not sufficientlyanticoagulated, his clotting factors and platelets are acti-vated and used up during the ECC, leaving the patientwith lower levels of available clotting potential after ECC.This also leads to coagulopathies Besides, reversal of an-ticoagulation in excess of the present anticoagulant mayalso add to coagulopathies

Other factors, directly or indirectly related to the use of

an ECC, influence the magnitude of iatrogenic blood loss

as well Blood remaining in the tubing, after tion of the procedure, adds to the blood loss Also, coag-ulopathy induced by anticoagulation and patient-specificfactors (e.g., a disturbed erythropoiesis in renal insuffi-ciency) contribute to the fact that patients requiring anECC are at higher risk for anemia than other patients Ac-cording to a study, daily blood loss in patients requiringdialysis or hemofiltration in an ICU was 5.8 times higherthan the blood loss in intensive care patients, not requiringsuch therapy [28]

discontinua-Possible solution: minimizing blood loss due to ECC

The use of an ECC inevitably causes blood loss Happily,the extent of these changes depends on a variety of factors,

most of which can be altered to reduce the effect of the

ECC on the blood

In former times, patients on an ECC, such as the

car-diopulmonary bypass, were transfused with a lot of blood

Even the ECC was primed with donor blood Today, this is

obsolete in most instances Primes of crystalloid solutions

are sufficient to start the pump This leads to

hemodi-lution While hemodilution is a benefit to patients

un-dergoing hypothermia and who experience the

accompa-nying increase in blood viscosity, some patients may not

benefit In such instances, retrograde autologous priming

is a method that reduces the hemodiluting effect of the

ECC The use of autologous blood to prime the circuit

reduces not only hemodilution but also the patient’s

ex-posure to transfusions [34] It maintains higher

intraop-erative hemoglobin levels Since it does not require extra

disposables, retrograde autologous priming is a very

inex-pensive technique [35] Several techniques for retrograde

autologous priming have been advocated Basically, the

circuit is partially primed with asanguinous fluids such as

crystalloids The patient’s own blood, draining from the

venous tube, is used to further fill the circuit

Preoperative normovolemic hemodilution and

blood component pheresis

Since the contact of blood with the ECC causes a

vari-ety of changes, one method to avoid this is to take some

blood out of the patient’s circulation before the ECC is

initiated Such procedures are performed mainly in

con-nection with the ECC initiated prior to cardiac surgery

Acute normovolemic hemodilution and the fractionation

of whole blood for platelet-rich and platelet-poor plasma

are methods to spare blood contact with the ECC

Platelet anesthesia

The term “platelet anesthesia” refers to a concept that is

still in the experimental stage It is a strategy to

mini-mize platelet activation and adhesion during the period

the blood is circulating via ECC (usually during

cardiopul-monary bypass) Short-acting platelet inhibitors are used

during the ECC period, which temporarily inhibit platelet

activation and adhesion When the action of the inhibitor

wears off after the end of the ECC, a larger number of

functionally adequate platelets are still available This is

thought to reduce postoperative blood loss and normalize

in vitro coagulation parameters

Several drugs can be used to achieve platelet

anesthe-sia Phosphodiesterase inhibitors, such as dipyridamole,

have been used However, the action of the drugs is notquickly reversible after the end of the ECC Prostanoids,such as prostacyclin, are also used, but cause severe hy-potension More promising drugs are glycoprotein IIb/IIIamembrane receptor inhibitors (e.g., ticlopidine, tirofiban)

or the direct thrombin inhibitor argatroban It remains

to be seen whether the concept of platelet anesthesia caneffectively reduce transfusions

Adaptation of the extracorporeal circuit

Technical details of the ECC influence the magnitude ofthe changes in the blood components

Blood contact with artificial surfaces leads to activation

of humoral and cellular elements of the blood The contactactivation or its effects can be reduced by using the differ-ent methods The most common approach is the coating

of tubing and other surfaces with heparin The benefits ofthe heparinization of surfaces include fewer alterations tothe blood as well as a reduced need for systemic anticoagu-lation In turn, blood loss may be reduced This was shown

in some, but not all, studies Allogeneic transfusions wereshown to be reduced with the use of heparinized circuits

as well [36] Further benefit may be added by a cyte filter in the ECC This filter may reduce the effects ofactivated leukocytes in the patient It has been theorizedthat the reduction of activated leukocytes may also reducecoagulation disturbances after ECC [36]

leuko-The choice of an appropriate oxygenator, in ECCs used

to oxygenate the blood is also important It has an impact

on the denaturation of blood proteins and the change

in the amount, function, and structure of blood cells Ingeneral, membrane oxygenators tend to influence in vitromarkers of protein activation and blood cell alterationsless than bubble oxygenators (the latter ones have a largerblood-surface interface) In vivo, membrane oxygenatorsseem to be superior to bubble oxygenators in patients un-dergoing long perfusion periods During shorter perfu-sion times, in vivo experiments did not show a reduction

in blood loss with membrane oxygenators [37]

Minimized extracorporeal circulation (MECC) forheart surgery may also reduce iatrogenic blood loss and isassociated with a low transfusion rate [38] An MECC con-sists of a heparin-coated tubing system with a pump andoxygenator A venous reservoir and a vent are not included.The priming volume is much lower than in conventionalextracorporeal circuits (ca 450 mL instead of about 1500

mL [38] For very small children, the cardiopulmonary pass system can be minimized so that the priming volume

by-is as low as 130–160 mL [39] Minimized extracorporeal

circuits were shown to cause higher hemoglobin levels and

decreased hemolysis when compared to the conventional

ECC, in patients undergoing a heart surgery [40]

Mini-mized extracorporeal circuits are helpful when

perform-ing heart surgery on small children, without exposure to

allogeneic blood [39]

Retransfusion of blood left in the ECC

Blood left in the tubing after termination of the ECC would

be wasted if not given back to the patient There are

differ-ent ways to return the remaining blood to the patidiffer-ent It

can just be reinfused or it can be processed and then given

back Blood can be centrifuged using a cell saver or it can

be hemoconcentrated with a filter The use of the

cen-trifuge removes platelets and plasma components, giving

back mainly the concentrated red cells It has the advantage

that heparin is not given back to the patient In contrast,

ultrafiltration and the return of unprocessed blood return

heparin to the patient, but also preserve plasma

compo-nents and platelets [41] Ultrafiltrated blood may be more

hemolyzed than unprocessed blood, but the

hemoconcen-tration achieved by ultrafilhemoconcen-tration prevents the return of

large amounts of fluids [42] The right choice of method

to return residual blood after ECC seems to have an

im-pact on the red cell mass, the degree of hemodilution,

the extend of coagulopathy, and the patient’s exposure to

allogeneic blood

Monitoring and reversal of anticoagulation

Since inadequate heparinization as well as excessive or

in-sufficient reversal of heparin may cause coagulopathies

and blood loss, anticoagulation calls for close

monitor-ing The individual patient’s response to heparin, is

vari-able A variety of laboratory values and tests are

instru-mental in monitoring anticoagulation Among them are

thrombin time, prothrombin time (PT), activated partial

thromboplastin time (aPTT), activated coagulation time

(ACT), and heparin concentration monitoring as well as

the use of the thrombelastogram However, no single one

of the mentioned tests is able to monitor anticoagulation

reliably The combination of two or more tests seems to

increase the reliability when the clinical picture is added

to the assessment (e.g., ACT and heparin concentration)

Some studies demonstrated a reduced blood product use

when appropriate monitoring techniques were employed

[43]

Appropriate reversal of anticoagulation also contributes

to a reduced blood loss and reduced exposure of the

pa-tient to allogeneic transfusions The preferred antidote forheparin is protamine Protamine is positively charged andbinds to the negatively charged heparin whereby it neu-tralizes the anticoagulant effect of heparin Excess of a pro-tamine, however, also impairs coagulation and reduces theplatelet count Since protamine can cause such abnormal-ities itself, it is beneficial to use only the amount required

to neutralize the heparin To this effect, monitoring ods for anticoagulation were proposed It remains to beseen whether these prove effective to reduce postoperativecoagulopathies and patient’s exposure to allogeneic trans-fusions The best method to avoid undue protamine use

meth-is still the appropriate use of heparin

Problem 7: timing influences blood loss

In some instances, elapsing time causes blood loss If apatient bleeds, immediate intervention to prevent furtherblood loss is mandatory Blood loss likens a bucket with

a hole To keep it filled, you can pour in more fluid (inour case, transfusing blood), or you can fix it by closingthe hole If hemorrhaging patients are not treated imme-diately, blood loss increases All blood loss that can po-tentially be stopped is, strictly speaking, iatrogenic bloodloss

On the other hand, rushing an unprepared patient into

a surgical or medical intervention, although he is not pared for it, may also increase blood loss and may increasehis likelihood to receive allogeneic transfusions

pre-Possible solution: carpe diem

Time is a precious commodity, especially for patients whobleed Achieving timely hemostasis must be of upper-most importance in a blood management program Thisshould be reflected in the way trauma and other surgi-cal and medical teams prepare for bleeding patients Up-to-date algorithms for hemorrhage, appropriate training,trauma drills, and equipment readily available and fullyfunctional contribute to minimize the time that elapsesuntil definite hemostasis is achieved Depending on theseverity of the ongoing blood loss, diagnostic measuresshould be expedited Such rapid treatment of patients notonly reduces blood loss and subsequent transfusion expo-sure, but may even improve survival rates This has beenshown for different kinds of hemorrhage, such as early en-doscopy in gastrointestinal hemorrhage [44] and traumapatients Similarly, patients who develop anemia or coag-ulopathy in a more gradual fashion also benefit from early

recognition and asanguinous treatment of their condition.

This is especially true for patients who develop anemia

while suffering from cardiovascular disease or renal

insuf-ficiency [45] Waiting under “transfusion protection” for

a possible spontaneous resolution of bleeding is futile and

dangerous A “wait and see attitude” definitely does not

have a place in the therapy of an acutely hemorrhaging

patient

In contrast, elapsing time may also be beneficial It

pro-vides a patient with the opportunity to recover from blood

loss Patients who underwent angiography, for instance,

may need surgery If this surgery can be postponed safely

for some days, the time may be sufficient for hematopoiesis

to synthesize blood components lost during the

diagnos-tic procedure [46] Another example where allowing time

may be beneficial is cord clamping after delivery of a baby

Waiting just 30–120 seconds before the cord is clamped

increases the hematocrit of the baby and reduces its

trans-fusion exposure [47] Early cord clamping would result in

blood loss for the baby

The role of iatrogenic blood loss

in blood management

After discussing common sources of iatrogenic blood loss,

you may ask yourself: “Does iatrogenic blood loss really

matter?”, “Does it have an impact on the use of

trans-fusions?”, and “Does avoiding such small and probably

insignificant blood losses enhance patient care, reduce the

patients exposure to allogeneic transfusions, or improve

the outcome?”

Unquestionably, medical personnel cause substantial

blood losses in their patients Among them, phlebotomy is

the most extensively studied example It seems that there is

a substantial overdraw of blood for laboratory testing In

the United States, hospitals caring for adults draw 2.5–10

times more blood for standard laboratory panels than

pe-diatric hospitals [48] A study performed in Great Britain

showed that attempts to reduce the blood loss stemming

from phlebotomy were rare In adult ICUs, only 18.4%

returned the dead space volume and only 9.3% used

pedi-atric tubes In contrast, pedipedi-atric ICUs return their dead

space volume in 67% of cases [49] This demonstrates

that there is still great room for improvement

Diagnos-tic blood loss is a major determinant of anemia in adult

and neonatal ICUs, accounting for substantial amounts

of transfused blood [1, 50] In fact, in the ICU setting,

the total amount of diagnostic blood loss is a

signifi-cant predictor of allogeneic transfusion [28] As shown

above, comprehensive blood management effectively duces phlebotomy-induced blood loss [51, 52] and suchattempts reduce the patient’s exposure to allogeneic trans-fusions [5, 53]

re-Apart from phlebotomy, there are many other itemsunder the control of a medical care team that affect theblood count of a patient In many instances, attention todetail helps to avoid unnecessary blood loss [7, 54, 55].Even if there are not many randomized controlled studiesdemonstrating that attention to every one of the above-mentioned details translates into reduction of transfusionsgiven or in improvement of outcome, it appears that this

is a reasonable recommendation

Key points

rBlood loss occurs directly and indirectly by the work of

medical caregivers, e.g., due to

◦Diagnostic phlebotomy

◦Bed rest

◦Occult gastrointestinal hemorrhage and stress ulcers

◦Invasive monitoring (arterial lines, etc.)

◦Drugs including anticoagulants

◦Extracorporeal circulation

◦Unnecessarily wasting time while the patient bleeds

◦Blunted erythropoiesis due to iatrogenic malnutrition

rIatrogenic blood loss accounts for increased use of

trans-fusions

rIatrogenic blood loss and with it the development

of iatrogenic anemia and coagulopathy can be mized

mini-rWays to minimize iatrogenic blood loss include:

◦Reduction of the frequency of phlebotomy and the ume of blood drawn

vol-◦Return of dead space volume

◦Ulcer prophylaxis

◦Attention to details in diagnostic or therapeutic ventions, including the choice of a skilled practitioner andchoice of a suitable technique

inter-◦Judicious use of drugs, including anticoagulants

◦Adaptation of procedures involving an ECC

◦Expedited hemostasis in all hemorrhaging patients

Questions for review

rWhat can be done to reduce blood loss induced by

phle-botomy?

rWhat diagnostic procedures are available that reduce

iatrogenic blood loss?

rHow can ECC be adapted to minimize blood loss?

rDoes timing play a role in avoiding iatrogenic blood loss?

rHow do sports influence iatrogenic blood loss?

Suggestions for further research

What different methods are available for autologous

retro-grade priming of a cardiopulmonary bypass? (compare:

http://perfline.com/textbook/local/rap/rap.html)

What is the suggested effect of leukocytes in the

devel-opment of coagulopathies after ECCs and how is this

affected by the use of leukocyte filtration during ECC?

How does thrombelastography work and how do the

trac-ings change with changes in amount and functionality

of plasmatic clotting factors, platelets, red cells, and

de-crease in temperature?

Exercises and practice cases

A 65-year-old diabetic man is admitted to the ICU with

a pneumonia and partial respiratory insufficiency His

weight is 70 kg, his height is 170 cm, his initial hematocrit

is 0.34 He is monitored with a central venous catheter and

an arterial line

Use the following information to estimate the blood

loss he suffers during his stay in the ICU

All blood draws are taken from the central line, except

the ones for the blood cultures, which are taken directly

from the vein Before a blood sample is drawn into the

sampling tubes from the central line, 10 mL of the blood

is discarded Before blood is drawn from the arterial line,

5 mL of the blood is discarded The blood tubes used are

the standard tubes in the ICU with the following volumes:

hematology 9 mL, serology 10 mL, coagulation profile

10 mL, blood glucose levels 3 mL, erythrocyte

sedimen-tation rate 2 mL, blood gases 2 mL, blood cultures 10 mL

each for aerobic, anaerobic, and fungal cultures

The order “ICU complete” means complete blood count

with differential, erythrocyte sedimentation rate, blood

glucose level, Quick, aPTT, D-dimer, troponin, C-reactive

protein, sodium, potassium, calcium, chloride, lactate,

liver panel, and kidney panel

The order “ICU small” means complete blood count,

blood glucose level, Quick, aPTT, C-reactive protein,

sodium, potassium, calcium, and chloride

Since the hospital laboratory is small, some blood issent to specialized laboratories One blood sample is sentfor serology of HIV and hepatitis, another sample is sent

to determine the procalcitonin (PCT)

On the first day, intensive diagnosis is made fore, the attending physician orders: “ICU complete,blood cultures now and in 2 hours, blood glucose lev-els×5, PCT, HIV/hepatitis serology, central venous oxy-gen saturation every 6 hours, arterial blood gases every

There-6 hours.”

On the second and on the following days, the attendingphysician orders: “ICU small, blood glucose levels×5,central venous oxygen saturation every 6 hours, arterialblood gases every 6 hours.”

Homework

rPractice giving back the dead space volume when you

draw blood the next time

rCheck the volumes for the blood tubes you currently use.

Implore whether there are alternative tubes with smallervolumes

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13 The physics of hemostasis

Sufficient hemostasis is vital to reduce the number of

al-logeneic transfusions A basic knowledge of the methods

is essential to enable a blood manager to critically

ap-praise the potential value of the various available methods

to prevent or stop surgical or post-trauma hemorrhage

Therefore, this chapter explores some of the physical

methods used during surgery to achieve hemostasis, their

indications, contraindications, and value to reduce blood

loss

Objectives of this chapter

1 Relate the basic principles of surgical cutting and

hemostasis

2 Explore alternatives to a scalpel.

3 Learn about surgical maneuvers to reduce blood loss.

Definitions

Cautery : The word cautery is derived from the Greek word

“causis” meaning “to burn” or the Latin word

“cau-terium” for “searing iron.” Cautery means the act of

co-agulating blood and destroying tissue with a hot iron,

by freezing, or by a caustic agent The term cautery

is also used for the instrument used to perform

cau-terization Electrocautery means cauterization (cutting

or hemostasis) is achieved by bringing an electrically

heated metal instrument into contact with the tissue

Diathermy : The word diathermy is derived from the

Greek “dia” for “through” and “thermos” for “heat.”

Diathermy means the generation of heat in the tissue

by means of electrical current Medical diathermy is

used for the therapeutical heating of tissue Surgical

diathermy (synonymous with electrosurgery) means the

localized heating of tissue for cutting and hemostasis

(electrocoagulation) by absorption of a high-frequency

electric current

Desiccatio : Coagulation resulting in dehydrated cells

Des-iccation is sometimes used synonymously with ration

fulgu-Thermal knife : Refers to any surgical cutting device that

uses heat as the acting physical principle for cutting

Surgical coagulation : The disruption of tissue by physical

means to form an amorphous residuum With respect

to blood vessels, two forms are distinguished:

rObliterative coagulation occurs by direct electrode

contact with or electrical arching to the tissue sel walls shrink and the lumen is occluded by con-tracted tissue and thrombosis It is the best methodfor vessels below 1 mm diameter

Ves-rCoaptive coagulation occurs by mechanically

appos-ing the edges of the vessel with a hemostat or forcepsand current applied to the hemostat The adventitia

of the vessel is destroyed, the muscular layer shrinks,and the intima fuses

A brief look at history

Surgical cutting and attempts to achieve hemostasis arenot new Ayurvedic medicine, which claims to be about

6000 years old, mentions the use of sharp bamboo ters for surgical cutting In early human history, all kinds ofknives were used as scalpels the use of which was not with-out problems Hemorrhage and death occurred as a result

splin-of injury or surgical interventions King Hammurabi splin-ofBabylon (1955–1912 bc) therefore introduced laws thatdealt with surgical cutting Hammurabi’s Code contains

a paragraph dealing with the surgeon who uses a bronzeknife (scalpel) for wound care: “If a physician makes awound and cures a freeman, he shall receive ten pieces ofsilver ( ) However it is decreed that if a physician treats

a patient ‘with a metal knife for a severe wound and hascaused the man to die—his hands shall be cut off ’” (Code

of Hammurabi) [1] This decree puts much emphasis onthe proper use of a scalpel and achieving hemostasis, and

172