Nghiên cứu sự biến đổi một số chỉ số sinh học và tác dụng của điều trị tái tăng áp trong bệnh giảm áp cấp tính thực nghiệm

Effects on clinical symptoms in acute decompression sickness rabbits 83 3.3.2.. Effects of recompression treatment on some biochemical indexes in in acute decompression sickness rabbits

CAO HONG PHUC

RESEARCH ON SOME OF BIOLOGICAL CHANGES AND EFFECTS OF RECOMPRESSION TREAMENT IN

EXPERIMENTAL DECOMPRESSION SICKNESS

MEDICAL DORTOR PHILOSOPHY THESIS

HA NOI-2018

CAO HONG PHUC

RESEARCH ON SOME OF BIOLOGICAL CHANGES AND EFFECTS OF RECOMPRESSION TREAMENT IN

EXPERIMENTAL DECOMPRESSION SICKNESS

Branch: Bio - Medicine Sciense

Code: 972 01 01

MEDICAL DORTOR PHILOSOPHY THESIS

SUPERVISORS:

1 Assoc.Prof Nguyen Tung Linh, PhD

2 Assoc.Prof Dang Quoc Bao, PhD

HA NOI-2018

After years of in-depth research, this thesis has been completed I wouldlike to show my sincerely thanks to the Party Committee, Broad of Directors:Vietnam Military Medical University, Military Hospital No 103, NationalInstitute Of Hygiene And Epidemiology for their facilitation

I would also like to thank: Department of Medicine of Arms, Department

of Medical Physiology, Department of Experimental Operation, Department

of Medical Physics (Vietnam Military Medical University), Departemt ofHematology and Tranfusion, Patho-Histology and Judical Medicine (MilitaryMedical No 103), Laboratory of Micro-Structure (Virus Department, NationalInstitute Of Hygiene And Epidemiology), Department of Post - GraduateTraining for their technical help in my study

In addition, I am completely grateful to my suppervisors: Asscoc.ProfNguyen Tung Linh, PhD (first suppervios), Asscoc.Prof Dang Quoc Bao, PhD(second suppervios) The doors of their offices were always open whenever Iran into a trouble spot about my reseach They consistently allowed this paper

to be my own work, steered me in the right direction in experimental period.They also set good examples for me to follow in doing all scientific tasks.Besides, I would like to express my heartfelt gratitude to my parents andparents - in - law for their bringing up and supporting me to make this workpossible Last but not least, I am deeply indebted to my wife and my son forbeing on my side, encouraging me a lots throughout my years of study

AUTHOR

Cao Hong Phuc

SUBTITLE PAGE

COMMITMENT i

ACKNOWLEGEMEND ii

CONTENT iii

ABBREVIATIONS AND DEFINITIONS viii

LIST OF TABLES xii

LIST OF FIGURES xvi

INTRODUTION 1

CHAPTER 1 OVERVIEW 3

1.1 CLINICAL, INVESTIGATING CHARACTERISTICS OF ACUTE DECOMPRESSION SICKNESS 3 1.1.1 Causes and risk factors 3

1.1.2 Clinical characteristics 7

1.1.3 Investigating characteristics 12

1.1.4 Diagnosis and classification 14

1.1.5 Treatment 16

1.2 INFLUENCES OF THE BUBBLES IN DECOMPRESSION SICKNESS 20 1.2.1 Bubble formation in the decompression sickness 21

1.2.2 Influences of the bubbles in decompression sickness 22

1.3 STUDIES ON ANIMAL MODELS AND BIOLOGICAL

1.3.1 Studies on animal models in decompression sickness 24

1.3.2 Some studies of peripheral blood cell changes in acute decompression sickness 26 1.3.3 Some studies of coagulation changes in decompression sickness 28 1.3.4 Some studies of biochemical changes in acute decompression sickness 30 CHAPTER 2 SUBJECTS AND METHODS 34

2.1 SUBJIECTS 34

2.1.1 Subjects 34

2.1.2 Laboratories 34

2.1.3 Period 35

2.2 METHODS 35

2.2.1 Study design 35

2.2.2 Study Issues 40

2.2.3 Study equipments 40

2.2.4 Research indexes and methods 42

2.2.5 Data Analysis 53

CHAPTER 3 RESULTS 55

3.1 ETABLISHING THE EXPERIMENTAL ACUTE

3.1.1 Influence of some diving factors on acute decompression

sickness 55

3.1.2 Comparision the efficacy of models to cause the

3.2.2 Changes in some of biochemical indexes in acute

decompression sickness rabbits 72

3.2.4 Some of pathohistological characteristics in acute

decompression sickness rabbits 73

3.3 EFFECTS OF RECOMPRESSION TREATMENT IN

3.3.1 Effects on clinical symptoms in acute decompression

sickness rabbits 83

3.3.2 Effects on hematological index in acute decompression

sickness rabbits 85

3.3.3 Effects of recompression treatment on some biochemical

indexes in in acute decompression sickness rabbits 94

4.1.2 Effecting comparison of experimental acute

decompression sickness of models 101

4.2 CHANGES IN SOME HEMATOLOGICAL,

BIOCHEMICAL, AND PATHOHISTOLOGICAL

INDEXES IN EXPERIMENTAL ACUTE

4.2.1 Changes of some hematological indexes in experimental

acute decompression sickness rabbits 104

4.2.2 Platelet activation in experimental acute decompression

sickness 114

4.2.3 Changes of some biochemical indexes in acute

decompression sickness rabbits 118

4.2.4 Changes of pathohistological indexes in experimental

acute decompression sickness rabbit 120

4.3 EFFECTS OF RECOMPRESSION TREATMENT ON

EXPERIMENTAL ACUTE DECOMPRESSION

SICKNESS 123

4.3.1 Effects of recompression treatment on clinical symptoms

in experimental acute decompression sickness rabbits 123

4.3.2 Effects of the recompression treatment on haematological

indexes in acute decompression sickness rabbits 128

4.3.3 Effect of recompression treatment on biochemical indices

in acute decompression sickness rabbit 134

CONCLUSION 137

ABBREVIATIONS AND DEFINITIONS

2 ADP Adenosine diphosphate

Alanine

4 APTT Activated Partial Thời gian thromboplastin

Thromboplastin Time hoạt hóa từng phần

7 AST Aspartate transaminase Enzym chuyển amin

Aspartate

8 ATA Atmospheres Absolute Áp suất khí quyển tuyệt đối

9 ATP Adenosine triphosphate

11 BTG Beta thromboglobulin

13 CPK Creatine phosphokinase

14 CSF Cerebrospinal fluid T-Tau Protein T-Tau trong dịch

Tomography

16 DCS Decompression sickness Bệnh giảm áp

Num Abbre Deffinition Vietnamese Meaning

17 DWI Diffusion Weighted

28 HMWK High Molecular Weight Kininogen khối lượng

29 HRP Horseradish peroxidase

30 HSP 70 Heat Shock Protein 70 Protein sốc nhiệt 70

31 ICAM-1 Intercellular Cell Adhesion Chất liên kết tế bào 1

Num Abbre Deffinition Vietnamese Meaning

35 LDH Lactate dehydrogenase

hemoglobin concentration trung bình hồng cầu

38 MCV Mean corpuscular volume Thể tích trung bình hồng

42 NSE Neuron-Specific Enolase

45 PF4 Platelet Factor 4 Yếu tố 4 tiểu cầu

50 sGPV Soluble Glycoprotein V Glycoprotein V hòa tan

51 T2WI T2 Weighted Image

52 TAT Thrombin-Antithrombin Phức hợp thrombin

53 TNF-α Tumor necrosis factor Yếu tố hoại tử u alpha

alpha

Num Abbre Deffinition Vietnamese Meaning

55 TTR Transthyretin

LIST OF TABLES

2.1 Classification of clinical severity in experimental acute

decompression sickness rabbits 44

2.2 Paralysis classification in acute decompression sickness rabbits 44 2.3 Classification of post-treatment response 44

2.4 Bubble grade in experimental decompression sickness 52

3.1 The rabbit number of decompression sickness with variable bottom time 55

3.2 Clinical severity of rabbits after experiment 56

3.3 The number of death rabbit after experiment with variable bottom time 56

3.4 The rabbit number of decompression sickness with variable ascent rate 57

3.5 Clinical severity of decompression sickness 57

3.6 The number of death rabbits after decompression 58

3.7 The rabbit number of decompression sickness 58

3.8 Clinical severity and consecutive compression 59

3.9 The number of death rabbit and consecutive compression 59

3.10 Influence of some diving factors on decompression sickness 60 3.11 The rate of decompression sickness and survival of rabbits after compressing as four models 61

3.12 Clinical severity of rabbit after compressing as four models 61 3.13 Bubble grade of rabbit after compressing as four models 62

Num Table Page

3.14 Changes in red blood cell count according to clinical

severity in acute decompression sickness 62

3.15 Changes in hemoglobin concentration according to

clinical severity in acute decompression sickness 63

3.16 Changes in hematocrit according to clinical severity

in acute decompression sickness 63

3.17 Changes in MCV, MCH, MCHC according to clinical

severity in acute decompression sickness 64

3.18 Changes in white blood cell count according to clinical

severity in acute decompression sickness 65

3.19 Changes in white blood cell percentage according to

clinical severity in acute decompression sickness 65

3.20 Changes in platelet count according to clinical severity

in acute decompression sickness 66

3.21 Change in MPV according to clinical severity in acute

decompression sickness 67

3.22 PT change according to clinical severity 68 3.23 APTT change according to clinical severity 69 3.24 Plasma fibrinogen concentration according to clinical

severity in acute decompression sickness 71

3.25 Changes in plasma platelet markers between pre and

post acute decompression sickness 71

3.26 Changes in liver enzyme activity 72 3.27 Changes in plasma concentration of ure and creatinin 73 3.28 The rabbit number of bubbles in micro pathohistological

images after acute decompression sickness in 1st phase 78

Num Table Page

3.29 Distribution of rabbits according to bubble grade and

paralysis grade in acute decompression sickness rabbits 80

3.30 Rabbit number of platelet activation after acute

decompression sickness 83

3.31 Changes in clinical symptoms between pre and post

treatment in acute decompression sickness rabbits 83

3.32 Changes in clinical severity between pre and post treatment

in acute decompression sickness rabbits 84

3.33 Treatment responding rabbits according to clinical category

84 3.34 Treatment responding rabbits according to clinical severity 85 3.35 Effects of recompression treatment on red blood

count in acute decompression sickness rabbits 85

3.36 Effects of recompression treatment on hemoglobin

concentration in acute decompression sickness rabbits 86

3.37 Effects of recompression treatment on hematocrit in acute

decompression sickness rabbits 87

3.38 Effects of recompression treatment on MCV, MCH

and MCHC in acute decompression sickness rabbits 87

3.39 Effects of recompression treatment on white blood

count in acute decompression sickness rabbits 88

3.40 Effects of recompression treatment on leukocyte

percentage in acute decompression sickness rabbits89

3.41 Effects of recompression treatment on platelet

count in acute decompression sickness rabbits 91

3.42 Effects of recompression treatment on MPV in acute

decompression sickness rabbits 91

Num Table Page

3.43 Effects of recompression treatment on PT in acute

decompression sickness rabbits 92

3.44 Effects of recompression treatment on APPT in acute

decompression sickness rabbits 93

3.45 Effects of recompression treatment on plasma

concentration of fibrinogen in acute decompression

sickness rabbits 93

3.46 Effects of recompression treatment on liver enzyme

activities in acute decompression sickness rabbits 94

3.47 Effects of recompression treatment on plasma ure

and creatinin concentration in acute decompression

sickness rabbits 95

LIST OF FIGURES

1.1 Cutis mamorata 9

1.2 Nitrogen bubbles in the left atrial chamber 13

1.3 Nitrogen bubble in spinal cord of decompression sickness dog

14 1.4 Liver injury caused by the bubbles 23

1.5 Platelet ultrastructure 27

2.1 Diagram of 1 phase of study st 36

2.2 Diagram of 2 phase of study st 37

2.3 Recompression treatment protocol 39

2.4 Experimental recompression chamber 41

2.5 Gold coating on electromicroscope specimen 53

3.1 The relation between platelet count and survival time post experiment 66

3.2 Change in platelet count between pre and post decompression sickness according to paralysis degree 67

3.3 Relation between PT and survival of rabbits after acute decompression sickness 68

3.4 Relation between PT and platelet count 69

3.5 Relation between APPT and survival time of rabbits 70

3.6 Relation between APTT and platelet count in rabbits after acute decompression sickness 70

3.7 Vessels in normal and acute decompression sickness rabbit 74 3.8 Adominal muscle vessels in normal and acute decompression sickness rabbit 74

3.9 Lumbar branch of vena cava in normal and acute decompression sickness rabbit 75

Num Figure Page

3.10 Mesenteric veins in normal and acute decompression

sickness rabbit 75

3.11 Vena cava in normal and acute decompression 76 3.12 Abdomincal aorta in normal and acute decompression 76 3.13 Bubbles in the blood drained out from the incised organs 77 3.14 Abdominal muscle in acute decompression sickness rabbits 77 3.15 Vein of abdominal muscle in acute decompression sickness

rabbits (HE x100) 77

3.16 Liver tissue in in acute decompression sickness rabbits 78 3.17 Lung tissue in acute decompression sickness rabbits 78 3.18 Kidney cappilary in acute decompression sickness rabbits 78 3.19 Kidney tissue in acute decompression sickness rabbits 78 3.20 Inside heart in acute decompression sickness rabbits 78 3.21 Coronary vessles in acute decompression sickness rabbits 78 3.22 Distribution of clinical severity according to bubble grade

in acute decompression sickness rabbits 80

3.23 Survival time of rabbits and bubble grade in acute

decompression sickness rabbits 81

3.24 Platele shape in normal rabbits 82 3.25 Pseudopods and oblong shape of platelet in acute

decompression sickness rabbits 82

3.26 Platelet deformation and degeneration in acute

decompression sickness rabbits 82

Decompression sickness is a occupational disease of divers, causesnoticeable economic harmfulness, a lot of complication and may cause death.Although patients were treated completely, some worse patients could stillbare seriously outcomes [1]

The number of decompression sickness patients has been a not - smallnumber in occupational disease group According to British Diving Coucil,the death patients were 98 cases in 2010 [2] In Denmark, Svendsen J.C et alrealised that there were 205 decompression sickness patients from 1993 to

2013, average 14 patients/year [3] In Vietnam, Nguyen Van Non et alreported that the rate of decompression sickness was 22% of fisherypopulation in Northern Bay [4] It is clear that decompression sickness should

be put in high consideration

So far, most reseachers presumed that bubble is a mainly factor causingdisorders of this desease [5], [6] Looking at ultrasound images, bubbles wereseen at vein, heart chambers, arteriole, thigh artery [6], [7] When appliedrecompression treatment to minimise the bubbles, it was seen that clinicalsymtomes were improved [8] Therefore they played an importanted role inmachenism of decompession sickness The relation, however, betweenbubbles and risk, severity and prognosis of this desease has not been studied

in detail

In reality, some patients were applied by recompression treatment didnot recover completely [9], [10] Moreover, a small number of patients gotmild improvement by using antiplatetet drugs (the drugs could not decreasebubble grade ) [11] Hence, a part form bubble role, there were otherbiological disorders which contributed to the disease machenism

Some previous studies also found out investigational changes in thisdisease [1], [6], including hematological, biochemical and immunologicalchanges Nevertheless, there was disagreement among these changes and theydeveloped in different trends Their role in decompression sickness was notevaluated fully and the changes in about mentioned factors in treatment periodhave not been described in detail The correlation between those changes andrisk, severity, prognosis as well as their roles in early dignosis ofdecompresion sickness have had unclear points.

Untill now, decompresion sickness studíe in Vietnam have been limited

A few authors studied the proportion of decompression sickness in someareas, others assessed the effect of treatment at shore and in hospital onclinical symtoms [4], [12] There have not been any reseacher who set up theexperimental decompression sickness model in animal And there have notbeen anyone looking deeply into hematological, biochemical,pathohisological changes in acute decompression sickness The study thatsurveys the drug effects have been few bacause there are not thedecompression sickness model in animal

Due to above reasons, we carried out this study “Research on some ofbiological changes and effects of recompression treament in experimentaldecompression sickness” which aims following 3 objectives:

1 Establishing up the decopression sickenss model in animal.

2 Determining some of hematological, biochemical, pathohistological changes in experimental decompresion sickness.

3 Evaluating the effects of recompression treatment in experimental decompression sickness.

CHAPTER 1 OVERVIEW

1.1 CLINICAL, INVESTIGATING CHARACTERISTICS OF ACUTE DECOMPRESSION SICKNESS

1.1.1 Causes and risk factors

* Rate of decompression sickness

Decompression sickness is an occupational disease of divers and personsworking in environments with variable pressure, which is shown by thesymptom of pathological disorders, caused by a rapid drop in pressureresulting in excessive satuproportionn of inert gas in the body, formingbubbles in the blood and in the tissues of organs [5], [13]

Clinically, decompression sickness is divided into 2 types: acute andchronic type [1], [13] Acute decompression sickness has symptoms which isdirectly related to a rapid drop in pressure occuring within 24 hours after thetime of drop in pressure [13] Chronic decompression sickness occurs later,normally from several months to several years, because of micro bubblesformed in a long time or unthorough treatment in the acute stage [13].Chronic decompression sickness includes 2 categories: primary category andsecondary category, in which primary category often causes injuries ofavascular necrosis at the head of long bones, and secondary category oftencauses injuries in spinal marrow and inner ear [13]

Decompression sickness usually occurs in fishermen who dive to catchaquatic species, professional divers, unprofessional divers, and submarinesailors in the process of escape The disease can also be found in aviation and

is often referred to as high-altitude decompression illness which only occurswith a small proportion

Decompression sickness has many different names: the bends,decompression illness, Caisson disease In Vietnam, nowadays it is known asdecompression sickness [1].

Gempp E et al showed that about 13% of catastrophes at sea in France iscaused by decompression sickness [14] Dardeau M.R et al found there were33/95 cases of decompression sickness injury from diving catastrophes inNorth America [15] Svendsen J.C et al indicated that there were 205 patientsengaged in decompression sickness from 1999 to 2013 in Denmark, averagely

14 patients/year [3] Among potentially fatal disease groups, decompressionsickness falls on the group of average risk [16]

In Vietnam, Pham Huy Nang et al showed that decompression sickness

in the North was 49.64% of total civil diving catastrophes [12] Nguyen VanNon et al reported the rate of patients engaged in decompression sickness inthe Gulf of Tonkin was 22% of total diving fishary men [4] Phung Thi Thanh

Tu et al showed that the proportion of persons engaged in diving catastrophesamong fishermen of Khanh Hoa was 78.8%, and the rate of fishermenengaged in polio (mainly caused by acute decompression sickness) was 5.3%(21 persons) [17]

Therefore, the quantity of patients engaged in decompression sickness isstill significant, appearing in a lot of places in the world, including Vietnam

* Causes

Decompression sickness is caused by rapid drop in pressure in the procss

of diving or during the dive or the airplane cockpit uncovered while flying[1], [5], [6]

* Risk and mitigating factors

- Risk factors:

+ Non-compliance with diving steps in the process of diving and

working underwater [1]

+ Movement intensity: The more movement intensity at the bottom is, the higher decompression sickness risk is [1].

+ Temperature of water environment: The higher the water temperature

is, the higher decompression sickness risk is [1] The water surfacetemperature is less than 100C, the decompression sickness risk is high

+ Components of breathing gas: The higher the nitrogen proportion is,the higher decompression sickness risk Connolly D.M et al find if thebreathing gas contains 21% nitrogen proportion (21% N2, 75% O2, 4% Ar),the decompression sickness risk is lower than gas mixtures with a nitrogen proportion 42% (42% N2, 56% O2, 2% Ar) [18]

+ Age: The older the person was, the higher decompression sickness riskwas and the less recovery from disease was [1] The experimental data byBuzzacott P et al on rats showed that the proportion of 13 week-old ratsengaged in decompression sickness (70%) was higher than the proportion of

11 week-old rats (18%) [19]

+ Mannitol: The consumption of mannitol increases decompressionsickness risk The study by Maistre S et al shows that the proportion ofdecompression sickness on rats increases from 40% for rats fed with normalfood to 80% for rats fed with mannitol [20]

+ Movement after diving: Movement after diving increaseddecompression sickness risk Madden D et al assumed that movement afterdiving increased the bubble risk of pulse and increases decompressionsickness risk [21]

+ Disease genes: Some genes related to decompression sickness such asthyroid hormone regulatory genes and production of TNF-α necrotic factors.Liu X et al found that spinal cord decompression sickness contained 2/9expression genes as thyroid hormone regulatory genes and TNF-α necrotic

factors; 2/7 expression reducing genes was the acyl-coA gene and membrane potential protein [22].

+ High-intensity sounds: High-intensity sounds (204dB, 8kHz) causesdecompression sickness risk and a mortality rate higher than moderate-intensity sounds or merely repeated sounds [23]

+ Atrial septal defect: Causes the increase of decompression sicknessrisk Furthermore, the size of atrial septal defect at 10mm or more can result

in the increase of decompression sickness severity [24], [25]

+ Obesity: increases decompression sickness risk [1]

+ Dehydration: Increases decompression sickness risk, especially

dehydration over 24 hours [1]

+ Alcohol: Drinking alcohol just before diving increases decompressionsickness risk [1] However, Buzzacott P et al found chronic alcoholism mightnot cause decompression sickness risk [26]

+ Repetitive diving in many times within 24 hours increases

decompression sickness risk [1]

+ Other factors: coming to the surface in many times, spinal cordsurgery, former patients engaged in decompression sickness increasedecompression sickness risk [1]

- Reductive factors:

+ Thermal contact: Thermal contact within 30 minutes (dry sauna)before diving may mitigate bubble level and reduce decompression sicknessrisk [27]

+ Whole-body vibration: Whole-body vibration at a frequency of 40Hz within 30 minutes before diving reduces bubble level, the quantity ofcellular debris, decompression sickness risk [28]

35-+ Movement before diving: reduces decompression sickness risk.Madden explained that movement before diving reduces the quantity ofbubbles in the veins, the quantity of cellular debris and increases theelimination of cellular debris [21].

+ Breathing with high pressure oxygen: Ni X.X et al said that breathingwith high pressure oxygen reduced decompression sickness risk, fatal risk anddecompression sickness severity The mechanism is assumed as an increase inprotein concentration against thermal stress on HSP 70 [29]

1.1.2 Clinical characteristics

Acute decompression sickness includes a lot of different symptoms Theappearance of symptoms depends on dive depth, time at the bottom, speed ofmoving to the surface and severity of decompression sickness

- Joint symptoms: the most common symptom of decompression

sickness [8], with high frequency of appearance and the first symptom of the

disease Based on the statistical data of Durham, among the total of 566 casesengaged in acute decompression sickness, there was 78.4% cases engaged inpain on muscles, bones and joints, about 33.9% cases engaged in painsymptom as a first symptom

Pain on muscles, bones and joints usually occurs very early, within thefirst 3 hours after diving In some cases, the symptom occurs within 10-15h.Pain on muscles, bones and joints usually occurs at knees, shoulders, wrists,ankles, elbows, thighs, legs, arms, forearms [8] Patients may be engaged inpain at one joint or one muscle, or at many joints and many muscles The pain

is unexpected, sudden, continuous, and movable Normally, its level ismoderate and severe, rarely mild It is difficult for a patient to identifywhether the pain is at the joint or at the muscle [8] The patients have samepain relief postures: such as raising hands [8] The pain symptoms oftenappears in patients with previous fracture and healed bone, injuries on skin,muscle and healed scar

The cause of pain on muscles, bones and joints is the appearance ofbubbles in the intercellular space and in the veins The bubbles in theintercellular space block the sympathetic nervous system Simultaneously, thebubbles in the veins form capillary which block the blood vessel nourishingthe injuried area The lack of nourishing blood, the sympathetic nervoussystem is blocked causing pain.

Pain symptoms on muscles, joints as above are only a sign of milddisease However, in the case the symptom occurs at other positions such asbelly, chest, between spine and ribs, between the ribs and breastbone or hipbone, it may be a sign of severe decompression sickness [8]

In addition to the pain symptoms on muscles, bones, joints in case ofdecompression sickness, it is found there is a knee joint crepitus The jointcrepitus usually occurs together with the symptoms of joint pain, rarely alone,

it is considered as a sign of pain on muscles, bones, joints related todecompression sickness

The joint crepitus is caused by the appearance of bubbles in the joint and

in the intercellular space Bubbles in the joint cause dry joint Bubbles in theintercellular space block arterioles nourishing joints, reduce the joint’ssynovial fluid, so there is feeling something stuck at the joint and a jointcrepitus

- Cutaneous symptoms: include skin pruritus, color skin eruption, swell

and pain on bubo Skin pruritus is uncommon with a low appearance Skinpruritus is found to only appear on 4.4-8.3% patients engaged in acutedecompression sickness (cited from [1]) And among the patients engaged inskin pruritus, only about 0.7 - 2.7% patients have the symptom as a firstsymptoms [1], [8]

Skin pruritus: the symptom usually appears on shoulders, chest andknees; rarely on the whole body; the symptom is mild in a short time without

any complications [8] Normally, most patients engaged in pruritus are thepersons engaged in mild decompression sickness However, in some cases,patients engaged in combined skin pruritus may be in more severe situation:such as skin pruritus combined with nerve pain, functional disorder of spinalcord, the disease may be more severe It is found that about 8-10% patientsengaged in skin pruritus which appears as a combined symptom [1] Skinpruritus is detected by asking the patients and by signs on the body: scratches,ooze blood, dry blood scab.

The cause of skin pruritus is explained that the bubbles in theintercellular space block sweat gland, oil-gland, ends of the cord in skin,which causes skin pruritus [1]

Figure 1.1 Cutis mamorata

in decompression sickness patients

*Source: Edmonds C (2002) [6]

In addition to skin eruption, cutis mamorata may occur on patients (figure1.1): with unfixed shapes; different sizes; it is flat, not puffed with belly; blue

or dark red; It usually appears at the chest, shoulders, neck, thighs, abdomen[1], [8] Some authors expressed that skin eruption may also be a sign ofinjury of brain stem nervous system, a sign of severe disease [30], [31].

- Digestive symptoms: include adominal pain, peritonitis reaction,

nausea, vomiting and diarrhoea Nausea and vomiting are two symptoms inthe digestive tract but not common causes to injuries of the organ but causesfrom injuries from other organs such as vestibular injury

The most common digestive symptoms are adominal pain, peritonitisreaction and diarrhea Digestive symptoms are not common symptoms, theyoften occur in the moderate to severe cases of disease Characteristics ofabdominal pain related to decompression are severe pains, hard abdominalwall, increasing abdominal reactions, sometimes accompanied by vomitingand diarrhea [1]

Adominal pain is caused by bubbles in the leiomyosarcoma blood vesselwhich block the circulation of blood vessel causing the increase in bowelmovement Therefore, severe bellyaches occur on patients [1] In some cases,

it is believed that the origin of bellyache is a combination of thrombosis bybubbles and internal bleeding of abdominal space [6] The evidence is thatpeople found the appreance of blood in abdominal cavity in the analysisprocess of dead body related to decompression sickness [6]

- Respiratory symptoms: include chest pain, hard breathing, respiratory

frequency disorder, breathing with fine crackle, coarse crackle and the patientmay be suffred from the suspension of breathing [1], [8] Normally,respiratory symptoms is a sign of severe disease

Normally, the appearance of respiratory symptoms is not much Mostrespiratory symptoms only occur in severe cases of decompression sickness.Commonly, chest pain, if any, is the pain on both rib sides and lower chest,and increasing pain in case of deep breathing [8] In addition to the chest pain,

patient has symptoms of hard, shallow breathing, rapid, short breathing,stimulation coughing, blood coughing , coarse and fine rales [1], [8].Normally, in the first stage, it is stimulation coughing, but in the later stage,when the block of pulmonary circulation system is more severe, the patientsuffers from short breathing or blood cough [1] Suspension of breathing isthe most severe respiratory symptom Suspension of breathing leads to death.Even patients may die before emergency measures are applied [1].

There are two causes resulting in suspension of breathing: Firstly, thebubbles block the central blood vessels of the respiratory tract resulting insuspension of breathing Secondly, the bubbles in the lungs block thepulmonary pulmonary, the pulmonary venule, and the pulmonary capillarysystem resulting in the blood lack for the air change of lung If there are about10% the quantity of bloked pulmonary capillary, the respiratory symptomswill appear typically [6]

- Cardiovascular symptoms: include symptoms such as left chest pain,

fast heart rate, hypotension, acute cardiac failure, ischemic heart disease andmyocardial infarction [1] Cardiovascular symptoms usually occur in patientsengaged in severe diseases

- Vestibular symptoms include symptoms such as nausea, vomiting;

feeling dizzy; tinnitus or deaf in one ear (Meniere syndrome) [1], [8].Accompanied symptoms such as autonomic nervous system disorders: paleskin, sweating, tremor The vestibular severity is determined by a clinicalseverity [32] The vestibular secompression sickness risk is breathing withadmixtire with heli and atrial septal defect [33]

- Neurological, mental symptoms: include movement disorders, sensory

disorders, orbicularis disorders, language disorders, and mental disorders [1],[8] Movement disorders of secompression sickness is paralysis Paralysis may

be caused by spinal cord injuries or brain injuries, the patient may be engaged

in the paralysi of two below limbs, hemiplegia or paralysis of one limb [1],[8], [34] Sensory disorders of secompression sickness is numbe skin onsense, sometimes, patients fell numb, paraesthesiae or pained [8] Mentaldisorder, if any, usually is the change of mental status, the change ofpersonality, forgetfulness, the appearance of odd acts [8]

1.1.3 Investigating characteristics

* Changes in peripheral blood cells

Some authors found that there ứa a phenomenon of decrease in thenumber of erythrocytes in decompression sickness, while few authors realisedthat the number of red blood cells increased (indirectly via hematocrit) [6],[35] Several studies showed increased erythrocyte sedimentation rate,erythrocyte shape abnormalities [6], [8] In addition, some researchers foundthat there is an increase in number of leukocytes, activation of leukocytes inpatients with decompression sickness [36] Few other studies showed thatthere was a decrease in the number of platelets [37]

* Changes in biochemistry and immunology

There is an increase in concentrations of catecholamines, cortisolisoenzym, free fatty acids, magnesium, plasma cholesterol, LDH enzymeactivity degree, CPK, AST (AST), ALT (ALT); a decrease in concentration ofserum sodium, plasma lactate in decompression illness There is also anincrease in concentration of cytokines, especially IL-6, the complementsystem and kinin in decompression illness [6]

* Changes in coagulation

Several authors found that phenomenon of increased fibrin and reducedfibrinogen in decompression illness [6] Several reports also record theprolonged PT, TT and APTT [38], [39]

* Changes in imaging diagnosis

Images of nitrogen bubbles in the blood vessels and chambers of theheart in Doppler or 2D ultrasound results (figure 1.2) [7] Placement of theultrasound probe is tip of the heart, the carotid artery, the femoral artery orthrough the esophagus [40], [41]

There are some images of lesions in the brain and spinal cord in thecomputerized tomography or magnetic resonance imaging film [42] Hadanny

A et al The report on late lesions to the blood-brain barrier in the magneticresonance imaging film [43] Guangkai G et al., Matsuo R et al indicatedthat there was an increase on T2WI, DWI films in positions: spinal cord graymatter, frontal lobe, hippocampus, brain, cerebral hemisphere shell, parietal -temporal [44], [45]

Figure 1.2 Nitrogen bubbles in the left atrial chamber

A B Figure 1.3 Nitrogen bubble in spinal cord of decompression sickness dog

A: normal spinal cord B: Spinal cord with nitrogen bubbles

inside (red arrow)

* Source: cited from Lê Văn Nghị (2005) [1]

1.1.4 Diagnosis and classification

* Definitive diagnosis

Definitive diagnosis of decompression illness is based on the following criteria [1]:

- Diving depth ≥ 10m

- Diving time ≥ 30 minutes

- One of the symptoms: joint pain, itching, breathlessness, nausea,vomiting, chest pain, dizziness, blurred vision, numbness, paresthesia,paralysis, shock

- Time of symptom: while rising up and/or within 24 hours from the end

of the dive

- Dive by air or mixtures with inert gas

- Fast speed rising, not following the depression mode when diving

* Differential diagnosis

Decompression sickness is diagnosed differently from the following diseases [1]:

+ Nitrogen shock: ≥ appears at a depth of 50m, during diving and/or working at the bottom.

+ Lung trauma due to pressure: Commonly occurred at shallow depth, the more shallow diving, the more probability it is

* Classification of decompression sickness

- Classification according to clinical symptoms (in England, France, USA)

 Neurological type: brain and spinal cord symptoms

 Inner ear type: vestibular symptoms.

 Cardiopulmonary arrest type: symptoms of lung cardiogenic shock.

- Classification by clinical symptoms (Iakovson, Russia) [1]:

+ Mild: lesions on the skin and musculoskeletal joint (joint pain, itchyskin)

+ Moderate: lesions on the digestive system, vestibular, visual

+ Severe: lesions on the nervous system, respiratory and circulatory.+ Lethal: symptoms of pulmonary cardiogenic shock

- Classification by degree of nitrogen bubbles on Doppler (Spencer) [1 ], [6]: + Degree 0: no nitrogen bubble signal on Doppler.

+ Degree I: irregular nitrogen bubble, often in breaking stage of heart.+ Degree II: lot of nitrogen bubbles, less than 50% of the cardiac cycle.+ Degree III: lot of nitrogen bubbles, in all of the cardiac cycles

+ Degree IV: lot of big nitrogen bubbles, constantly in the cardiaccycles, causing overcrowding in the heart

1.1.5 Treatment

* Emergency

Emergency measures include:

- Place the patient on a flat surface: In the past, it is said that the patient

should be placed in the Trendelenburg position (head low position) inemergency, however, this position does not improve treatment efficacy.Appropriate posture is that placing the patient on a flat surface, the legshorizontally [42]

- Oxygen breath: Breathing by pure oxygen or oxygen-rich air mixture

should be conducted as soon as possible to enhance oxygen conveying,increase the exhaust of nitrogen from the body [11], [46] If oxygen breathinglasts over 4 hours, it should be applied periodically "25- 5" cycle: oxygenbreathing in 25 minutes, breathing air in 5 minutes [8]

- Infusion: Infusion is to improve clinical status [11] Selected infusion

included: 5% glucose, Ringer lactate, Dextran The total volume of glucose5% and Ringer Lactate is 1000ml/24 hours for each Much infusion shouldnot be applied because the infusion process can cause cerebral edema andpulmonary edema by the phenomenon of increased vascular permeability indecompression sickness [42]

- Emergency repetitive dive: a method for repetitive dive for patients in

the field (river, sea or hydropower reservoir) Patients need to reach theindication for repetitive dive Repetitive dive should be conducted in 1 of 2ways using common air and oxygen-rich air [8]

+ Repetitive dive procedure using common air: Applying diving depth and time according to the US Navy's 1A treatment table (Appendix 4)

+ Repetitive dive procedure using oxygen-rich air: using divingequipment with hooded mask; diving to a depth of 30 feet (equivalent to adepth of 9 meters), maintaining 60 minutes with decompression patient of

Type I and 90 minutes with decompression patient of Type II; if symptomsstill persist, patient should rise up at the stop station of 20 feet (equivalent to adepth of 6 meters) stop for 60 minutes; the stop station of 10 feet (equivalent

to a depth of 3 meters) stop for 60 minutes; then rise up from the water Afterrising, the patient continues to breathe oxygen for 3 hours continuously [8].Emergency repetitive dive is likely to improve clinical symptoms.Blatteau et al found that out of total 24 patients provided emergency service

by repetitive dive, 19/24 patients (79%) recovered completely, only 5/24patients (21%) recovered incompletely [47] If there is a booster chamber,booster treatment on site should be done as the efficiency will be higher thanthe treatment in hospitals [48]

* Recompression treatment

There are two therapy methods of re-pressurization: using common airand using oxygen-rich air [8]

- Recompression treatment using air: Application of 1A, 2A, 3 and 4

therapy tables of the US Navy [8] (appendix 4)

+ Table 1A is applied when pain is improved from 0-66 feet in depth (or depth 0-20 meters)

+ Table 2A is applied when table 1A is applied but the pain is not

relieved

+ Table 3 is applied in cases with severe symptoms without oxygen-richair for treatment If symptom is improved within 30 minutes at a depth of 165feet (equivalent to 50 meters), go on the treatment according to this table.+ Table 4 is applied as a substitute for Table 3 when therapy of Table 3

is applied for 30 minutes, but the pain is not relieved [8]

- Recompression treatment using oxygen-rich air: Apply the therapy of

tables 5, 6, 6A and 7 of the US Navy [8] (appendix 4)

+ Table 5 is applied to decompression patients of type I without hives on the skin

+ Table 6 is indicated for patients: decompression patients of type I withhives on the skin; decompression patients of type I with severe symptoms,symptom is not relieved after 10 minutes of treatment on the lower therapytable; decompression patients of type II and clogged arteries caused bynitrogen bubbles.

+ Table 6A is indicated in the following cases: decompression patients

of type I but symptom is not relieved after 20 minutes of treatment at thelower therapy table; and clogged arteries caused by nitrogen bubbles

+ Table 7 is indicated in the following cases: severely clogged arteriescaused by nitrogen bubbles; decompression sickness threatens the life withoutresponding to the common therapy tables [8]

Re-compression therapy using oxygen will reduce symptoms morerapidly, reducing the incidence of disease, especially in neurologicaldecompression sickness [49], increasing the partial pressure of oxygen in alltissues [50] Geng M Et al [51], Arieli R Et al [52] demonstrated that re-compression therapy using oxygen reduces pulmonary lesions and reduces thenumber of nitrogen bubbles in the veins

* Other treatments

- Oxygen breathing: indicated when re-compression therapy is notapplied (specific treatment) [8], [52] The breathing rate is 15 liters/minute Ifcontinuous breathing for more than 4 hours, the periodical "25 - 5" cycleshould be applied [9]

- Infusion: indicated for all decompression patients Infusion reducesblood viscosity, increases the oxygen conveyability to tissues, rebalanceelectrolytes [8], [42]

- Corticosteroid: should be careful prescription when being used [8],[42] Corticosteroid is effective in anti-inflammatory, spreading inflammatoryreaction prevention But Corticosteroid can exacerbate the situation ofsecondary infection later If being indicated, hydrocortisol at doses of 1-2

grams/24 hours is preferred to be used [42], prednisone of 80mg/24 hours by oral way; dexamethasone 10mg/24 hours by intravenous way [8].

- Non-steroid: should be carefully weighed when being used [8], [42].This drug is indicated in cases of symptoms of arthralgia or neuropathy.Ketoprofen is preferred to be used to prevent pains

Some studies showed that blood clotting time was long in decompression sickness Anticoagulants can exacerbate this disorder If being indicated, low molecular

- Anti-platelet drug: should be carefully weighed when being used [8],[42] Aspirin is preferred to be used, this drug should be used early (beforediving or within 24 hours from the time of rising up from water), dose of 500mg/24 hours [42]; abciximab is effective in prevention, using before divingcan reduce incidence and lethal rate caused by decompression sickness [53]

- Lidocaine: should be carefully considered when being used [8], [11],[42] Lidocaine may be effective in decompression patients without aeremia.this drug is effective in: resisting rapid sinus rhythm, atrial fibrillation andseizures [8] The mechanism of action is said that lidocaine reduces nerve cellmetabolism, stabilizes cell membrane, resists hypertensive rhythm and resistsinflammation [54])

- Anticonvulsants: effective in resisting seizures occurring on the patientswith shock or nitrogen bubble lesion in the brain But the drug can causecomplications or severe respiratory disorders than respiratory arrest [8], [42]

- Simvastatin: prophylactic effects that reduce the incidence of diseaseand relieve the sickness [55] The mechanism is said that Simvastatin helpsreducing the risk of forming nitrogen bubbles in veins and reduces activation

of inflammation factors

- Vitamin C: dose of 2grs/day, 6 continuous days before diving reducesthe activation of leukocytes and decreases number of cell fragments afterdecompression [56].

- Fluoxetine: dose of 50mg/kg before diving 18 hours reduces incidence

of sickness, increases survival rate and prevents depletion of platelets, reducesIL-6 concentration [57] This effect of fluoxetine is enhanced when beingused in conjunction with new generation antidepressant - spadin [58]

- NO releasing drugs: glycerol trinitrate, isosorbide-5-mononitrate areeffective in prevention of decompression sickness The mechanism is said thatthe drugs help reducing endothelial cell lesions [59]

- Perfluorocarbon: relieves sickness, especially for the spinal cord whenPerfluorocarbon used with oxygen is able to reduce the incidence of abnormalspinal cord electric wave [60] The mechanism is said that perfluorocarbon isable to re-dissolve nitrogen bubbles and convey it to the lungs faster (citedfrom [61])

- Ecsin: effective in reducing the incidence and lethal rates, prolongingthe life for patients with decompression sickness The mechanism is said thatecsin is effective in anti-inflammation and protect the endothelium [62]

1.2 INFLUENCES OF THE BUBBLES IN DECOMPRESSION

SICKNESS

Up to now, the bubble has been considered to be the cause ofpathological disorders in decompression sickness [5], [63] The bubbles affectthe elements of blood, blood vessel wall and the tissue, leading to secondaryphysiological disorders The specific treatment for decompression sicknessmainly affects the bubble

1.2.1 Bubble formation in the decompression sickness

* Evidence of the bubbles in decompression sickness

There is evidence of the bubbles presence in decompression sickness [1],[6]. The classic experiments of Boyle (1670), Giovani (1769), Hoppe-Seyler(1857) have shown the existence of the bubbles in the tissue (according to [1]).Bousuges, A., et al have found that there are the bubbles in the left atrium, rightatrium, cerebral blood vessels and blood vessel of the lower limb [64] BloggS.L et al used 2D ultrasound to detect the bubbles in the left ventricle and leftatrium [40] L'Abbate A et al detected the bubbles in the portal gaps of the liverand in the liver cells [65] The study of Quiros Y.B et al showed the presence ofthe bubbles in the blood vessels, mesentery, bladder [66], [67]

* The positions of the bubbles

There are four basic formation positions of the bubbles: the veins,

arteries, tissues and cells

- The intravenous bubble is the bubble that are formed and move in thevein The intravenous bubble is formed by three mechanisms: self-forming inthe vein; merge of nearby intravenous bubbles; liberation from the tissue [6]

- The arterial bubble is the bubble that are formed and move in thearteries The bubble in the arteries is formed primarily from the automation ofthe intravenous bubbles [8]

- The tissue bubble is the bubble that are formed in the tissues Thebubble in the tissue is usually present in the spinal cord, adipose tissues andtissues around the arteries [8]

- The bubble in the cell is the bubble that are formed in the cell, for example: in the liver cells [65]

* Mechanism of bubble formation

The bubble is formed by the saturation mechanism of Haldane [1], [6] When diving, the pressure of the external environment increases, which