Out of the Decompression Matrix

About the Author 14 Foreword 15 Preface 16 My Thanks 18 References - General 19 Chapter 1 - In the Beginning 23 Introduction 23 Early Equipment 23 Rebreathers 27 Human Torpedoes and Clammy Death 27 Decompression Illness (The Bends) 29 Gases other than Air 30 Modern Recreational Diving 31 Decanting Air 32 CMAS 33 Modern Diving Gear 33 DeeP Diving and Accelerated Decompression a Step Change - in Hindsight 35 Nitrox 41 Saturation Diving 41 Finally 42 A Brief Backward Glance 43 Chapter 2 - I Did Nothing Wrong, So It Can't Be Decompression Illness! 45 Introduction 45 DCI Workshop 45 Unearned DCI 46 The Common Problem 49 Contents 4 The Take Home Message 50 Update 50 And Finally - Diving is a Relatively Safe Sport 50 Chapter 3 - Traditional Decompression 53 Introduction 53 Traditional Decompression Theory 57 1. The Uptake and Elimination of Gas by a Tissue takes the Exponential Form 58 2. The Rate of Saturation Varies from Tissue to Tissue 60 3. The Gas Tension in any Tissue Should Never Exceed Approximately Twice the Ambient Pressure. 63 4. Decompression Should be Initiated by a Relatively Large Drop in Ambient Pressure 64 M-Values (Maximum values) 67 Tissue Compartment Critical Tolerances 69 Rounding up the 2:1 Ratio, M-Values and CTs 73 Short Bottom Times and Multiple Ascents 74 Reverse Dive Profiles 75 Beyond Haldane 75 Chapter 4 - Physiology and Gas Movement Part 1 - General 77 Introduction 77 Gas Movement 77 The Oxygen Window 78 Tissue Compartment Tension Tolerances - Supersaturation 81 Analogies 83 Tissue Compartment Half-Times 84 The Lymphatic System 86 Micro-Bubbles 87 Other Major Aspects 89 i. Carbon Dioxide (CO2) 89 ii. Eye Damage in Divers 89 Out of the Decompression Matrix 5 iii. Temperature 90 iv. Dehydration 91 v. Alcohol and Diving 91 vi. Anxiety 91 vii. Biochemistry 91 viii. Smoking and Gas Exchange 92 Conclusion 93 Chapter 5 - Physiology and Gas Movement Part 2 - Shunts 95 Introduction 95 Background 95 PFO, to Dive or not to Dive? Introduction 96 PFOs may be Dynamic 100 Putting PFOs and Diving in Perspective 100 How can you tell if you have a PFO? 100 Testing for a PFO 102 PFO Closure (Transcatheter Closure of an Atrial Septal defect) 102 Consider the Options 103 Diver Behaviour 103 Arteriovenous Malformation or AVM, an Overview 103 Lung Shunts - Pulmonary Arteriovenous Malformations (PAVMs) 103 Common Issues 104 Furthermore 104 The Take Home Message 105 Finally 106 Comments From a Highly Experienced Cardiologists/Diver 107 Pacemakers, Warfarin and Diving 107 Chapter 6 - Women and Decompression 109 Introduction 109 Physiology 109 The Menstrual Cycle 110 Contents 6 The Oral Contraceptive Pill (OCP) 110 Breast Implants 110 Breast Swelling and Soreness after Diving 111 Decompression Illness and the Menstrual Cycle 111 DCI Susceptibility - Men vs Women 112 Pregnancy and Diving 113 Recommendations 114 Diving after Childbirth 114 Chapter 7 - DCI Avoidance Strategies 115 Introduction 115 Workload 117 Surface Air Consumption (SAC) Rate Assessment 119 Dive Planning 119 Pre-dive and Post-dive Exercise 121 Temperature 122 Pre-dive Cooling 122 Dive Assessment/Planning 123 Post-dive Cooling 125 Post-dive Sunbathing/Hot Showers, etc 125 Micro-bubbles {MBs} (free-gas) 126 Diver Behaviour 127 Saw-tooth and Yo-yo Dive Profiles 129 Dive Depth Sequence 129 Prevention is Better than Cure 130 Where did the Deep-Stop Concept Come From? 134 Ascent Training 135 Other Factors Beyond the Tables and PDCs 135 CO2 Retention 135 Dehydration 136 Flying Before Diving 137 Out of the Decompression Matrix 7 Alcohol and Diving 138 Smoking and Diving 138 Diving with or after a Cold 138 Ear Clearing 139 Seasickness 139 Diarrhoea 139 Blood Donation 140 Eating After Diving 140 Medication (drugs) 140 Illegal Drugs (IDs) DCI Risk and Diving 141 Stress 141 Obesity 142 Cracking Joints (Tribonucleation) 142 Take Home Message 142 Chapter 8 - Personal Decompression Computers (PDCs) 143 Background 143 The Big Shake-up 145 An Overview of PDCs 146 Current Developments 148 Rate of Descent 149 Bottom Time 149 Yo-yo and Saw-tooth Dive Profiles 150 Skin Cooling 151 Work-rate 151 Ascent Rates 152 Surface Intervals (SI) {or Zero-metre Decompression Stop} 154 Choosing a PDC 154 Dive Logs 155 Pre-dive Check-list 156 What Style of PDC? 156 Contents 8 Chapter 9 - Multi-level PDC Assisted Diving 157 Nearer the Limit 157 Stage-Stop Diving is Akin to Cave Diving! 158 Leading Tissue Compartments 158 Air/Gas Planning 160 Saw-tooth Dive Profiles 160 Yo-yo Dive Profiles 161 Dive Depth Sequence 162 Multi-level versus Square Profile Diving 162 The Awakening 163 Dive Planning & PDCs 165 Keep in Mind 166 PDCs and Holiday Travel 166 Chapter 10 - An Introduction to some Other Decompression Systems 167 Introduction 167 Nitrox 167 Other Breathing Mixtures 170 Heliox 172 Isobaric Counter-Diffusion (ICD) - A Simplistic View 173 Trimix and Heliair 176 The Run-Time System 178 Personal Decompression Computers (PDCs) 179 Rebreathers 179 Semi-closed Circuit Rebreathers (SCRs) 180 Caution Required 182 Using a PDC 183 Closed Circuit Rebreathers (CCR) 183 Take Time for a Long Hard Think 185 Adjusting Critical Tolerances/M-values - Gradient Factors 186 Important Notice 187 Out of the Decompression Matrix 9 Chapter 11 - Buoyancy and Ascent Management 189 Background 189 Introduction 189 Ideal Buoyancy 190 Air Spaces - In the Body 190 Air Spaces - Equipment 190 Dry Suit Inflation 191 Cold Water Freeze Ups 191 Gas Consumption and Buoyancy 192 Static Weighting 192 Swimming Trim Attitude (STA) 196 Holiday Adjustments 196 Buoyancy Compensation 197 Ascent Management 197 Forced Fast Ascent - Faulty BCD/Dry Suit Valves 198 Poor Kit Configuration 198 What Causes BCD and Dry Suit Valves to Malfunction? 199 Inflator Routine (between dives) User Maintenance 199 Blue Water Diving Holidays 200 Dry Suit Auto-dump Valves 200 Cuff Dump Valves (manual) 200 BCD Dump Valves 200 BCD Pressure Relief Valves 201 Pre-dive Double Check 201 General 201 Dealing with Positive Buoyancy 202 Finally - Tethered Ascent (TA) 202 The Tethered Ascent - Self-rescue Method 203 Line Recovery 204 The Take Home Message 205 Contents 10 Chapter 12 - Got Enough Gas for the Job at Hand? 207 Introduction 207 The Cheap and Simple Look-up Air Table System 209 Worked Example 209 Assessing Your Own Air Consumption Rate Per Minute 211 Using the Air Estimating Table 213 Being Prepared 214 Rule of Thirds 214 Have you got Enough Emergency Gas? 216 Modern Technology 216 Single Point Failure 217 Plan with a Friend 218 Conclusion 218 Chapter 13 - Risk Assessment, why Bother? 219 Introduction 219 What is Risk Assessment? 220 How to Assess the Risk 220 Step 1 - Looking for the Hazards 221 Step 2 - Determine those at Risk and How 221 Step 3 - Are your Current Precautions Appropriate? 222 Step 4 - Record your Findings 222 Step 5 - Review your Assessment and Alter if Necessary 222 Learn from Others 222 Chapter 14 - An Introduction to Practical Decompression - In the Real World 223 Introduction 223 An Analogue 223 Team Work 223 Longer Decompression Hangs 224 1. Using the Shot-line 225 Out of the Decompression Matrix 11 2. Ascending a shot-line and drifting on a DSMB 226 3. Free-hanging from a DSMB 226 4. Decompression Stations 228 5. The Weather, Time, Tide and Your Skipper 230 6. Exiting the Water 232 General 233 Chapter 15 - DCI and Diver Denial 235 Introduction 235 Decompression Illness (DCI) 235 The Magic Bullet 238 Treat the Bubble not the Trouble 239 Diver Denial 240 Sign a Waiver 240 It's a Sports Injury 241 Does this Equipment Deliver 100% Oxygen? 241 Be Prepared 242 Bend Watch 243 Emergency Oxygen Supplies 244 Oxygen Administration Training 244 My Own Experiences of Diver Denial and DCI 245 Conclusion 246 Chapter 16 - DCI Recognition, First Aid and Treatment 249 Introduction 249 The Magic Bullet 249 Symptoms and Signs of DCI - Check-list 250 Diver Denial 250 Types of DCI 251 The DCI Response 253 Oxygen is a Wonder Gas, but be Careful! 254 Preparation 254 Contents 12 DCI Progress 256 Medication (Pain Killers) 257 DCI Recognition, O2 First Aid Treatment and Missed Stops/Fast Ascents 257 Caffeine, Alcohol and DCI 258 In-water Recompression 258 Recap 258 Chapter 17 - Re-immersion Recompression? 259 Introduction 259 Re-immersion using Air 260 Standard Hyperbaric Treatment 261 The Thermal Constraints for the Re-immersed Diver 261 Dehydration 262 Medication 262 Finally 262 Missed Stops/Fast Ascents without Symptoms - What to do? 263 The Take Home Message 264 Oxygen Administration Training? 265 Insurance 266 Summing up 266 Chapter 18 - Nitric Oxide - A Clue to DCI Prevention or a Red Herring? 267 Introduction 267 So What is Nitric Oxide? 268 Exercise, Nitric Oxide (NO), Diving and DCI 269 The Condition of the Container (The body) 269 Conclusion 270 Chapter 19 - Rounding Up 271 Introduction 271 Progression 271 Deep-stops Efficacy Questioned 271 Out of the Decompression Matrix 13 Diver Education 272 Summary 272 Holiday of a Lifetime? 274 Appendices - Introduction to Check-lists 275 Appendix 1 - Glossary of terms 276 Appendix 2 - Useful pro forma - Check-list 279 Appendix 3 On-site Decompression Illnesses Check-list 280 Introduction 280 Mental Status 280 Eyes 280 Face 281 Hearing 281 Shoulders 281 Gag 281 Tongue 281 Muscle strength 282 Body sensory check 282 Balance and co-ordination 282 Important 282 Appendix 4 - 1. DCI Accident Management Flowchart 2. Medical Emergency Distress Signal at Sea 284 Appendix 5 - Symptoms and Signs of DCI - Check-list 285 Appendix 6 - Health Base-line Form 286 Appendix 7 - DCI Incident Log 287 Appendix 8 - Breathing Gas Estimating Tables 288 Appendix 9 - Decompression and Gas Planning Work-sheet 291 Appendix 10 - Hyperbaric Chambers Check-list, World-wide 292