JOINT SERVICES 60th ANNIVERSARY EXPEDITION 2001-medical report

Introduction.

1. Dr David Adey, a Trimix qualified diver and HSE Medical Examiner of Divers, trained and refreshed by the Institute of Naval Medicine (INM) was a member of the Expedition and provided on site medical support. He ensured adequate medical preparation and cover were in place prior to, and throughout the expedition.

Pre-Deployment

2. Fitness to dive. All Divers were to HSE Medical Standard of Fitness to Dive or Service equivalent.

3. Immunisations. All Divers were in date with the following immunisations;
Hepatitis, Tetanus, Typhoid, Polio. The risk of Malaria was considered to be low as Singapore and the South China Sea 80nm off shore is regarded as a low risk area for malaria therefore NO prophylaxis was recommended.

4. Medical Insurance. All members were Divers Alert Network [DAN] insured for hyperbaric and medical treatment as well as for medical evacuation and repatriation.

5. Additional preparation. Local conditions were predicted to be 32 to 40 deg C with 9 hours of predicted sunshine. Despite the British summer a degree of acclimatisation was possible prior to departure.

In Theatre.

6. Medical Pack. This was held by the Expedition Doctor and was designed to
treat common illnesses and support injury. It included controlled drugs and appropriate clearances were obtained from the Home Office and the Singapore Health Authority prior to deployment.

7. Summary of Medical Problems Encountered There was only one diving related medical problem, which was a perforated ear drum, encountered on day 1 which occurred on descent at a depth of 35M. The diver was aware of what had happened and aborted the dive. The diver was treated with prophylactic anti-biotics and taken off diving. Further minor medical problems included, one case of minor heat exhaustion, several cases of fungal infections, and jellyfish stings, as well as minor cuts and abrasions. The minor case of heat exhaustion was treated by aggressive re-hydration. The jellyfish stings were treated with loratadine anti-histamine and the fungal infections were treated with terbinafine as well as daily talc to keep moist areas dry. Minor cuts were treated with mupirocin ointment.

8. Heat Exhaustion Prevention. An awning on the rear deck prevented divers working and kitting up in direct sunlight. It was an individual responsibility to ensure that they were well hydrated. Divers wore sun cream and kept well covered as appropriate. The crew 'wetted down' divers while kitted up.

9. Hygiene. Virtually all food was prepared on board with bottled water to reduce GI infections. Prevention of wound infection was a priority and anti-biotics were available.

10. Diving Specific. Safe diving practices were adopted to manage risk.

a. Laptop generated conservative profiles using V-planner were provided for each diver, because standby and Surface Supervisors duties, altered the inert gas loading for each pair of divers. A safety margin of 20% was factored into the dive profiles. Individual computer tracking allowed the DO and Doctor to monitor the following:

(1). Cumulative inert gas loading.
(2). CNS and pulmonary cumulative oxygen monitoring.
(3). Individual diver profiles due to different diving duties.

b. All dives were undertaken on Trimix or Heli-air. One dive per diver per day was undertaken in accordance with BSAC rules. There was also a one-day break in diving between diving HMS Prince of Wales and HMS Repulse to maximise surface interval to off gas.

c. Safe diving practices included:

(1). The team using accurately analysed mixes.
(2). Decompression staging in-water, to readily provide, decompression gas.
(3) The team has adopted Doppler bubble tracking, a new use of an existing technology, as a means of monitoring the well being of the divers.

d. Doppler Bubble Tracking.

(1). Introduction The Doppler device is usually used to monitor, foetal hearts or arterial and venous blood flow. In this context a hand held device was used to listen for inert gas bubble formation in the heart. A high grade of bubble formation detected would not guarantee Decompression Illness, however most divers with Decompression Illnes are those found to be producing high grades of bubble formation.

(2) On site Monitoring. The team, received advice from both the INM and DCIEM, as to the best time to monitor.
The monitoring originally took place of each diver after surfacing, at one, two and three hours, following INM advice that bubble peaks could be expected at 60 minutes. No bubbles or abnormal heart sounds were detected, therefore we reduced the interval at which we monitored the divers to 15 minutes, 30 minutes and 60 minutes.

(3). Practical Results. We found that monitoring, in real on-site conditions, readings at 15 minute intervals up to an hour after surfacing were most useful, as suggested by DCIEM. On only two occasions were bubbles heard at 30 minutes in two different individuals that disappeared at 60 minutes. These individuals had been immediately rested and taken off standby duties. At no time did any diver exhibit symptoms of decompression illness, and every diver felt well after diving.

(4). Funding. As with almost every aspect of this Expedition, the purchase of a Doppler monitor was self funded.

(5) Further Research. The Expedition Doctor intends to become fully trained in this particular use of Doppler technology, which is subjective and hence more of an art than a science. This was a trial in the practical usage of on site Doppler Tracking and after full training in the interpretation of bubble sounds, the expedition Doctor, intends that this will be a normal feature of post-diving safety monitoring

(6). Conclusions. On future Expeditions a more detailed quantitative Doppler research would contribute to the knowledge in this area of Joint Services Diving and to the increased safety of Divers conducting this sort of mixed gas diving.

e. Decompression illness. Most Trimix bends occur at 5-6 hours presenting only minor signs. Trimix divers usually do well if there has been no missed decompression. Trimix divers have high partial pressures of oxygen by decompressing on nitrox mixtures with increased percentages of oxygen. There were large amounts of oxygen available on this technical diving boat, with a special oxygen adaptor to allow a J-bottle of oxygen to be connected to an ambubag with an oro-nasal mask and oxygen reservoir. All the divers were trained oxygen administrators.

f. Arterial gas embolus. This was the major area of serious concern. A rapid ascent from 70m would virtually guarantee a bend. A gas embolus is likely, which would carry with it the likelihood of a very poor outcome.
This could equally occur on air from any depth. Considering the role of recompression chambers, they are to treat decompression illness. They cannot treat gas embolus, from rapid ascent, unless they are immediately on site such as next to the top of the Submarine Escape Training Tank [SETT]. The diving team had undertaken rigorous training to prevent this, and V Planner specifically slows the rate of ascent by 3 metre decompression stops from depth.

g. The Use of One Man Chambers. The Diving Team decided not to use one man chambers, on site, for the following reasons:

(1). The attending Doctor is crucially unable to maintain the casualty's airway and cannot monitor deterioration
(2). One-man chambers have been shown to take 5 minutes to depressurise, so that whilst the diver will not suffer an immediate decompression, neither can the attending Physician gain immediate access to a deteriorating casualty.
(3). If the diver is well they don't need to be in a one-man chamber. If the diver is ill they should not go into one.

Further problems with one man portable chambers include:

(1). Needing access to a large enough receiving chamber to enable transfer of the Casualty under pressure
(2). Helicopters may have problems under-slinging them.
(3). The Casualty is unattended during any evacuation.
(4). One on site could delay a Casualty evacuation
(5). These chambers, require training and time in their use.

h. The decision not to entertain in-water recompression.
(1) The water however warm is below body temperature resulting in additional heat loss in a diver who has already lost body heat using helium.
(2) It is impossible to maintain an airway underwater.
(3) An oxygen fit underwater would not be survivable.
(4) Sufficient gas would be needed for any necessary recompression and
as an example 50m deep air recompression takes 39 hours.

i. Team Plans for the Treatment of Decompression illness

(1). Administer oxygen
(2). Re-hydrate using intravenous fluids, [Hartmann's solution], giving 3-4 litres rapidly intravenously in a fit individual.
(3). Inform DAN South East Asia Pacific
(4). Apply the Emergency procedures plan arrived at with International SOS Singapore +65 330 9783
(5). Inform the Singapore Naval Chamber +65 750-5546
(6). We shared our emergency procedures prior to deployment with SOS Singapore, DAN South East Asia Pacific, and Col. Low of the Singapore Chamber. The Singapore Chamber is on standard 24-hour standby.
(7). A Satellite phone link to the Institute of Naval Medicine was available during the Diving Operations.
(8). The INM were aware of the Expedition. The INM Duty Diving Officers' number is 07831 151523 24 hours
(9). The Diving Location is BST + 7 hours / GMT + 8 hours
(10). We planned helicopter evacuation in the International SOS Risk Management Plan (page 4, Para 6).

11. Summary of risk management.

a. The Team undertook training to eliminate rapid ascent, and used V Planner that slows the ascent to 3 metre stops.

b. We prevented decompression illness by adopting safe diving practices.

c. We planned to treat decompression illness with 100% oxygen.

d. Bags of Hartmann's Solution were distributed amongst the team to enable rapid I-V and re-hydration of the casualty.

e. The Singapore Naval Base chamber is on standard 24-hour standby.

f. Helicopter evacuation was planned in the Emergency Procedures Plan.

g. Satellite communication to the INM and DA Singapore.

h. The DAN SEAP emergency assistance number was +61-3 9886 9166
Dan Europe International +41-1-14-14.

i. The Emergency Procedures Plan was widely shared with International SOS Singapore, Col. Low of the Singapore Chamber and DAN SEAP.

12. Resources and events that contributed to a successful exercise.

a. Detailed Risk Assessment discussions with the Institute of Naval Medicine

b. Training at Dorothea quarry Snowdonia.

c. The assistance from the Wirral recompression chamber.

d. The team dealt with one civilian diving emergency casualty evacuation from Dorothea.

13. Final summary.

a. Comprehensive risk assessment was undertaken for the safety of the team.

b. Trained and experienced personnel took part.

c. This exercise complied with regulations BSAC Guidelines and JSSADC Regulations.

d. Dives on Trimix to these depths is regularly conducted in recreational community.

e. This Adventurous Training Exercise breaks new ground for service adventurous diving.

MEDICAL REPORT
Introduction. 1. Dr David Adey, a Trimix qualified diver and HSE Medical Examiner of Divers, trained and refreshed by the Institute of Naval Medicine (INM) was a member of the Expedition and provided on site medical support. He ensured adequate medical preparation and cover were in place prior to, and throughout the expedition. Pre-Deployment 2. Fitness to dive. All Divers were to HSE Medical Standard of Fitness to Dive or Service equivalent. 3. Immunisations. All Divers were in date with the following immunisations; Hepatitis, Tetanus, Typhoid, Polio. The risk of Malaria was considered to be low as Singapore and the South China Sea 80nm off shore is regarded as a low risk area for malaria therefore NO prophylaxis was recommended. 4. Medical Insurance. All members were Divers Alert Network [DAN] insured for hyperbaric and medical treatment as well as for medical evacuation and repatriation. 5. Additional preparation. Local conditions were predicted to be 32 to 40 deg C with 9 hours of predicted sunshine. Despite the British summer a degree of acclimatisation was possible prior to departure. In Theatre. 6. Medical Pack. This was held by the Expedition Doctor and was designed to treat common illnesses and support injury. It included controlled drugs and appropriate clearances were obtained from the Home Office and the Singapore Health Authority prior to deployment. 7. Summary of Medical Problems Encountered There was only one diving related medical problem, which was a perforated ear drum, encountered on day 1 which occurred on descent at a depth of 35M. The diver was aware of what had happened and aborted the dive. The diver was treated with prophylactic anti-biotics and taken off diving. Further minor medical problems included, one case of minor heat exhaustion, several cases of fungal infections, and jellyfish stings, as well as minor cuts and abrasions. The minor case of heat exhaustion was treated by aggressive re-hydration. The jellyfish stings were treated with loratadine anti-histamine and the fungal infections were treated with terbinafine as well as daily talc to keep moist areas dry. Minor cuts were treated with mupirocin ointment. 8. Heat Exhaustion Prevention. An awning on the rear deck prevented divers working and kitting up in direct sunlight. It was an individual responsibility to ensure that they were well hydrated. Divers wore sun cream and kept well covered as appropriate. The crew 'wetted down' divers while kitted up. 9. Hygiene. Virtually all food was prepared on board with bottled water to reduce GI infections. Prevention of wound infection was a priority and anti-biotics were available. 10. Diving Specific. Safe diving practices were adopted to manage risk. a. Laptop generated conservative profiles using V-planner were provided for each diver, because standby and Surface Supervisors duties, altered the inert gas loading for each pair of divers. A safety margin of 20% was factored into the dive profiles. Individual computer tracking allowed the DO and Doctor to monitor the following: (1). Cumulative inert gas loading. (2). CNS and pulmonary cumulative oxygen monitoring. (3). Individual diver profiles due to different diving duties. b. All dives were undertaken on Trimix or Heli-air. One dive per diver per day was undertaken in accordance with BSAC rules. There was also a one-day break in diving between diving HMS Prince of Wales and HMS Repulse to maximise surface interval to off gas. c. Safe diving practices included: (1). The team using accurately analysed mixes. (2). Decompression staging in-water, to readily provide, decompression gas. (3) The team has adopted Doppler bubble tracking, a new use of an existing technology, as a means of monitoring the well being of the divers. d. Doppler Bubble Tracking. (1). Introduction The Doppler device is usually used to monitor, foetal hearts or arterial and venous blood flow. In this context a hand held device was used to listen for inert gas bubble formation in the heart. A high grade of bubble formation detected would not guarantee Decompression Illness, however most divers with Decompression Illnes are those found to be producing high grades of bubble formation. (2) On site Monitoring. The team, received advice from both the INM and DCIEM, as to the best time to monitor. The monitoring originally took place of each diver after surfacing, at one, two and three hours, following INM advice that bubble peaks could be expected at 60 minutes. No bubbles or abnormal heart sounds were detected, therefore we reduced the interval at which we monitored the divers to 15 minutes, 30 minutes and 60 minutes. (3). Practical Results. We found that monitoring, in real on-site conditions, readings at 15 minute intervals up to an hour after surfacing were most useful, as suggested by DCIEM. On only two occasions were bubbles heard at 30 minutes in two different individuals that disappeared at 60 minutes. These individuals had been immediately rested and taken off standby duties. At no time did any diver exhibit symptoms of decompression illness, and every diver felt well after diving. (4). Funding. As with almost every aspect of this Expedition, the purchase of a Doppler monitor was self funded. (5) Further Research. The Expedition Doctor intends to become fully trained in this particular use of Doppler technology, which is subjective and hence more of an art than a science. This was a trial in the practical usage of on site Doppler Tracking and after full training in the interpretation of bubble sounds, the expedition Doctor, intends that this will be a normal feature of post-diving safety monitoring (6). Conclusions. On future Expeditions a more detailed quantitative Doppler research would contribute to the knowledge in this area of Joint Services Diving and to the increased safety of Divers conducting this sort of mixed gas diving. e. Decompression illness. Most Trimix bends occur at 5-6 hours presenting only minor signs. Trimix divers usually do well if there has been no missed decompression. Trimix divers have high partial pressures of oxygen by decompressing on nitrox mixtures with increased percentages of oxygen. There were large amounts of oxygen available on this technical diving boat, with a special oxygen adaptor to allow a J-bottle of oxygen to be connected to an ambubag with an oro-nasal mask and oxygen reservoir. All the divers were trained oxygen administrators. f. Arterial gas embolus. This was the major area of serious concern. A rapid ascent from 70m would virtually guarantee a bend. A gas embolus is likely, which would carry with it the likelihood of a very poor outcome. This could equally occur on air from any depth. Considering the role of recompression chambers, they are to treat decompression illness. They cannot treat gas embolus, from rapid ascent, unless they are immediately on site such as next to the top of the Submarine Escape Training Tank [SETT]. The diving team had undertaken rigorous training to prevent this, and V Planner specifically slows the rate of ascent by 3 metre decompression stops from depth. g. The Use of One Man Chambers. The Diving Team decided not to use one man chambers, on site, for the following reasons: (1). The attending Doctor is crucially unable to maintain the casualty's airway and cannot monitor deterioration (2). One-man chambers have been shown to take 5 minutes to depressurise, so that whilst the diver will not suffer an immediate decompression, neither can the attending Physician gain immediate access to a deteriorating casualty. (3). If the diver is well they don't need to be in a one-man chamber. If the diver is ill they should not go into one. Further problems with one man portable chambers include: (1). Needing access to a large enough receiving chamber to enable transfer of the Casualty under pressure (2). Helicopters may have problems under-slinging them. (3). The Casualty is unattended during any evacuation. (4). One on site could delay a Casualty evacuation (5). These chambers, require training and time in their use. h. The decision not to entertain in-water recompression. (1) The water however warm is below body temperature resulting in additional heat loss in a diver who has already lost body heat using helium. (2) It is impossible to maintain an airway underwater. (3) An oxygen fit underwater would not be survivable. (4) Sufficient gas would be needed for any necessary recompression and as an example 50m deep air recompression takes 39 hours. i. Team Plans for the Treatment of Decompression illness (1). Administer oxygen (2). Re-hydrate using intravenous fluids, [Hartmann's solution], giving 3-4 litres rapidly intravenously in a fit individual. (3). Inform DAN South East Asia Pacific (4). Apply the Emergency procedures plan arrived at with International SOS Singapore +65 330 9783 (5). Inform the Singapore Naval Chamber +65 750-5546 (6). We shared our emergency procedures prior to deployment with SOS Singapore, DAN South East Asia Pacific, and Col. Low of the Singapore Chamber. The Singapore Chamber is on standard 24-hour standby. (7). A Satellite phone link to the Institute of Naval Medicine was available during the Diving Operations. (8). The INM were aware of the Expedition. The INM Duty Diving Officers' number is 07831 151523 24 hours (9). The Diving Location is BST + 7 hours / GMT + 8 hours (10). We planned helicopter evacuation in the International SOS Risk Management Plan (page 4, Para 6). 11. Summary of risk management. a. The Team undertook training to eliminate rapid ascent, and used V Planner that slows the ascent to 3 metre stops. b. We prevented decompression illness by adopting safe diving practices. c. We planned to treat decompression illness with 100% oxygen. d. Bags of Hartmann's Solution were distributed amongst the team to enable rapid I-V and re-hydration of the casualty. e. The Singapore Naval Base chamber is on standard 24-hour standby. f. Helicopter evacuation was planned in the Emergency Procedures Plan. g. Satellite communication to the INM and DA Singapore. h. The DAN SEAP emergency assistance number was +61-3 9886 9166 Dan Europe International +41-1-14-14. i. The Emergency Procedures Plan was widely shared with International SOS Singapore, Col. Low of the Singapore Chamber and DAN SEAP. 12. Resources and events that contributed to a successful exercise. a. Detailed Risk Assessment discussions with the Institute of Naval Medicine b. Training at Dorothea quarry Snowdonia. c. The assistance from the Wirral recompression chamber. d. The team dealt with one civilian diving emergency casualty evacuation from Dorothea. 13. Final summary. a. Comprehensive risk assessment was undertaken for the safety of the team. b. Trained and experienced personnel took part. c. This exercise complied with regulations BSAC Guidelines and JSSADC Regulations. d. Dives on Trimix to these depths is regularly conducted in recreational community. e. This Adventurous Training Exercise breaks new ground for service adventurous diving.