- Email: [email protected]
Undersea medical society meeting
Conferences
related to these policy state were papers by Professors Burenstam~Linder. Norman and Strommc Svendsen. These papers dealt with market processes and expressed concern for liberal trade and shipping policies and the operation of free markets in a world that displays increasingly protectionist tendencies. Closely
ments
Liberal policies and objectives
- conflicts
The international shipping scene is characterized by excesses of capacity ranging from modest to severe, depending upon the sector, a prolonged recession in demand which also varies in severity according to sector, an enormous oversupply of shipbuilding government strong capacity. involvement in both shipbuilding and shipping in many countries, and a
commitment on the part of developing countries and possibly also by state trading countries to increase their share of shipping markets. This creates such a difficult and competitive situation that it would be naive to believe that free market processes would find an easy solution, or give some stability even if they were allowed to operate over a sufficiently wide spectrum of the market. Equally, the formulation of shipping policy is no easy matter for the developed market economies. Some elements of a liberal policy may be suggested. These include a commitment to the needs of developing countries; a policy of retention of those cross-trading freedoms which are essential for the efficient deployment of efficient ships; some control over financial and shipbuilding policies which exacerbate oversupply: the establishment of certain benchmarks
Penetrating the oceans - the biology Undersea 2June
Medical
Society
Meeting,
Biscayne,
Florida,
USA,
29
May-
1979
The southern Florida weather was kind to over 300 scientists attending the the scientific meeting of annual Undersea Medical Society, an event its international which continued tradition by attracting participants from four continents. The meeting opened with an in-depth consideration of the medical aspects of modern commercial diving. The need to send a diver to great depths (now in excess of 400 metres) under conditions which allow him to perform useful work in safety is a challenge which has not yet been fully met. The traditional means of saturation diving consists of a topside support facility designed to maintain a diving team under pressure. When needed, divers lock into a bell which also carries necessary tools and equipment, and descend to the working depth. The water is cold, requiring the use of a wet suit. Life support is provided by tneans of an umbilical
324
Key
connecting the bell and divers to topside. When they are ready to return to the surface they re-enter the diving bell and remain under pressure until decompressed in the deck chamber. The appears to be simple but, system working in several hundred metres of sea water, at pressures which increase the density of the breathing gas by 25 times or more, is extremely taxing on the body. The act of breathing itself work. Decompression becomes sometimes requires many days. The entire procedure is stressful and timeconsuming, and the financial costs of a working dive is well into six figures. There are few alternatives. Small submarines and manoeuvrable articulated armoured diving suits have the advantage of rapid deployment and eliminate the need for decompression. They are practical in performing underwater work at depths beyond presently available dive capabilities.
with regard to shares and shipping capacity requirements; and rules for which participation aid market processes in their task of harmonization. Even the statement of these objectives suggests certain internal conflicts between them. However, there have been some favourable developments in recent months, and the signing of the UNCTAD Code would appear to be one such move. It is to be hoped that progress is made in UNCTAD studies for policy on the bulk trades and the formulation of US policies on liner trades, and that such progress can be sustained in the development of other national policies.
Marine
Sidney
Gilman
Transport
Centre
University
of Liverpool Liverpool,
r
OT
UK
pressure
Their weight in water is only about 25 kg, and the articulated limbs are designed to be neutrally buoyant. so the only work required in motion is that needed to overcome joint friction. In theory, the length of time a man can stay in such a suit is limited only by the workload. Although medical scientists have determined that the physiological costs of operating the suit decrease somewhat with the experience of the operator, energy expenditure is still heavy. Locomotion is slow and laboured. especially on soft bottoms or in heavy currents. Vertical mobility is especially restricted, limited to lifting or lowering by means of a cable, and work efficiency in the dangling mode is especially poor.
Medical
expertise
These considerations have placed the scientific community under pressure to provide solutions for the problems diving plaguing the commercial industry. Some diving contractors report that they are not always pleased with the state of diving medical practices. For example, no universal
MARINE
POLICY
October
1979
Conferences
diver certification criteria are in force. Although much progress has been made in management of diving accidents, treatment may depend on the experience of the physician in charge. For these reasons, it was announced that the education committee of the Undersea Medical Society (UMS) has begun the important task of developing criteria for certifying physicians as diving medical examiners or specialists. To qualify as a specialist, the physician would have to manage competent to prove uncomplicated as well as complicated cases requiring recompression therapy. It is envisaged that this certification programme may develop to the level that an independent certifying board Another be established. would innovation is the creation, in the USA, of a national diving network under the leadership of the UMS. A WATS telephone line will be available in the autumn of I979 for reporting a diving accident from anywhere in the USA, including Alaska and Hawaii, and receiving immediate authoritative help. Ultimately, the quality of medical expertise depends on the combined experience of diving companies and experimental dives conducted under controlled conditions, in land-based dry chambers. The newest and deepest operational facility in the USA is a 1 100 metre chamber and wet-pot in the F.G. Hall Laboratory’s hyperbaric chamber complex at Duke University. Dr P.B. Bennett, its director, announced a highly successful dive to 457 metres with record compression time (I 2 hours and 20 minutes) to this depth.
Safety concerns saturation diving, however, Deep constitutes but a small fragment of all the concerns of the diving medical community. A perennial question limits of concerns the safe decompression. This is because distribution of dissolved gases in the multitude of body tissues (fat, muscle, cartilage, bone etc), unequally perfused circulation, results in the by complicated interactions not easily modelled in the laboratory. The most recent innovation is the inclusion of phenomena into counterdiffusion’ calculations. decompression The underlying difficulty, however, is the
MARINE
POLICY
October
1979
mechanism of fact that the sickness (DS, the decompression ‘bends’) is poorly understood even in the case of limb bends, which constitutes 90% of all cases. Experience has resulted in very successful treatment regimes (recompression, fluid therapy), but the initiation of the primary event of DS is still not very well understood. Particularly puzzling are those cases in sickness which decompression symptoms are delayed for hours after surfacing. Most research interests have centred around soft tissues (muscle, fat) and fluid compartments (plasma, cerebrospinal fluid, inner ear). Much less is known about the role of bones and tendons which are also living tissue, perfused by blood, and rich in sensory nerve endings. Another curiosity which begs explanation is that shallow dives result largely in limb bends while deep vestibular dives produce largely symptoms (nausea, dizziness). It was DS cannot be pointed out that overcome simply by slowing down: decompression can be either too slow or too fast. If the initial decompression the pressure stop early, is too differential is too small, and not enough inert gas is eliminated. This gas must be allowed to leave the body at a longer stop later in the schedule. If the initial ‘pull’ is too great, decompression sickness may set in, and has to be corrected for with a ‘therapeutic’ decompression. Periodic breathing of pure oxygen accelerates the elimination of inert gases and is an extremely important gas in furthering safe decompression. investigators presented Several for results of their search pharmacological means of altering either susceptibility to or the course of the bends. Common aspirin is already known to be beneficial in decreasing platelet aggregation which contributes in towards circulatory impairment DS. Numerous other pharmacological agents: steroids, beta adrenergic agents and phosphodiesterase inhibitors, have had little effect on the course of the illness. The most recent studies show that vitamin E can decrease decompression morbidity and mortality in test animals provided the enriched diet is introduced at least six weeks prior to exposure. Central nervous system effects of DS seem to be
primarily of vascular origin. Arrest of blood flow for long enough to cause some tissue damage results in focal resistance to of increased areas microcirculatory perfusion when blood flow is restored. Because of this ‘no reflow phenomenon’, emphasis is placed on drugs which affect tissue reperfusion after periods of ischemia.
Hypothermia In the keynote address, UMS members were treated to an excellent exposition on the practical aspects of hypothermia by Dr J.S. Hayward. Accidental hypothermia is a potential problem in any dive setting. In 4°C water, an unprotected human can die after 2-3 hours of exposure. Inability of the body to maintain core temperature above the minimum 28°C is the vital factor. A hypothermic person cannot feel his internal temperature, and even a ‘rescued’ individual can, if improperly rewarmed, continue to lose body heat from the core to the shell and die. Body size is very important in survival time: the larger the bulk, the longer core temperature can be maintained. Curiously, this also leads to better survivability of children in cold water drowning accidents. Since the metabolic demands of their brain drop much faster, irreversible nervous system damage is postponed. The single most important factor for increasing survival time in cold water is good thermal protection such as a wet suit or a modern convertible life jacket. Once hypothermia sets in, efforts should be directed primarily at rewarming the trunk - the periphery (limbs) should be left for later. The meeting concluded with a tour of the National Oceanic and Atmospheric Administration facility at Key Biscayne, demonstrating its various hyperbaric chambers and capabilities of dealing with diving casualties.
Peter G. Kaufmann Duke University Durham,
Medical
Center
NC 2 7 7 10, USA
’ Peter G. Kaufmann. ‘Diving capabilities _ the medical challenge’, Marine Policy, Vol 1, No 4, 1977, pp 350-352.
325
related to these policy state were papers by Professors Burenstam~Linder. Norman and Strommc Svendsen. These papers dealt with market processes and expressed concern for liberal trade and shipping policies and the operation of free markets in a world that displays increasingly protectionist tendencies. Closely
ments
Liberal policies and objectives
- conflicts
The international shipping scene is characterized by excesses of capacity ranging from modest to severe, depending upon the sector, a prolonged recession in demand which also varies in severity according to sector, an enormous oversupply of shipbuilding government strong capacity. involvement in both shipbuilding and shipping in many countries, and a
commitment on the part of developing countries and possibly also by state trading countries to increase their share of shipping markets. This creates such a difficult and competitive situation that it would be naive to believe that free market processes would find an easy solution, or give some stability even if they were allowed to operate over a sufficiently wide spectrum of the market. Equally, the formulation of shipping policy is no easy matter for the developed market economies. Some elements of a liberal policy may be suggested. These include a commitment to the needs of developing countries; a policy of retention of those cross-trading freedoms which are essential for the efficient deployment of efficient ships; some control over financial and shipbuilding policies which exacerbate oversupply: the establishment of certain benchmarks
Penetrating the oceans - the biology Undersea 2June
Medical
Society
Meeting,
Biscayne,
Florida,
USA,
29
May-
1979
The southern Florida weather was kind to over 300 scientists attending the the scientific meeting of annual Undersea Medical Society, an event its international which continued tradition by attracting participants from four continents. The meeting opened with an in-depth consideration of the medical aspects of modern commercial diving. The need to send a diver to great depths (now in excess of 400 metres) under conditions which allow him to perform useful work in safety is a challenge which has not yet been fully met. The traditional means of saturation diving consists of a topside support facility designed to maintain a diving team under pressure. When needed, divers lock into a bell which also carries necessary tools and equipment, and descend to the working depth. The water is cold, requiring the use of a wet suit. Life support is provided by tneans of an umbilical
324
Key
connecting the bell and divers to topside. When they are ready to return to the surface they re-enter the diving bell and remain under pressure until decompressed in the deck chamber. The appears to be simple but, system working in several hundred metres of sea water, at pressures which increase the density of the breathing gas by 25 times or more, is extremely taxing on the body. The act of breathing itself work. Decompression becomes sometimes requires many days. The entire procedure is stressful and timeconsuming, and the financial costs of a working dive is well into six figures. There are few alternatives. Small submarines and manoeuvrable articulated armoured diving suits have the advantage of rapid deployment and eliminate the need for decompression. They are practical in performing underwater work at depths beyond presently available dive capabilities.
with regard to shares and shipping capacity requirements; and rules for which participation aid market processes in their task of harmonization. Even the statement of these objectives suggests certain internal conflicts between them. However, there have been some favourable developments in recent months, and the signing of the UNCTAD Code would appear to be one such move. It is to be hoped that progress is made in UNCTAD studies for policy on the bulk trades and the formulation of US policies on liner trades, and that such progress can be sustained in the development of other national policies.
Marine
Sidney
Gilman
Transport
Centre
University
of Liverpool Liverpool,
r
OT
UK
pressure
Their weight in water is only about 25 kg, and the articulated limbs are designed to be neutrally buoyant. so the only work required in motion is that needed to overcome joint friction. In theory, the length of time a man can stay in such a suit is limited only by the workload. Although medical scientists have determined that the physiological costs of operating the suit decrease somewhat with the experience of the operator, energy expenditure is still heavy. Locomotion is slow and laboured. especially on soft bottoms or in heavy currents. Vertical mobility is especially restricted, limited to lifting or lowering by means of a cable, and work efficiency in the dangling mode is especially poor.
Medical
expertise
These considerations have placed the scientific community under pressure to provide solutions for the problems diving plaguing the commercial industry. Some diving contractors report that they are not always pleased with the state of diving medical practices. For example, no universal
MARINE
POLICY
October
1979
Conferences
diver certification criteria are in force. Although much progress has been made in management of diving accidents, treatment may depend on the experience of the physician in charge. For these reasons, it was announced that the education committee of the Undersea Medical Society (UMS) has begun the important task of developing criteria for certifying physicians as diving medical examiners or specialists. To qualify as a specialist, the physician would have to manage competent to prove uncomplicated as well as complicated cases requiring recompression therapy. It is envisaged that this certification programme may develop to the level that an independent certifying board Another be established. would innovation is the creation, in the USA, of a national diving network under the leadership of the UMS. A WATS telephone line will be available in the autumn of I979 for reporting a diving accident from anywhere in the USA, including Alaska and Hawaii, and receiving immediate authoritative help. Ultimately, the quality of medical expertise depends on the combined experience of diving companies and experimental dives conducted under controlled conditions, in land-based dry chambers. The newest and deepest operational facility in the USA is a 1 100 metre chamber and wet-pot in the F.G. Hall Laboratory’s hyperbaric chamber complex at Duke University. Dr P.B. Bennett, its director, announced a highly successful dive to 457 metres with record compression time (I 2 hours and 20 minutes) to this depth.
Safety concerns saturation diving, however, Deep constitutes but a small fragment of all the concerns of the diving medical community. A perennial question limits of concerns the safe decompression. This is because distribution of dissolved gases in the multitude of body tissues (fat, muscle, cartilage, bone etc), unequally perfused circulation, results in the by complicated interactions not easily modelled in the laboratory. The most recent innovation is the inclusion of phenomena into counterdiffusion’ calculations. decompression The underlying difficulty, however, is the
MARINE
POLICY
October
1979
mechanism of fact that the sickness (DS, the decompression ‘bends’) is poorly understood even in the case of limb bends, which constitutes 90% of all cases. Experience has resulted in very successful treatment regimes (recompression, fluid therapy), but the initiation of the primary event of DS is still not very well understood. Particularly puzzling are those cases in sickness which decompression symptoms are delayed for hours after surfacing. Most research interests have centred around soft tissues (muscle, fat) and fluid compartments (plasma, cerebrospinal fluid, inner ear). Much less is known about the role of bones and tendons which are also living tissue, perfused by blood, and rich in sensory nerve endings. Another curiosity which begs explanation is that shallow dives result largely in limb bends while deep vestibular dives produce largely symptoms (nausea, dizziness). It was DS cannot be pointed out that overcome simply by slowing down: decompression can be either too slow or too fast. If the initial decompression the pressure stop early, is too differential is too small, and not enough inert gas is eliminated. This gas must be allowed to leave the body at a longer stop later in the schedule. If the initial ‘pull’ is too great, decompression sickness may set in, and has to be corrected for with a ‘therapeutic’ decompression. Periodic breathing of pure oxygen accelerates the elimination of inert gases and is an extremely important gas in furthering safe decompression. investigators presented Several for results of their search pharmacological means of altering either susceptibility to or the course of the bends. Common aspirin is already known to be beneficial in decreasing platelet aggregation which contributes in towards circulatory impairment DS. Numerous other pharmacological agents: steroids, beta adrenergic agents and phosphodiesterase inhibitors, have had little effect on the course of the illness. The most recent studies show that vitamin E can decrease decompression morbidity and mortality in test animals provided the enriched diet is introduced at least six weeks prior to exposure. Central nervous system effects of DS seem to be
primarily of vascular origin. Arrest of blood flow for long enough to cause some tissue damage results in focal resistance to of increased areas microcirculatory perfusion when blood flow is restored. Because of this ‘no reflow phenomenon’, emphasis is placed on drugs which affect tissue reperfusion after periods of ischemia.
Hypothermia In the keynote address, UMS members were treated to an excellent exposition on the practical aspects of hypothermia by Dr J.S. Hayward. Accidental hypothermia is a potential problem in any dive setting. In 4°C water, an unprotected human can die after 2-3 hours of exposure. Inability of the body to maintain core temperature above the minimum 28°C is the vital factor. A hypothermic person cannot feel his internal temperature, and even a ‘rescued’ individual can, if improperly rewarmed, continue to lose body heat from the core to the shell and die. Body size is very important in survival time: the larger the bulk, the longer core temperature can be maintained. Curiously, this also leads to better survivability of children in cold water drowning accidents. Since the metabolic demands of their brain drop much faster, irreversible nervous system damage is postponed. The single most important factor for increasing survival time in cold water is good thermal protection such as a wet suit or a modern convertible life jacket. Once hypothermia sets in, efforts should be directed primarily at rewarming the trunk - the periphery (limbs) should be left for later. The meeting concluded with a tour of the National Oceanic and Atmospheric Administration facility at Key Biscayne, demonstrating its various hyperbaric chambers and capabilities of dealing with diving casualties.
Peter G. Kaufmann Duke University Durham,
Medical
Center
NC 2 7 7 10, USA
’ Peter G. Kaufmann. ‘Diving capabilities _ the medical challenge’, Marine Policy, Vol 1, No 4, 1977, pp 350-352.
325