Undersea Medicine Chapter 19 UNDERSEA MEDICINE GRACE LANDERS, MD* and JAMES CAVINESS, MD, MS† INTRODUCTION UNDERSEA OPERATIONS ILLNESS OR INJURY KNOWN TO RESULT FROM DIVING PHYSICAL PROPERTIES Pressure Oxygen Toxicity Nitrogen Narcosis Visibility Sound Temperature Contaminated Diving PROBLEMS WITH UNDERWATER BREATHING EQUIPMENT Hypoxia Hypercapnia Dyspnea UNDERWATER HAZARDS Marine Life Sound Navigation and Ranging SUBMARINES Submarine Types and Classes The Submarine Environment Monitoring the Submarine Atmosphere Disabled Submarines The Working Schedule and Sleep SUMMARY *Lieutenant, Medical Corps, US Navy; Naval Medical Center Portsmouth; Resident, Emergency Medicine, 620 John Paul Jones Circle, Portsmouth, Virginia 23708 †Occupational Medicine Physician, Branch Health Clinic China Lake, Department of Occupational Health, 1 Administration Circle, Building 1403, China Lake, California 93555 347 Occupational Health and the Service Member INTRODUCTION Humans have explored the sea for as long as re- This chapter focuses on the occupational health corded history. President Kennedy remarked: aspects of undersea operations. Undersea medicine encompasses an understanding of the underwater I really don’t know why it is that all of us are so com- environment, a familiarity with the ship and diving mitt ed to the sea, except I think it’s because in ad- systems that allow survival in such an environment, dition to the fact that the sea changes, and the light a thorough knowledge of the duties and workplace changes, and ships change, it’s because we all came hazards present in undersea settings, and an un- from the sea. And it is an interesting biological fact derstanding of the physiological and medical issues that all of us have, in our veins the exact same per- centage of salt in our blood that exists in the ocean, unique to undersea operations. As a result of increased and therefore, we have salt in our blood, in our sweat, joint operations, the remote locations of many military in our tears. We are tied to the ocean. And when we operations, and the military’s role in humanitarian and go back to the sea—whether it is to sail or to watch recovery operations that include underwater salvage it—we are going back from whence we came.1 and repair, it is essential that military physicians be familiar with undersea medicine. Though humans have always felt a connection to This chapter reviews the physical properties of the world’s seas and oceans, these water bodies can be diving to foster an understanding of physiological deadly. Surface water temperatures in most regions of consequences with respect to undersea medicine. the world can cause hypothermia and death for unpro- Additionally, it examines environmental hazards tected or overexposed individuals. Waves at sea create that threaten the health or mission success of un- hazardous conditions for maneuvering personnel and dersea operations and discusses unique aspects and supplies, and numerous forms of marine life can inflict considerations of the submarine environment. This severe or fatal injuries. There is no air, and in very few chapter is neither a complete guide to the treatment places is there any significant warmth. Humans have of diving casualties nor a complete overview of little physical aptitude for survival on or in the water, diving medicine. Readers are directed to compan- and under-the-surface survival depends completely on ion chapters in the Textbooks of Military Medicine technology. Although advances in technology make series; the US Navy Diving Manual, Revision 6; and underwater operations possible, they also expose references such as Bennett and Elliott’s Physiology other limits, such as the human body’s vulnerability and Medicine of Diving, or Bove and Davis’ Diving to depth pressure. Medicine.2–4 UNDERSEA OPERATIONS Occupational health aspects of undersea operations and land units with divers. Figure 19-1 shows US Navy are numerous and varied. The environment, the nature divers participating in a salvage operation to recover of the mission, the equipment, and the physiological nine missing crewmen and personal items following conditions of personnel are all factors. Whereas com- the submarine USS Greeneville’s (SSN-772) collision with mercial industries, such as those involved in oil and gas and subsequent sinking of the Ehime Maru. Figure 19-2 exploration, conduct diving and undersea operations, shows divers being lowered to the Ehime Maru wreck site. military undersea operations have unique constraints. While it may seem obvious that the majority of Operating with stealth, under time limits, and in remote undersea operations are conducted by the Navy, all and possibly contaminated locations or under the threat military branches have divers. The US Marine Corps of enemy fire are inherent conditions to military opera- trains combatant divers as members of elite recon- tions. The key to safety in these conditions is to under- naissance units to reconnoiter and infiltrate coastal stand and prepare for the environment and its dangers. areas in advance of amphibious landings. In addition Onboard each US Navy submarine, including fast at- to Special Forces personnel who complete the combat tack and ballistic submarines, selected crew are trained as diver qualification course, the US Army has four light divers and can conduct security swims of the submarine and two heavy dive teams. Light dive teams are highly perimeter or perform limited ship management. Navy mobile and can perform both scuba (self-contained divers conduct thousands of dives annually to perform underwater breathing apparatus) and surface-supplied limited ship management. The Navy also has under- diving. Heavy dive teams also conduct scuba and water construction teams; mobile diving and salvage surface-supplied diving but mainly in support of com- units; explosive ordinance disposal units; and sea, air, manders controlling harbors, ports, and coastal areas. 348 Undersea Medicine Figure 19-1. November 2001. US Navy divers swim along the Ehime Maru wreck site in Honolulu, Hawaii, to salvage personal effects and remains from the vessel off Honolulu International Airport’s reef runway. US Navy photo by Chief Petty Officer Andrew McKaskle. Reproduced from: http://www.cpf.navy.mil/subsite/ehime- maru/images/011105shipsside-high.jpg. Both light and heavy dive teams provide support for the Army Corps of Engineers. The US Air Force’s special Figure 19-2. Two divers from Mobile Diving and Salvage Unit tactics elite ground combat force, comprised of combat One and a Japanese diver in MK 21 dive suits are lowered controllers, pararescue, and combat weather personnel, to the Ehime Maru wreck site. US Navy photo by Chief Petty Officer Andrew McKaskle. are dive trained. Whether part of special tactics or in the Reproduced from: http://www.cpf.navy.mil/subsite/ehime- conduct of their own occupational specialty, each ser- maru/images/011105diveplatform-high.jpg. vice may be required to participate in dive operations. ILLNESS OR INJURY KNOWN TO RESULT FROM DIVING While diving is inherently dangerous, and the is more common in saturation diving and is prevalent environment is deadly if equipment such as under- across the world in caisson workers, but it can occur water breathing apparatus fails, there is very little without extreme depth exposures.6,7 Lesions that are documented evidence of occupational illness or injury juxta-articular effectively end a diver’s career.8 Dys- from diving when correct safety and decompression baric osteonecrosis rates are very low in military divers procedures are followed. A number of small studies, and almost nonexistent in the submarine force, most case reports, and case series suggest there may be po- likely due to high fitness levels and attention to div- tential neurologic, pulmonary, and neuro-psychiatric ing. A recent German study of military divers found changes associated with diving, mainly in those who they had the same rate of dysbaric osteonecrosis as have suffered decompression sickness (DCS).5 matched nondivers.9 The only well-documented diving occupational Many divers and medical experts feel diving results injury or illness that occurs even when current safety in hearing loss, while others feel any hearing loss seen procedures and decompression schedules are followed in divers is a result of barotraumas such as squeezes, is dysbaric osteonecrosis. Dysbaric osteonecrosis is a and late or forceful Valsalva maneuvers. The diving condition in which necrotic lesions develop in the hip, instruction courses at the Naval Diving and Salvage shoulder, or long bones, and arise after an ischemic Training Center in Panama City, Florida, have long insult to the bone’s vascular supply. Widely accepted taught the most common injury to Navy divers is the as a rare but serious complication of deep diving, the middle ear squeeze. This fact is reiterated in several exact mechanism by which it occurs remains elusive. It review articles,10–12 and a recent study of over 700 ex- 349 Occupational Health and the Service Member perienced divers from the United States and Australia cies above 4000 Hz, meaning that sea, air, and land found 52% of divers had middle ear barotraumas, unit personnel are at a higher risk for hearing loss at making it the most common dive-related injury.13 A this frequency versus Navy divers. For Navy divers, comparison of Navy divers and sea, air, and land there was no increased risk compared to those in the team personnel’s hearing thresholds to data from the hearing conservation program.14 Although diver hear- Navy’s hearing conservation program revealed sea, ing loss is likely multi-factorial, the high incidence of air, and land units were at significantly greater risk of ear barotraumas among divers places them at risk for hearing threshold loss greater than 40 dB for frequen- hearing loss. PHYSICAL PROPERTIES Pressure overinflation syndrome. The alveolar membranes can rupture under a pressure differential of 70 mm Hg, On land and at sea level, the pressure surrounding or roughly 4 ft.