Dr. Raymond Sawchuk, Pathologist
DEVELOPED By
Owen Sound General and Marine Hospital
Owen Sound, Ontario N4K 5H3
AND
Dr. George Harpur, Coroner
Tobermory Hyperbaric Facility
Tobermory, Ontario NOX 2R0
AUTOPSY PROTOCOL FOR VICTIMS
OF DIVING ACCIDENTS
I.INTRODUCTION
This autopsy protocol is designed to assist both investigating officers, physicians, coroners and pathologists In the investigation and post mortem examination or a diving ratility. It is a fact of
life that in the majority of instances, the professional individuals involved with Investigation or one of these cases may have virtually no experience in dealing with the various aspects of the investigation.
It must be born In mind that diving accidents may occur In other than scuba diving conditions. The area or interest obviously In which we have the most Concern is that of air embolization, either as a primary insult or secondary to overly vigorous resuscitation. However, air embolization can occur in the circumstances other than scuba diving and instances of air embolization occurring in exiting from a submerged motor vehicle or embolization secondary to breathing air from an inverted pail at the bottom of a swimming pool have been well documented.
First and foremost must be the fact that a high index of suspicion must be maintained in these investigations. If the possibility of air embolism is not entertained, Post Mortem will progress in a normal fashion and artifactual changes will alter the entire interpretation of the case.
It is extremely important that the investigating individuals have available for the pathologist at the time of autopsy, information relative to items such as the diving conditions, environment, previous medical history of the victim, and the events immediately preceding or following the demise of the involved individual. Primarily, this autopsy protocol is designed for implementation when the deceased is identified as being a scuba diver who has died in the course of a diving accident. Individuals In diving accidents may have died consequent upon direct trauma, such as being run down by a motorboat, simple drowning or, in tropical waters, bites or stings of venomous marine animals. The conduct and investigation of autopsy findings in simple drowning is carried out as part of any diving death but will not be considered here separately as they are covered in numerous
standard reference texts.
Our main concern in reference to diving deaths is the unique investigation for evidence of air embolization. We know air embolism can occur in water depths of as little as 6 to 8 feet in experiments with animals. It has been shown transpulmonic pressure differential of 80 mm of mercury is enough to rupture the wall of the alveoli or air sacs forcing air into the pulmonary vasculature. This pressure gradient corresponds to a change in water depth or pressure of approximately 4 to 6 feet. If the deceased initially survived the event but subsequently expired, all information relative to resuscitation attempts, headache, chest pain, neck pain, nausea, shortness of breath, weakness, visual problems, muscle Inco-ordination, speech difficulties must be available.
PRELIMINARY PREPARATION
1. Do the post mortem as soon as possible after the event or recovery of the body.
2. As the individual responsible for the performance of the post mortem determine the history eliciting all information as to depth of diver, water temperature, evidence of vomiting at the scene, froth within and in place face mask, history of possible use of alcoholic agents or restricted or prohibited drugs or agents.
3. X-ray the head, neck and abdomen with particular emphasis on evidence or soft tissue emphysema. Examination of the skull and neck is directed to the search for evidence of cervical fracture dislocation or evidence of atlas skull separation. Xrays of the chest may demonstrate evidence of either pneumothoraces or grass acute traumatic emphysema. Horizontal beam Xrays are particularly useful, the body being tipped on one side, the Xray beam being passed through the body in a horizontal direction. The advantage of this procedure
is the demonstration of fluid air levels within structures such as the heart. It is only in this mode that such a finding may be demonstrated.
AUTOPSY PROTOCOL FOR VICTIMS OF DIVING ACCIDENTS--THE AUTOPSY
INSPECTION
Examine the body for signs of trauma and palpate clavicle and neck regions for evidence of subcutaneous emphysema. It is usually appropriate at this time to wash the conjunctiva and with an opthamloscope, check the retinal arteries for evidence of air bubbles. Examination of the face for evidence of mask squeeze is performed. The skin is examined for evidence of either cyanosis or the anticipated cherry red colour of carbon monoxide. Obviously, in the usual circumstance the body presents a bluish colour consequent upon the temperatures of the water to which the body has been exposed. Even with carbon monoxide Intoxication, the colour may be masked by the bluish discoloration.
HEAD
Given the proper conditions, the head and brain should be examined next. Reflect the scalp in the usual way, carefully examining the incised subcutaneous vessels for evidence of bubbling. Incise the skull itself in the usual manner, taking particular care to avoid severing the meningeal vessels. Incise, in the vertex of the skull, an additional square approximately 5.0 cm. on side, avoiding again, injurying underlying vessels. Remove the severed calvarium, applying fingers to the previqu sly indicated square, holding the underlying brain and membranes in place through this opening. inspect the pial vessels at this point for evidence of air embolization. With appropiate hemoclip, applicator, double-clip the internal carotids and the basilar artery, severing between the cEips. Double clipping prevents air entering the cerebral1 vasculature artefactually, as well as preventing air from progressing to the jugular and cardiac regions. Remove the brain and grossly inspect all arterial channels for evidence of air embolizatlon. At this point, the brain may be placed in a water-filled sink with water running and dissection and careful observation for evidence of air embolization performed.
Thorax and Contents
Before actually reflecting the usual "Y"-shaped incision, insert a long spinal needle' with a three-way valve connected by a length of flexible tubing to a large syringe beneath the xiphoid process into the medlastinal tissues. The tubing is connected to a syringe partially filled with water and upon opening the valve, observation for the presence of air bubbling from the space is performed.
Reflect the skin in the usual "Y"-shaped inision, being careful not to enter the pleural cavities. At this time, check for any evidence of bubbling Issuing from the cut skin vessels. Pool water In each reflected thoracic fold and after Inverting a water filled SO cc. cylinder In place1 Itisert a blunted 16 or 14 gauge needle through one of the intercostal spaces. If a1rEis present in either pleural space, the quantity may be measured and if in excess of the 50 cc. cylinder capacity, a finger may be applied over the hub end of the needle until the cylinder may be refilled. Pneumothoraces are demonstrated in approximately 10% of cases of air embolization according to the literature. Cut the ribs with a cutter so as not to injure the underlying pulmonary visceral pleura. Transect the sternum below the sternoclavicular joint, again being careful not to injure the great vessels at the base of the neck Flood the chest cavity with water and check the pericardia space for evidence of pneumopericardium employing the same methodology as used In the examination of the pleural cavities. Upon completion of evaluation for air in the pericardial SaC, fluid Is drained from the chest cavity. The pericardlal sac is incised in a linear fashion and then filled with water. By introducing the needle Into the right and left ventricles in the same way with the use of the Inverted cylinder, evaluation of the quantity and presence of air In right and left chambers may be performed. The coronary vessels may be examined at the same time for evidence of embolization of air. The lungs are examined as well "in situ" for evidence of enibolizatlon of air in the vessels of the visceral pleura. The lungs are checked, in addition, for any indication of bulla or bleb formation. The great vessels of the hilum of both lungs are double-clamped and tied with the lungs being then removed by Incision between the double ties. The main vessels of the heart are also tied in the same fashion. Upon removal of the lungs1 they may be placed in a sink filled with water, air gently injected by needle and syringe into a bronchus to check for potential pleural rupture sites. Upon completion of this part of the ekaminatlon1 the bronchi may be dissected and opened and inspected for evidence of either mucus plugs, tumor or foreign body. It is important to evaluate the actual content of the bronchi for any evidence of debris or aspirated gastric contents. The heart, upon being removed, and the coronary vessels are examined under water.
At this point, the major vessels of the. abdominal cavity may be inspected for evidence of air embolization including the vena cava1 pottal vessels, hepatic vessels, renal vessels and mesenteric vessels. At this paint blood,Eurlne and tissue samples may be obtained for toxicological assay. if the post mortem examination has been delayed significantly from the presumed time of death, microbiological cultures of blood and tissue may be performed on material obtained at this point to exclude an artifactual picture of air eunbolization secondary to gas formation from post mortem bacterial growth.
SUMMARY
It Is only with accurate data that we can begin to hope to fully understand the causes for these deaths. When such data has been obtalned1 It has been possible to apply effective preventive measures and as a result, the diving statistics for scuba diving have been steadily improving. With the full co-operative efforts of coroner, investigating officers and pathologist, these figures would undoubtedly be even better in the future.
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3. BAYNE, C. GRESHAM, and WURZBACHER, Terrie. Can pulmonary barotrauma cause cerebral air embolism in a non-diver? Chest, 81: 648-650, 1982.
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9. KINOWAEL, Eric P. Autopsy protocol for victims of scuba diving accidents.
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11. KIZER, KENNETH W. The role of computed tomography In the management of dysbaric diving accidents. Radiology 140: 705-707, 1981.
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