REVIEW

ANN MARIE McMULLIN, MD Department of Emergency Medicine, Cleveland Clinic

Scuba diving: What you and your patients need to know

■ ABSTRACT ORE THAN 7 MILLION PEOPLE are estimat- M ed to participate in self-contained Self-contained underwater apparatus (SCUBA) underwater breathing apparatus (scuba) div- diving continues to gain popularity. General practitioners ing,1 so you are highly likely to encounter one need to know the health requirements and in your practice. contraindications so they can counsel patients requires rigorous health appropriately. SCUBA diving injuries may not be apparent screening to prevent injury or accidents. Most immediately and require knowledge and understanding reputable diving instructors and schools for accurate diagnosis and treatment. require a medical statement from prospective divers. Health care professionals must be ■ KEY POINTS aware of the requirements, contraindications, and possible injuries of diving so that they are General considerations for diving clearance, requirements able to advise their patients properly and diag- for further workup, and contraindications to diving must nose diving-related injuries. be reviewed for each patient. This article describes general recommen- dations for screening scuba divers and suggests specific workups and contraindications to div- In the event that a patient presents with health concerns ing. It also provides an overview of potential after a diving trip, , sickness, diving injuries and their treatment. and air embolus should be considered as possible diagnoses. ■ PREDIVE MEDICAL CLEARANCE

Divers Alert Network (DAN) is a good medical resource General considerations for screening patients for physicians and patients should they have more are shown in TABLE 1.2 specific questions. DAN can be contacted at 1-919-684- Each patient should have a predive clear- 2948, www.diversalertnetwork.org, or www.WRSTC.com. ance workup based on his or her medical his- tory and complaints. The patient’s medical and surgical histories should be reviewed and further evaluation considered on the basis of the medical history (TABLE 2).2–5 A review of systems will ensure that no cur- rent health condition will hinder diving, and a physical examination should be performed to complement the history. Absolute contraindications to scuba div- ing include, but are not limited to, hyper-

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TABLE 1 General considerations for assessing capacity to dive Exercise tolerance Equipment is bulky and heavy (> 35 lb) and sometimes must be carried over uneven terrain and for excessive distances or up and down the ladder of a boat Swimming is easier in fins and a vest, but is still difficult in certain currents Breathing When ascending from depth, any process that prevents airflow from the lungs (eg, emphysema, bulla, other causes of air trapping) puts at risk for pulmonary overinflation, which can lead to alveolar rupture and air embolus Mental status Life-threatening events can occur underwater that require certain actions A diver must not be at increased risk of change or loss of consciousness such as would occur with a seizure or hypoglycemic episode is a normal response to even non-life-threatening events at depth, but a diver with an abnormal panic or anxiety response may put himself or others at risk if he or she reacts inappropriately Recent health A vomiting or coughing diver can drown A diver with an upper respiratory infection who cannot equalize the in the ears or sinuses can rupture a tympanic membrane or sinus Recent surgical wounds can easily get infected Uncontrolled hypertension puts a diver at increased risk of pulmonary edema Medications Review medications that can alter mental status or impair exercise tolerance The real bottom line is: if a patient requires a medication to dive (eg, a decongestant, antiemetic, antiseizure medication, or antidysrhythmic), he or she should be advised not to dive

trophic cardiomyopathy, right-to-left intracar- the unclear risk of fetal emboli. Abnormal diac shunt, seizures, history of cerebrovascular facial anatomy may affect mask or mouthpiece accident, spontaneous pneumothorax, gastric fit. None of these examples is an absolute con- outlet obstruction, recurrent bowel obstruc- traindication, but all must be addressed fully tion, claustrophobia, untreated panic disorder, prior to clearing a patient to dive. A more and numerous ear, nose, and throat disorders. complete list of considerations can be found in The major concern in these cases is sudden TABLE 2. loss of consciousness, increased risk of decom- pression sickness and barotrauma, or risk to ■ POTENTIAL DIVING INJURIES other divers due to inappropriate response to stress while diving. In the unlikely circumstance that you are the There are many other situations in which first person to evaluate a patient for a com- a patient should be cautioned or sent for fur- plaint after a recent diving trip, you should be ther evaluation prior to clearance. For familiar with the potential diving injuries and instance, a history of coronary artery disease their treatment. may necessitate a stress test to prove exercise tolerance. Patients with a pacemaker must Barotrauma ensure the device is certified to withstand Barotrauma can involve any gas-filled body changes in pressure. Patients who have had space and involves tissue damage due to a fail- previous or dive-relat- ure of that space to equalize its pressure with ed injury should have a specialist evaluation the ambient water pressure.6 All forms of prior to clearance to determine risk of recur- barotrauma can occur even at very shallow rence. Pregnant women should be advised of depths if the proper procedure for ascent is not

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followed or if preexisting conditions allow for decompression injury is noted gradually on air trapping. ascent or after exit from the water.7 Middle ear barotrauma. The most prevalent Treatment of inner ear barotrauma injury associated with diving is middle ear baro- involves referral to an otolaryngologist, bed trauma or “ear squeeze.” Middle ear barotrauma rest, elevating the head of the bed to 30 most often occurs on descent when a diver fails degrees, and stool softeners to avoid increas- to equalize the pressure between the air in the ing intracranial pressure. middle ear and the ambient water. Pressure and Sinus, tooth, and facial barotrauma. volume follow Boyle’s law: PV = K (where K is a Barotrauma can also affect the sinuses, caus- constant; at a constant , the volume ing headache, epistaxis, and sinus pain, or the [V] of a gas varies inversely with the pressure [P] teeth, causing localized dental pain, usually at to which that gas is subjected).7 the site of a filling. For example, as a diver descends, the Tooth squeeze will require treatment by a increase in ambient water pressure compresses dentist with replacement or repair of the fill- the gas in air-filled body spaces such as the ing, and sinus barotrauma is treated with middle ear. The diver must address this vol- decongestants.8 If a sinus has ruptured, further ume loss by adding more gas to this space workup is needed to assess for pneumo- (equalizing it) to prevent injury. cephalus, and the patient should be referred to Divers equalize the pressure on descent an otolaryngologist.7 with a gentle , but this Gastric barotrauma. By the same mecha- maneuver may be impaired if the eustachian nism, barotrauma on ascent can occur in the tube is blocked. The external pressure may be gastrointestinal tract, where gas is trapped, so great as to implode (rupture) the tympanic and may lead to rupture of a hollow viscus. membrane, or it may just cause pain and tym- Gastric barotrauma or hollow viscus rup- panic membrane hemorrhage. Other associat- ture is rare but requires emergency treatment. ed symptoms may include vertigo, tinnitus, Pulmonary barotrauma. If the diver and hearing loss. holds his or her breath on ascent and does not The most Treatment of middle ear barotrauma exhale properly or has significant underlying common diving includes decongestants, and if the tympanic pulmonary disease, the lungs can overinflate. membrane is ruptured, the addition of antibi- Overinflation of the lungs can lead to baro- injury is middle otics (only if there is purulent drainage, in trauma of the alveoli, causing them to rupture, ear barotrauma which case one should start with typical treat- with emphysema extending into the neck or ment for otitis media), analgesia, and referral mediastinum, and possibly to air embolus. (‘ear squeeze’) to an otolaryngologist. No diving should be Pneumothorax is rare, but it must be consid- permitted until symptoms are improved and ered if the symptoms are suggestive.9 the tympanic membrane is healed. Pulmonary barotrauma rarely requires Inner ear barotrauma. Similar symptoms specific treatment other than observation, but (vertigo, tinnitus, hearing loss) may occur as indicated in TABLE 2, evaluation by a pulmo- with inner ear barotrauma, which is generally nologist is needed before the patient dives caused by a too-forceful Valsalva maneuver, again. resulting in rupture of the round or oval win- Eye injury. pressure must be dow due to unequalized pressure between the equalized by gentle exhalation through the nose middle and inner ear. If inner ear barotrauma on descent; mild superficial trauma can occur to is suspected, no findings will be noted on eval- the skin and eyes in the form of petechiae and uation of the tympanic membrane (which dis- subconjunctival hemorrhages if this is not done. tinguishes it from middle ear barotrauma). It must, however, be distinguished from inner Decompression sickness ear decompression injury, as the treatments One form of , termed for each are markedly different. The two con- decompression sickness or “the bends,” results ditions can usually be distinguished by the his- from the inflammatory response to bubbles of tory. Barotrauma more often occurs on inert gas forming in the blood and body tissues descent and continues thereafter, whereas when the pressure is significantly and rapidly

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TABLE 2 Suggested predive evaluation based on medical history Cardiovascular conditions Neurologic contraindications Coronary artery bypass grafting History of seizure other than childhood or febrile Percutaneous coronary angioplasty Concerns: Significant probability of unconsciousness Coronary artery disease puts a diver at risk of Concerns: Exercise tolerance is vital to diving—a History of transient ischemic attack or cerebrovascular stress test in which 13 metabolic equivalents (METs) is accident accomplished with no electrocardiographic changes or Concerns: Spinal cord or brain areas with abnormal symptoms is required for clearance to dive if ability is in may increase risk of decompression sickness question and may be helpful for coronary artery disease History of previous serious decompression sickness with in patients > 40 years old residual deficit Congestive heart failure Concerns: Significantly decreased left ventricular function Pulmonary conditions may affect the body’s ability to handle the excess volume Asthma or reactive airway disease load, as the body shunts blood centrally in cold water, Exercise-induced bronchospasm putting patients at increased risk of pulmonary edema. Solid, cystic, or cavitating lung lesion Hypertension Pneumothorax secondary to thoracic surgery, trauma, or Dysrhythmia requiring medication previous dive injury Significant valve regurgitation Obesity Pacemakers History of immersion pulmonary edema Concerns: Consider the condition that necessitated Other previous lung-related dive injury placement Interstitial lung disease Pacemaker must be certified to withstand pressure Concerns: Any active disease, abnormal pulmonary changes involved in function tests, or positive exercise challenge is very worrisome for diving Cardiovascular contraindications Increased risk of breathing challenge with scuba Intracardiac right-to-left shunt device as well as possible increased risk of pulmonary Concerns: Increased risk of venous emboli entering the overexpansion cerebral and spinal cord circulation Forced expiratory volume in 1 second and peak Hypertrophic cardiomyopathy and valvular stenosis expiratory flow rate should be within normal limits for Concerns: Increased risk of unconsciousness during exertion diver’s age, sex, race, and height History of ventricular tachycardia or > 1 episode of Exercise test should be negative sustained ventricular tachycardia Pulmonology consult should likely be arranged before clearance for diving in any of these cases Neurologic conditions Complicated migraines Pulmonary contraindications Head injury History of spontaneous pneumothorax Herniated nucleus pulposus Multiple sclerosis Gastrointestinal conditions Trigeminal neuralgia Peptic ulcer disease associated with pyloric obstruction History of cerebral gas embolism Severe gastroesophageal reflux disease Concerns: Ability to exercise in patients with certain Unrepaired hernia of the abdominal wall big enough to neurologic disorders should be considered become incarcerated Patients with symptoms that come and go may be Concerns: The concern is for air trapping and incorrectly diagnosed with decompression sickness if expanding on ascending symptoms present after diving Inflammatory bowel disease (if debilitating) Risk of seizure should be considered Concerns: May impair abilities, or if diving in distant Those with previous cerebral embolism must be fully locale, treatment may not be available evaluated to determine that risk of recurrence is low CONTINUED ON PAGE 719

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Gastrointestinal contraindications Mental health conditions Gastric outlet obstruction of a degree sufficient to Developmental delay produce recurrent vomiting History of drug or alcohol abuse Concerns: May cause vomiting, which can lead to drowning History of psychosis Chronic or recurrent small-bowel obstruction Use of psychotropic medications Achalasia Concerns: Patient must be mentally able to learn the Periesophageal hernia information vital to and react appropriately Concerns: Air trapping and expansion could lead to rupture as instructed Orthopedic conditions Mental health contraindications Amputation Claustrophobia Scoliosis Agoraphobia Back pain Active psychosis Concerns: Impairment of mobility or respiratory Untreated panic disorder function must be considered Drug or alcohol abuse Aseptic necrosis Concerns: Diver would be ill-equipped to handle Concerns: Aseptic necrosis may progress if stressful situations in diving decompression sickness affects the joint Otolaryngologic conditions Hematologic and rheumatologic conditions Recurrent otitis externa Sickle cell disease Significant obstruction of external auditory canal Concerns: Increased risk of decompression sickness Eustachian tube dysfunction may exist (theoretically), and sickle cell crisis may be Recurrent otitis media or sinusitis incorrectly diagnosed as decompression sickness History of tympanic membrane perforation, tympanoplasty, Polycythemia vera mastoidectomy Leukemia Significant conductive or sensorineural hearing loss Hemophilia, impaired coagulation Facial nerve paralysis not associated with barotrauma Concerns: Bleeding disorders could worsen the effects History of round window rupture or inner ear barotrauma of barotrauma and exacerbate injury associated with Concerns: Any of these conditions is likely to affect the decompression sickness ability to equalize pressure of sinuses or ears during Raynaud syndrome ascent and descent and to increase the possibility of Concerns: Digit function may become impaired, barotraumas hindering diving abilities Full prosthedontic devices Systemic lupus erythematosus History of mid-face fractures Concerns: Pulmonary function and exercise tolerance Unhealed oral surgical sites should be evaluated prior to diving Therapeutic radiation to the head or neck Temporomandibular joint dysfunction Metabolic and endocrine conditions Concerns: These conditions may affect the manner in which Hormonal excess or deficiency the mouthpiece fits or is held or the way the mask fits Obesity Renal insufficiency Otolaryngologic contraindications Concerns: Exercise tolerance must be proven Monomeric tympanic membrane Open tympanic membrane perforation Metabolic and endocrine contraindications Stapedectomy Insulin-dependent diabetes mellitus Tube myringotomy Concerns: Risk of potential rapid change in Ossicular chain surgery consciousness resulting in drowning Inner ear surgery Pregnancy Facial nerve paralysis due to barotrauma Concerns: Risk to fetus of venous emboli formed Inner ear disease other than presbycusis during decompression is unknown Laryngectomy or partial laryngectomy Tracheostomy Uncorrected laryngocele History of vestibular decompression sickness

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lowered, as on rapid ascent from diving or ness can occur, causing vertigo, tinnitus, nau- from flying too soon (earlier than 18 to 24 , vomiting, nystagmus, and hearing loss. hours) after diving. This is a result of Henry’s If bubbles form in pulmonary arteries, law: c = p/H (where c is the of symptoms can mimic pulmonary embolus, with the gas dissolved in liquid, p is the partial pres- cough, substernal chest pain, dyspnea, cyanosis, sure of the gas, and H is a constant, taking into and shock. Coronary artery bubbles can cause account the of the gas and atmos- myocardial infarction or dysrhythmias.7 pheric pressure). Management. Evaluation and treatment Therefore, the amount of nitrogen dis- of decompression injury includes hydration, solved in the diver’s body tissue or blood is supplemental , evaluation of elec- directly proportional to its , trolytes (hypokalemia and hyperkalemia have which in a diver’s case is determined by the both been noted), a chest radiograph to rule time and depth of the dive. In contrast to out pneumothorax, and arterial blood gas barotrauma and classic air embolus, the measurements. patient must have spent significant time at The necessary treatment in all of these depths greater than about 30 feet for nitrogen cases, no matter how inconsequential the ini- to accumulate in the tissues. tial symptoms may seem, is recompression in a The volume and location of bubbles hyperbaric oxygen chamber. Recompression determine whether symptoms will occur and decreases bubble volume and therefore how the patient will present. A large collec- decreases tissue distortion and vascular com- tion of bubbles can cause mechanical obstruc- promise. Results are best when recompression tive symptoms. In 75% of cases, patients note is done within 12 hours of the onset of symp- the onset of their symptoms within 1 hour of toms, but recompression should still be pur- ascent (their “decompression”). In 90% of sued even outside this window. En route to the cases, symptoms begin within 12 hours; very dive chamber, 100% oxygen should be provid- few patients present with symptoms more than ed, as well as intravenous hydration. Although 24 hours after a dive.7 symptoms may completely resolve with this Recompression Symptoms. General symptoms may pretreatment by itself, recompression should is best done include fatigue, malaise, and a sense of fore- still be undertaken because relapse is possible boding, all of which may predict further pro- without it.7 within 12 hours, gression. If the location is in the skin, itching, but it should erythema, cyanosis, and mottling may occur. A Air embolus peau d’orange effect may be seen with bubbles Air embolus, another form of decompression still be pursued that cause blockage of the lymphatic drainage. illness, is ultimately caused by any breach of a even later Fifty percent to 70% of patients describe vascular wall that allows contact of air and achy limb pain that is initially vague and then blood. In scuba diving, these breaches most becomes periarticular, most often around the commonly occur in uncontrolled ascents with shoulder. breath-holding and pulmonary overinflation Extremity symptoms are the single most (ie, pulmonary barotraumas). The alveolar- common presentation of decompression sick- capillary wall ruptures, and air enters the vas- ness, and few patients have objective physical cular system. findings. Sixty percent of patients have some If the injury is due to pressure gradients on nervous system effects in a spinal cord distrib- descent, pneumothorax or tension pneumoth- ution, which may include weakness or para- orax may result on ascent (decompression). plegia. They may also complain of hypoesthe- Air embolus can also occur from venous sia, hyperesthesia, or paresthesia, which indi- bubble formation associated with decompression cates peripheral nerve involvement. sickness; the bubbles coalesce and cross a cardiac Further central nervous system symptoms septal defect or pass through the pulmonary cap- can include personality change, memory loss, illary network to enter the arterial system. As lit- seizures, visual disturbance, and acute psychosis. tle as 0.5 cc of air can cause fatal dysrhythmias or As noted in the section on barotrauma, acute myocardial infarction. Central nervous inner ear and vestibular decompression sick- system symptoms can result, such as seizure,

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Downloaded from www.ccjm.org on September 29, 2021. For personal use only. All other uses require permission. hemisensory or motor deficits, loss of vision, and ■ PATIENT EDUCATION: altered level of consciousness.7 Bilateral asym- DIVING PRECAUTIONS metrical deficits are common. An embolus can also affect the kidneys, Reminders for your scuba diving patients with hematuria, proteinuria, and acute renal should include the following. failure, or the gastrointestinal tract causing • Assess your health prior to each dive. If bleeding.1 you have had a change in a chronic medical Evaluation of suspected air embolus condition or need medications in order to should routinely include a chest radiograph to dive, you should not dive without a medical evaluate for pneumothorax, but otherwise reevaluation. depends on the symptoms and may include • Do not fly less than 24 hours after a measurement of blood urea nitrogen, serum dive.3 This is a general recommendation that creatinine, cardiac serum markers, hemoglo- is critical after longer, deeper, or repetitive bin, hematocrit, and glucose; urinalysis; elec- dives but should be applied if there is any trocardiography; an examination for gastroin- uncertainty. testinal or vaginal bleeding; and possibly com- • Do not dive until the symptoms of a pre- puted tomography of the head. vious injury are resolved and you have been Treatment of air embolus is recompres- cleared to resume. sion in a hyperbaric chamber, intravenous • If you have developed air embolus or pul- hydration, and 100% oxygen. Repetitive monary barotrauma on past dives, you need a recompression treatments may be required. full evaluation before diving again to ensure Outcomes are best if treatment is within 4 that your risk is not increased for further hours. Flying may worsen the patient’s condi- adverse events. tion, and flight by helicopter or at the lowest • If unusual symptoms occur after diving, safe altitude to the recompression chamber seek medical care and evaluation immediately. may be necessary.7 • If you plan to leave the country to dive, Distinguishing air embolus from decom- you may be required to bring supporting pression injury does not alter the treatment paperwork to confirm your current health In suspected but is accomplished in most cases by history. status. air embolus, For example, a diver who has spent time at depths of more than 30 feet and has spinal ■ OTHER RESOURCES obtain a chest cord or peripheral neurologic symptoms is radiograph to likely to have decompression sickness. On the For other specific questions, a good medical other hand, a diver who has spent little time resource for you or your patients is DAN (Divers evaluate for below 30 feet, gives a history of holding his or Alert Network), 1-919-684-2948, www.divers- pneumothorax her breath on ascent, and has neurologic alertnetwork.org or www.WRSTC.com. More lesions more like those of a stroke is more like- details may be found in standard diving texts, if ly to have an air embolus.8 desired.10,11

■ REFERENCES

1. Pelletier JP. Recognizing injuries. Dimens Crit Care Nurs 6. Melamed Y, Shupak A, Bitterman H. Medical problems associated 2002; 21:26–27. with . N Engl J Med 1992; 326:30–35. 2. Recreational scuba Training Council. Guidelines for recreational 7. Hardy KR. Diving-related emergencies. Emerg Med Clin North Am scuba diver’s physical exam. http://WRSTC.com/downloads. Choose 1997; 15:223–240. “medical statement.” 8. Moon RE. Treatment of diving emergencies. Crit Care Clin 1999; 3. . http://diversalertnetwork.org/medical. 15:429–456. 4. British Thoracic Society Group, Subgroup of the 9. Smith DJ. Diagnosis and management of diving accidents. Med Sci British Thoracic Society Standards of Care Committee. British Sports Exerc 1996; 28:587–590. Thoracic Society guidelines on respiratory aspects of fitness for div- 10. Bennett PB, Elliott DH, editors. The Physiology and Medicine of ing. Thorax 2003; 58:3–13. Diving, 4th ed. Philadelphia: W.B. Saunders, 1993. 5. Harrison D, Lloyd-Smith R, Khazei A, Hunte G, Lepawsky M. 11. Bove AA, Davis JC, editors. , 2nd ed. Philadelphia: Controversies in the medical clearance of recreational scuba W.B. Saunders, 1990. divers: updates on asthma, diabetes mellitus, coronary artery dis- ADDRESS: Ann Marie McMullin, MD, Department of Emergency Medicine, ease, and patent foramen ovale. Curr Sports Med Rep 2005; E19, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; e-mail 4:275–281. [email protected].

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