Can I Dive After COVID?

The Pre-brief

I want to SCUBA dive but I just had COVID

Prebrief

With just under 3 million active SCUBA divers and 40 million and counting COVID-19 cases in the United States, there is a small but growing population of SCUBA divers who’ve been infected with the SARS-CoV-2 virus.  These divers range from recreational divers who dive once a year to the commercial and military divers who make their living underwater.  With drastic changes to pulmonary and cardiovascular physiology unique to the underwater environment, all of these COVID-19 recovered divers are finding their way to dive medicine, pulmonary medicine, or primary care offices with a legitimate question:  Is it safe to return to diving after COVID-19?  While we still know very little about the long-term consequences or physiologic sequelae of COVID-19, the following is a discussion of current recommendations to safely return to diving after COVID-19. 

Considerations in cardiopulmonary function and diving

Among the variety of potential diving injuries, the following comes to the forefront when considering potential COVID-19 related sequelae.  

Barotrauma: Healthy lungs are considered a requisite for clearance to dive.  Lungs with potential for air trapping (i.e. pulmonary blebs) are subject to overexpansion injury and gas embolism even with routine ascent.  Structural changes as sequelae of COVID-19 may predispose divers to pulmonary barotrauma, pneumothorax, and gas embolism.  

Exercise tolerance: Similar to any sport, there is exertional demand on both the pulmonary and cardiac systems with swimming inherent to diving.  With unexpected currents or navigational errors, intense kicking and exertion can be required of a diver.  Unlike most other sports though, fatigue and poor exercise tolerance can be detrimental and even lead to drowning in the underwater environment.  With specific exceptions, asthma and COPD patients are excluded from diving activities.  COVID-19 patients with persistent pulmonary function or exercise tolerance derangements similarly need vigilant evaluation regarding fitness to dive.   

Cardiac output: Troponin elevations are reported in as many as 1 in 4 hospitalized COVID-19 patients and are associated with more severe disease.  While a single etiology of troponin elevation is often unclear, potential explanations include systemic hyperinflammation, hypercoaguable state and ACS, myocarditis, and extreme cardiac demand due to a shock state.  

With immersion, a central shift in blood volume as well as increased systemic vascular resistance create a degree of cardiac stress.  This is coupled with exercise demand, as discussed.  In a healthy individual, these stressors are inconsequential.  With a cardiac functional deficit following COVID-19 though, a diver may not be able to mount the necessary physiologic response and may be at risk for immersion pulmonary edema.  This manifests similarly to flash pulmonary edema, and occurring at depth becomes a serious threat for panic and drowning.  Accordingly, patients recovering from COVID-19 with absolutely any cardiac manifestations need rigorous evaluations in order to consider returning to diving.      

Decompression sickness (The Bends): Under normal circumstances, the pulmonary capillary bed acts as a natural filter for bubbles during diving.  This occurs even after shallow, routine dives in the absence of decompression sickness.  It is unclear whether COVID-19 related pulmonary injury can alter the bubble filtering ability at the capillary level.  If so, divers would potentially be predisposed to decompression sickness, even with conservative dive profiles.    

Fitness to Dive Recommendations

In addition to being such a new disease with currently limited understanding of long term effects, a difficult part in gauging COVID-19 sequelae is that they are likely as variable as initial manifestations which range from no symptoms to death.  Even in asymptomatic to mild cases, radiographic ground glass opacities can be demonstrated one month after SARS-CoV-2 diagnosis.  Accordingly, a ‘fitness to return to diving’ evaluation is recommended, even for asymptomatic COVID-19 patients.  Given such limited data to date, some of the current recommendations outlined below are based on past experience with related coronaviruses (i.e. fibrotic changes to lung parenchyma following SARS-CoV-1 and MERS).  Post COVID-19 patients, whether asymptomatic or recovering from a stint on a ventilator, likely benefit most from a collaborative follow up course including both pulmonary medicine and dive medicine specialists when assessing safety to return to diving. A universal recommendation is that divers should abstain from diving for a period of time after COVID-19 infection.  The duration of abstention varies based on the severity of infection and testing of pulmonary and cardiac function prior to dive clearance.  The following recommendations are a composite of expert opinion and guidelines from Sadler et al. and the Diving Medical Advisory Council (DMAC).  

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Though not currently routinely recommended in formal guidelines, the diffusion capacity of the lungs for carbon monoxide (DLCO) can also be considered as an adjunctive measure of lung function.  Recent data in SARS-CoV-2 patients, as well as historical data in SARS-CoV-1 patients, suggest DLCO to be more sensitive than chest CT at detecting pulmonary deficits.  Also of note, commercial and military diving operations typically have stricter regulations for fitness to dive evaluations as governed by their respective organizations.  

Other Considerations

Central nervous system (CNS): CNS deficits are also being reported following COVID-19.  Cognitive error can be fatal for even the recreational diver.  While CNS deficits can be difficult to objectively measure, any suspicion for such should preclude clearance to dive until return to cognitive and functional baseline.

Research: A recurring commentary on this topic is how little we currently know.  Diver’s Alert Network (DAN), a large organization involved in diving safety protocols,  is actively enrolling a cohort of post-COVID-19 divers to follow prospectively (see: DRACO study).  In addition to this study, information and experience in safely returning patients to diving after COVID-19 is continually growing and evolving.