What is Immersion Pulmonary Edema?
Scuba diving is generally considered safe when someone is adequately trained and follows the right safety measures. However, problems can occur if the conditions are not right or if safety rules are not followed. One such problem is immersion pulmonary edema, an issue that can occur during diving.
Immersion pulmonary edema is a medical term that covers scuba divers’ pulmonary edema (SDPE) and swimming-induced pulmonary edema (SIPE). Both these conditions have similar symptoms, ways to diagnose, and treatments. From studies done from the 1980s till now, we know that there are differences in causes and risk factors for these conditions.
Unfortunately, we don’t fully understand why these conditions happen, and they are likely underdiagnosed because autopsies on people who had pulmonary edema show non-specific findings such as heavy water-logged lungs and frothy sputum (a mixture of saliva and mucus) in the airways. These symptoms can also be found in cases of drowning and after prolonged attempts to revive someone.
What Causes Immersion Pulmonary Edema?
There are a lot of factors that can make someone more likely to develop immersion pulmonary edema, a condition where the lungs fill with fluid after being underwater. This could be due to drinking too much water, being in cold water, breathing in too hard, having illnesses like asthma or diabetes, taking certain medications like beta-blockers, having heart issues, doing a lot of physical activity, having a history of this problem, or having high blood pressure.
Cold water is a main factor that can contribute to this issue. However, there have been reports and studies of this happening to people who were diving in warm tropical waters that were about 86 to 95 degrees Fahrenheit. For the most part, this happens during diving in warm water. But it has been reported with people swimming who were doing intense exercise or who drank too much water.
Risk Factors and Frequency for Immersion Pulmonary Edema
Case studies from Europe suggest that the occurrence of Immersion Pulmonary Edema (IPE) is about 1.1%. Swim Induced Pulmonary Edema (SIPE) generally appears more frequently in males who are in great physical health, with no other existing health conditions. It is most common among military swimmers, combat swimmers, and triathletes, and is often linked to intense physical efforts and possibly increased breathing resistance.
Scuba Diver Pulmonary Edema (SDPE), on the other hand, is more often seen among recreational divers, especially middle-aged females, and is typically associated with pre-existing conditions such as high blood pressure, heart disease, and possibly reversible cardiomyopathies like Takotsubo Cardiomyopathy. The most frequent fatalities occur in females aged over 50.
- There’s a recurrence rate of about 30%, but this might be
undervalued because many people quit diving or rarely dive after their first episode, making it tough to monitor recurrences. - The overall frequency of IPE is tricky to estimate because the reported fatalities directly attributed to IPE have been minimal, and virtually all were in-hospital fatalities. This could be due to the heavy reliance on bystanders to report worsening symptoms and early signs since IPE can’t be distinguished from other causes of death common in swimming and diving after death.
Signs and Symptoms of Immersion Pulmonary Edema
Immersion Pulmonary Edema (IPE) is a condition that generally starts within 10 minutes of swimming or diving. The symptoms can vary quite a bit in their severity. It could start as a mild difficulty in breathing, accompanied by foamy spit. In more extreme cases, it might cause coughing up of blood, low levels of oxygen in the blood, and even death. Usually, patients suffering from IPE will have high blood pressure, and will feel extremely tired. It’s important to know that these symptoms tend to get worse as divers resurface, possibly due to the strain put on the heart during the diving session.
Testing for Immersion Pulmonary Edema
If a person is suspected to have immersion pulmonary edema (IPE), radiography might confirm it, but the condition could be so mild that a more advanced scan, such as a computed tomography (or CT) scan, might be needed as they are more precise. Similarly, swimming-induced pulmonary edema (SDPE) might have temporary respiratory or heart problems underlying it, so tests to check on the lungs and blood gases are recommended.
A thorough examination of the heart is also important, including checks for substances called troponins, creatine kinase-MB, B-type natriuretic peptide (BNP), repeated electrocardiograms (which map the movement of the heart), and an early ultrasound of the heart (echocardiogram). The heart’s arteries might also need to be examined and any abnormalities in the heart could potentially need to be treated. If the heart tests come up as abnormal, they should be repeated to check whether the abnormalities are temporary or can be reversed, which can happen in certain heart conditions like Takotsubo cardiomyopathy and reversible heart muscle dysfunction.
With IPE, tests often show high levels of BNP. A hormone called antidiuretic hormone (ADH) can be monitored by measuring copeptin, which is a stable part of the hormone ADH. People with IPE often have lower than usual levels of sodium in the blood (natremia) and the presence of albumin in urine (albuminuria). An increase in a substance called ischemia-modified albumin is also typical and it usually decreases after treatment with oxygen at normal atmospheric pressure, which helps to reduce low levels of oxygen in blood (hypoxemia).
Substances called biomarkers can be helpful in early diagnosis and in distinguishing IPE from a similar condition known as decompression sickness.
Treatment Options for Immersion Pulmonary Edema
When swimmers or divers come out of the water, the effect of the water pressure, or hydrostatic effect, on their bodies decreases. This results in reduced pressure inside the blood vessels. To prevent constriction of blood vessels and an excessive accumulation of blood in the central part of the body, it’s advisable to keep swimmers or divers warm when they leave the water. If they are awake, they should also be kept upright.
For most people, full recovery from the effects of the hydrostatic pressure of water immersion can be achieved within one to two days. This recovery may involve resting, receiving normal pressure oxygen to treat low oxygen levels in the blood, and/or undergoing beta-mimetic therapy- a type of treatment that uses drugs to relax muscles in the walls of the airways, allowing the airways to open up.
In severe cases, inversions in the water can result in heart muscle injuries or loss of consciousness, which could lead to potentially dangerous conditions like breathing in a foreign substance such as food, fluid, or stomach contents into the lungs (aspiration) or even death.
What else can Immersion Pulmonary Edema be?
Immersion pulmonary edema (IPE) can get mixed up or occur along with other diving-related health problems like lung damage (pulmonary barotrauma) and decompression sickness. However, there’s no proven link between decompression illness and Swim-Induced Pulmonary Edema (SIPE), another name for IPE. But there have been several instances when SIPE symptoms started during rising to the surface, which can create some confusion.
There are several reasons why ascending can make IPE symptoms worse. These include:
- Damage to tiny blood vessels in the lungs (pulmonary capillaries) due to increased lung blood pressure (pulmonary hypertension) caused by the lung filtering out bubbles during decompression
- Position-related effects related to water pressure leading to difficulties in breathing in (negative inspiratory pressures)
- The natural development of the disease
- Changes in the volume of gas within the chest (intrathoracic gas) moving around fluids related to lung swelling (pulmonary edema), due to Boyle’s Law
- A decrease in the amount of oxygen in the lungs during ascent, due to Henry’s law
It’s vital to distinguish SIPE from decompression sickness and a condition where bubbles block blood vessels (arterial gas embolism). This is because the treatment typically used in decompression sickness and arterial gas embolism, which involves a hyperbaric chamber, isn’t recommended for SIPE and could potentially cause harm.
In older swimmers and divers, there have been records of temporary heart muscle disorders (reversible stress cardiomyopathies), which could potentially explain why immersion triggers the disease in some cases. Because of its similarity and overlap, another lung disease caused by inhaling food, stomach acid, or saliva into the lungs (aspiration pneumonitis) should also be ruled out.
What to expect with Immersion Pulmonary Edema
Generally, once removed from the water, patients tend to get better quickly. However, there have been cases where some individuals needed intensive care, and there have even been instances of people becoming unconscious or dying. With the right supportive treatment, patients usually recover fully, with all symptoms disappearing and medical scans and tests returning to normal within a few days.
Possible Complications When Diagnosed with Immersion Pulmonary Edema
The risk of recurrence for immersion pulmonary edema (IPE) is approximately 30%. If undiagnosed, it can lead to serious or even fatal results. The best course of action is to identify and treat the root causes of IPE before taking part in more intense water activities like diving, snorkeling, or high-energy swimming.
If one doesn’t promptly investigate potential heart problems like reversible heart muscle diseases, the temporary abnormalities might return to normal. Testing many days post-event might end up providing wrong results which could then lead to mistaken medical and cardiac clearance for resuming water activities. This could cause unfortunate incidents and, worst-case scenario, death.
If a person chooses to continue diving and snorkeling, precautions need to be taken to minimize all contributing factors, such as:
- Wearing thermal protection to maintain body temperature
- Avoiding overhydration
- Maintaining equipment to ensure minimal resistance
- Avoiding excessive physical effort
- Avoiding beta-blockers or sympathomimetics, drugs that influence heart function
- Always diving with a companion
- Having emergency oxygen and capabilities to immediately seek medical attention on hand at all times
