polyvera

Polycythemia Vera

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Question:
Subject: Hydrea & Interferon

Are there any specific concerns about these medications & diving? How about blood viscosity (hematocrit levels that vary from 46 to 54) & diving? The patient has Polycythemia Vera & is taking 500mg Hydroxyurea 3 times a day & 5 mil IU of interferon 3 times a week.

To my knowledge, there have not been any diving or hyperbaric studies on these medications specifically. As is the case most often, we will approach this query indirectly by using some guidelines that we have developed:

Factors to be considered in evaluating the relationships between drugs and diving:

The condition/illness/disease for which the medication is being given.
Any side-effects that could be dangerous underwater.
Effects of the drug that alter consciousness or cause alteration in decision-making ability.
Complex relationships between drugs, the individual, other medications, diet and the conditions for which the drugs are taken.

What is Polycythemia?
It is a condition in which the body produces too many red blood cells. There are few references to this condition in any of the major textbooks of Diving or Hyperbaric Medicine. Some symptoms of the condition that might effect diving or mimic diving accidents include headache, dizziness, itchiness, (especially following a warm bath), fullness in the left upper abdomen, red coloration, especially of the face, shortness of breath, breathing difficulty lying down, symptoms of phlebitis [inflammed veins in the legs].

Other symptoms that may be associated with this disease: vision abnormalities, red skin spots, bluish skin discoloration and fatigue. Complaints usually can be attributed to the expanded blood volume and hyperviscosity [increased thickness], which may be manifest as weakness, headache, light-headedness, visual disturbances, fatigue, or dyspnea [shortness of breath]. Easy bruising and bleeding are common. The face may be flushed, and the retinal veins engorged.

How is this condition dangerous to a diver?

Enlarged Spleen
An enlarged liver is frequently seen and over three fourths of the patients have a hugely enlarged spleen, a situation that would be extremely dangerous to a diver due to possible rupture from pressure from gear and weight belts or trauma from entry and exit with a dive.

Problem With Increased Thickness of the Blood
Complications of the disease are mainly due to the increased viscosity (thickness) of the blood, increased clotting and increased blood volume. These include: thrombosis (clotting, a cause of stroke and heart attack) and heart failure. What changes occur due to increased partial pressures of gases due to the diving environment are not known. The red blood cells are already prone to 'Rouleaux' [like a roll of coins] formation and it's possible that this may be increased by bubble formation.

Problem With Clotting
Problems with hemostasis [clotting] frequently occur because of abnormalities of platelet [small blood particles] function. It was my experience as a surgeon that we never operated on these people until the disease was under control with a PCV [packed cell volume] of less than 42% and a platelet count of less than 600,000/µL. I can see no reason why this same rule should not apply to diving. Divers with bleeding tendencies have an increased risk hemorrhage associated with barotrauma to the ears, sinuses and lungs. It is also thought that there is an increased risk of worsening of a spinal decompression accident.

Drugs

Hydrea (hydroxyurea), a medication used to treat polycythemia, can cause some or all of the following side effects: Nausea, vomiting, diarrhea, drowsiness. It may also cause the following symptoms: fever, chills, cough, lower back or side pain, painful or difficult urination; tiredness or weakness; sores in mouth or on lips; unusual bleeding or bruising, black, tarry stools, blood in urine or stools, small red spots on the skin; confusion, dizziness, convulsions, hallucinations, headache; joint pain, swelling of feet or lower legs.

Interferon can cause •anemia •angina •confusion •delirium •depression •dizziness •dyspnea •fatigue •hallucinations •hypotension •infection •myalgia •nausea/vomiting •paranoia •paresthesias •peripheral neuropathy •pruritus •rhinitis •sinus tachycardia •suicidal ideation •thrombocytopenia .

It should be apparent that some of these side effects can alter a diver's level of consciousness and ability to make decisions and participate in buddy responsibilities. It is probable that most diving physicians would be quite reluctant to give their approval for this patient to dive considering all the possibilities for disaster.

Advice to a Diver

Treated polycythemia with near normal blood counts, a normal sized spleen and none of the side effects of medication should be allowed to dive - on a case by case basis, with the approval of the diver's attending physician.