Part of being a prepared rescuer is knowing how to get an injured diver or person out of the water and up onto a boat or dock. The first step is to strip all the gear off a diver, if this hasn’t already been done. The next step is to keep the patients horizontal when removing them from the water. This is especially important for patients who have had long immersion times and who are hypothermic. Here’s why in a simple nutshell.
When immersed or submerged blood pools in our core due to the effects of water pressure and cold. This raises our blood pressure (more fluid in a small space). The body doesn’t like our blood pressure to be raised, so it suppresses anti-diuretic hormone (ADH). This tells the kidneys to go on line and filter fluid out of the blood, thereby making urine and lowering total blood volume. A decrease in blood volume results in a decreased blood pressure (BP). Voila the body is happy. The process is called immersion diuresis (urine production from immersion) and cold diuresis in cold water.
The problem is when patients are removed from the water – moving them from a high pressure to a low pressure environment (water to air). Some of you may have heard or have used MAST – military anti-shock trousers. They make a useful analogy. MAST were applied to some patients in shock with significantly low blood pressure to pool the blood I the core in order to raise BP. If you ripped MAST off a patient they could experience such a drastic reduction in BP as the blood re-entered the lower extremities that they could lose consciousness and even die.
Something similar can happen to patients with low blood volume who are pulled vertically out of water. Hence, a good way to remove a patient from the water is to use the technique of parbuckling. This can be achieved with rope, 3 inch webbing (like weight belt webbing), or even better with a rescue net. The person at the head is in charge and controls the speed as the patient’s upper body is wider than the lower body. If you’re using webbing, place one midway between the shoulders and elbows and the other midway between the knees and hips. As soon as the patient’s head approaches the gunnel or dock, use one hand to cradle the head so that it doesn’t bang into anything hard. The patient needs to remain limp with arms straight down.