The Difference Between DCS and DCI

Most divers do not know there is a difference between Decompression Sickness (DCS) and Decompression Illness (DCI). There is a large difference.

First we must define what we mean by DCS. There is an overall term called Decompression Illness (DCI) which most divers get confused and call decompression sickness (DCS), the same. No it is not the same. DCI is the over all term that has 2 subjects below it: 1) DCS and 2) Lung Over expansion Injuries.

DCS refers to the conditions caused by inert nitrogen gas coming out of solution within the body. Lung Over expansion Injuries refer to those injuries that are caused by holding your breath on ascent.

There are basically 2 types of DCS: Type I deal with skin and pain only which would include the sub type a) Cutaneous DCS and b) Joint and limb pain DCS. While Type II covers the more life-threatening which are the c) neurological DCS and d) Pulmonary DCS.

A) CUTANEOUS DECOMPRESSION SICKNESS

Bubbles coming out of solution in skin capillaries can cause this type.

B) JOINT AND LIMB PAIN DECOMPRESSION SICKNESS

Bubbles growing around and inside the tendons, ligaments and related muscles are the immediate cause. Symptoms may be found in one place on the same limb or bilateral symptoms. This type may be serious because it can lead to a mores serious problem.

C) NEUROLOGICAL DECOMPRESSION SICKNESS

Effects on the nervous system produce some of the more serious cases in DCS. Bubbles in the nervous tissue may block blood flow "backing up" the system and reduce arterial flow in the affected areas. This affects the spinal cord most often often causing numbness and paralysis in the lower legs. It tend creeps upwards to affect from the neck down.


D) PULMONARY DECOMPRESSION SICKNESS

This is DCS that manifesting itself in the lung capillaries resulting in the onset of life-threatening symptoms. Silent bubbles reach the pulmonary capilaries defusing into the alveoli. In some cases, bubbles accumulate faster than they diffuse and can block and back up blood flow to the lungs. With less blood flowing to the lungs, the left side of the heart gets less blood, causing the heart rate to rise and a drop in blood pressure. With no treatment, the circulatory system may fail.

There are four type of Lung Overexpansion Injuries

A) AIR EMBOLISM

This is if air enters the bloodstream through a ruptured alveoli into the pulmonary capillaries.

B) PNEUMOTHORAX

If lung over pressurized tears at the surface, the expanding air leaks between the lung and the peural lining.

C) MEDIASTINAL EMPHYSEMA

This is where air accumulates in the mediastinum.

D) SUBCUTANEOUS EMPHYSEMA

Follows that of Mediastinal Emphysema as air seeks its way from the mediastinum, foloowing the path of least resistance into the soft tissues at the base of the neck.