World Diving Review

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Scuba Diving Article of the Month

Diving Accidents Requiring Recompression - Part4/4

Note: if you missed the previous part please follow the links: Scuba Diving Accident Part1, Scuba Diving Accident Part2, Scuba Diving Accident Part3.

II] Carbon Monoxide Poisoning

1. Cause.

Breathing air contaminated by exhaust fumes or other sources of carbon monoxide by accident. Carbon monoxide self-poisoning is also used as a suicide technique and chamber operators are likely to treat such cases, which are generally more severe than the CO poisoning which occasionally occurs in divers.

RedBloodCell

On the left side the system is working properly with the hemoglobin carrying O2 and CO2. On the right side the CO is trapping the hemoglobin so that O2 and CO2 are less and less carried.

2. Prevention

Always ensure that the air intakes of air compressors are upwind of and well away from any exhaust fumes.
If possible, avoid air intakes drawing air from inside compartments; intakes should be sited outside in the open.
Breathing gas must be obtained from authorized, reputable sources.

3. Symptoms and Signs.

Symptoms are similar to those of hypoxia but also include: pallor (the classical 'cherry red' lips are rare), severe headache, dizziness, nausea and vomiting, dimness of vision and eventually loss of consciousness.

Note. To some extent, the symptoms of CO poisoning may be masked at depth by the raised P02. Therefore, although the rate at which CO is absorbed increases with depth, the symptoms are likely to become more severe during the ascent phase of a dive.

4. Management

Allow the patient to breathe 100% 02 if available.
Deeply unconscious patients needing ventilatory assistance should be intubated and stabilized prior to recompression. A suitably qualified medical officer should accompany the intubated patient into the chamber.

Note. In cases of suspected co poisoning in divers the source of breaching gas should he isolated, and samples sent for analysis as soon as possible.

III] Summary Table of Common Diving Illnesses

Table 1 shows the common illnesses associated with diving. The table gives an index of how likely various diving conditions are to present at different phases of a dive. The most likely diagnosis for each phase is shown with +++, diagnoses which are not possible are shown as such. The table is divided into two parts. Those conditions above the double line are possible in most forms of diving whereas those below the double line are only likely to be associated with closed or semi-closed breathing circuits. Nitrogen narcosis will not occur when the breathing gas is oxy-helium.

Table 1. Diagnosis of Common Diving Complaints by Time of Onset (Phase of Dive)

	DESCENT	BOTTOM PHASE	ASCENT	ON SURFACE	ON SURFACE
	DESCENT	BOTTOM PHASE	ASCENT	< 10 MINUTES	> 10 Minutes
DECOMPRESSION ILLNESS	Not Possible	Not Possible	+	+ + +	+++
DECOMPRESSION ILLNESS			(Profile dependent & more likely near the surface)	(Profile dependent)	(Profile dependent)
AURAL AND SINUS BAROTRAUMA	+++	+/-	+ + +	++	+/-
AURAL AND SINUS BAROTRAUMA		Barotrauma usually associated with travel; possible delayed onset from descent	Reverse squeezes	Delayed onset of symptoms (e.g. perilymph fistula)	Delayed onset of symptoms
ALTERNOBARIC CALORIC VERTIGO	+	+/-	+	+	Not Possible
ALTERNOBARIC CALORIC VERTIGO		Delayed onset from descent	Possible. most likely time	Only possible in the first few minutes
NITROGEN NARCOSIS	+/-	+++	+ /-	Not Possible	Not Possible
NITROGEN NARCOSIS	Only near the bottom	Deep diving on air or Nitrox	Symptoms should improve with ascent
CO2 POISONING-HYPERCAPNIA	+/-	++	+	+/-	Not Possible
CO2 POISONING-HYPERCAPNIA	With too low flow, or accumulation in diving dress on surface	With too low flow, inadequate CO, scrubbing or improper breathing	With too low flow or exhaustion of CO, canister	Unlikely unless continuing to breath from rig on the surface	Recovery should be rapid
OXYGEN DEFICIENCY - HYPOXIA ANOXIA	++	+	++	+/-	Not Possible
OXYGEN DEFICIENCY - HYPOXIA ANOXIA	Possible: if mix improper, inadequate flow, reducer obstruction	Less likely due 10 increased partial pressure		Only possible if breathing improper mix on surface
CNS OXYGEN TOXICITY	+/-	+	+/-	+/-	Not Possible
CNS OXYGEN TOXICITY	Possible if improper mix	With long bottom time and high PO2	Less likely since PO2 is decreasing	'Off- phenomenon'