Text & Photos by: Bruce Konefe
Just about every dive boat that you will dive from carries a large oxygen cylinder in case of a diving emergency.
We were taught all the way bay back in our open water courses that oxygen is used to treat an assortment of diving related accidents.
To breathe oxygen at higher partial pressures gives us an even greater benefit during treatment. The best way to achieve a higher partial pressure is to use a hyperbaric chamber. There are a few different types of hyperbaric chambers but the two we will be discussing are the mono-place and the multi-place chambers. Just from the names you can understand that a mono-place chamber can hold only one person and that a multi-place can hold more than one patient at a time. In this article I just want to cover the advantages and the disadvantages of the two different types of chambers. I do not want this to scare you away from getting treated, but to increase your knowledge of the subject. If you ever suspect yourself or your dive partner of having Decompression Illness (DCI), get them to the nearest hyperbaric chamber whether it is a mono-place or a multi-place chamber. Let the highly experienced doctors treat you in the best way they know how.
The larger multi-place chamber is designed more for the treatment of DCI. A mono-place chamber is better designed for treatment to heal wounds. Normally treatments for DCI will take anywhere from 2.5 hours to almost 5 hours. In the more difficult treatments the schedule can be extended by more than an hour. This is one reason why a multi-place is better suited for DCI treatments in that you do have room to move around and are not in a confined space and a tender or doctor can be in there with you in case you need further help.
Treatments for healing wounds including burns normally take around 1½ hours. One of the greatest benefits of multi-place chambers is that many can treat divers at a higher pressure, some up to a 6 ATA limit; most mono-place chambers have a maximum depth equivalent of 18 metres. In some very bad cases greater pressures are needed for treatment. However, the majority of treatments are done at the equivalent of 18 metres with the patient on 100% O2, meaning the patient is at a 2.8 ATA. This treatment can be carried out in both a mono-place and a multi-place chamber.
Oxygen toxicity in a multi-place chamber
During the majority of DCI treatments the patient will be breathing oxygen at 2.8 ATA; this is a lot higher exposure than the body is used to. Being at this higher oxygen exposure can affect the central nervous system and cause pulmonary damage, depending on the pressure and length of exposure time. These high exposures can cause a seizure which is one of the main concerns. A seizure can normally last a couple of minutes; during which the patient will loose control of his or her body. During this time a patient having a seizure can hurt themselves from loss of control, mainly to the head area. If you are in a mono-place chamber the chamber needs to be ventilated and in an emergency an emergency decompression procedure has to be performed. When a patient is having a seizure there is a chance the patient will hold his or her breath which can cause more complications during the emergency decompression procedure. One thing that has to be understood is that in a mono-place chamber the patient is in there alone without any assistance from a tender. During all treatments performed in a multi-place chamber there is an assigned chamber tender that is in the chamber with the patient to help and assist them in case a seizure does occur or if they need any other medical assistance.
Most multi-place chambers have what is called a Double Lock entrance. A double lock system allows for a doctor or a further patient to enter while a treatment is underway. What makes this convenient is that in case of an emergency a fully qualified doctor (diving medical officer) can enter a small separate chamber, which is then pressurised to equalise with the pressure in the main chamber. Once the pressure between the two chambers is the same, the doctor can pass through into the main chamber. The same system is used for a Med Lock, medical supplies, water, etc can be passed from the outside to the tender inside of the chamber.
Upkeep of chambers
Multi-place chambers take up a lot more space inside a hospital especially when you have a chamber that can hold 6-12 patients at one time. In case of an emergency you need to have enough air/O2 supplies to finish the treatments. Multi-place chambers need to have much larger storage tanks to hold this air/O2.
Mono-place chambers are much more compact and can be pushed out of the way when not being used; it is normally impossible to move a large steel chamber. The maintenance on the multi-place costs a lot more money, especially when you consider how much it costs to maintain the large air compressors, plus electricity and other facility costs.
Conclusion Whatever the case may be, if you think there is a possibility that you have DCI call a DAN-supported dive emergency hotline and get advice about whether you should get yourself to a chamber immediately. In the event of DCI, the sooner you start breathing near-100% oxygen, and the sooner you get recompressed, the better your chances are of making a full recovery. DO NOT WAIT!