Role of hyperbaric oxygen therapy in the rapid control of gas gangrene infection and its toxaemia.
Fifteen cases of proved gas gangrene infection were studied to assess the rapidity of control of infection and associated toxaemia, by hyperbaric oxygen therapy at 2 1/2 atmospheres pressure. Within 3-5 sittings, all the cases (100%) were found to become devoid of clostridial organisms as judged by smear and culture methods.
Gas gangrene is an inflammatory necrotising process, always accompanied by an impaired circulation and is caused by the spore-bearing Clostridial species of organisms consisting of a) saccharolytic group viz. C. perfringens, C. oedematiens and C. septicum and b) proteolytic group viz. C. sporogenes and C. histolyticum. The use of oxygen in the treatment of this infection is based on the anaerobic nature of the causal micro-organism. This study was conducted to find out the efficacy and rapidity of control of the infection by hyperbaric oxygen at our set-up.
The present study includes 15 cases of microbiological ly proved gas gangrene treated at the 'Hyperbaric Oxygen Therapy Unit' of Nair Hospital during 1984-85. The cases comprise 13 adults (12 males and 1 female) and 2 children (both males). Each case was examined and a swab was taken for smear and anaerobic culture from the wound after inspection. This was followed by cleansing of the wound and opening up of all the dead spaces, making sure that the initial debridement was adequate before starting the treatment.
Treatment schedule for hyperbaric oxygen is illustrated in [Figure - 1].
In short, all the patients were subjected to 100% oxygen for 2 hours at 25 lb/sq. inch pressure, which approximates to 2½ atmospheres. Each one received a minimum of 3 successive sittings, at an interval of 1 hour each, after which a repeat swab was taken from the wound for smear and culture. The next treatment schedule was based on smear and culture results and toxic signs and symptoms of the patient. If positive for the organisms, then the sittings at hourly intervals were continued, with swabs taken after every 2 sittings. These sittings were given till swab became negative for spore-bearing organisms. In toxic patients with a negative swab report, the sittings were given at intervals of 6-8 hours till the general toxicity of the patient was controlled. After this 4 extra sittings, with much wider intervals in between (12-24 hours) were given. The non-toxic patients with negative swab report received the 4 extra sittings as mentioned for the earlier group.
All the 15 patients with gas gangrene had unhealthy wounds with foul smelling discharge. Crepitus was found to be present in only 4 patients. Signs of toxaemia in the form of mild stupor or disorientation, high fever and rapid pulse were found to be present in 8 patients; more common in those having proximal limb involvement. All the cases showed Gram +ve spore-bearing rods and racquet shaped organism on smear. The swab taken prior to the treatment revealed clostridial species on culture.
At the end of 3 sittings with hyperbaric oxygen, 11 patients had swabs negative for spore-bearing organisms. The culture also revealed the same findings. The remaining 4 patients showed smear and culture negativity after 5 sittings. By this time, neither the foul smell nor the crepitus was found in all wounds. This means that within 18 hours, in all patients (100%) the infection was well controlled. The general toxicity improved remarkably in all the 8 cases, within 36 hours' duration, which consisted of 5-6 sittings of hyperharic oxygen at longer intervals.
No serious complications of this treatment per se were experienced. Three of the patients complained of slight pain in the ear, which stopped on slowing the rate of compression and decompression, and asking the patients to swallow more often.
The success of hyperharic oxygen therapy in the control of gas gangrene infection by clostridial organisms is based on 2 factors- (i) Henry's law of solubility of gases, and (ii) anaerobic character of the micro-organisms.
Henry's law of solubility of gases states that the solubility of gases in the blood is directly proportional to pressure of the gases in alveoli. At normal atmospheric pressure, only 0.3 ml of oxygen is dissolved in plasma. However, when pure 100% oxygen is administered at 2 atmospheres pressure, then 4 ml of oxygen gets physically dissolved and at 3 atmospheres, 6 ml gets dissolved in plasma,. Thus, the tissues get totally drenched with oxygen, which creates an environment incompatible with the survival of anaerobic organisms.
Previously, local injections of oxygen around the infected area have been tried,, but this only restricts spread of the anaerobic infection and does not cure it. Also, this method cannot be used for intra-peritoneal infections and septicaemia.
Most of the workers have used hyperbaric oxygen at 3 atmospheres pressure,,,. However, we have found satisfactory results even with 2 ½ atmospheres pressure.
We feel that 5 sittings of hyperbaric oxygen therapy are enough to control gas gangrene. The additional 4 sittings, given to each patient following smear negativity, are only as a safety factor.
The amazingly rapid control of the toxaemia can be explained on the basis of (i) stoppage of production of toxins 2 viz. lecithinase, proteinase, hyaluronidase and hemolysin by clostridial organisms, as a result of lethal effect of hyperbaric oxygen on organisms; and (ii) improvement in circulation 4 following the cessation of clostridial gas production.
The control of necrotizing infection and improvement in local circulation decrease the need for radical surgery. In addition, improvement in general condition of the patient favours the outcome of surgery.
Hence we advocate the hyperbaric oxygen therapy prior to definitive surgery.