HBO for Acute CVA (stroke)
The potential benefits of HBOT include the reversal of hypoxia through increased oxygen delivery and reduction of cerebral oedema (Hills 1999; Sukoff 1982).
It has been proposed that HBOT protects marginally viable brain (often termed 'the ischaemic penumbra') from further damage on reperfusion through these mechanisms that act to regulate abnormal cellular metabolites (Badr 2001; Selman 2004).
Despite 40 years of interest in the delivery of HBOT in stroke patients, little comparative evidence of effectiveness exists. Most reports have been of single or multiple cases, with the largest study being a series of 122 cases reported in 1980 (Neubauer 1980). A review of these studies calculated that more than half of cases improved clinically or electrophysiologically with HBOT and concluded that there was a case for setting up controlled studies (Nighoghossian 1997).
There have been three small randomised trials using HBOT for ischaemic stroke, and they have delivered somewhat contradictory and confusing results (Nighoghossian 1995, Anderson 1991, Rusyniak 2003). Given the small number of participants in these trials, we cannot be certain that a benefit from HBOT has been excluded. There is a case for further carefully planned trials. More information may be useful on a subset of disease severity and the timing of therapy. The effect of differing oxygen dosage and of other therapies administered simultaneously is not known.
Any future trials would need to consider, in particular:
appropriate sample sizes with power to detect clinically important differences;
careful definition and selection of target patients;
appropriate range of oxygen doses per treatment session (pressure and time);
appropriate and carefully defined comparator therapy;
use of an effective sham therapy;
effective and explicit blinding of outcome assessors;
appropriate outcome measures, including those listed in this review;
careful elucidation of any adverse effects;
the cost-utility of the therapy.
Such research may support anecdotal evidence and comments by others such as:
"Hyperbaric oxygen therapy might be useful for treatment of selected patients with ischemic neurological symptoms secondary to air embolism or Caisson disease". (level V). Data are lacking to support its general use in patients with acute ischemic stroke (levels III and IV).
Guidelines for the Early Management of Patients With Ischemic Stroke A Scientific Statement From the Stroke Council of the American Stroke Association.
If the efficacy can be established the results may produce a significant improvement in stroke recovery and reduced costs of rehabilitation.