Adjunctive hyperbaric oxygen for necrotizing fasciitis

BACKGROUND

Hyperbaric oxygen therapy (HBOT) involves the therapeutic administration of 100% oxygen in a pressure chamber at pressures above one atmosphere absolute. This therapy has been used as an adjunct to surgery and antibiotics in the treatment of patients with necrotizing fasciitis with the aim of reducing morbidity and mortality.

OBJECTIVES

To review the evidence concerning the use of HBOT as an adjunctive treatment for patients with necrotizing fasciitis (NF). Specifically, we wish to address the following questions.1. Does administration of HBOT reduce mortality or morbidity associated with NF?2. What adverse effects are associated with use of HBOT in the treatment of individuals with NF?

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE Ovid (1966 to September 2014); the Cumulative Index to Nursing and Allied Health Literature (CINAHL) Ovid (1982 to September 2014); EMBASE Ovid (1980 to September 2014); and the Database of Randomised Controlled Trials in Hyperbaric Medicine (DORCTHIM, M Bennett) (from inception to September 2014). In addition, we performed a systematic search of specific hyperbaric literature sources. This included handsearching of relevant hyperbaric textbooks; hyperbaric journals (Hyperbaric Medicine Review, South Pacific Underwater Medicine Society Journal, European Journal of Underwater and Hyperbaric Medicine, Aviation Space and Environmental Medicine Journal); and conference proceedings of the major hyperbaric societies (Undersea and Hyperbaric Medical Society, South Pacific Underwater Medicine Society, European Underwater and Baromedical Society, International Congress of Hyperbaric Medicine).

SELECTION CRITERIA

We included all randomized and pseudo-randomized trials (trials in which an attempt at randomization has been made but the method was inappropriate, for example, alternate allocation) that compared the effects of HBOT with the effects of no HBOT (no treatment or sham) in the treatment of children and adults with necrotizing fasciitis.

DATA COLLECTION AND ANALYSIS

We planned independent data collection by two review authors using standardized forms.

MAIN RESULTS

We found no trials that met the inclusion criteria.

AUTHORS' CONCLUSIONS

This systematic review failed to locate relevant clinical evidence to support or refute the effectiveness of HBOT in the management of necrotizing fasciitis. Good quality clinical trials are needed to define the role, if any, of HBOT in the treatment of individuals with necrotizing fasciitis.

The medical use of oxygen: a time for critical reappraisal

Oxygen treatment has been a cornerstone of acute medical care for numerous pathological states. Initially, this was supported by the assumed need to avoid hypoxaemia and tissue hypoxia. Most acute treatment algorithms, therefore, recommended the liberal use of a high fraction of inspired oxygen, often without first confirming the presence of a hypoxic insult. However, recent physiological research has underlined the vasoconstrictor effects of hyperoxia on normal vasculature and, consequently, the risk of significant blood flow reduction to the at-risk tissue. Positive effects may be claimed simply by relief of an assumed local tissue hypoxia, such as in acute cardiovascular disease, brain ischaemia due to, for example, stroke or shock or carbon monoxide intoxication. However, in most situations, a generalized hypoxia is not the problem and a risk of negative hyperoxaemia-induced local vasoconstriction effects may instead be the reality. In preclinical studies, many important positive anti-inflammatory effects of both normobaric and hyperbaric oxygen have been repeatedly shown, often as surrogate end-points such as increases in gluthatione levels, reduced lipid peroxidation and neutrophil activation thus modifying ischaemia-reperfusion injury and also causing anti-apoptotic effects. However, in parallel, toxic effects of oxygen are also well known, including induced mucosal inflammation, pneumonitis and retrolental fibroplasia. Examining the available 'strong' clinical evidence, such as usually claimed for randomized controlled trials, few positive studies stand up to scrutiny and a number of trials have shown no effect or even been terminated early due to worse outcomes in the oxygen treatment arm. Recently, this has led to less aggressive approaches, even to not providing any supplemental oxygen, in several acute care settings, such as resuscitation of asphyxiated newborns, during acute myocardial infarction or after stroke or cardiac arrest. The safety of more advanced attempts to deliver increased oxygen levels to hypoxic or ischaemic tissues, such as with hyperbaric oxygen therapy, is therefore also being questioned. Here, we provide an overview of the present knowledge of the physiological effects of oxygen in relation to its therapeutic potential for different medical conditions, as well as considering the potential for harm. We conclude that the medical use of oxygen needs to be further examined in search of solid evidence of benefit in many of the current clinical settings in which it is routinely used.