Published data

There are no double-blind randomized studies on the effectiveness of HBO combined with antibiotic therapy and surgery against anaerobic germ infections. However many open series have been published. Although they include a varying proportion of anaerobic myonecrosis and necrotizing fasciitis infections, they provide useful data. These studies fall into two categories - the first where treatment included surgery and both antibiotic and HBO therapies, and the second where surgery was combined with antibiotic therapy only. The results provided by the first category were relatively homogeneous - recovery rates of 78 to 80 % and mortality rates of 20 %. In the second category, mortality was around 36 %, except in Altemeier's study of 1971 where gas gangrene affected mostly extremities limbs and over 50 % of amputations were carried out (Table 2.2.4-5)65.

Table 2.2.4-5. Results of clinical studies sorted by the therapies used21.

Author

Patients

Recoveries (%)

Deaths (%)

Arm surgery - antibiotics - HBO

Roding, 1972

130

101 (78)

29 (22)

Hitchcock, 1975

133

100 (75)

33 (25)

Hart, 1983

139

112(81)

27 (19)

Darke, 1977

66

46(70)

20 (30)

Holland, 1975

49

36 (73)

13 (27)

Unsworth, 1984

53

46 (87)

7(13)

Hirn, 1988

32

23 (72)

9 (28)

Gibson, 1986

29

20 (70)

9 (30)

Werry, 1986

28

21(75)

7 (25)

Kofoed, 1983

23

20 (87)

3 (13)

Tonjum, 1980

14

12 (86)

2 (14)

Total

696

537 (78)

159 (22)

Surgery and antibiotics only

Altemeier, 1971

54

46 (85.2)

8 (14.8)

Hitchcock, 1975

44

24 (55)

20 (45)

Gibson, 1986

17

5 (29)

12 (71)

Freischiag, 1985

8

3 (37)

5 (63)

Total

123

78 (64)

45 (36)

In France, a multi-centre retrospective clinical study involving nearly 800 patients treated for soft-tissue anaerobic infections was published by Goulon in 198028. Percentages of recoveries and mortality were more or less similar to those of the other studies for patients provided with triple therapy (i.e., surgery, antibiotics and HBO), whereas there was a significant difference in recovery percentages in those treated with surgery and antibiotics. To eliminate the bias that might have been introduced by a possible extra mortality in the group without HBO (the severity of some of these cases having possibly lead to patient death before they could be provided with HBO), only patients having survived longer than 8 days were included in the study. The difference of mortality for myonecrosis infections still remained in favour of those who received HBO.

Some studies of necrotizing fasciitis, although not randomized, have studies the effects of HBO on standard management with surgery and antibiotics. Shupak reported on a series of 37 patients, 12 without HBO, 25 with HBO, with no significant difference in mortality93. However, since decisions regarding the use of HBO were made by the surgeon, the proportion of patients with severe signs (i.e., coma, acute kidney failure, shock, and infection located on the trunk) was greater in the HBO group, even though this did not reach the threshold of statistical difference. Another series of 54 patients with necrotizing fasciitis of the trunk (24 without HBO, 30 with HBO) showed lower mortality in the group given HBO (30 %) than in the other group (42 %) Yet again this did not reach the threshold of significance94. However, Riseman reported on a study involving 29 patients (12 without HBO, 17 with HBO) where a significant difference was shown in mortality (23 % with HBO, 66 % without HBO, p < 0.02) and on the number of surgical debridements needed (1.2 with HBO, 3.3 without HBO, p < 0.03)95.

The heterogeneity of these results can be explained by a number of facts. Studies were not randomized and the respective antibiotic, surgical and dressing regimens were not standardized. They were also not stratified for known prognostic factors making it impossible to compare the outcomes: the severity of sepsis; initial location; progression; ability to eradicate the sepsis focus; etc. were not specified. The enormous variability in mortality in groups without HBO (25 % for Shupak93, 42 % for Brown94 and 66 % for Riseman95) clearly shows the varying degree of severity of the infections considered.

The fact that the only positive study is the one where mortality in the control group is the highest confirms the impression given by clinical experience. The usefulness of HBO is most obvious when patients' conditions are most severe and the prognosis most serious. This was the decision of the jury of the Consensus Conference on indications for HBO that took place in Lille in 1994 and this was confirmed again in 2004. The jury strongly recommended the use of HBO in strictly anaerobic or mixed necrotizing infections (myonecrosis, necrotizing fasciitis) in view of the fact that this therapy could have a positive effect on survival. On the other hand, the jury was more doubtful about the usefulness of HBO for treating patients with milder disease and its use in cellulitis was therefore considered optional96.

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