Hyperbaric oxygen therapy: Types of injury and number of sessions a review of 1506 cases

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1 Hyperbaric oxygen therapy: Types of injury and number of sessions a review of 1506 cases M. D AGOSTINO DIAS 1,B. FONTES 2,R. S. POGGETTI 3,D. BIROLINI 4 1 Medical Supervisor, Intensive Care Unity, Emergency Surgery Service of the III Division of Surgical Clinics of the Clinics Hospital of the University of São Paulo School of Medicine; 2 Medical Supervisor, Emergency Surgery Service of the III Division of Surgical Clinics of the Clinics Hospital of the University of São Paulo School of Medicine; 3 Associate Professor, University of São Paulo School of Medicine; Director, Emergency Surgery Service of the III Division of Surgical Clinics of the Clinics Hospital of the University of São Paulo School of Medicine; 4 Full Professor, Trauma Discipline, Department of Surgery, University of São Paulo School of Medicine. D Agostino Dias M, Fontes B, Poggetti RS, Birolini D. Hyperbaric oxygen therapy: Types of injury and number of sessions a review of 1506 cases. Undersea Hyperb Med 2008; 35(1): Objective: The aim of this work was to identify clinical data indicative of the number of hyperbaric oxygen therapy sessions that should be prescribed for adjuvant treatment of tissue injuries of differing severity. Patients: A total of 1730 cases of patients treated with using an open protocol (without a predetermined number of sessions) was examined in this study. Method: A retrospective study involving charts review was conducted. Severity had been previously determined for the treatment of acute (fasciitis, myositis, gangrene, contaminated/infected perineal or lower extremity traumatic injuries) or chronic (osteomyelitis, pressure sore, diabetic or ischemic ulcer) injuries. Only patients that met or exceeded the supposed effective minimal treatment doses (5 sessions for acute, 10 sessions for chronic injuries) were included in the present study Results. The data analysis included 1506 cases. These consisted of 1014 patients with acute injuries, who required 11 to 18 sessions (depending on injury severity), and 492 patients with chronic injuries, who required a greater (p < 0.001) number of sessions (approximately 30/patient, independent of injury severity). Global mortality was 79/1506 patients. Conclusion: These results seem to support the initial indication of 15 sessions for the treatment acute injuries, and 30 for treatment of chronic injuries. Prospective studies may better determine the number of sessions for the treatment of different types of injuries. INTRODUCTION Therapeutic application of pure oxygen above atmospheric pressure, termed hyperbaric oxygen therapy ( ), has been used since the 1960s (1) as an adjuvant treatment of infectious, ischemic, inflammatory and necrotizing injuries. Experimental (2,3) and clinical studies (4,5,6) have demonstrated that treatment reduces injury resolution time, preserving tissue and sparing lives. However, controversies remain regarding its use, with the results of adjuvant application in clinical studies being considered sometimes favorable (7,8,9) and sometimes unfavorable (10). This inconsistency suggests that further research is required (11,12). When analyzing use data, the treatment application mode, including the number of sessions employed, should be taken into account. For example, in a retrospective multicenter study carried out in Canada (13), 24 patients with infectious necrotizing truncal injuries received conventional treatment only, whereas 30 received adjuvant using 2.5 Copyright 2008 Undersea and Hyperbaric Medical Society, Inc 53

2 to 3 atmospheres absolute (ATA), 90 minutes (min) duration sessions. The mortality rates of the conventional treatment group (42%, 10/24) and the group (30%, 9/30) did not differ statistically. However, 80% of the patients in the group received just 1 to 4 sessions; only six patients received five or more sessions. Thus, it is questionable whether the group in that study (13) should be considered representative of treated patients in general. effects depend on the O 2 pressure employed, as well as on session duration, frequency, and the number of sessions applied. The O 2 pressure recommended by the Undersea and Hyperbaric Medical Society (UHMS) and used in most protocols is at least 2.5 ATA (150 KPa) (14,15). Pressures of 2.1 to 2.4 ATA (110 to 140 KPa) may be employed in special cases, e.g. in children, but pressure less than 2 ATA (100 KPa) should never be used. The duration of each session is usually 90 min (13). Although there is no agreement regarding the length of the time interval between sessions, one session per day is commonly used, while some authors recommend 2 or even 3 sessions per day at the beginning of the treatment of particularly devastating tissue injuries such as gaseous gangrene, or rapidly progressing necrotizing fasciitis (16). Although the total treatment duration prescribed, either in terms of cumulative time or number of sessions, generally differs depending on injury characteristics and severity, the relationship between these factors and the amount of that is optimal has not been clearly established. Furthermore, although some authors have suggested a minimal effective dose for acute or chronic injuries (16,17,18), the minimal effective doses, in terms of number of sessions for the treatment of various types of injuries have not been firmly established. In this context, and with the purpose of identifying data which suggests the number of sessions that should be prescribed for adjuvant treatment of different types of tissue injury, we performed a retrospective analysis of 1506 patients that were subjected to for treatment of various types of tissue injuries. METHODS The patients included in this study had received routine treatment in a hyperbaric chamber (Sechrist 2500B) at the University of São Paulo over a ten-year period ( ). Based on the data obtained at the beginning of the treatment, the injuries were classified into two groups: acute injuries (fasciitis, trauma, surgical incision dehiscence, etc), and chronic injuries (diabetic foot, Crohn s disease fistula, skin ulcer [pressure, ischemic or mixed], and osteomyelitis, etc) (Table 1). Table 1. 54

3 The severity of the cases was classified according to the USP Severity Scale (19) (Table 2). Severity score: 1 to 10 points = score I (mild severity) 11 to 20 points = score II (moderate severity) 21 to 30 points = score III (high severity) 31 to 41 points = score IV (very high severity) This scale comprises 21 variables including diverse injury characteristics, patient age, and co-morbidities. Each variable is quantified as 1, 2, or 3 points, and the sum of the points for the variables present in each patient (total range: 1 to 41 points) indicates the severity score for the patient: score I (mild severity) = 1 to 10 points, score II (moderate severity) = 11 to 20 points, score III (high severity) = 21 to 30 points, score IV (very high severity) = 31 to 41 points (19). Each session consisted of pure oxygen application for 2 h (including total compression and decompression time of 20 to 30 min), at 2.2 to 2.8 ATA (120 to 180 KPa) pressure. Pressure variations depended on the type of tissue involved, the response to treatment, the treatment phase, and the patient s tolerance to the treatment. The inter-session interval was 24 hours for the first sessions, in general up to the tenth session and then 48 hours until resolution of the injuries. Of the patients with acute injuries, 271 (18%) were in the intensive care unit (ICU) at the beginning of the treatment, with mechanical ventilation assistance and/or being medically treated with vasoactive drugs. Sessions applied to patients with extensive and complex injuries, such as burns and traumatic injuries requiring surgery, were interrupted for the performance of surgical procedures, and continued thereafter. The collected data included injury type and severity, number of sessions applied, time of day of application, total treatment duration, and mortality. Initially, data from a total of 1730 cases were considered. For this study, a minimum treatment criterion was adopted, consisting of 5 sessions for acute, and 10 sessions for chronic injuries. Consequently, patients who did not reach this minimum number of sessions, either due to death, treatment withdrawal or being discharged from the hospital, were excluded from the analysis. Also patients who abandoned 55

4 the hyperbaric treatment after having received any number of sessions, but before the injuries were clinically resolved, were excluded. Thus, a total of 1506 patients who met the initially established minimum number of sessions and who were discharged with cured injuries, or who died before the complete resolution of the injuries, were included in this study. RESULTS The population of 1506 cases analyzed comprised 1014 (67.3%) patients with acute injuries, and 492 (32.7%) patients with chronic injuries. The patient distributions among the four severity levels for each injury type (acute or chronic) are summarized in Figure 1. The number of sessions administered until injury resolution, according to severity, with the exclusion of patients who died, is shown in Figure 2. In the statistical analysis, a 95% confidence interval (with exclusion of 5% patients with great dispersion values) was adopted. There was a total of 79 deaths (5.24%) comprising 63 of the patients with acute injuries, and 16 with chronic injuries (Figure 3). Death distributions among the different patient groups, according to severity, are also shown in Figure 3. The homogeneity of the groups, regarding mortality rate, was statistically evaluated by the chi-squared test or Fisher s exact test (20). For comparison of two independent groups, regarding number of sessions (quantitative variables), the non-parametric Mann-Whitney test for two independent samples (20) was used. For comparison of three groups, the non-parametric Kruskal-Wallis test for three independent samples, with multiple comparisons by the Dunn test (20) was used. A descriptive analysis of the number of sessions was performed by determining the minimum and maximum values, and calculating means and standard deviations, using the 95% confidence interval for the mean (20). For mortality rate analysis, the absolute and relative frequencies were calculated. In all tests, a 5% level of significance was adopted. DISCUSSION In the present study the aim was to identify data which may contribute to the determination of the number of sessions that should be prescribed for adjuvant treatment of different types of tissue injuries. Minimum number of sessions. Although common in other therapeutic modalities, an established dose regimen in terms of minimum number of sessions and session duration required for efficacy is lacking (13). Several studies have employed closed protocols, in which a predetermined number of sessions was used for all cases, independent of injury type or severity, or patient response to the initial treatment (12,21,22,23). This approach may impede the evaluation of efficacy (13,14). For example, in the treatment of burns, the use of a maximum number of sessions equal to the percentage of burned body area, independent of the depth of injury or response to initial treatment, has been reported (22). However, the difference in mortality rate between -treated and control patients was not significant. The patients examined herein were on open protocols (without a pre-determined number of sessions), with continuation of the sessions until injury resolution or death. The minimum session exposure adopted for the present study (5 sessions for acute injuries, and 10 sessions for chronic injuries) was based on a review of several studies of for acute and chronic injuries (16,17,18). According to the official recommendation of the UHMS (16) and 56

5 Figure 1 Fig. 1. Numbers of acute and chronic patients, according to the severity score and percent distribution in the acute or chronic group. Figure 2 Fig. 2. Number of sessions required by acute and chronic injuries according to their severity. The number of sessions for chronic injuries did not vary with injury severity, and was higher (*p < 0.001) than that for acute injuries of the same severity level. Increased acute injury severity correlated with number of sessions (**P < 0.001, vs. low severity or high severity groups). There was no patient with very high severity chronic injury in this study. Only patients discharged with healed lesions were included in this analysis. Figure 3 Fig. 3. Mortality according to the severity of acute or chronic injuries. The number of deaths as a fraction of the total of patients in each group is indicated above each bar. Total numbers of acute and chronic injury patients are indicated in the legend. Mortality of patients with chronic injuries did not vary significantly with injury severity. Patient groups with high or very high severity acute injuries had higher mortality rates than groups with less severe injuries (*p < vs. all other groups; **p < vs. groups with mild or medium severity injuries). A similar correlation was observed when the acute and chronic patients of the same injury severity level were pooled (p < 0.001). 57

6 the view that less than a total of five sessions should never be performed for the treatment of gaseous gangrene (18), the presently adopted criteria allow one to suppose that patients who may not have received the normal benefit of the treatment due to inadequate treatment exposure were excluded. In a review of 267 patients with USP scores III and IV injury severity, who were treated in an ICU, Dias reported that, compared to survivors, patients who died received on average 4.8 sessions of, which was significantly less than the average of 14.2 sessions received by patients who survived until being discharged; the global mortality observed in Dias study was 27.5% (18). These data support the establishment of a 5-session minimum for initial. Injury classification. The diversity of lesions commonly treated with, in terms of injury type and severity, suggests that there is a need for an injury classification rubric that includes severity grade and that provides an indication of the adequate number of sessions that should be prescribed for optimal therapeutic efficacy. There is evidence of differences between acute and chronic patient responses to in the literature. For instance, treatment of patients with crush trauma was very successful after application of 12 sessions (8), while, on average 38 sessions were required for effective treatment of diabetic ulcers (7). In one study, diabetic ulcers that had not been resolved after three months of conventional treatment alone showed improvement after 20 sessions (24). In a double-blind study involving 16 patients (8 treated with and 8 controls), it was observed that 30 sessions led to complete ulcer closure in 62% and partial closure in 38% of the cases (25). Most of the 1014 acute and the 492 chronic patients in this study had medium or high severity levels (Figure 1). Although an optimal number of sessions for treatment of acute and chronic injuries in general has not been established, it has been observed that the treatment tends to be prolonged for chronic injuries, (26) and the UHMS recommends that diabetic ulcer patients be administered at least 10 sessions (16). Our study revealed that in acute injury patients, the number of applied sessions increased with injury severity (Figure 2). Meanwhile the number sessions did not vary with severity in chronic injury patients, and was greater than that that was required for acute injuries with severity degrees I, II and III. It was also observed that the mean number of sessions applied until patient discharge or death was approximately 15 (range: 11 to 18 sessions) for acute injuries, and 30 (range: 25 to 37 sessions) for chronic injuries, for 95% of the patients. These findings support the adoption of minimum treatment criteria, and double-dosage for chronic relative to acute injury treatment. The total number of sessions required, both in acute and in chronic cases, is likely to be influenced by several factors, including procedures that may disrupt the regimen but that are commonly needed by patients, such as surgical debridement, grafting, flap rotation, wound border approximation, and performance of wound dressings (27,28), as well as transfer of the patient to the ICU while he or she is still undergoing (16). The global mortality rate of 5.24% (70/1506 cases) observed in this study comprised the 6.21% rate (63/1014 cases) in the acute group, and the 3.24% rate (16/494 cases) in the chronic group. All deaths were attributed to the underlying pathology, and none to, thus conforming with the assertion that respecting safety rules, treatment with presents minimal side effects and a high safety level (14,29). Similar to the observation regarding the number of sessions, in patients with acute, but not chronic injuries, mortality rate increased with injury severity. 58

7 The relatively low mortality of the present study could be a result of exclusion of patients with the most severe acute injuries, who did not receive an effective minimum treatment. A study assessing the mortality rate of patients receiving less than 5 sessions for diverse severity score injuries, relative to a control group with no treatment, would be needed to determine whether this is the case. Because there was not an a priori established maximum number of sessions for this study, some may question whether patients would have continued to improve after was discontinued, which might then suggest that continuation was unnecessary. On the other hand, it is important to consider that premature discontinuation of therapy could have negative or even tragic consequences for the patient. Prospective studies examining the effects of a wide range of session numbers for the treatment of diverse types of injury are needed to resolve these questions. CONCLUSIONS The present data support the initial indication of 15 sessions for the treatment of acute injuries, and 30 sessions for the treatment of chronic injuries. Our findings further suggest that establishment of an injury classification rubric may help ensure that each patient receives an treatment regimen that is appropriate for the nature and severity of his or her injuries. Future prospective studies may enable the optimal number of sessions for the treatment of different types of injuries to be determined. REFERENCES 1. Jain, K.K. Hyperbaric Medicine around the world. In K.K. Jain, ed. Textbook of Hyperbaric Medicine. Germany: Hogrefe & Huber Publ, 1999: Kiyan G, Aktas S, Ozel K, Isbilen E, Kotiloglu E, Dagli TE. Effects of hyperbaric oxygen therapy on caustic esophageal injury in rats. J Pediatr Surg 2004;39(8): Imperatore F, Cuzzocrea S, Luongo C,et al. Hyperbaric oxygen therapy prevents vascular derangement during zymosan-induced multipleorgan-failure syndrome. Intensive Care Med 2004;30(6): Zgonis T, Garbalosa JC, Burns P, Vidt L, Lowery C. A retrospective study of patients with diabetes mellitus after partial foot amputation and hyperbaric oxygen treatment. J Foot Ankle Surg 2005; 44 (4): Kessler L, Bilbault P, Ortega F, et al. Hyperbaric oxygenation accelerates the healing rate of nonischemic chronic diabetic foot ulcers: a prospective randomized study. Diabetes Care 2003;26(8): Escobar SJ, Slade JB Jr, Hunt TK, Cianci P. Adjuvant hyperbaric oxygen therapy (HBO2) for treatment of necrotizing fasciitis reduces mortality and amputation rate. Undersea Hyperb Med 2005;32(6): Faglia E, Favales F, Aldeghi A. Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcer. Diab Care 1996;19: Bouachour G, Cronier P, Gouello JP. Hyperbaric oxygen therapy in the management of crush injuries: a randomized double-blind placebo-controlled clinical trial. J Trauma 1996;41(2): Roeckel-Wiedmann I. Bennett M, Kranke P. Systematic review of hyperbaric oxygen in the management of chronic wounds. Br J Surg 2005;92: Ciaravino ME, Friedell ML, Kammerlocher TC. Is hyperbaric oxygen a useful adjunct in the management of problem lower extremity wounds? Ann Vasc Surg 1996;10(6): Wang C, Schwaitzberg S, Berliner E, Zarin DA, Lau J. Hyperbaric oxygen for treating wounds: a systematic review of the literature. Arch Surg 2003;138(3): Garcia-Covarrubias L, McSwain NE Jr, Van Meter K, Bell RM. Adjuvant hyperbaric oxygen therapy in the management of crush injury and traumatic ischemia: an evidence-based approach. Am Surg 2005;71(2): Brown DR, Davis NL, Lepawsky M, A multicenter review of the treatment of major truncal necrotizing infections with and without hyperbaric oxygen therapy. Am J Surg 1994;167: Hart G. The monoplace chamber. In: Kindwall EP, Whelan HT, eds. Hyperbaric Medicine Practice. USA: Best Publishing Company 1999: Brummelkamp WH, Hoogendijk J, Boerema I. Treatment of anaerobic infections (Clostridium myositis) by drenching the tissue with oxygen under 59

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