Clinical Hyperbaric Oxygen Therapy,Wound Perfusion,and Transcutaneous Oximetry

Hyperbaric oxygen therapy (HBOT) is an important adjunct in the management of problem wounds which exist in chronic oxygen deficiency and in which the local oxygen tension is below optimal for healing. In the treatment of hypoxic and ischemic wounds, the most important effects of hyperbaric oxygenation are the stimulation of fibroblast proliferation and differentiation, increased collagen formation and cross-linking, augmented neovascularization, and the stimulation of leukocyte microbial killing. Ischemic soft tissues also benefit from hyperoxygenation through improved preservation of energy metabolism and reduction of edema. Hyperbaric oxygen is administered in either a multiplace or a monoplace hyperbaric chamber. Normally, pressures of 2 to 2.5 ATA are used for a period of 90 minutes once or twice daily. For an objective assessment of wound perfusion and oxygenation, transcutaneous oximetry provides a simple, reliable, noninvasive, diagnostic technique. It can be used for assessment of tissue perfusion in the vicinity of the problem wound. Transcutaneous oximetry may be used in the assessment of wound healing potential, selection of amputation level, and patient selection for HBOT. In diabetic patients with chronic foot ulcers peri-wound transcutaneous oxygen tensions (TcPo₂) over 400 mmHg in 2.5 ATA hyperbaric oxygen or over 50 mmHg in normobaric pure oxygen predict healing success with adjuncted HBOT with high accuracy.     

Transcutaneous oxygen measurements predict a beneficial response to hyperbaric oxygen therapy in patients with nonhealing wounds and critical limb ischemia.

Hyperbaric oxygen (HBO) therapy may be a useful adjunct in the treatment of patients with wounds associated with critical limb ischemia. These patients either cannot undergo a successful bypass or may not heal after vascular reconstruction alone. Identification of patients likely to benefit from HBO is essential before treatment, as this therapy is time-consuming, costly, and not without risk. Transcutaneous oxygen measurements (TCOM) can be used to evaluate the degree of hypoxia in ischemic tissue. In this study we evaluated whether TCOM could be used to identify those patients who would or would not benefit from HBO therapy. Our hypothesis is that a difference in transcutaneous oxygen tension readings measured near the ischemic lesion with the patient breathing room air and while breathing 100 per cent oxygen at ambient pressure may be predictive of wound healing with adjunctive hyperbaric oxygen therapy. Thirty-six patients with critical limb ischemia and nonhealing ulcers were referred for HBO therapy. They were deemed either nonreconstructible from a vascular surgical viewpoint, had failed prior revascularization attempts, or could not achieve complete wound healing even after a successful revascularization. Pretreatment assessment included a room air and post-100 per cent-O2 challenge TCOM reading obtained in the vicinity of the open wound. Hyperbaric oxygen treatments at 2.0 to 2.5 atm were then administered until healing occurred or failure was confirmed. All patients undergoing HBO had a baseline TCOM of <40 torr. Twenty-seven patients had an increase in TCOM of >10 torr with oxygen inhalation at initial evaluation. Of these patients, 19 (70%) healed their wounds with HBO therapy. Conversely the increase in TCOM was <10 torr in nine patients, and only one of these patients (11%) ultimately healed (P < 0.01). Patients with nonhealing ischemic extremity wounds may heal with adjunctive HBO therapy. We can predictably identify patients who are likely to benefit from this modality using TCOM at the time of initial evaluation. An increase of tissue O2 tension of > or =10 torr when breathing pure O2 suggests that the patient may benefit from HBO therapy. Those patients with an increase of <10 torr are unlikely to receive benefit from this treatment modality.     

Post-traumatic limb ischemia: prediction of final outcome by transcutaneous oxygen measurements in hyperbaric oxygen

In limb injuries (amputation, laceration injuries, or compartment syndrome), a circulatory insufficiency with a total or subtotal ischemia may occur and jeopardize the result of reconstructive surgery. Transcutaneous oxygen monitoring has been shown to reflect tissue perfusion and has been advocated to predict the final outcome of major vascular trauma of the limb. Unfortunately, in normal atmospheric conditions, this test is not sufficiently discriminative; we evaluate the effect of hyperbaric oxygen on the efficiency of this test. 23 patients with major vascular trauma of the limbs were evaluated by clinical examination and transcutaneous oxygen pressure (PTCO2) measurements. Sixteen had arterial repair and seven had clinical evidence of peripheral ischemia without an arterial lesion. In normal air, the transcutaneous oxygen values in the traumatized limb, of these 23 patients, were significantly lower than in the nontraumatized limb. But neither the absolute PTCO2 value nor the ratio between the traumatized limb's PTCO2 and that of the nontraumatized one can predict the final outcome (amputation). In hyperbaric oxygen (2.5 ATA), this ratio is significantly higher in the group where the surgery will succeed than in the group where final amputation will be needed (81.2 +/- 26.0 vs. 15.2 +/- 13.1; p less than 0.01). The overall sensitivity and specificity of prediction of the limb's final outcome when the bilateral PTCO2 ratio in 2.5 ATA pure oxygen is less than 0.40, are 100% and 94%, respectively. But what is perhaps more interesting is that, when considering a ratio value of less than 0.20, amputation can be predicted with a 100% true predictive value.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transcutaneous oxygen measurements under hyperbaric oxygen conditions as a predictor for healing of problem wounds

Controversy exists as to what transcutaneous oxygen (P(tc)O2) levels are required for wound healing and what role hyperbaric oxygen has for this. Current information suggests that 30 to 40 mmHg juxta-wound oxygen tensions in room air are required. We recorded P(tc)O2 measurements in room air and with hyperbaric oxygen in 190 patients with foot wounds; then looked retrospectively and prospectively whether there was any effect on healing. Transcutaneous oxygen measurements under hyperbaric oxygen conditions defined a responder group (P(tc)O2 > 200 mmHg) with a sensitivity of 0.80 and a positive predictive value of 0.88 for healing, regardless of room air measurements when hyperbaric oxygen was used as an adjunct to wound management. This information helps to objectify the indications for hyperbaric oxygen and predict healing especially in those patients with problem wounds of the foot and ankle.     

Subcutaneous tissue oxygen and carbon dioxide tensions during hyperbaric oxygenation: an experimental study in rats.

OBJECTIVE: To investigate the response of subcutaneous tissue oxygen (O2) and carbon dioxide (CO2) tensions to hyperbaric oxygenation. DESIGN: Experimental study. SETTING: University hospital, Finland. SUBJECTS: 10 Wistar rats. INTERVENTION: Subcutaneous tissue PO2 and PCO2 were directly measured with an implanted Silastic tube tonometer and capillary sampling technique while breathing air and exposed to hyperbaric oxygen (HBO) at 2.5 or 2.8 ATA pressure. Hyperbaric exposures were carried out in a large multiplace chamber pressurised with air. MAIN OUTCOME MEASURES: Subcutaneous tissue PO2 and PCO2. RESULTS: The mean subcutaneous PO2 rose from the baseline of 8 kPa (60 mmHg) to 16 kPa (112 mmHg) when rats breathed room air during pressurisation to 2.8 atm. When the rats breathed oxygen at 2.5 ATA the maximal mean tissue PO2 was four times higher than the mean starting value. During the HBO treatment at 2.8 ATA the tissue PO2 rose to a value about five times above baseline. The tissue PCO2 values almost doubled during the exposure to HBO at 2.5 ATA, probably because elimination of carbon dioxide was impaired. CONCLUSION: Measurements of tissue PO2 and PCO2 with an implanted Silastic tonometer and a capillary sampling technique can successfully be adapted to hyperbaric conditions. The method yielded reproducible results and is applicable to clinical use in hyperbaric medicine.     

The Role of Hyperbaric Oxygen Therapy in Ischaemic Diabetic Lower Extremity Ulcers: a Double-blind Randomised-controlled Trial

OBJECTIVE: ischaemic lower-extremity ulcers in the diabetic population are a source of major concern because of the associated high risk of limb-threatening complications. The aim of this study was to evaluate the role of hyperbaric oxygen in the management of these ulcers. METHOD: eighteen diabetic patients with ischaemic, non-healing lower-extremity ulcers were recruited in a double-blind study. Patients were randomly assigned either to receive 100% oxygen (treatment group) or air (control group), at 2.4 atmospheres of absolute pressure for 90 min daily (total of 30 treatments). RESULTS: healing with complete epithelialisation was achieved in five out of eight ulcers in the treatment group compared to one out of eight ulcers in the control group. The median decrease of the wound areas in the treatment group was 100% and in the control group was 52% (p=0.027). Cost-effectiveness analysis has shown that despite the extra cost involved in using hyperbaric oxygen, there was a potential saving in the total cost of treatment for each patient during the study. CONCLUSION: hyperbaric oxygen enhanced the healing of ischaemic, non-healing diabetic leg ulcers and may be used as a valuable adjunct to conventional therapy when reconstructive surgery is not possible.     

Transcutaneous oxygen measurements predict healing of leg wounds with hyperbaric therapy.

Twenty-six patients with chronic leg wounds had transcutaneous oxygen measurements taken from the peri-wound area and a chest reference site before undergoing hyperbaric oxygen therapy in order to evaluate the utility of transcutaneous oxygen measurements in predicting the response of wounds to hyperbaric therapy. Wound scores and wound areas were determined before treatment and after 10 hyperbaric exposures. Patients whose wounds averaged a 5% or greater reduction in wound score per treatment were designated "responders." Nine patients' wounds exhibited at least a 5% reduction in wound score per treatment. There were no differences observed between responders and the 17 nonresponders in age, duration of the wound, initial wound area, initial wound score, or in wound or reference transcutaneous oxygen measurements. Responders required significantly fewer treatments to achieve wound closure than did nonresponders. Peri-wound transcutaneous oxygen pressure when the patient was exposed to 2.4 atmospheres absolute correlated directly with the improvement in wound score per treatment (r = 0.64, p = 0.03). An inverse correlation was noted between surface peri-wound transcutaneous oxygen pressure and improvement in wound score per treatment (r = -0.74, p = 0.006). Elevated peri-wound transcutaneous oxygen measurements at 2.4 atmospheres absolute and reduced peri-wound oxygen measurements at 1 atmosphere absolute were associated with a more rapid response to hyperbaric oxygen treatments in patients with chronic leg wounds. The use of these measurements should allow this expensive and time-consuming therapy to be limited to those patients most likely to benefit.     

Efficacy of Hyperbaric Oxygen Therapy in Diabetic Foot Ulcers Based on Wagner Classification

Diabetic foot ulcer is a common chronic complication of diabetes mellitus. In addition to conventional primary therapy, there are adjuvant therapy methods such as hyperbaric oxygen therapy for the healing of diabetic foot ulcer wounds. The present study aimed to determine the efficacy of hyperbaric oxygen therapy in diabetic foot ulcers based on Wagner classification. It was performed retrospectively from prospectively collected data. One hundred thirty patients with diabetic foot ulcers were assessed in 2 groups: 1 group received hyperbaric oxygen therapy; the other group did not. Patients were examined according to age, sex, ulcer grade based on Wagner classification; ulcer healing status; whether hyperbaric oxygen therapy was received; duration of diabetes in years; HbA1C, sedimentation, C-reactive protein levels; and presence of accompanying diseases, including peripheral arterial disease, chronic obstructive pulmonary disease, hypertension, chronic kidney disease, neuropathy, and retinopathy. The mean follow-up period was 19.5?±?4.45 months (range 12 to 28 months). Seventy-one (54.6%) patients received hyperbaric oxygen therapy, and 59 (45.4%) patients did not. All patients in Wagner grade 2 healed in both groups. In the group that received hyperbaric oxygen therapy for grade 3 and 4 patients, 35 (87.5%) and 11 (84.6%) healed, respectively. In total, 60 (84.5%) patients in the group that received hyperbaric oxygen therapy healed. The subgroup comparison conducted according to Wagner classification revealed no differences between the 2 groups of grades 2 and 5 patients. It also revealed that treatment had higher levels of efficacy in the healing of ulcers in grade 3 and 4 patients.     

Intracranial pressure responses during hyperbaric oxygen therapy.

The responses of intracranial pressure (ICP) to hyperbaric oxygen (HBO) therapy and arterial gas pressures were investigated. ICP was measured through a ventricular or spinal drainage catheter in patients with brain tumor or cerebrovascular disease. Changes in ICP, heart rate (HR), arterial blood pressure (ABP), and transcutaneous partial pressure of carbon dioxide (PtcCO2) or oxygen (PtcO2) were recorded continuously during air or 100% O2 breathing at 1 and 2.5 atmospheres absolute (ATA). HR and PtcCO2 decreased and mean ABP was unchanged during HBO inhalation. ICP was reduced at the beginning and tended to increase gradually during HBO inhalation. The change from air to O2 without altering respiratory frequency and volume caused a gradual increase of ICP and PtcCO2 with a transient ICP reduction in an artificially respirated patient. Intentionally reduced respiration to maintain PtcCO2 at the value at 2.5 ATA with air caused the ICP to return to near the value at 2.5 ATA with air even during HBO inhalation. These findings suggest that reduced ICP is initially due to direct cerebral vasoconstriction caused by hyperoxia and is maintained mainly by induced hypocapnia during HBO inhalation. Care is required when giving HBO therapy to patients with a high ICP and/or who are respirated artificially.     

Treatment of diabetic foot complications with hyperbaric oxygen therapy: A retrospective experience

BackgroundThe aim of this study is to evaluate the role of hyperbaric oxygen in the treatment of diabetic foot ulcers.MethodsWe performed a retrospective observational study of all patients with diabetic foot ulcers treated at the Institution's hyperbaric chamber between January 2010 and August 2012. Patient data was obtained upon patient hospital visit and prospective clinical record consultation.ResultsTwenty-six foot lesions including 13 foot ulcers Wagner grade 2 or greater and 13 amputation stump ulcers were submitted to hyperbaric oxygen therapy between January 2010 and August 2012 in our Institution. Of these, 23 foot lesions completed treatment and complete epithelialization of the primary lesion was achieved in 15 (65%). The mean healing period since the first hyperbaric oxygen therapy session was 16 weeks. Above-ankle amputations were performed in 3 limbs and transmetatarsal amputations in 2 limbs.ConclusionHyperbaric oxygen may be associated with ulcer healing in selected diabetic foot ulcers with impaired cicatrization.     

Hyperbaric oxygen in the treatment of calciphylaxis: a case series.

BACKGROUND: Calciphylaxis, also referred to as calcific uraemic arteriolopathy, is a syndrome associated with end-stage renal disease (ESRD), and causes necrotic skin ulcers, often leading to a fatal outcome. Hyperbaric oxygen (HBO(2)) therapy has been used to enhance wound healing, but its role in the treatment of calciphylaxis is unclear. METHODS: We undertook a retrospective study of patients on renal replacement therapy with biopsy-proven calciphylaxis who were treated with HBO(2) between March 1997 and February 2000. RESULTS: Five patients were treated with HBO(2): three patients were on continuous ambulatory peritoneal dialysis (CAPD) and two were on chronic haemodialysis therapy. None of the patients had uncontrolled hyperparathyroidism and none underwent parathyroidectomy. The patients each received 25-35 treatments of HBO(2) at 2.5 atmospheres for 90 min per treatment. Two of these patients had complete resolution of extensive necrotic skin ulcers, with no adverse effects of HBO(2) therapy. Both had improvement in wound area transcutaneous oxygen pressure (P(tc)O(2)) with administration of 100% oxygen when measurements were taken at normobaric and hyperbaric pressures. In the other three patients receiving HBO(2), the skin lesions did not resolve. P(tc)O(2) was measured in two of these patients, neither of whom showed improvement with 100% oxygen administered at normobaric pressure. CONCLUSIONS: The data support a role for HBO(2) in the treatment of some patients with calciphylaxis, particularly as in the absence of uncontrolled secondary hyperparathyroidism there are few therapeutic options.     

Management of clostridial gas gangrene and the role of hyperbaric oxygen.

BACKGROUND AND AIMS: Clostridial gas gangrene is one of the most dreaded infections in surgery. The aim of this study was to investigate the efficacy of surgery, antibiotic treatment, surgical intensive care and especially the role of hyperbaric oxygen in the management of clostridial gas gangrene. MATERIAL AND METHODS: 53 patients, 42 of them submitted from other hospitals in Finland. After the diagnosis had been made the patients underwent surgical debridement, broad spectrum antibiotic therapy and a series of hyperbaric oxygen (HBO) treatments at 2.5 ATA pressure. The necrotic tissue was excised and incisions were made in the affected areas. Amputations were performed when necessary. RESULTS: Twelve patients died (22.6%). Hyperbaric oxygen therapy decreased the systemic toxicity and prevented further extension of the infection thereby improving the overall outcome of the patients. CONCLUSION: Hyperbaric oxygen therapy of gas gangrene seems to be life-, limb- and tissue saving. Early diagnosis remains essential. Patient survival can be improved if the disease is recognized early and appropriate therapy applied promptly. Surgical and antibiotic therapy as well as HBO treatment combined with surgical intensive care must be started as soon as possible.     

Treatment of diabetic foot ulcers with hyperbaric oxygen

The delivery of oxygen to the wound site is crucial in healing diabetic foot ulcers, and impairment of this process in people with diabetes leads to delayed wound repair. Hyperbaric oxygen therapy works by elevating the plasma oxygen level. Fibroblasts synthesise and modify collagen, and both these activities require relatively high partial pressures of oxygen. Hyperbaric oxygen can promote healing by stimulating fibroblast activity and collagen formation. Increasing oxygen tensions also has a direct and toxic effect on anaerobes, therefore hyperbaric oxygen therapy has a special role in treating diabetic foot infections. Studies on hyperbaric oxygen therapy in general show it to be a beneficial adjunctive therapy for diabetic foot ulcers. However much of the work is anecdotal and more controlled trials are required.     

The predictive value of transcutaneous oxygen tension measurement in diabetic lower extremity ulcers treated with hyperbaric oxygen therapy: a retrospective analysis of 1144 patients

The objective of this retrospective analysis was to determine the reliability of transcutaneous oxygen tension measurement (TcPO2) in predicting outcomes of diabetics who underwent hyperbaric oxygen therapy for lower extremity wounds. Six hyperbaric facilities provided TcPO2 data under several possible conditions: breathing air, breathing oxygen at sea level, and breathing oxygen in the chamber. Overall, 75.6% of the patients improved after hyperbaric oxygen therapy. Baseline sea-level air TcPO2 identified the degree of tissue hypoxia but had little statistical relationship with outcome prediction because some patients healed after hyperbaric oxygen therapy despite very low prehyperbaric TcPO2 values. Breathing oxygen at sea level was unreliable for predicting failure, but 68% reliable for predicting success after hyperbaric oxygen therapy. TcPO2 measured in chamber provides the best single discriminator between success and failure of hyperbaric oxygen therapy using a cutoff score of 200 mmHg. The reliability of in-chamber TcPO2 as an isolated measure was 74% with a positive predictive value of 58%. Better results can be obtained by combining information about sea-level air and in-chamber oxygen. A sea-level air TcPO2 < 15 mmHg combined with an in-chamber TcPO2 < 400 mmHg predicts failure of hyperbaric oxygen therapy with a reliability of 75.8% and a positive predictive value of 73.3%.     

Hyperbaric nitrogen prolongs breath-holding time in humans

Either an increase in PaCO(2) or a decrease in PaO(2), can affect respiratory stimulation through respiratory centers, thus influencing breath-holding time (BHT). This study was designed to determine whether and how hyperbaric air could influence BHT in comparison with hyperbaric oxygen in humans. We studied 36 healthy volunteers in a multiplace hyperbaric chamber. BHT, pulse oximeter, and transcutaneous carbon dioxide tension were measured at 1 and 2.8 atmosphere absolute (ATA) in two groups. Group A (n = 20) breathed air. Group O (n = 16) breathed oxygen with a face mask (5 L/min). BHTs were 108 +/- 28 s at 1.0 ATA and 230 +/- 71 s at 2.8 ATA in Group A, and 137 +/- 48 s at 1.0 ATA and 180 +/- 52 s at 2.8 ATA in Group O. Transcutaneous carbon dioxide tension in Group A (59 +/- 2 mm Hg) was higher than that in Group O (54 +/- 2 mm Hg) at the end of maximal breath-holding at 2.8 ATA. The prolongation of BHT in hyperbaric air is significantly greater than that in hyperbaric oxygen. Implications: Breath-holding time is significantly prolonged in hyperbaric air than it is in hyperbaric oxygen. The mechanism involves the anesthetic effect of nitrogen suppressing the suffocating feeling during breath-holding.     

Hyperbaric oxygen therapy in the treatment of wounds, in plastic and reconstructive surgery]

After recalling the mechanism of action of hyperbaric oxygen (HBO) on healing processes, the authors review the principal indications for this technique in plastic and reconstructive surgery, such as crush injuries and acute post-traumatic ischemia of the limbs, skin flaps and skin grafts, when there is a risk of their not taking, and burns. They stress the importance of strict, stratified therapeutic protocols with control of the hyperoxygenation induced by HBO. In the authors' experience, transcutaneous measurements of the partial pressure of oxygen under the hyperbaric atmosphere is a very useful method with a predictive value to determine the indications for treatment with HBO and to monitor its effects.     

Hyperbaric oxygen

This cutting edge article discusses the most frequent uses of hyperbaric oxygen for the orthopedic surgeon. Hyperbaric oxygen therapy is an adjunct to orthopedic interventions when healing problems are anticipated due to wound hypoxia or uncontrolled infection.     

Hyperbaric oxygen therapy in acute necrotizing infections with a special reference to the effects on tissue gas tensions

Clostridial gas gangrene and perineal necrotizing fasciitis or Fournier's gangrene are rare but serious infections with an acute onset, rapid progression, systemic toxemia and a high mortality rate. The aim of this study was to investigate the efficacy of surgery, antibiotic treatment, surgical intensive care and in particular the role of hyperbaric oxygen (HBO) in the management of these infections. An experimental rat model was used to investigate the possibilities for measuring tissue oxygen and carbon dioxide tensions during hyperbaric oxygen treatment. In addition to this preliminary experimental study, Silastic tube tonometer and capillary sampling techniques were tested to measure the effect of hyperbaric oxygen treatment on subcutaneous oxygen and carbon dioxide tensions in patients with necrotizing fasciitis and healthy controls. Between January 1971 and April 1997, 53 patients with Clostridial gas gangrene were treated in the Department of Surgery, University of Turku. The patients underwent surgical debridement, broad spectrum antibiotic therapy and a series of hyperbaric oxygen treatments at 2.5 atmospheres absolute pressure (ATA). Twelve patients died (22.6%). Hyperbaric oxygen therapy in gas gangrene seems to be life-, limb- and tissue saving. Early diagnosis remains essential. Patient survival can be improved if the disease is recognized early and appropriate therapy instituted promptly. Between February 1971 and September 1996, 33 patients with perineal necrotizing fasciitis were treated in the Department of Surgery, University of Turku. The management included surgical debridement of the necrotic tissue with incisions and drainage of the involved areas, antibiotic therapy, hyperbaric oxygen treatment at 2.5 ATA pressure and surgical intensive care. Three patients died giving a mortality rate of 9.1%. The survivors received hyperbaric oxygen therapy for 2-12 times. Our results indicate that hyperbaric oxygenation is an important therapeutic adjunct in the treatment of Fournier's gangrene. Electrical equipment should not be used unsheltered in a hyperbaric chamber due to the increased risk of fire. The subcutaneous tissue gas tensions of rats were therefore measured using a subcutaneously implanted Silastic tube tonometer and a capillary sampling technique. The method was successfully adapted to hyperbaric conditions. The subcutaneous oxygen tension levels increased five fold and the carbon dioxide tension levels two fold compared to initial levels. The PO2 and PCO2 of subcutaneous tissue and arterial blood were measured directly in six patients with necrotizing fasciitis and three healthy volunteers in normobaric conditions and during hyperbaric oxygen exposure at 2.5 ATA pressure. The measurements were carried out in healthy tissue and at the same time in the vicinity of the infected area of the patients. During HBO at 2.5 ATA subcutaneous oxygen tensions increased several fold from baseline values and carbon dioxide tensions also increased, but to a lesser degree in both healthy and infected tissues. When examining the subcutaneous PO2 levels measured from patients with necrotizing fasciitis, the PO2 was regularly higher in the vicinity of the infected area than in healthy tissue. In general, HBO treatment resulted in a marked increase in tissue oxygenation in both healthy tissue and in the vicinity of infected tissue. The hyper-oxygenated tissue zone surrounding the infected area may be of significance in preventing the extension of invading microorganisms.     

Chronology and determinants of tissue repair in diabetic lower-extremity ulcers

The natural history of tissue repair and the critical determinants of faulty healing of diabetic ulcers remain obscure despite recent advances in our knowledge of the cellular physiology of normal cutaneous healing. To characterize the chronology and identify important factors affecting healing, we applied an objective method to quantify the rate of wound healing of full-thickness lower-extremity ulcers in 46 diabetic outpatients who received local wound care under a standardized clinical protocol. The initial ulcer healing rate, eventual status of tissue repair, and definitive clinical outcome were not significantly associated with age; diabetes type, duration, or treatment; level or change in glycosylated hemoglobin; current smoking; presence of sensory neuropathy; ulcer location or class; initial infection; or frequency of recurrent infections. However, direct measures of local cutaneous perfusion, estimated by periwound measurements of transcutaneous O2 tension (TcPo2) and transcutaneous CO2 tension (TcPco2), were significantly associated with the initial rate of tissue repair (P = 0.003 and 0.005, respectively). The strong prediction of early healing by these parameters of local skin perfusion was independent from the effects of segmental Doppler arterial blood pressure at the dorsalis pedis, although eventual ulcer reepithelialization was significantly related to foot blood pressure and periwound TcPo2 and TcPco2. We conclude that periwound cutaneous perfusion is the critical physiological determinant of diabetic ulcer healing, indicating a 39-fold increased risk of early healing failure when the average periwound TcPo2 is less than 20 mmHg.     

Bone allograft contamination in multiorgan and tissue donors

Fifty patients with chronic diabetic foot ulcers in whom conventional therapy had failed were treated with topical hyperbaric oxygen alone (15 patients) or in combination with a low energy laser (35 patients). Eleven of these patients were treated on an ambulatory basis with topical hyperbaric oxygen. The mean time the ulcer was present before therapy was 9 ± 6.6 months. The mean number of treatments was 25 ± 13, and the mean duration of therapy was 3 ± 1.8 months. Forty-three of the 50 patients were cured. No adverse reactions were noted. Our impression is that topical hyperbaric oxygen alone or in combination with a low power laser are valuable adjuvants to conventional therapy for diabetic foot ulcers. Received: 3 January 1997