The role of hyperbaric oxygen for acute traumatic ischemias.

Acute traumatic ischemias are an array of disorders that range from crush injuries to compartment syndromes, from burns to frostbite and from threatened flaps to compromised reimplantations. Two unifying components common to these conditions are a history of trauma be it physical, thermal, or surgical coupled with ischemia to the traumatized tissues. Their pathophysiology resolves around the self-perpetuating cycle of edema and ischemia, and their severity represents a spectrum from mild, almost non-existent, to tissue death. Since ischemia is a fundamental component of the traumatic ischemias and hypoxia is a consequence of ischemia, hyperbaric oxygen is a logical intervention for those conditions where tissue survival, infection control and healing is at risk. Unfortunately, even with mechanisms of hyperbaric oxygen that strongly support its usefulness in traumatic ischemias coupled with supportive clinical data, clinicians are disinclined to utilize it for these conditions. This focuses on the orthopedic aspects of the traumatic ischemias, namely crush injury and compartment syndrome, and show how hyperbaric oxygen treatments can mitigate their severity.

Delayed recognition of Type II decompression sickness in a diver with chronic atrial fibrillation.

Introduction: This case report describes an initially overlooked Type II decompression sickness (DCS) occurrence that was confused with a cerebral vascular accident in a patient with chronic atrial fibrillation (AF). The purpose of this case report is to reinforce the maxim that DCS needs to be suspected anytime a scuba diver experiences signs or symptoms compatible with DCS after completing a scuba dive. Methods: A 71-year-old scuba diver with a history of AF and who was taking warfarin made four dives, all with maximum depths less than 60 fsw (20 msw) over a 10-hour interval. Shoulder pain developed before entering the water on the fourth dive and was worse after exiting from the fourth dive. Twenty minutes later the diver collapsed while standing and was unable to make a grip using his left hand. A literature review failed to locate any case reports of divers with AF presenting with strokelike symptoms only to find the cause was Type II DCS.. Findings: Initially the patient's findings were reviewed with a diving medicine team. The recommendation was for the patient to be managed for a stroke. The patient was transferred to a hospital for a computed tomography scan, but no recommendation was made for a hyperbaric oxygen recompression treatment. The scan showed no brain bleed or infarct. The attending neurologist (not diving medicine-trained) was concerned that the patient's findings were diving-related and arranged for transferring the patient to a hyperbaric medicine facility 25 hours later. With hyperbaric oxygen (HBO2) therapy the patient's symptoms remitted over several weeks. Conclusion: The presence of symptoms attributed to a stroke immediately after a scuba dive should not deter a trial of HBO2 therapy. The delay in starting HBO2 therapy is concerning and perhaps the reason recovery was delayed and the need for repetitive HBO2 therapies.

Toxic inoculation associated with a presumptive stingray injury.

INTRODUCTION: Stingray spine injuries are among the most common marine animal injuries in humans. While most resolve with immersion in warm water, a few become infected and require antibiotics. We present a case report of a presumptive stingray injury that evolved to a major slough and which required prolonged healing in a patient with diabetes mellitus. Our literature review was unable to find a similarly reported case. MATERIALS: A co-author was asked to evaluate and manage an ominous-appearing wound on the right foot of a diabetic. The problem developed after the individual had been wading in shallow ocean beach water. The patient's diabetic sensory neuropathy obscured the immediate association of the problem with a stingray injury, but this became the presumptive diagnosis when pain developed and necessitated that he seek medical care. FINDINGS/CLINICAL COURSE: After an initial urgent care visit, increasing pain and worsening appearance of the patient's foot necessitated a visit to our emergency department. The patient was admitted the next day due to symptoms of systemic sepsis. On the fourth hospital day, a large bulla on the lateral side of the right foot was excised. This unroofed a full-thickness slough to the periosteum level of the underlying bones. Not until the 16th hospital day had enough improvement occurred to discharge the patient. Over the next 16 weeks, the wound improved, developed a vascular base and epithelialized. CONCLUSION: With a dearth of literature about stingray injuries in patients with diabetes mellitus reported, our case is unique: The patient's wound course more closely resembled a toxic inoculation than the typical puncture wound-cellulitis presentations associated with stingray injuries.

The Gradient Perfusion Model Part 1: Why and at what sites decompression sickness can occur.

INTRODUCTION: Decompression sickness (DCS) is manifested by the quantity and location of bubbles in body tissues after reduction in ambient pressures. Models have been formulated to explain why bubbles form, but none provide satisfactory explanations as to why the findings of DCS occur as they do. This first of a three-part series explains why and at what sites DCS occurs. MATERIALS AND METHODS: Over a 50-year span and 500 cases of DCS we have managed, it has become apparent that almost all "unexplained" DCS (i.e., cases with no obvious explanation as to how/why they occurred) have physiological explanations. The vagaries of the physiology of tissue perfusion and the physics of gradients as a cause of autochthonous bubble formation were analyzed. FINDINGS: Perfusion is highly variable, with so-called "fast" tissues (i.e., tissues with a rapid rate of saturation) requiring a constant blood supply, "intermediate" tissues requiring a blood supply proportional to needs, and "slow" tissues having minimal perfusion requirements. The 5-liter blood volume in a vascular system with greater than a 20-liter capacity requires careful regulation. Disruptions in the regulation and/or overwhelming gradients explain why DCS occurs. CONCLUSIONS: Our Gradient-Perfusion Model provides an explanation as to why disordering events account for almost all cases of unexplained DCS. We propose that this latter term be discarded and "disordering events" be sought for DCS cases that have no obvious explanations.

The Gradient Perfusion Model Part 2: Substantiation of the GPM with clinical cases.

Introduction: In Part 1 of this three-part series, we provided an explanation as to why and at what sites decompression sickness (DCS) occurs, using the Gradient-Perfusion Model (GPM). In this part, we provide information to substantiate the concept and present clinical cases that were initially labeled as "unexplained DCS," but later disordering events were identified to explain the clinical presentations. Materials and Methods: Among 500 cases of DCS we have managed for over 50 years, a cohort of these patients was initially diagnosed as unexplained DCS. However, some have shown that disordering events are the likely cause of their DCS. Results: By pairing the tissue involved with the patient's dive history, a gradient-perfusion imbalance connection was identified. In all serious (Type 2) presentations of DCS, alterations in perfusion of the fast tissues were able to account for the clinical findings. The consequences demonstrated that the gradients overwhelmed the ability of altered perfusion to offgas/offload the inert gas. Pain-only and peripheral neuropathy presentations involved both intermediate and slowly perfused tissues. Rather than perfusion, gradient limitations were the reasons for the clinical presentations of these patients. Conclusions: The GPM accounts for signs and symptom presentations in DCS. This provides the basis for appropriate treatments and logical recommendations for return to diving. We recommend that the label "unexplained DCS" be discontinued and that the GPM be used to determine the cause. Once the cause is established, "DCS due to disordered decompression" becomes the appropriate term.

The Gradient Perfusion Model Part 3: An extraordinary case of decompression sickness.

INTRODUCTION: Decompression sickness (DCS) has been associated with unusual circumstances such as breath-hold diving, shallow depths, and short bottom times. We report a case of DCS with an extraordinary cause and course. MATERIALS AND METHODS: A 72-year-old healthy Hispanic female was referred to our 24/7 Hyperbaric Medicine Unit for emergency hyperbaric oxygen recompression treatment (HBO2 RCT) after developing lower-extremity paralysis following a hyperbaric air exposure in a homemade hyperbaric chamber. RESULTS: After an uneventful exposure to hyperbaric air at a maximum 72-foot depth (3.2 ATA, 32.3 psig), the patient had the delayed onset of abdominal pain and paraplegia after eating a meal. After HBO2 RCT in accordance with our management algorithm, the patient had a full recovery. CONCLUSIONS: This patient's presentation and course corresponded to what we label as "disordered decompression" and conformed to our Gradient Perfusion Model. With a finite blood volume and the need to perfuse two "intermediate" tissues simultaneously, we postulate that a "steal" syndrome arose to cause the abdominal and paralysis symptoms.

Scuba in older-aged divers.

As the population gets older, coupled with increased awareness of good health practices and the recognition that fitness contributes to participation in activities generally appropriate for younger individuals, decisions need to be made about what are appropriate activities for the older-aged scuba (self-contained underwater breathing apparatus) diver. It is essential to appreciate the distinction between chronological and physiological age. Three factors, namely fitness, comorbidities, and mobility and strength are fundamental when making decisions about participation in activities in general as well as in scuba diving for older adults. There is almost always a time to call it quits for everything.

The validity of transcutaneous oxygen measurements in predicting healing of diabetic foot ulcers.

INTRODUCTION: In 2002 Fife and Strauss (Fife, et al. Wound Rep Reg, 10:198-207; Strauss, et al. Foot Ankle Intl, 23:933-937) studied the predictability of transcutaneous oxygen measurements (TCOMs) for healing diabetic foot ulcers (DFUs). This paper analyzes the validity of the two studies and combines their information to predict which DFU will heal with adjunctive hyperbaric oxygen (HBO2) treatments. METHODS: A statistical review of the Fife and Strauss papers was performed. The numbers presented in the papers were subjected to analyses to compare like by like data as well as test for p-values and odds ratios for predicting healing of DFUs with HBO2. RESULTS: In the Strauss paper 143 subjects were studied in retrospective and prospective series. In those TCOMs which exceed 200 mmHg with HBO2 healing occurred in 87.5% even if the room air TCOM was ⟨ 30 mmHg (p ⟨ 0.001). The Fife paper studied retrospectively a subset of 221 patients who had TCOMs with HBO2. Failure rates for healing decreased progressively from 35.7% to 14.3%, with TCOMs grouped in 100-mmHg increments from 200 mmHg to 699 mmHg. This resulted in absence of statistical significance for any 100-mmHg range over 200 mmHg with HBO2 due to the small number of subjects for each 100-mmHg grouping. CONCLUSIONS: Although differences exist between the study designs, each complements the other. If TCOMs exceed 200 mmHg with HBO2, both authors observed that almost 90% of DFUs healed regardless of the room air readings when HBO2 was used as an adjunct to management.

A clinical practice guideline for the use of hyperbaric oxygen therapy in the treatment of diabetic foot ulcers.

BACKGROUND: The role of hyperbaric oxygen (HBO2) for the treatment of diabetic foot ulcers (DFUs) has been examined in the medical literature for decades. There are more systematic reviews of the HBO2/DFU literature than there have been randomized controlled trials (RCTs), but none of these reviews has resulted in a clinical practice guideline (CPG) that clinicians, patients and policy-makers can use to guide decision-making in everyday practice. METHODS: The Undersea and Hyperbaric Medical Society (UHMS), following the methodology of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group, undertook this systematic review of the HBO2 literature in order to rate the quality of evidence and generate practice recommendations for the treatment of DFUs. We selected four clinical questions for review regarding the role of HBO2 in the treatment of DFUs and analyzed the literature using patient populations based on Wagner wound classification and age of the wound (i.e., acute post-operative wound vs. non-healing wound of 30 or more days). Major amputation and incomplete healing were selected as critical outcomes of interest. RESULTS: This analysis showed that HBO2 is beneficial in preventing amputation and promoting complete healing in patients with Wagner Grade 3 or greater DFUs who have just undergone surgical debridement of the foot as well as in patients with Wagner Grade 3 or greater DFUs that have shown no significant improvement after 30 or more days of treatment. In patients with Wagner Grade 2 or lower DFUs, there was inadequate evidence to justify the use of HBO2 as an adjunctive treatment. CONCLUSIONS: Clinicians, patients, and policy-makers should engage in shared decision-making and consider HBO2 as an adjunctive treatment of DFUs that fit the criteria outlined in this guideline. The current body of evidence provides a moderate level of evidence supporting the use of HBO2 for DFUs. Future research should be directed at improving methods for patient selection, testing various treatment protocols and improving our confidence in the existing estimates.

The effect of hyperbaric oxygen in crush injuries and skeletal muscle-compartment syndromes.

Crush injuries represent a spectrum of injury to body parts as result of trauma. Presentations vary from minor contusions to limb-threatening damage. Typically, the injury involves multiple tissues, from skin and subcutaneous, to muscle and tendons, to bone and joints. In their most severe presentations, predictable complications--including osteomyelitis, non-union of fractures, amputations and failed flaps--occur in approximately 50 percent of the cases with standard of practice surgical and medical interventions. Skeletal muscle-compartment syndrome (SMCS) is another consequence of trauma, but in this situation the target tissues are muscles and nerve. Edema and/or bleeding within the confines of the fascial envelope can increase the pressure within the skeletal muscle-compartment. When the tissue fluid pressure within the compartment exceeds the capillary perfusion pressure to the muscles and nerves in the compartment, these tissues are rendered ischemic and manifest the signs and symptoms of SMCS. The SMCS, especially in its incipient stages before a fasciotomy is required, is a therapeutic challenge since no means to arrest its progression exist other than hyperbaric oxygen (HBO2). Unfortunately, HBO2 is woefully neglected as an adjunct for managing crush injury and SMCS. Strong arguments exist for its use based on evidenced-based information and how HBO2 mitigates the pathology of these conditions.

Effects of cigarette smoking on tissue gas exchange during hyperbaric exposures.

OBJECTIVES: In this study we investigate whether differences exist in human skeletal muscle (MM) and subcutaneous (SC) tissue gas tensions between chronic cigarette smokers and non-smokers measured under room air and hyperbaric conditions. METHODS: Gas tensions in resting MM and SC tissues were recorded using a mass spectrometer at four-minute intervals during two and one-half to three-hour period in smokers and non-smokers during normobaric, normoxic (room air) and hyperbaric conditions. Two hyperbaric oxygen (HBO2) protocols were utilized: Protocol A employed the continuous breathing of oxygen (O2) at 2 ATA, a typical monoplace hyperbaric chamber treatment, while Protocol B utilized intermittent air breaks between O2 breathing periods at 2 ATA representative of a multiplace hyperbaric chamber treatment. RESULTS: All tissue gas tensions changed significantly (repeated measures of variance, p=0.00001) with time as pressures and gas mixtures breathed were altered. Significant Individual Step Analysis (ISA) differences occurred with unloading of nitrogen (N2) from the muscle compartment in both protocols (T-test and Wilcoxon Rank Sum). The interaction of grouping variable and time revealed significant differences between smokers and non-smokers in unloading MM N2 in both protocols: Protocol A (p=0.02) and in Protocol B (p=0.022). Carbon dioxide (CO2) levels in both protocols decreased significantly with time when exposed to HBO2 while increasing when breathing air at 2 ATA. CONCLUSIONS: This study demonstrates: 1) Smokers release MM N2 more slowly than nonsmokers during hyperbaric oxygen exposures regardless of the treatment protocol used; 2) There were no significant differences in O2 loading of MM and SC tissues during HBO2 exposures between smokers and nonsmokers; 3) The CO2 levels in both protocols decrease with time when exposed to HBO2 while increasing with breathing air at 2 ATA; 4) The known vasoconstriction effect in subcutaneous tissue from nicotine lasts less than one hour with the topical adiabatic heating increasing the O2 loading specifically in the SC tissues of smokers; 5) Wounds heal more slowly due to the chronically injured endothelium from carbon monoxide, hydrogen cyanide, and other toxic products in smoke rather than from the transient elevations of nicotine.

Clinical Applications and Validation of an Innovative Wound Score.

OBJECTIVE: This study demonstrates the applicability of an innovative wound score that summates 5 assessments using 2-point (best) to 0-point (worst) grades based on specific findings to generate a 0- to 10-point wound score for categorizing diabetic foot ulcers as well as validates its effectiveness. MATERIALS AND METHODS: Long Beach Wound Scores (LBWS) were determined prospectively over an 18-month period in 105 hospitalized patients, with or without diabetes, with lower extremity wounds. Wounds were categorized as healthy, problem, or end-stage from their initial LBWS. Outcomes were graded as good or poor using a 5-level scale. Outcome information was available and statistically analyzed for comparisons with initial evaluation LBWSs in 85 patients. RESULTS: In the healthy category, 66.7% healed or improved and were designated as good outcomes. In the problem category, 83.3% had good outcomes. In the end-stage category, 50.0% had good outcomes. Outliers for poor outcomes in the healthy category were due to the patients' comorbidities, and good outcomes in the end-stage category were explained by successful revascularizations and/or healing of minor amputations. The accuracy of the LBWS for predicting good versus poor outcomes was 75.3%. CONCLUSIONS: The 0- to 10-point LBWS utilizes objective criteria for grading wounds, has validation data to confirm its efficacy for predicting outcomes, categorizes wound management, and is a practical tool to use for Comparative Effectiveness Research of wound care products and quantifying Minimal Clinically Important Improvement.

Does hyperbaric oxygen exposure affect high-intensity, short-duration exercise performance?

Hyperbaric oxygen (HBO) exposure involves the breathing of 100% oxygen under conditions of elevated atmospheric pressure and is used to increase the oxygen content of the plasma fraction of arterial blood. The purpose of this study was to determine the effects of acute HBO exposure on selected physiological responses and performance in response to maximal lower extremity or upper extremity short-term, high-intensity exercise. The study was performed with 2 separate experiments incorporating double-blinded and randomized protocols. In experiment 1, 9 subjects ran on a treadmill at a speed of 268 m x min(-1) with a predetermined grade. In experiment 2, 9 different subjects performed a repetitive bench press exercise. Both exercise protocols were designed to induce fatigue within 1-2 minutes. Within each experiment, subjects received either a 1-hour HBO exposure inspiring 100% O2 at 202.6 kPa (2.0 atmospheres absolute pressure [ATA]) or a 1-hour sham exposure inspiring ambient air at 121.5 kPa (1.2 ATA) before exercise. No significant differences (p > or = 0.05) were observed in postexercise blood lactate concentrations, peak heart rate, ratings of perceived exertion, or performance as determined by treadmill running time or number of completed lifts. Unlike other methods that elevate oxygen content of the blood, acute HBO exposure appears to have no significant effect on subsequent high-intensity running or lifting performance.

The Incidence of Confounding Factors in Patients With Diabetes Mellitus Hospitalized for Diabetic Foot Ulcers.

INTRODUCTION: Uncontrolled deformity, deep infection, and/or ischemia-hypoxia are highly associated with healing challenges of diabetic foot ulcers (DFUs). This paper reports the occurrences of these factors that the authors label the "Troublesome Triad" (TT) in a prospective series of 62 patients with diabetes mellitus (DM), who were hospitalized because of their DFUs. MATERIALS AND METHODS: With Institutional Review Board approval, the authors gathered data in a prospective series of patients hospitalized because of lower extremity wounds. From this data, they analyzed the DFU cohort for the incidence of each of the components of the TT. The severity of the wound was graded with the authors' 0 to 10 Wound Score in the patients who had components of the TT and compared with those who did not. RESULTS: One or more components of the TT were observed in 57 patients (91.9%). As the number of confounders increased, mean Wound Scores decreased from 5.2 for 1 confounder to 2.9 for 3 confounders (P = 0.003). Most patients had 1 or 2 confounders (38.7% and 45.2%, respectively), while only 5 (8.1%) patients had all 3 confounders. Unresolved infection was the major confounder in 38 (61.3%) patients, uncontrolled deformity in 31 (50.0%), and ischemia-hypoxia in 26 (41.9%). CONCLUSION: For those patients with DM who were hospitalized because of DFUs, confounders that require remedial interventions were present in more than 90% of patients. Recognition and management of the TT eliminates wasteful uses of resources in an attempt to heal lower extremity wounds in patients with DM where the confounders need to be addressed first.