Successful hyperbaric oxygen treatment of a patient with a HeartMate III left ventricular assist device.

A 53-year-old woman with a HeartMate III left ventricular assist device (LVAD) was successfully treated under hyperbaric conditions for haemorrhagic cystitis. The HeartMate III LVAD inserted in this patient had not previously been tested or certified for use under hyperbaric conditions. To our knowledge this is the first report of the HeartMate III LVAD being used to support a patient undergoing hyperbaric treatment. The overview detailed here of the safety and technical aspects of managing this patient for hyperbaric treatment was possible due to the collaboration of a multi-disciplinary team. We believe that our experience has demonstrated a pathway to safe hyperbaric treatment of patients dependent upon a HeartMate III LVAD.

Hyperbaric Oxygen for Lower Limb Trauma (HOLLT): an international multi-centre randomised clinical trial.

INTRODUCTION: Hyperbaric oxygen treatment (HBOT) is sometimes used in the management of open fractures and severe soft tissue crush injury, aiming to reduce complications and improve outcomes. METHODS: Patients with open tibial fractures were randomly assigned within 48 hours of injury to receive standard trauma care or standard care plus 12 sessions of HBOT. The primary outcome was the incidence of necrosis or infection or both occurring within 14 days of injury. RESULTS: One-hundred and twenty patients were enrolled. Intention to treat primary outcome occurred in 25/58 HBOT assigned patients and 34/59 controls (43% vs 58%, odds ratio (OR) 0.55, 95% confidence interval (CI) 0.25 to 1.18, P = 0.12). Tissue necrosis occurred in 29% of HBOT patients and 53% of controls (OR 0.35, 95% CI 0.16 to 0.78, P = 0.01). There were fewer late complications in patients receiving HBOT (6/53 vs 18/52, OR 0.22, 95% CI 0.08 to 0.64, P = 0.007) including delayed fracture union (5/53 vs 13/52, OR 0.31, 95% CI 0.10 to 0.95, P = 0.04). Quality of life measures at one and two years were superior in HBOT patients. The mean score difference in short form 36 was 2.90, 95% CI 1.03 to 4.77, P = 0.002, in the short musculoskeletal function assessment (SMFA) was 2.54, 95% CI 0.62 to 4.46, P = 0.01; and in SMFA daily activities was 19.51, 95% CI 0.06 to 21.08, P = 0.05. CONCLUSIONS: In severe lower limb trauma, early HBOT reduces tissue necrosis and the likelihood of long-term complications, and improves functional outcomes. Future research should focus on optimal dosage and whether HBOT has benefits for other injury types.

Cerebral arterial gas embolism from attempted mechanical thrombectomy: recovery following hyperbaric oxygen therapy.

Cerebral arterial gas embolism is a recognised complication of endovascular intervention with an estimated incidence of 0.08%. Its diagnosis is predominantly clinical, supported by neuroimaging. The treatment relies on alleviating mechanical obstruction and reversing the proinflammatory processes that contribute to tissue ischaemia. Hyperbaric oxygen therapy is an effective treatment and has multiple mechanisms to reverse the pathological processes involved in cerebral arterial gas embolism. Symptomatic cerebral arterial gas embolism is a rare complication of endovascular intervention for acute ischaemic stroke. Although there are no previous descriptions of its successful treatment with hyperbaric oxygen therapy following mechanical thrombectomy, this is likely to become more common as mechanical thrombectomy is increasingly used worldwide to treat acute ischaemic stroke.

A pleural vacuum relief device for pleural drain unit use in the hyperbaric environment.

INTRODUCTION: When a standard water-seal pleural drain unit (PDU) is used under hyperbaric conditions there are scenarios where excessive negative intrapleural pressure (IPP) and/or fluid reflux can be induced, risking significant morbidity. We developed and tested a pleural vacuum relief (PVR) device which automatically manages these risks, whilst allowing more rapid hyperbaric pressure change rates. METHODS: The custom-made PVR device consists of a one-way pressure relief valve connected in line with a sterile micro filter selected for its specific flow capacity. The PVR device is designed for connection to the patient side sampling port of a PDU system, allowing inflow of ambient air whenever negative pressure is present, creating a small, controlled air leak which prevents excessive negative pressure. The hyperbaric performance of a Pleur-Evac A-6000 intercostal drain was assessed with and without this added device by measuring simulated IPP with an electronic pressure monitor connected at the patient end of the PDU. IPP readings were taken at 10, 15, 20 and 30 cmH2O of suction (set on the drain unit) at compression rates of 10, 30, 60, 80, 90 and 180 kPa·min⁻¹ to a pressure of 280 kPa. RESULTS: At any compression rate of > 10 kPa·min⁻¹, the negative IPP generated by the Pleur-Evac A-6000 alone was excessive and resulted in back flow through the PDU water seal. By adding the PVR device, the generated negative IPP remains within a clinically acceptable range, allowing compression rates of at least 30 kPa·min⁻¹ with suction settings up to -20 cmH2O during all phases of hyperbaric treatment. CONCLUSIONS: The PDU PVR device we have developed works well, minimising attendant workload and automatically avoiding the excessive negative IPPs that can otherwise occur. This device should only be used with suction.

Hyperbaric Oxygen in Lower Limb Trauma (HOLLT); protocol for a randomised controlled trial.

INTRODUCTION: Open fractures with significant soft tissue injury are associated with high rates of complications, such as non-union, infection, chronic pain and disability. Complications often require further inpatient care, and in many cases, multiple operations and prolonged rehabilitation. Use of hyperbaric oxygen therapy as an adjunct to standard orthopaedic trauma care has the potential to reduce the complications of musculoskeletal injury and thus improve outcomes. Two previous randomised trials have suggested some positive effect, but neither functional measures nor long-term outcomes were reported. METHODS AND ANALYSIS: An international, multicentre, randomised, open-label, clinical trial. Patients with trauma with an acute open fracture of the tibia with severe soft tissue injury (Gustilo grade 3) and high risk of injury-related complications were recruited from participating major trauma hospitals with hyperbaric facilities. Patients were enrolled with the expectation of commencing 12 sessions of hyperbaric oxygen therapy within 48 h of injury. The primary outcome measure is the incidence of acute complications of the open fracture wound at 14 days. Other short-term outcome measures include amputation, need for fasciotomy, time until wound closure, breakdown of closed wounds, time until definitive orthopaedic fixation, number of operative procedures, intensive care stay and hospital stay. Long-term follow-up will continue for 2 years postinjury. ETHICS AND DISSEMINATION: Ethics approval was given by The Alfred Health Human Ethics Committee (206/04) and the Monash University Human Research Ethics Committee (CF07/4208). Approval was also obtained from the institutional research ethics committee at each participating site. This study will make a significant contribution to the trauma literature and should answer the question of whether hyperbaric oxygen therapy can significantly improve outcomes in severe lower limb trauma. Collective study results will be published in international journals and presented at relevant conferences. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov: NCT00264511; Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12607000559415.

Hyperbaric intensive care technology and equipment.

In an emergency, life support can be provided during recompression or hyperbaric oxygen therapy using very basic equipment, provided the equipment is hyperbaric-compatible and the clinicians have appropriate experience. For hyperbaric critical care to be provided safely on a routine basis, however, a great deal of preparation and specific equipment is needed, and relatively few facilities have optimal capabilities at present. The type, size and location of the chamber are very influential factors. Although monoplace chamber critical care is possible, it involves special adaptations and inherent limitations that make it inappropriate for all but specifically experienced teams. A large, purpose-designed chamber co-located with an intensive care unit is ideal. Keeping the critically ill patient on their normal bed significantly improves quality of care where this is possible. The latest hyperbaric ventilators have resolved many of the issues normally associated with hyperbaric ventilation, but at significant cost. Multi-parameter monitoring is relatively simple with advanced portable monitors, or preferably installed units that are of the same type as used elsewhere in the hospital. Whilst end-tidal CO2 readings are changed by pressure and require interpretation, most other parameters display normally. All normal infusions can be continued, with several examples of syringe drivers and infusion pumps shown to function essentially normally at pressure. Techniques exist for continuous suction drainage and most other aspects of standard critical care. At present, the most complex life support technologies such as haemofiltration, cardiac assist devices and extra-corporeal membrane oxygenation remain incompatible with the hyperbaric environment.

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.

Hyperbaric oxygen therapy reduces the severity of ischaemia, preservation and reperfusion injury in a rat model of liver transplantation.

BACKGROUND: Approaches to increase organ availability for orthotopic liver transplantation (OLT) often result in the procurement of marginal livers that are more susceptible to ischaemia, preservation and reperfusion injury (IPRI). METHODS: The effects of post-OLT hyperbaric oxygen (HBO) therapy on IPRI in a syngeneic rat OLT model were examined at various time-points. The effects of IPRI and HBO on hepatocyte necrosis, apoptosis, proliferation, and sinusoidal morphology and ultrastructure were assessed. RESULTS: Post-OLT HBO therapy significantly reduced the severity of IPRI; both apoptosis [at 12 h: 6.4 ± 0.4% in controls vs. 1.6 ± 0.7% in the HBO treatment group (p < 0.001); at 48 h: 2.4 ± 0.2% in controls vs. 0.4 ± 0.1% in the HBO treatment group (p < 0.001)] and necrosis [at 12 h: 18.7 ± 1.8% in controls vs. 2.4 ± 0.4% in the HBO treatment group (p < 0.001); at 48 h: 8.5 ± 1.3% in controls vs. 3.4 ± 0.9% in the HBO treatment group (P= 0.019)] were decreased. Serum alanine transaminase was reduced [at 12 h: 1068 ± 920 IU/l in controls vs. 370 ± 63 IU/l in the HBO treatment group (P= 0.030); at 48 h: 573 ± 261 IU/l in controls vs. 160 ± 10 IU/l in the HBO treatment group (P= 0.029)]. Treatment with HBO also promoted liver regeneration [proliferation at 12 h: 4.5 ± 0.1% in controls vs. 1.0 ± 0.3% in the HBO treatment group (p < 0.001); at 48 h: 8.6 ± 0.7% in controls vs. 2.9 ± 0.2% in the HBO treatment group (p < 0.01)] and improved sinusoidal diameter and microvascular density index. CONCLUSIONS: Hyperbaric oxygen therapy has persistent positive effects post-OLT that may potentially transfer into clinical practice.

Changes in oxygenation in mechanically ventilated critically ill patients following hyperbaric treatment.

BACKGROUND: Some ventilated intensive care unit (ICU) patients may experience reduced oxygenation following hyperbaric oxygen treatment (HBOT). METHODS: In a prospective, single-centre, observational study, we documented changes in oxygenation and the need for associated changes in ventilator settings in 25 consecutive, mechanically ventilated ICU patients immediately post-treatment and 1, 2, 3 and 6 hours following 61 HBOT sessions. The primary outcome measure of oxygenation was the ratio of arterial partial pressure of oxygen (P(a)O2) against the level of inspired oxygen (F(i)O2), P(a)O2/F(i)O2. RESULTS: Following HBOT, the P(a)O2/F(i)O2 ratio decreased by 27% on return to ICU (P < 0.001, 95% confidence intervals (CI) 20.6 to 34.2); 22% at 1 hour post-HBOT (P < 0.001, 95% CI 15.1 to 28.6); and 8% at 2 hours post (P = 0.03, 95% CI 0.8 to 14.4). The ratio showed no significant differences from pre-HBOT at 3 and 6 hours post-HBOT. P(a)O2/F(i)O2 ratio changes necessitated adjustments to ventilation parameters upon return to ICU following 30 of 61 HBOT sessions in 17 out of the 25 patients. The most common ventilation parameter altered was F(i)O2 (n = 20), increased by a mean of +0.17 (95% CI 0.11 to 0.23) above baseline for two hours following HBOT. CONCLUSIONS: Following HBOT, oxygenation is reduced in a majority of mechanically ventilated ICU patients and requires temporary alterations to mechanical ventilation settings. Further study to identify predictive characteristics and to determine causation for those at risk of needing ventilation alterations is required.

Hyperbaric oxygen improves capillary morphology in severe acute pancreatitis.

OBJECTIVES: This article aims to determine the effect of acute pancreatitis on microvascular morphology and the impact of treatment with hyperbaric oxygen (HBO). METHODS: Sixty-seven male Wistar rats were induced with acute pancreatitis by retrograde bile duct injection. Rats were randomized to 12-hourly HBO or control treatment. Two rats in each group were killed at baseline and 24, 48, and 72 hours postinduction, and a cast of the pancreatic microvasculature was examined using scanning electron microscopy. RESULTS: Normal pancreatic vasculature is a dense network with a consistent capillary diameter. In acute pancreatitis, mean capillary diameter is increased at 24 hours (P < 0.001) and further increased at 48 hours (P = 0.007). From 24 hours, diameter heterogeneity is increased (P < 0.001) and capillary density is reduced (P < 0.001). Hyperbaric oxygen has a significant effect on vascular morphology changes from 48 hours after induction. Capillary diameter and heterogeneity of diameter are decreased by HBO (both P < 0.001). Capillary density is increased by HBO at 48 and 72 hours (P < 0.001). CONCLUSIONS: In acute pancreatitis, structural capillary diameter and heterogeneity of diameter increase and capillary density decreases. These parameters are all improved by HBO treatment. Hyperbaric oxygen treatment normalizes the pancreatic microvasculature after acute pancreatitis and may be a potentially effective treatment of this disease.

Hyperbaric oxygen therapy in the treatment of skin ulcers due to calcific uraemic arteriolopathy: experience from an Australian hyperbaric unit.

INTRODUCTION: Calcific uraemic arteriolopathy (CUA), also known as 'calciphylaxis', is a syndrome of ischaemic necrotic ulcers occurring in uraemic patients with end-stage renal failure. It is a debilitating condition with a high morbidity and mortality. Hyperbaric oxygen (HBO) has been used to treat such wounds for many years but evidence of its efficacy is limited. AIM: We aimed to study the efficacy of HBO on the healing of problem ulcers secondary to CUA. METHOD: A retrospective case review of all patients with chronic skin ulcers secondary to CUA treated at the Alfred Hospital Hyperbaric Unit from July 1997 to March 2006 (n = 20). RESULTS: HBO was beneficial in eleven (55%) patients, with six of these (30%) experiencing complete resolution of their ulcers on completion of their treatment. Advancing age was identified as a predictor of a positive outcome (P = 0.02). There was no statistical correlation between the number of HBO treatments and ulcer healing. CONCLUSIONS: HBO can benefit patients with chronic non-healing wounds secondary to CUA, but its precise role remains undefined.

Hyperbaric oxygen therapy for severe acute pancreatitis.

Despite improvements in the supportive management of severe acute pancreatitis over the last decade, the morbidity and mortality rate remains high. The main feature of this condition is pancreatic necrosis leading to sepsis, with both localized and systemic inflammatory response syndromes. Early pathophysiological changes of the pancreas include alterations in microcirculation, ischemia reperfusion injury, and leukocyte and cytokine activation. The efficacy of hyperbaric oxygen (HBO) therapy in improving these pathophysiological disturbances is documented for various conditions. However, its effect in the treatment of severe acute pancreatitis is undetermined. This report documents the case of a 56-year-old woman presenting with severe acute pancreatitis treated by HBO therapy. The severity of disease was based on an Acute Physiology and Chronic Health Evaluation (APACHE II) illness grading score of 11 and a Baltazar based computed tomography severity index (CTSI) score of 9. Administration of 100% oxygen was commenced within 72 h of presentation at a pressure of 2.5 atmospheres for 90 min and given twice daily for a total of 5 days. Therapy was well tolerated with improvements in APACHE II and CTSI grading scores. HBO therapy for severe acute pancreatitis appeared to be safe and may have a role in improving treatment outcomes. Further study is required.

Evaluation of the effect of SMA-pirarubicin micelles on colorectal cancer liver metastases and of hyperbaric oxygen in CBA mice.

Tetrahydropyranyladriamycin (THP or pirarubicin) destroys tumors via several mechanisms; one of which involves the production of ROS that requires molecular oxygen for its generation. SMA forms stable self-assembled associated micelles with pirarubicin (SMA-pirarubicin), and confers macromolecular characteristics to pirarubicin. This micellar macromolecular drug is selectively delivered to solid tumors via the EPR effect and its preferential tumor accumulation suppresses the systemic toxicity whilst its prolonged high concentration at the site of tumor enhances its efficacy much higher compared to free pirarubicin. Administration of SMA-pirarubicin micelle under HBO can further enhance the delivery of molecular oxygen that facilitates tumor selective generation of ROS, thus augmenting its antitumor potency. In this study, we evaluated the efficacy of SMA-pirarubicin micelles either as single drug or in combination with HBO in a mouse metastatic colorectal cancer model. At or below the maximum tolerated dose, SMA-pirarubicin remarkably reduced metastatic tumor nodules and it was far more effective than free pirarubicin. The data also suggests a potential benefit of combined therapy of HBO with micellar anthracyclins.

Hyperbaric oxygen therapy reduces severity and improves survival in severe acute pancreatitis.

Severe acute pancreatitis is characterized by pancreatic necrosis, resulting in local and systemic inflammation. Hyperbaric oxygen (HBO) therapy modulates inflammation, but has not been extensively studied in pancreatitis. This study investigates the effects of HBO in a rat model of severe acute pancreatitis. Sixty-four rats were induced with severe pancreatitis using 4% sodium taurocholate and randomized to HBO treatment or control. HBO was commenced 6 h after induction (100% oxygen at 2.5 atmospheres for 90 min) and continued every 12 h for a maximum of eight treatment episodes. Surviving animals were killed at 7 days. Severity of pancreatitis was graded macroscopically and microscopically. Lung edema was calculated using wet and dry lung weights. Macroscopic and microscopic severity scores (mean +/- SE) of HBO-treated animals with pancreatitis (8.3 +/- 0.7; 9.6 +/- 0.4) were lower than those of controls (10.5 +/- 0.5; 11.1 +/- 0.4) (p = 0.02 and p = 0.03, respectively). The HBO-treated group had reduced pancreatic necrosis compared to controls (40 +/- 4% vs. 54 +/- 4%; p = 0.003). There was no difference in pulmonary edema between the groups. Median survival in the HBO-treatment group was 51 h, compared to 26 h in controls. Day-7 survival was significantly improved in the HBO-treated animals compared to controls (40% vs. 27%; p = 0.04). HBO therapy reduces overall severity, decreases the extent of necrosis, and improves survival in severe acute pancreatitis.

Preliminary report of the safety and efficacy of hyperbaric oxygen therapy for specific complications of lung transplantation.

BACKGROUND: Lung transplantation (LTx) is a complex therapy requiring immunosuppression and is associated with significant infective morbidity and mortality. Hyperbaric oxygen (HBO) therapy has been used successfully in the treatment of specific serious infections, ischemic injuries and cerebral arterial gas embolism. The purpose of this study was to evaluate the efficacy and safety of HBO therapy after LTx, generally as indicated for refractory infectious complications. METHODS: This investigation was a retrospective study of all lung transplant recipients treated with HBO therapy at the Alfred Hospital between March 1990 and August 2005. RESULTS: In this study we describe 9 patients (1.7%) from a total of 544 overall lung transplants performed over the period. Indications included: sternal osteomyelitis (n = 4); refractory cellulitis (n = 2); refractory septic arthritis (n = 1); ischemic toes (n = 1); and cerebral arterial gas embolism (n = 1). The patients received 1 to 25 HBO treatments at 100% Fio(2) and 100 to 180 kPa for 100 minutes per treatment. The treatment was generally well tolerated, although 2 patients ceased therapy prematurely due to a seizure and ear barotrauma (n = 1 each). Five patients had complete resolution of these life-threatening complications. Long-term survival and graft function were excellent, although graft function temporarily fell. CONCLUSIONS: HBO is a safe therapy for traditional HBO indications after LTx and appears useful, particularly in the management of infectious complications, whereas other therapies have failed or are contraindicated.

The hospital costs of treating necrotizing fasciitis.

BACKGROUND: Management of necrotizing fasciitis places significant demands upon hospital and medical resources. A successful management usually requires extensive surgical intervention and an adjunct hyperbaric oxygen treatment. The cost impact on the health care system has not been well characterized. We have, therefore, analysed the cost of treating this disease at an Australian tertiary referral hospital with extensive case experience and well-developed financial costing systems and have compared this with the current casemix-based government funding arrangements applying in Victoria, Australia. METHODS: Data was extracted from the medical records of 92 sequential patients treated by the Alfred Hospital (Melbourne, Australia) during the four financial years 2000-04. Clinical costing data and government funding data was provided by the hospital's Finance Departments. RESULTS: The total Alfred Hospital in-patient costs for treating the patients was $5,935,545 with a mean cost per patient of $64,517 (range, $1025 to $514,889). The total casemix-based funding allocation derived from treating these patients was calculated at $3,208,664 with the per patient mean $34,887 (range, $1331 to $387,168). This analysis does not include allowance for non-Alfred Hospital costs such as those incurred by the ambulance service, referring hospitals, for rehabilitation or as a result of the burden of residual disability. CONCLUSIONS: This study has confirmed that a significant economic burden is involved in treating necrotizing fasciitis. There is a substantial difference between the hospital costs and government funding for treating these patients in the Australian setting.

Where to now with carbon monoxide poisoning?

The controversy regarding the role of hyperbaric oxygen (HBO) in the treatment of carbon monoxide (CO) poisoning has been re-ignited following the publication of a further randomized controlled trial by Weaver et al., the results of which appear to conflict with our findings. Comparative analysis suggests that the apparent outcome differences may be secondary to the design, analysis and interpretation of the results of the two studies. Following careful analysis of these two papers and further results from a study by Raphael et al on 385 CO-poisoned patients, we can still find no convincing evidence favouring HBO therapy. Pending further research to determine optimal oxygen therapy for CO-poisoning, current therapy should involve stratifying patients for risk of a poor outcome. This stratification may be aided by the evolving availability of biochemical markers of brain injury and the finding that patients with transient loss of consciousness and poor performance on neuropsychological tests of the supervisory attention system are at higher risk of neuropsychological sequelae. We propose that those patients most at risk be admitted and receive more prolonged normobaric oxygen therapy whilst those with more minor CO-poisoning should be provided with normobaric oxygen of no less than 6 h duration and certainly until sign and symptom free.