Medical and surgical management of pneumothorax in diving and hyperbaric chambers.

The presence of a pneumothorax within a pressurized chamber represents unique diagnostic and management challenges. This is particularly the case in the medical and geographic remoteness of many chamber locations. Upon commencing chamber decompression, unvented intrapleural air expands. If its initial volume and/or degree of chamber pressure reduction is significant enough, a tension pneumothorax will result. Numerous reports chronicle failure to diagnose and manage in-chamber pneumothorax with resultant morbidity and one fatal outcome. Such cases have occurred in both medically remote and clinically based settings. This paper reviews pneumothorax and tension pneumothorax risk factors and clinical characteristics. It suggests primary medical management using the principle of oxygen-induced inherent unsaturation in concert with titrated chamber decompression designed to prevent intrapleural air expanding faster than it contracts. Should this conservative approach prove unsuccessful, and surgical venting becomes necessary or otherwise immediately indicated, interventional options are reviewed.

Pneumothorax during manned chamber operations: A summary of reported cases.

In-chamber pneumothorax has complicated medically remote professional diving operations, submarine escape training, management of decompression illness, and hospital-based provision of hyperbaric oxygen therapy. Attempts to avoid thoracotomy by combination of high oxygen partial pressure breathing (the concept of inherent unsaturation) and greatly slowed rates of chamber decompression proved successful on several occasions. When this delicate balance designed to prevent the intrapleural gas volume from expanding faster than it contracts proved futile, chest drains were inserted. The presence of pneumothorax was misdiagnosed or missed altogether with disturbing frequency, resulting in wide-ranging clinical consequences. One patient succumbed before the chamber had been fully decompressed. Another was able to ambulate unaided from the chamber before being diagnosed and managed conventionally. In between these two extremes, patients experienced varying degrees of clinical compromise, from respiratory distress to cardiopulmonary arrest, with successful resuscitation. Pneumothorax associated with manned chamber operations is commonly considered to develop while the patient is under pressure and manifests during ascent. However, published reports suggest that many were pre-existing prior to chamber entry. Risk factors included pulmonary barotrauma-induced cerebral arterial gas embolism, cardiopulmonary resuscitation, and medical or surgical procedures usually involving the lung. This latter category is of heightened importance to hyperbaric operations as an iatrogenically induced pneumothorax may take as long as 24 hours to be detected, perhaps long after a patient has been cleared for chamber exposure.

Hyperbaric Oxygen as Radiation Sensitizer for Locally Advanced Squamous Cell Carcinoma of the Oropharynx: A Phase 1 Dose-Escalation Study.

PURPOSE: To explore, in a dose-escalation study, the feasibility of hyperbaric oxygen (HBO) treatments immediately before intensity modulated radiation therapy in conjunction with cisplatinum chemotherapy for squamous cell carcinoma of the head and neck (SCCHN). METHODS AND MATERIALS: Eligible patients presented with SCCHN (stage III-IV [M0]), life expectancy >6 months, and Karnofsky performance status ≥70. Enrollees received intensity modulated radiation therapy, 70 Gy in 35 fractions over 7 weeks with weekly cisplatinum. Patients received HBO-100% oxygen, 2.4 atmospheres absolute (ATA) for 30 minutes-twice per week initially. Subsequent patients were escalated to 3 and then 5 times per week. Intensity modulated radiation therapy began within 15 minutes after HBO. Patients were followed for 2 years after RT with quality-of-life questionnaires (Performance Status Scale-Head and Neck Cancer and the Functional Assessment of Cancer Therapy-Head and Neck Cancer) and for 5+ years for local recurrence, distant metastases, disease-specific survival, and overall survival. RESULTS: Twelve subjects enrolled from 3 centers. Two withdrew during radiation therapy and 1 within 14 weeks after radiation therapy. The remaining 9 had primary oropharyngeal disease and were stage IVA (7) or IVB (2). No dose-limiting toxicities were observed with daily HBO. Two patients (22%) required pressure equalization tubes. The average time between HBO and radiation therapy was 8.5 minutes, with 2 of 231 administrations delivered beyond 15 minutes (0.5%). Per-protocol analysis showed a clinical complete response in 7 and a pathologic complete response without tumor in salvage neck dissections in 2. With minimum follow-up of 61 months, per-protocol 5-year overall survival was 100%, local recurrence 0%, and distant metastases 11%. Patient-reported outcomes for quality of life (Functional Assessment of Cancer Therapy-Head and Neck Cancer) were comparable to published results for chemoradiotherapy without HBO. CONCLUSIONS: While acknowledging the study's small size and early attrition of 3 patients, our in-depth review of the acquired data indicates the feasibility of combining HBO with chemoradiation.

Potential roles of hyperbaric oxygenation in the treatments of brain tumors.

Over the past 50 years hyperbaric oxygen (HBO2) therapy has been used in a wide variety of medical conditions, and one of them is cancer. Many clinical studies have been conducted to evaluate potential therapeutic effects of HBO2 as a part of cancer treatment. This review briefly summaries the potential role of HBO2 therapy in the treatment of malignant tumors and radiation injury of the brain. HBO2 therapy is used for the enhancement of radiosensitivity in the treatment of some cancers, including malignant brain tumors. Radiotherapy within 15 minutes following HBO2 exposure, a relatively new treatment regimen, has been studied at several institutes and has demonstrated promising clinical results for malignant gliomas of the brain. HBO2 therapy also increases sensitivity to some antineoplastic agents; non-randomized clinical trials using carboplatin-based chemotherapy combined with HBO2 show a significant advantage in survival for recurrent malignant gliomas. The possibilities of combining HBO2 therapy with radiotherapy and/or chemotherapy to overcome newly diagnosed and recurrent malignant gliomas deserve extensive clinical trials. HBO2 therapy also shows promising potential for the treatment and/or prevention of radiation injury of the brain after stereotactic radiosurgery for brain lesions. The possibilities with HBO2 to enhance the therapeutic effect of irradiation per se, and to even increase the radiation dose if there are ways to combat the side effects, should boost new scientific interest into the whole field of oncology looking for new armamentaria to fight cancer.

Per-capita claims rates for decompression sickness among insured Divers Alert Network members.

Decompression sickness (DCS) in recreational diving is a rare and usually self-limiting injury, but permanent disability can occur. Incidence rate estimates are difficult to establish because the number of divers at risk is usually unknown in population samples with well-documented DCS. We estimated the annual per-capita DCS incidence rates for 2000-2007 based on insurance claims submitted by members of the Divers Alert Network (DAN), Durham, N.C., with dive accident insurance. The overall per-capita DCS claims rate (DCR) was 20.5 per 10,000 member-years. Based on the age-adjusted DCR, males submitted 28% more claims than females. Male-to-female difference was greatest between 35 and 40 years of age and disappeared by the mid-50s. Highest rates were observed in the 30- to 39-year age category, after which DCR declined with increasing age. Highest yearly DCR was estimated in 2002. Insurance dropout rate was greater among those who had DCS in the first year of their insurance compared to those who did not have DCS in their first year.

Hyperbaric oxygen treatment of chronic refractory radiation proctitis: a randomized and controlled double-blind crossover trial with long-term follow-up.

PURPOSE: Cancer patients who undergo radiotherapy remain at life-long risk of radiation-induced injury to normal tissues. We conducted a randomized, controlled, double-blind crossover trial with long-term follow-up to evaluate the effectiveness of hyperbaric oxygen for refractory radiation proctitis. METHODS AND MATERIALS: Patients with refractory radiation proctitis were randomized to hyperbaric oxygen at 2.0 atmospheres absolute (Group 1) or air at 1.1 atmospheres absolute (Group 2). The sham patients were subsequently crossed to Group 1. All patients were re-evaluated by an investigator who was unaware of the treatment allocation at 3 and 6 months and Years 1-5. The primary outcome measures were the late effects normal tissue-subjective, objective, management, analytic (SOMA-LENT) score and standardized clinical assessment. The secondary outcome was the change in quality of life. RESULTS: Of 226 patients assessed, 150 were entered in the study and 120 were evaluable. After the initial allocation, the mean SOMA-LENT score improved in both groups. For Group 1, the mean was lower (p = 0.0150) and the amount of improvement nearly twice as great (5.00 vs. 2.61, p = 0.0019). Similarly, Group 1 had a greater portion of responders per clinical assessment than did Group 2 (88.9% vs. 62.5%, respectively; p = 0.0009). Significance improved when the data were analyzed from an intention to treat perspective (p = 0.0006). Group 1 had a better result in the quality of life bowel bother subscale. These differences were abolished after the crossover. CONCLUSION: Hyperbaric oxygen therapy significantly improved the healing responses in patients with refractory radiation proctitis, generating an absolute risk reduction of 32% (number needed to treat of 3) between the groups after the initial allocation. Other medical management requirements were discontinued, and advanced interventions were largely avoided. Enhanced bowel-specific quality of life resulted.