Is more complex safer in the case of bail-out rebreathers for extended range cave diving?

Nowhere is redundancy more indispensable than extended range cave diving. Training and practice in this discipline ensure divers are equipped with backup regulators, gauges, lights, and adequate breathing gas for a safe exit, emergencies, and decompression. Depending on penetration distances and depth, open circuit cave diving may require carrying more gas cylinders than can be logistically managed by the diver themselves while maintaining safe gas supply margins. Consequently, divers are forced to either stage cylinders in the cave prior to the dive or rely on resupply from support divers. Both scenarios have significant drawbacks. Due to the improved efficiency of breathing gas utilisation and other advantages, closed circuit rebreathers (CCR) have enabled extended range cave diving. With increasing depths, penetration distances, and bottom times, these divers must also plan for an increasing amount of open circuit bail-out gas in the event of CCR failure. Staged cylinders have traditionally been utilised, but this strategy has limitations due to the advanced dives needed to place them and equipment degradation due to prolonged water immersion, which can often result in cylinder and regulator corrosion with consequent leakage of contents over time. Consequently, a growing number of CCR divers are foregoing open-circuit bailout altogether by carrying an additional CCR system for bailout. Although these bailout rebreathers may facilitate further exploration and have certain advantages, the risks of diving with two complex machines remain to be clearly defined.

Hyperbaric oxygen therapy for cerebral air gas embolism following orthotopic heart transplant: case report.

Air gas embolism (AGE) is a rare complication of cardiac surgery, with high morbidity and mortality. We present a case of suspected AGE following orthotopic heart transplant. The patient received hyperbaric oxygen therapy with near-complete resolution of symptoms at follow-up. This case exemplifies the difficulty in diagnosis of AGE, the considerations involved in the treatment of a critical care patient in a hyperbaric chamber, and utility in treating a patient for AGE even after a delay in diagnosis.

A favorable outcome despite a 39-hour treatment delay for arterial gas embolism: case report.

Cerebral arterial gas embolism (CAGE) occurs when gas enters the cerebral arterial vasculature. CAGE can occur during sitting craniotomies, cranial trauma or secondary to gas embolism from the heart. A far less common cause of CAGE is vascular entrainment of gas during endoscopic procedures. We present the case of a 49-year-old male who developed a CAGE following an esophagoduodenoscopy (EGD) biopsy. Due to a delay in diagnosis, the patient was not treated with hyperbaric oxygen (HBO2) therapy until 39 hours after the inciting event. Despite presenting to our institution non-responsive and with decorticate posturing, the patient was eventually discharged to a rehabilitation facility, with only mild left upper extremity weakness. This delay in HBO2 treatment represents the longest delay in treatment to our knowledge for a patient suffering from CAGE secondary to EGD. In addition to the clinical case report, we discuss the etiology of CAGE and the evidence supporting early HBO2 treatment, as well as the data demonstrating efficacy even after considerable treatment delay.

Terlipressin with limited fluid resuscitation in a swine model of hemorrhage.

BACKGROUND: Principles of damage control resuscitation include minimizing intravenous fluid (IVF) administration while correcting perfusion pressure as quickly as possible. Recent studies have identified a potential advantage of vasopressin over catecholamines in traumatic shock. Terlipressin (TP) is a vasopressin analogue used to reverse certain shock etiologies in some European countries. STUDY OBJECTIVE: We evaluated three dosages of TP when combined with a limited colloid resuscitation strategy on mean arterial pressure (MAP) and lactatemia in a swine model of isolated hemorrhage. METHODS: Sixty anesthetized swine underwent intubation and severe hemorrhage. Subjects were randomized to one of four resuscitation groups: 4 mL/kg Hextend(®) (Hospira Inc, Lake Forest, IL) only, 3.75 µg/kg TP + Hextend, 7.5 µg/kg TP + Hextend, or 15 µg/kg TP + Hextend. MAP and heart rate were recorded every 5 min. Baseline and serial lactate values at 30-min intervals were recorded and compared. RESULTS: Subjects receiving 7.5 µg/kg TP had significantly higher MAPs at times t15 (p = 0.012), t20 (p = 0.004), t25 (p = 0.018), t30 (p = 0.032), t35 (p = 0.030), and t40 (p = 0.021). No statistically significant differences in lactate values between TP groups and controls were observed. CONCLUSION: Subjects receiving 7.5 µg/kg of TP demonstrated improved MAP within 10 min of administration. When combined with minimal IVF resuscitation, TP doses between 3.75 and 15 µg/kg do not elevate lactate levels in hemorrhaged swine.