Paul N. Austin

Work of breathing characteristics of seven portable ventilators

Portable ventilators (PVs) are used for patient transport with increasingly frequency. Due to design differences it would not be unexpected to find differences among these ventilators in the imposed work of breathing (WOBI) during spontaneous respiratory efforts. The purpose of this investigation was to compare the WOBI characteristics during spontaneous breathing of seven PVs; Bird Avian, Bio-Med Crossvent 4, Pulmonetics LTV 1000, Hamilton Max, Drägerwerk Oxylog 2000, Impact Uni-Vent 750, and Impact Uni-Vent 754 using a model of spontaneous breathing. Differences between the PVs in regards to the measured parameters increased with increases in simulated breathing demand. WOBI, peak inspiratory pressure, and pressure-time product were consistently less with the LTV 1000 over the range of simulated breathing conditions. During pressure support ventilation these parameters were significantly less with the LTV 1000 compared with the Crossvent 4. Only the WOBI produced by the LTV was consistently lower than the physiologic work of breathing across the simulated spontaneous breathing conditions. Based on these results it is predicted PVs with flow triggering and positive end-expiratory pressure compensation will consistently offer the least WOBI. Clinicians should be aware of these characteristics when using PVs with spontaneous breathing patients.

A literature review of the prehospital use of neuromuscular blocking agents by air medical personnel to facilitate endotracheal intubation

Air medical personnel in the United States have used neuromuscular blocking agents to facilitate endotracheal intubation in the field for more than a decade. This literature review examines 15 studies to investigate their experience and explores the following specific areas: the intubation success rate in patients who did or did not receive these agents, the intubation success rate of air medical personnel before and after they incorporated these agents into their practice, the neuromuscular blocking agents and adjunct medications used by air medical personnel, and the disposition of patients who could not be intubated after an agent was given. The data suggest that, overall, air medical personnel use these agents safely and effectively. Suggestions are offered for future studies, including examining ground time when agents are used to facilitate intubation, complications of their use in this setting, and the use of simulators to train personnel in the administration of these medications.

Readiness Estimate and Deployability Index for Air Force Nurse Anesthetists

Air Force (AF)-certified registered nurse anesthetists (CRNAs) play an important role in the support of the global war on terror. The purpose of the investigation was to use an AF CRNA-specific modification of the Readiness Estimate and Deployability Index Revised for AF Nurses to assess readiness for deployment. Dimensions included clinical competency, operational competency, soldier/survival skills, personal/psychosocial/physical readiness, leadership and administrative support, and group integration/identification. Readiness skills verification for AF CRNAs was used to develop clinical competency questions. Validity was assessed by two experts, and internal consistency reliability was evaluated by using Cronbachs alpha. Available stateside AF CRNAs (n=105) were surveyed, with a 60% response rate. Descriptive statistics were used to describe the sample, providing a mean score for each variable. Using a 5-point scale, participants rated themselves with an overall readiness score of 4.09, which suggests that AF CRNAs perceive themselves as ready to deploy.

Comparison of oxygen reservoir tube length and imposed work of breathing with the universal portable anesthesia complete.

The Universal Portable Anesthesia Complete is supplied with a 12-inch oxygen reservoir. Previous work suggested that using a longer (greater-volume) reservoir results in a greater inspired oxygen concentration. This study assessed the work of breathing imposed by lengths of reservoir tubing (18, 30, and 48 inches) during simulated spontaneous breathing of an adult anesthetized with isoflurane. Peak negative pressure (PNP) was used as a surrogate of imposed work. There were no clinically significant differences between the PNP with the supplied reservoir tubing and the three lengths of 22-mm corrugated tubing. The PNP ranged between -1.5 and -1.7 cm H2O for the anesthetized condition and between -4.3 and -4.7 cm H2O for the condition modeling emergence from general anesthesia. The morphologic features of the pressure-volume curves corroborated these findings and revealed that little imposed work was attributable to the length of reservoir tubing. These findings should help future investigators seeking to modify the Universal Portable Anesthesia Complete.

Cardiopulmonary resuscitation during spaceflight: examining the role of timing devices.

INTRODUCTION The majority of International Space Station (ISS) astronauts represent nonmedical professions. In order to serve as Crew Medical Officers (CMO), future crewmembers receive 40-70 h of medical training within 18 mo before missions, including cardiopulmonary resuscitation (CPR) per the Guidelines of the American Heart Association. CPR compliance with the Guidelines is known to vary even among trained clinicians, let alone minimally trained caregivers (e.g., bystanders, nonphysician astronauts). The purpose of this study was to evaluate the effect of timing devices, including audible metronomic tones, on CPR performed by nonmedical personnel, specifically 40 astronaut analogues trained in a fashion and within a timeframe similar to an ISS astronaut. METHODS Twenty bystander pairs performed two-person CPR for 4 min on a simulated cardiac arrest patient using three interventions: 1) CPR with no timing devices; 2) CPR with metronomic tones for chest compressions; and 3) CPR with a timing device and metronome for coordinating ventilation and compression rates, respectively. Each CPR performance was evaluated for compliance with the (then current) 2000 AHA Guidelines. RESULTS Numbers of breaths and compressions significantly deviated from target values in the first two interventions (38 and 42 breaths vs. target of 32 breaths; 282 and 318 compressions vs. target of 240 compressions); the use of timing devices for both components of CPR resulted in significant improvement (32 breaths and 231 compressions). CONCLUSIONS CPR timing devices that coordinate both breaths and compressions improve compliance of astronaut analogue rescuers with CPR guidelines, and may improve overall CPR performance and outcome.