High-dose diazepam facilitates core cooling during cold saline infusion in healthy volunteers.

Studies have suggested that inducing mild hypothermia improves neurologic outcomes after traumatic brain injury, major stroke, cardiac arrest, or exertional heat illness. While infusion of cold normal saline is a simple and inexpensive method for reducing core temperature, human cold-defense mechanisms potentially make this route stressful or ineffective. We hypothesized that intravenous administration of diazepam during a rapid infusion of 30 mL.kg-1 of cold (4 degrees C) 0.9% saline to healthy subjects would be more comfortable and reduce core body temperature more than the administration of cold saline alone. Fifteen subjects received rapidly infused cold (4 degrees C) 0.9% saline. Subjects were randomly assigned to receive, intravenously, 20 mg diazepam (HIGH), 10 mg diazepam (LOW), or placebo (CON). Main outcomes were core temperature, skin temperature, and oxygen consumption. Data for the main outcomes were analyzed with generalized estimating equations to identify differences in group, time, or a group x time interaction. Core temperature decreased in all groups (CON, 1.0 +/- 0.2 degrees C; LOW, 1.4 +/- 0.2 degrees C; HIGH, 1.5 +/- 0.2 degrees C), while skin temperature was unchanged. Mean (95% CI) oxygen consumption was 315.3 (253.8, 376.9) mL.kg-1.min-1 in the CON group, 317.9 (275.5, 360.3) in the LOW group, and 226.1 (216.4, 235.9) in the HIGH group. Significant time and group x time interaction was observed for core temperature and oxygen consumption (p < 0.001). Administration of high-dose diazepam resulted in decreased oxygen consumption during cold saline infusion, suggesting that 20 mg of intravenous diazepam may reduce the shivering threshold without compromising respiratory or cardiovascular function.

Characterization of the atmosphere within vapor-resistant encapsulating personal protective equipment during treadmill exercise.

BACKGROUND: Hazardous materials technicians may be required to wear fully encapsulated vapor-resistant (Level A) personal protective equipment (PPE) to contain and mitigate a hazardous materials emergency. It is commonly taught and practiced in hazardous material technician courses that if the wearer's self-contained breathing apparatus (SCBA) fails, the technician can remove the SCBA face piece and breathe the in-suit expired air while exiting the incident or awaiting rescue. OBJECTIVE: To determine the composition of expired air present within an encapsulating suit during exercise. METHODS: Subjects (n = 4) walked on a motor-driven treadmill (3.2 km x h(-1)) for 30 minutes while wearing encapsulating PPE and SCBA. Oxygen (O(2)) and carbon dioxide (CO(2)) levels within the PPE were monitored. Subject vital signs and end-tidal CO(2) (EtCO(2)) were continuously monitored. After treadmill exercise, rescue air from an external source was introduced into the suit. RESULTS: Mean oxygen levels inside the PPE fell below the Occupational Safety and Health Administration (OSHA) definition of oxygen-deficient environment (< 19.5% O(2)) after 2 minutes of treadmill walking and were below 17% at the end of 30 minutes. Carbon dioxide levels inside the PPE exceeded 3% in all subjects by the end of the exercise protocol. Rapid return to a room-air composition of oxygen and CO(2) within the suit was accomplished with introduction of positive-pressure air from an alternate external air source. CONCLUSION: A toxic atmosphere is rapidly created within fully encapsulating PPE during treadmill exercise of moderate intensity. Breathing the expired air within the PPE cannot be recommended during technician training. Application of an external air source to flush the suit can return the PPE atmosphere to safe limits, but requires an intentional suit breach to accomplish.

The effect of hyperhydration on physiological and perceived strain during treadmill exercise in personal protective equipment.

Work in personal protective equipment (PPE) impairs thermoregulation causing cardiovascular stress, increased core body temperature, and hypohydration. We examined the effect of pretreating first responders performing treadmill exercise in PPE with an infusion of normal saline on physiological and perceptual strain. Ten (eight males, two females) euhydrated subjects performed treadmill exercise on two occasions wearing a chemical resistant coverall, air purifying respirator, butyl gloves, and heavy boots. During the hyperhydration session, normal saline was rapidly infused through an arm vein prior to donning PPE. Exercise duration and maximum core temperature did not differ between euhydrated and hyperhydrated conditions. Perceptual strain index (PeSI) was higher than physiological strain index (PhSI) in the euhydrated condition (P = 0.002) but neither index differed between the control and experimental conditions. Intravenous hyperhydration did not reduce physiological stress, increase exercise, or influence perceptual strain time when compared to the euhydrated condition in moderately fit individuals.

IO versus IV access while wearing personal protective equipment in a HazMat scenario.

OBJECTIVE: Determine the time difference obtaining intraosseous (IO) versus intravenous (IV) access while wearing personal protective equipment (PPE) in simulated HazMat scenarios. METHODS: Twenty-two EMT-P providers established anterior tibial IO access using the EZ-IO system and routine antecubital IV access in three mannequin and PPE HazMat scenarios: 1) provider and mannequin not in PPE, 2) only provider in Level C PPE, and 3) provider and mannequin both wearing Level C PPE. Primary outcome measures were the average time in seconds for skin access, vascular access, and fluid infusion with each method in these configurations. RESULTS: For the provider and mannequin not in PPE condition, needle to skin time favored the IV (6.2 vs. 9.3 seconds; p < 0.001). whereas vascular access time (12.8 vs. 36.3 seconds; p < 0.001) and fluid infusion time (26.2 vs. 36.5 seconds; p = 0.02) favored the IO approach. For the provider in PPE and mannequin not in PPE condition, needle to skin times were similar for IO and IV (10.4 vs. 12.7 seconds; p = 0.591), whereas vascular access time (14.0 vs. 46.0 seconds; p < 0.001) and fluid infusion time (28.3 vs. 45.7 seconds; p < 0.001) both favored the IO approach. With the provider and mannequin in PPE, needle to skin time (12.7 vs. 24.9 seconds; p < 0.001), vascular access time (16.9 vs. 62.7 seconds; p < 0.001), and fluid infusion time (29.5 vs. 66.1 seconds; p < 0.001) all favored the IO approach. Fluid infusion times for the provider not in and in PPE (26.2 vs. 28.3 seconds; p < 0.05) with the mannequin not in PPE revealed no significant time burden associated with using the EZ-IO device with the provider in PPE. CONCLUSIONS: Overall, the EZ-IO system under HazMat conditions provides vascular access and fluid more quickly than standard intravenous access. When providers and mannequins were both in PPE, the time differential between IO and IV access was the greatest, favoring the IO approach. Donning PPE did not hinder the providers' use of the EZ-IO device and may be useful for obtaining vascular access when wearing PPE.

Physiological responses during graded treadmill exercise in chemical-resistant personal protective equipment.

BACKGROUND: As the likelihood of terrorist acts increases, prehospital personnel have been forced to train in the proper use of chemical-resistant personal protective equipment (PPE). This protective ensemble has been reported to be physiologically taxing for the wearer, imposing an additional thermal load resulting in hypohydration, hyperthermia, and reduced work time. Victim extrication, the rescue-the-rescuer role of the rapid intervention team and rapid self-extrication, typically requires high-intensity work that can be maintained only for short time intervals. The additional physiological burden imparted by the level C PPE during high-intensity work is unknown. OBJECTIVE: We hypothesized that the added thermal burden resulting from work in PPE would shorten work time and result in a higher core temperature during incremental treadmill exercise. METHOD: In this prospective, crossover, laboratory study, EMS providers (n = 8, 5 male) completed a Bruce treadmill test on two occasions: once in a chemical-resistant coverall and air-purifying respirator (PPE) and once in shorts and t-shirt (CON). Oxygen consumption, vital signs, core and skin temperature, and perceptual measures of exertion, thermal sensation, and comfort were monitored throughout the test. RESULTS: Subjects achieved maximal oxygen consumption and more than 90% of age-predicted maximum heart rate in both conditions. Heart rate, skin temperature, and measures of perceived exertion, comfort, and thermal sensation increased during the treadmill exercise but did not differ between the PPE and CON conditions. Core temperature increased in both the CON and PPE conditions (0.8 +/- 0.5 vs. 0.7 +/- 0.3, p = 0.40). CONCLUSION: High-intensity work in level C PPE is primarily limited by cardiovascular capacity. The thermal burden associated with this short bout of work in PPE (approximately 10 minutes) is not different than high-intensity work in short pants and cotton t-shirt. Consideration should be given to cardiorespiratory fitness when assigning providers to work in chemical-resistant PPE, especially on tasks that require high-intensity work.

Training retention of Level C personal protective equipment use by emergency medical services personnel.

OBJECTIVES: To assess the six-month training retention for out-of-hospital providers donning and doffing Level C personal protective equipment (PPE). METHODS: In this prospective observational study, 36 out-of-hospital providers enrolled in a paramedic program were trained in Level C (chemical-resistant coverall, butyl gloves, and boots and an air-purifying respirator) PPE use. A standardized training module and checklist of critical actions developed by a hazardous materials (hazmat) technician were used to evaluate donning and doffing. Students were trained until they were able to correctly don and doff the Level C PPE. An investigator used the checklist accompanying the training module to assess proficiency and remediate mistakes. Six months after initial training, the subjects were reassessed using the same investigator and checklist. Errors were designated as either critical (resulted in major self-contamination of the airway, such as early removal of the respirator) or noncritical (potentially resulted in minor self-contamination not involving the airway). RESULTS: Only five subjects (14.3%) were able to don and doff PPE without committing a critical error. The most common critical errors were premature removal of the respirator (65.7%; n = 23) and actions allowing the contaminated suit to touch the body (54.3%; n = 19). The most common noncritical error was possible self-contamination due to the boots not being removed before exposing other body parts (37.1%; n = 13). Of the seven subjects (20%) with additional prior hazmat training, only two donned and doffed PPE without committing a critical error. CONCLUSIONS: Retention of proper donning and doffing techniques in paramedic students is poor at six months after initial training. Even in subjects with previous hazmat, firefighter, and emergency medical services training, critical errors were common, suggesting that current training may be inadequate to prevent harmful exposures in emergency medical services personnel working at a hazmat or weapons of mass destruction incident.

Use of an emergency department by nonurgent patients.

OBJECTIVES: The objectives of this study are (1) to determine whether patients seeking emergency department (ED) nonurgent care have primary care providers (PCP) or know of other care sources and (2) to determine the reasons why they choose to use the ED. METHODS: A cross-sectional survey in a university ED was administered to self-referred nonurgent patients for 6 weeks. Use of a PCP, knowledge and attempts to seek other care, past use of the ED, urgency self-report, time of visit, and reasons for choosing an ED were recorded. RESULTS: Of the 563 approached subjects, 314 were eligible and 279 agreed to participate. One hundred fifty-seven (56%) had PCPs. For 183 (66%) subjects, the ED was the only place they knew to go for their present problem, and 75 (27%) reported that they depended on the ED for all medical care. Of those patients with a PCP, 73 (47%) rated the ED better for unscheduled care. Eighty-one (52%) subjects thought their PCP would be more efficient and 66 (42%) thought their PCP would be cheaper. CONCLUSIONS: Although most ED nonurgent patients were not dependent upon the ED, the majority was unaware of other places to go for their current health problem. Even those patients with a PCP sought care in the ED because the ED was believed to provide better care despite its perceived increase in both waiting time and cost.