N. Stuart Harris

National study of Emergency Department visits for burn injuries, 1993 to 2004.

No studies have examined U.S. burn epidemiology from the perspective of the Emergency Department. We sought to describe patient characteristics, injury types, and Emergency Department practice patterns. Data were collected from the National Hospital Ambulatory Medical Care Survey between 1993 and 2004. Emergency Department visit rates for burn injury decreased from 1993 to 2004 with a peak of 2.8 (95% confidence interval [CI] 2.1–3.4) per 1000 U.S. population in 1995 and a nadir of 1.6 (95% CI 1.2–2.0) per 1000 in 2004. The Emergency Department visit rate for burn injuries was greater for men than women (2.7 [95% CI 2.4–3.0] vs 1.8 [95% CI 1.6–2.0] per 1000) and for black than white subjects (3.4 [95% CI 2.8-3.9] vs 2.1 [95%CI 1.9–2.3] per 1000), though all these groups showed decreases. Emergency Department visit rates for burns were greatest in the first and third decades (3.3 [95% CI 2.8–3.7] and 3.5 [95% CI 3.0–4.0] per 1000, respectively) and decreased thereafter. The upper extremity was the most commonly burned part of the body (37% of total) and most burns of specified depth were partial thickness (48% of total). Less than half of patients received analgesics (47%) or topical antibiotics (38%). Emergency Department visits for burns are declining, but rates remain high in men, black individuals, and children. Burn-prevention efforts should target these groups. Upper-extremity and partial-thickness injuries are common, and less than half of patients receive analgesics or topical antibiotics. Collaboration between burn specialists and Emergency Department personnel should focus on the care of these types of injuries.

High altitude headache: efficacy of acetaminophen vs. ibuprofen in a randomized, controlled trial

Ibuprofen has been shown to be more effective than placebo in the treatment of high altitude headache (HAH), but nonsteroidal anti-inflammatory agents have been linked to increased incidence of gastrointestinal (GI) side effects and high-altitude pulmonary edema (HAPE). We postulated that acetaminophen, which does not share ibuprofens theorized causal link to GI side effects or HAPE, could provide effective HAH therapy. We conducted a prospective, randomized, double-blind, clinical trial of ibuprofen vs. acetaminophen in the Solu Khumbu, Nepal: Mt. Everest Base Camp, Pheriche, Dingboche (4240 m to 5315 m). Seventy-four consecutive patients (ages 13 to 61 years) were randomized, were assessed with the Lake Louise Acute Mountain Sickness (AMS) criteria, and received a physical examination (which included vital signs, oxygen saturation as measured by pulse oximetry (SpO(2)), and assessment of clinical Lake Louise AMS criteria). Patients then received either 400 mg of ibuprofen (IBU) or 1000 mg of acetaminophen (ACET), and were asked to rate their cephalgia using a 10-cm visual analog scale (VAS). Thirty-nine patients received IBU, and 35 received ACET. Baseline Lake Louise AMS scores were identical in the two groups (mean = 5.9). No differences in mean VAS scores between IBU and ACET groups were noted at time 0 (presentation), 30, 60, or 120 min. No cases of HAPE or high altitude cerebral edema were noted during the study period. In this study population, acetaminophen was as effective as ibuprofen in relieving the pain of HAH.

Optic nerve sheath diameter correlates with the presence and severity of acute mountain sickness: evidence for increased intracranial pressure

Increased intracranial pressure is suspected in the pathogenesis of acute mountain sickness (AMS), but no studies have correlated it with the presence or severity of AMS. We sought to determine whether increased optic nerve sheath diameter, a surrogate measure of intracranial pressure, is associated with the presence and severity of AMS. We performed a cross-sectional study of travelers ascending through Pheriche, Nepal (4,240 m), from March 3 to May 14, 2006. AMS was assessed using the Lake Louise score. Optic nerve sheath diameter was measured by ultrasound. Ultrasound exams were performed and read by separate blinded observers. Two-hundred eighty seven subjects were enrolled. Ten of these underwent repeat examination. Mean optic nerve sheath diameter was 5.34 mm [95% confidence interval (CI) 5.18-5.51 mm] in the 69 subjects with AMS vs. 4.46 mm (95% CI 4.39-4.54 mm) in the 218 other subjects (P < 0.0001). There was also a positive association between optic nerve sheath diameter and total Lake Louise score (P for trend < 0.0001). In a multivariate logistic regression model of factors associated with AMS, optic nerve sheath diameter was strongly associated with AMS (odds ratio 6.3; 95% CI, 3.7-10.8; P < 0.001). In 10 subjects with repeat examinations, change in Lake Louise score had a strong positive correlation with change in optic nerve sheath diameter (R(2) = 0.84, P < 0.001). Optic nerve sheath diameter, a proxy for intracranial pressure, is associated with the presence and severity of AMS.

National study of United States emergency department visits for acute pancreatitis, 1993-2003.

BackgroundThe epidemiology of acute pancreatitis in the United States is largely unknown, particularly episodes that lead to an emergency department (ED) visit. We sought to address this gap and describe ED practice patterns.MethodsData were collected from the National Hospital Ambulatory Medical Care Survey between 1993 and 2003. We examined demographic factors and ED management including medication administration, diagnostic imaging, and disposition.ResultsED visits for acute pancreatitis increased over the study period from the 1994 low of 128,000 visits to a 2003 peak of 318,000 visits (p = 0.01). The corresponding ED visit rate per 10,000 U.S. population also increased from 4.9 visits (95%CI, 3.1–6.7) to 10.9 (95%CI, 7.6–14.3) (p = 0.01). The average age for patients making ED visits for acute pancreatitis during the study period was 49.7 years, 54% were male, and 27% were black. The ED visit rate was higher among blacks (14.7; 95%CI, 11.9–17.5) than whites (5.8; 95%CI, 5.0–6.6). At 42% of ED visits, patients did not receive analgesics. At 10% of ED visits patients underwent CT or MRI imaging, and at 13% of visits they underwent ultrasound testing. Two-thirds of ED visits resulted in hospitalization. Risk factors for hospitalization were older age (multivariate odds ratio for each increasing decade 1.5; 95%CI, 1.3–1.8) and white race (multivariate odds ratio 2.3; 95%CI, 1.2–4.6).ConclusionED visits for acute pancreatitis are rising in the U.S., and ED visit rates are higher among blacks than whites. At many visits analgesics are not administered, and diagnostic imaging is rare. There was greater likelihood of admission among whites than blacks. The observed race disparities in ED visit and admission rates merit further study.

New-Onset Anxiety Disorders at High Altitude

Abstract Objective.—Studies on the neurologic effects of high-altitude travel have focused on psychometric and cognitive testing and the long-term effects of hypoxia on memory and cognition. Few authors have discussed overt clinical psychiatric illness during high-altitude travel, and those few have focused on patients with preexisting psychiatric diagnoses. We describe a series of patients with new-onset anxiety disorders at high altitude treated at the Himalayan Rescue Association (HRA) clinic in Pheriche, Nepal (4240 m) in the spring season of 2006. Methods.—We report on all 6 cases of anxiety-related illness diagnosed at the HRA Pheriche Clinic during the spring season, 2006. Three cases, representing the 3 discrete types of illness we encountered, are described in detail. Results.—Six of 76 foreign patients and none of the 224 Nepalis seen during the season had anxiety-related primary diagnoses. None of the 6 patients had a history of psychiatric disorders or anxiety-related problems at low altitude. Three of the 6 patients were seen after hours, and all 6 required multiple visits. We describe 3 types of anxiety-related disorders: limited-symptom panic attacks induced by nocturnal periodic breathing, excessive health-related anxiety, and excessive emotionality. Conclusions.—Anxiety-related illness requires significant use of medical resources by high-altitude travelers. Further research is needed to define the epidemiology of anxiety-related disorders at high altitude, to quantify the contributions of various etiologic factors, and to identify safe, effective treatments.

The impact of moderate-altitude staging on pulmonary arterial hemodynamics after ascent to high altitude.

Staged ascent (SA), temporary residence at moderate altitude en route to high altitude, reduces the incidence and severity of noncardiopulmonary altitude illness such as acute mountain sickness. To date, the impact of SA on pulmonary arterial pressure (PAP) is unknown. We tested the hypothesis that SA would attenuate the PAP increase that occurs during rapid, direct ascent (DA). Transthoracic echocardiography was used to estimate mean PAP in 10 healthy males at sea level (SL, P(B) approximately 760 torr), after DA to simulated high altitude (hypobaric chamber, P(B) approximately 460 torr), and at 2 times points (90 min and 4 days) during exposure to terrestrial high altitude (P(B) approximately 460 torr) after SA (7 days, moderate altitude, P(B) approximately 548 torr). Alveolar oxygen pressure (Pao(2)) and arterial oxygenation saturation (Sao(2)) were measured at each time point. Compared to mean PAP at SL (mean +/- SD, 14 +/- 3 mmHg), mean PAP increased after DA to 37 +/- 8 mmHg (Delta = 24 +/- 10 mmHg, p < 0.001) and was negatively correlated with both Pao(2) (r(2) = 0.57, p = 0.011) and Sao(2) (r(2) = 0.64, p = 0.005). In comparison, estimated mean PAP after SA increased to only 25 +/- 4 mmHg (Delta = 11 +/- 6 mmHg, p < 0.001), remained unchanged after 4 days of high altitude residence (24 +/- 5 mmHg, p = not significant, or NS), and did not correlate with either parameter of oxygenation. SA significantly attenuated the PAP increase associated with continuous direct ascent to high altitude and appeared to uncouple PAP from both alveolar hypoxia and arterial hypoxemia.

Ultrasound and Ski Resort Clinics: Mapping Out the Potential Benefits

BACKGROUND Skiing and snowboarding are popular activities that involve high kinetic energies, often at altitude, and injuries are common. As a portable imaging modality, ultrasound may be a useful adjunct for mountainside clinics. This review briefly discusses skier and snowboarder injury profiles and focuses on the role of ultrasound for each injury type. METHODS Twenty-two sources including 17 reviews and observational studies were obtained describing skier and snowboarder injuries. Forty-nine studies were identified defining ultrasound applications for these injuries, including 38 reviews and observational studies, 6 case reports or case series, 3 cross-sectional studies, and 2 randomized, blinded studies. RESULTS Approximately 200 000 rider injuries are evaluated in the Unites States seasonally. Musculoskeletal injuries are the most common, and head, face, neck, and abdominal injuries are also prevalent, as are exacerbations of preexisting disease. Ultrasound has been shown to be useful and accurate for evaluating the aforementioned injury types, including joint, ligament, tendon, and fracture evaluation. Ultrasound has not been extensively studied in the prehospital setting, and only limited data address the utility of how it might influence management in a mountainside clinic setting. CONCLUSIONS Ultrasound has the potential to be a useful diagnostic modality in ski resort clinics. The most promising areas for future, applied studies include evaluation of musculoskeletal injuries (especially injuries to joints and tendons and ruling out fractures), assessing for elevated intracranial pressure in minor head injuries and symptoms of altitude illness, and focused assessment with sonography for trauma and extended focused assessment with sonography for trauma examinations for cases of chest and abdominal trauma of unknown significance.

Evidence for cerebral edema, cerebral perfusion, and intracranial pressure elevations in acute mountain sickness

We hypothesized that cerebral alterations in edema, perfusion, and/or intracranial pressure (ICP) are related to the development of acute mountain sickness (AMS).

Ultrasound for High Altitude Research

This review describes ultrasound techniques of potential use to high altitude researchers and discusses technical issues related to using ultrasound for high altitude research. Ultrasound allows portable, noninvasive evaluation of many physiologic parameters of interest to high altitude researchers. We discuss techniques that have been extensively used and emerging techniques that can be used to assess parameters of particular interest to high altitude researchers. We do not provide a definitive description of all ultrasound scanning methods but references to instructive sources are included. Potential drawbacks of ultrasound use, such as the need for sometimes extensive training and the potential for interobserver variation, are discussed and strategies for mitigating these are suggested. This review is meant to encourage other high altitude researchers to consider using ultrasound, either as a primary investigative modality or as an adjunct for monitoring parameters of interest in studies of physiology, altitude illness, or therapeutics.

A Randomized Trial of Temazepam versus Acetazolamide in High Altitude Sleep Disturbance

This study is the first comparative trial of sleep medications at high altitude. We performed a randomized, double-blind trial of temazepam and acetazolamide at an altitude of 3540 meters. 34 healthy trekkers with self-reports of high-altitude sleep disturbance were randomized to temazepam 7.5 mg or acetazolamide 125 mg taken at bedtime for one night. The primary outcome was sleep quality on a 100 mm visual analog scale. Additional measurements were obtained with actigraphy; pulse oximetry; and questionnaire evaluation of sleep, daytime drowsiness, daytime sleepiness, and acute mountain sickness. Sixteen subjects were randomized to temazepam and 18 to acetazolamide. Sleep quality on the 100 mm visual analog scale was higher for temazepam (59.6, SD 20.1) than acetazolamide (46.2, SD 20.2; p=0.048). Temazepam also demonstrated higher subjective sleep quality on the Groningen Sleep Quality Scale (3.5 vs. 6.8, p=0.009) and sleep depth visual analog scale (60.3 vs. 41.4, p=0.028). The acetazolamide group reported significantly more awakenings to urinate (1.8 vs. 0.5, p=0.007). No difference was found with regards to mean nocturnal oxygen saturation (84.1 vs. 84.4, p=0.57), proportion of the night spent in periodic breathing, relative desaturations, sleep onset latency, awakenings, wake after sleep onset, sleep efficiency, Stanford Sleepiness Scale scores, daytime drowsiness, or change in self-reported Lake Louise Acute Mountain Sickness scores. We conclude that, at current recommended dosing, treatment of high-altitude sleep disturbance with temazepam is associated with increased subjective sleep quality compared to acetazolamide.