The Journal of Emergency Medicine
Stingray Envenomation: A Retrospective Review of Clinical Presentation and Treatment in 119 Cases
Stingrays cause more human envenomations than any other marine vertebrate and account for approximately 1500 emergency department (ED) visits per year in the United States. When a victim steps or leans on a stingray, the whipping motion of its tail can cause a traumatic laceration and concomitant envenomation. The exact chemical composition of stingray venom is unknown, but envenomation usually causes severe localized pain with rare occurrence of systemic symptoms. Stingray venom is heat labile, and immersion of the injury in hot water (43.3°C to 46.1°C) is the most commonly prescribed treatment for stingray injury. However, to date, no large study has been performed to assess the effectiveness of this therapy.
In this retrospective chart review, ED records for 119 stingray injury visits were reviewed to examine the effectiveness of hot water immersion in relieving pain associated with stingray envenomation. Patient records were reviewed with an emphasis on the use of hot water immersion therapy, the administration of analgesics, documentation of pain relief, the use of prophylactic antibiotics, and evidence of return visits for wound infection. Patients were divided into 2 groups (acute and subacute) for analysis based on the amount of time elapsed between injury and presentation (<24 hours versus ≥24 hours), with the primary difference being that most subacute patients did not require pain management for their injuries.
All of the patients in the acute group that required pain management (97/100) received hot water immersion as initial therapy in the ED. Of these 97 patients, 74 received hot water immersion as their sole initial therapy, and the remaining 23 received hot water immersion with concurrent administration of opioid or nonsteroidal analgesics. Of the patients that received only hot water immersion therapy, 65/74 (88%) had documented pain relief with no further treatment. The remaining 9/74 (12%) required administration of analgesic medication at some point during the ED visit >30 minutes after hot water immersion. None of the patients that received hot water immersion as their initial therapy required discharge prescriptions for pain medication. Of the 23 patients that received concurrent hot water immersion and analgesia as their initial therapy, 21 (91%) required no further pain management, and 2 (9%) required discharge prescriptions for pain medications. There were no documented complications from hot water immersion therapy.
Seventy-one patients in the acute group received prophylactic antibiotics before discharge from the ED, and only 1 (2%) of these patients had documentation of wound infection at a later date. Of the 30 patients in the acute group that did not receive prophylactic antibiotics, 5 (17%) returned to the ED with probable wound infection.
The authors conclude that hot water immersion alone was effective in eliminating the pain associated with most stingray envenomations in their case series. In addition, the authors note that the higher rates of wound infection seen in patients who were not given prophylactic antibiotics suggest that a course of antibiotics may be prudent to help prevent secondary wound infection. The main limitation of this study is its retrospective design, and the authors recognize the difficulty of drawing broad conclusions based upon retrospectively collected data. Still, the results of this review, in tandem with previous studies of the in vitro effects of hot water on stingray venom, support the use of hot water immersion therapy and prophylactic antibiotics in the treatment of stingray envenomation injuries.
(J Emerg Med. 2007;33:33–37) RF Clark, RH Girard, D Rao, et al. Prepared by Susan Brim, MS4, MPH&TM candidate, Tulane University, New Orleans, LA, USA
Archives of Surgery
Reduction of the Incidence of Amputation in Frostbite Injury with Thrombolytic Therapy
Although new treatments for frostbite, such as hyperbaric oxygen, anticoagulation, and sympathectomy, have been studied in recent years, the mainstays of treatment remain tissue rewarming, watchful waiting, and delayed amputation. Several recent studies, including one by Twomey et al 1 (previously reviewed in this journal), have suggested that tissue plasminogen activator (tPA) may improve revascularization to damaged areas. To further study this idea, these authors designed a study to evaluate the effect of tPA given within 24 hours of exposure on the need for amputation.
This retrospective study was completed at the University of Utah and included all patients presenting with frostbite from 1995 to 2006. The control group included patients not treated with tPA, while the test group included those patients presenting with severe frostbite from 2001 to 2006 that did receive tPA. During the test period, patients with severe frostbite were evaluated by a burn surgeon at the time of admission and underwent the classic treatment of immediate rewarming and fluid resuscitation. After vascular examination, those patients with circulatory compromise were further studied by digital angiography. If perfusion was severely compromised, tPA and heparin were infused into the affected extremity by intra-arterial catheter. Repeat angiograms were completed every 8 to 12 hours until either the extremity was perfused or until an endpoint of 48 hours. Exclusion criteria included concurrent trauma, neurological impairment, recent surgery or hemorrhage, or bleeding diathesis.
A total of 32 patients were treated for frostbite from 1995 to 2006. Seven received tPA from 2001 to 2006, 6 within 24 hours of the exposure. The amputation rate of those receiving tPA was 10% compared to 41% in those that did not receive tPA (P < .05). There was 1 reported complication in the patients receiving intra-arterial tPA (retroperitoneal hemorrhage treated nonoperatively). There was no difference in length of stay, number of readmissions, total costs, or costs per digit between the 2 groups.
Based on the results of this study, the authors suggest that ideal candidates for tPA treatment of frostbite would be those with severe frostbite on examination, those with perfusion abnormalities (based on angiogram or pyrophosphate scanning), and those presenting within 24 hours of exposure. No thrombolytics should be used on those with only superficial frostbite or involvement of only the tips of the digits, or those with any contraindications to the treatment. Limitations of this study include the retrospective design, the small size, the lack of randomization, the lack of information on functional outcomes, and the variance of the size of the 2 groups. It is unclear from this study design which patients might have recovered without the use of thrombolytics. However, the results of this study as well as those from Twomey et al 1 suggest that tPA may become part of the treatment for those presenting with severe frostbite within 24 hours of rewarming when vascular compromise is present.
(Arch Surg. 2007;142:546–553) KJ Bruen, JR Ballard, SE Morris, et al. Prepared by Karen Nolan Kuehl, MD, FACEP, Carilion Emergency Medicine, Roanoke, VA, USA
The New England Journal of Medicine
Effect of Aircraft-Cabin Altitude on Passenger Discomfort
Although commercial aircraft are pressurized to prevent the effects of low barometric pressures on its passengers, the equivalent of sea level barometric pressure (760 mmHg) cannot be maintained in an aircraft. Airlines attempt to keep cabin pressure at 565 mmHg or higher (equivalent of an altitude of 8000 feet), since unacclimatized individuals can experience symptoms of acute mountain sickness, including headache, nausea, vomiting, and sleep disturbance, at altitudes as low as 6500 feet. Since passengers on long commercial flights complain of similar symptoms, these authors (including 2 individuals from Boeing) designed a study to investigate the effects of decreased barometric pressure simulating commercial air travel on passengers’ oxygen saturations, complaints suggestive of altitude illness, and generalized discomfort.
This prospective, single-blind, controlled study of healthy adult volunteers took place in a hypobaric chamber. Volunteers were between the ages of 21 and 75 years and had not been to altitudes greater than 4000 feet (1219 m) or traveled by commercial airline for greater than 3 hours in the previous month. Each subject was monitored over 20 hours to simulate a 20-hour commercial flight. Barometric pressures to simulate terrestrial altitudes of 650, 4000, 6000, 7000, and 8000 feet were studied. At the beginning of each session, the “cabin” was depressurized at 500 feet/minute and, at the end of the session, was repressurized at 350 feet/minute to simulate commercial aviation. A subset of participants was selected to exercise on a treadmill during the session.
A pulse oximeter was used to check arterial oxygen saturation after depressurization at 1, 3, 5, 7, 9, 11, 13, 16, and 19 hours and for 2 hours after repressurization. Criterion scoring was used to evaluate for acute mountain sickness during the study period.
A total of 502 subjects were included in the study, and 209 subjects under the age of 60 years were randomized to exercise during the study period. Mean oxygen saturation fell as altitude increased, with a maximum of 4.4 percentage points. Acute mountain sickness complaints were found in 7.4% of the subjects but did not vary significantly among the studied altitudes. Complaints of fatigue and discomfort were directly related to increased altitude and inversely related to oxygen saturations. Women and older individuals complained less of physical discomfort, and women were found to have slightly higher oxygen saturations compared to men. In the exercise group, oxygen saturations were lower after exercise than before (1.3 percentage points), but these individuals complained of less discomfort than those that did not exercise.
The results show that rapid ascent from ground level to 8000 feet (simulated) caused lowered oxygen saturations and increased prevalence of discomfort, especially after 3 to 9 hours of simulated travel at levels equivalent to 7000 to 8000 feet. However, the degree of hypoxemia did not seem to affect the occurrence of acute mountain sickness–type symptoms. Although the study does not take into account other complications of long travel including dehydration, prolonged immobilization, and jet lag, the results suggest that a cabin “altitude” of 6000 feet or less on long flights may reduce passenger discomfort.
(N Engl J Med. 2007;357:18–27) JM Muhm, PB Rock, DL McMullin, et al. Prepared by Karen Nolan Kuehl, MD, FACEP, Carilion Emergency Medicine, Roanoke, VA, USA
American Journal of Emergency Medicine
A Clinical Score Predicting the Need for Hospitalization in Scorpion Envenomation
According to these authors, 40 000 people are envenomated by scorpions each year in Tunisia, with the most likely scorpion being Androctonus australis. Approximately 20 000 victims are evaluated each year in the hospital where this study took place, with many cases coming from surrounding rural areas. Many complications and deaths could be avoided if high-risk cases were quickly identified and transferred urgently from outlying rural areas to a hospital with the ability to provide critical care. These authors set out to design a clinical scoring system that would allow prediction of potential complications and need for hospital admission based on the initial emergency department evaluation.
This prospective study was completed from June 1995 to December 1997 and from January 1998 to September 1999. Inclusion criteria included all individuals over the age of 10 years with a documented scorpion sting. Exclusion criteria included life-threatening envenomation (hypotension, respiratory distress, significant mental status changes) and serious comorbidities. All included patients were observed for 4 hours and were discharged at the end of the observation period if asymptomatic or if exhibiting only localized symptoms. Variables of the scoring system were included if they were significantly associated with the hospitalization decision (P < .05). Scores were validated in patients who met the same inclusion and exclusion criteria as the test and thus who served as “controls.”
A total of 1303 victims of 1399 patients presenting to the emergency department with scorpion envenomation satisfied entry criteria and were included in the study. Almost 14% (182 patients) were admitted to the hospital after the 4-hour observation period. Of the 182 patients, 19% (35) were admitted to the intensive care unit. Seven independent predictors of hospitalization were found: priapism, vomiting, hypertension (systolic blood pressure >160 mmHg), corticosteroid administration before arrival to the emergency department, greater than 30 minutes delay in arrival to the emergency department, temperature >38°C, and tachycardia (heart rate >100 beats/min).
The authors did successfully design a clinical decision model for more efficient admission of scorpion envenomation victims in Tunisia based on a clinical score. This model can be used effectively in Tunisia; however, it is important to note that this scoring mechanism cannot be applied to all types of scorpions. This limitation was well described in a Letter to the Editor by Drs Quan and LoVecchio of Phoenix, Arizona, who state that the clinical score developed for Tunisia “is not applicable to North American scorpion envenomations.” 1 As noted by these physicians, Centuroides exilicauda is the most common cause of serious scorpion envenomation in the United States, and its most severe symptoms (muscle jerking, upper airway dysfunction, hypersalivation, and visual changes) usually occur within 14 minutes after envenomation. If victims do not have symptoms in 140 minutes, then they will not develop them and may be released from the hospital. Priapism has not been observed in this type of envenomation. An alternative scoring system would have to be developed for other areas.
(Am J Emerg Med. 2007;25:414–419) S Nouira, R Boukef, N Nciri, et al. Prepared by Karen Nolan Kuehl, MD, FACEP, Carilion Emergency Medicine, Roanoke, VA, USA
Nutrition
Nutritional Status of Adventure Racers
Adventure racing has grown rapidly since its beginnings in the early 1980s. This sport places unique stresses on its participants and, therefore, on those who provide care to them. Little research, however, has addressed how adventure racers prepare for their events and how injury and illness might be prevented.
This prospective cohort study evaluated the nutritional status of 24 highly ranked Brazilian adventure racers in training (18 men and 6 women). The authors collected 3-day food records, performed body mass plethysmography and maximum oxygen consumption (VO2 max) testing, and took blood samples. Dietary intake of macro- and micronutrients was compared against estimated energy requirement and several recommended diets. For micronutrients, probability of adequacy was calculated. Blood was tested for basic hematologic parameters, iron and ferritin, glucose, creatinine, and lipids.
Racers of both sexes had diets high in fat and protein relative to recommended diets, and diets that were high in cholesterol. For female athletes, the total energy intake was above that recommended for women. Both men and women had low probabilities of adequate intake of magnesium, zinc, and potassium. Women also had low probability of adequate intake of vitamin E and calcium. The women ingested below recommended values of potassium, iron, and zinc. Body fat content for 5 of the 6 female racers was above the ideal value suggested for women athletes. All blood tests were within normal limits, excepting the mean total cholesterol and low-density lipoprotein cholesterol (LDLc) in women.
This study is the first to address the nutritional status of a group of adventure racers. It finds interesting discrepancies between recommended and actual food intake in this group. This study suggests that there may be an opportunity to improve training efficiency by altering the macronutrient concentration of racers’ diets. Because serum potassium and magnesium were not measured, it is difficult to ascertain the significance of the below-recommended intake. However, the low intake points to a potential opportunity to prevent illness by improving stores of essential electrolytes.
(Nutrition. 2007;23:404–411) I Zalcman, HV Guarita, CR Juzwiak, et al. Prepared by Marlow Macht, MS4, MPH&TM candidate, Tulane University, New Orleans, LA, USA