Michael V Vance

Envenomation by the Scorpion Centruroides Sculpturatus

Envenomation by the scorpion C. sculpturatus can be life threatening. The action of the venom is to produce prolonged and excessive firing of neuronal axons which results in a wide variety of signs and symptoms. Records of 670 patients suffering from scorpion stings in central Arizona in 1982 were reviewed to characterize the clinical course of these patients. While adults appear to be stung more often than children, children are more likely to develop a severe illness requiring intensive supportive care. The intravenous administration of specific C. sculpturatus antivenom results in resolution of serious signs and symptoms within minutes, with patients completely asymptomatic within 1 1/2 hours. The administration of antivenom is recommended as the treatment of choice for severe envenomations after the initiation of appropriate supportive care.

Digital hydrofluoric acid burns: Treatment with intraarterial calcium infusion

Hydrofluoric acid (HF) produces a unique chemical burn due to tissue penetration by fluoride ion. Fluoride ion interferes with calcium activity in a variety of cell membranes and calcium-dependent processes, resulting in severe pain and deep tissue destruction. The currently accepted methods of treating HF burns include application of topical soaks or ointments with calcium or magnesium salts for minor burns and local injection of calcium gluconate for more severe burns. Digital burns also may require nail removal and direct injection into the nail bed. We present the cases of a series of patients with moderate to severe HF burns involving one or more fingers who were treated with selective intraarterial calcium infusion of dilute (1.66%) calcium salts. All patients had excellent relief of symptoms and marked improvement of the burn lesions following one to three four-hour infusions of calcium chloride or calcium gluconate. One patient required subsequent surgical intervention for grafting of a full-thickness burn, and one patient developed transient spasm at the site of percutaneous arterial line insertion. Intraarterial calcium infusion for the treatment of HF burns of the fingers provides many therapeutic advantages, including elimination of painful calcium injection directly into fingertips, avoidance of debilitating procedures such as fingernail removal, and assurance that all affected cells are receiving adequate amounts of calcium to replenish depleted stores and to complex with remaining free fluoride ion.

Massive diphenhydramine poisoning resulting in a wide-complex tachycardia : successful treatment with sodium bicarbonate

Diphenhydramine poisoning is characterized most often by anticholinergic effects. Cardiotoxicity and circulatory collapse have rarely been reported after massive ingestions of diphenhydramine and other H1-receptor-blocking agents, although these substances have local anesthetic properties and have been studied as antiarrhythmics. We report the case of a patient who developed a wide-complex tachycardia as a complication of acute diphenhydramine poisoning that responded to IV sodium bicarbonate.

First-order elimination kinetics following baclofen overdose

We followed serial plasma baclofen concentrations in a woman who ingested more than 2 g of baclofen in a suicide attempt, the largest ingestion of baclofen reported to date. The plasma clearance of baclofen was characterized by first-order elimination kinetics with a half-life of 8.6 hours. The persistent central nervous system depression noted in our patient after the return of plasma baclofen levels to the therapeutic range is best explained by delayed clearance of baclofen from the CNS. She made a full recovery with supportive care. No evidence of saturable elimination kinetics was found.

The legitimacy of rattlesnake bites in Central Arizona

Previous authors have classified poisonous snake bites as being legitimate or illegitimate, depending on whether the victim was taking unnecessary risks with a snake before being bitten. We reviewed medical records of 86 consecutive rattlesnake bite victims cared for at a single medical center to determine legitimacy of snake bites. A bite was considered illegitimate if, before being bitten, the victim recognized an encounter with a snake but did not attempt to move away from the snake. A legitimate bite was said to have occurred if a person was bitten before an encounter with a snake was recognized or was bitten while attempting to move away from a snake. The study group was made up of 75 male (87.2%) and 11 female (12.8%) victims. Seventy-four percent were 18 to 50 years old, and 15% had been bitten previously. Only 43.4% of all bites were considered legitimate, and pet (captive) snakes accounted for almost one third of all illegitimate bites. The ingestion of alcoholic beverages was associated with 56.5% of illegitimate bites versus 16.7% of legitimate bites (P less than .001). While 74.4% of bites were to upper extremities, only 27% of upper extremity bites were legitimate. All bites to the lower extremity were legitimate (P less than .001). Of 14 individuals bitten by pet snakes, all were men and 64.3% were under the influence of alcohol at the time of the bite.(ABSTRACT TRUNCATED AT 250 WORDS)

Life-Threatening Airway Obstruction From Rattlesnake Bite to the Tongue

We describe the case of a 41-year-old man who suffered a bite to the tongue from the Western Diamondback rattlesnake (C atrox). Life-threatening obstruction of his upper airway secondary to massive edema of the tongue and other soft tissue structures quickly followed envenomation. Nasotracheal intubation, IV antivenin, and supportive care resulted in complete recovery with no permanent deficits. Rattlesnake bites to the tongue are rare and pose an unusual cause of airway obstruction.

Noninvasive vascular studies in management of rattlesnake envenomations to extremities

Twenty-five consecutive patients suffering rattlesnake envenomation to an extremity underwent noninvasive vascular arterial studies using contralateral extremities as controls. All but one received antivenin, and none underwent early surgical decompression. Pulse volume amplitudes in the envenomated extremities, reflecting pulsatile arterial blood flow, were increased in 24 of 25 patients (P less than .02) in spite of edema and discoloration. Ischemia requiring surgical procedures developed in three of seven patients with decreased skin temperatures, as compared to none of 18 with increased or mixed skin temperatures on the envenomated extremity (P less than .02). One of 24 survivors suffered a functional deficit. Most victims of rattlesnake bites have increased arterial pulsatile blood flow in an envenomated extremity and do well with medical therapy. Noninvasive arterial studies help select those who are more likely to require special surgical intervention.

Cardiovascular effects of toxic concentrations of theophylline in the dog

A canine model of theophylline toxicity was used to study the cardiovascular effects seen in severe theophylline poisoning. Eight mongrel dogs were divided equally into two groups. The dogs were anesthetized with pentobarbital and paralyzed with pancuronium bromide. They were ventilated with 100% oxygen and underwent the placement of pulmonary arterial, central venous, femoral arterial, and peripheral venous lines. Group 1 animals received 5.6 mL/kg D5W intravenously (IV) over 20 minutes. Group 2 animals received 140 mg/kg (5.6 mL/kg) of aminophylline IV over the same period. Peak theophylline levels in Group 2 animals averaged 208.9 micrograms/mL. Group 2 animals suffered a marked fall in mean arterial pressure (MAP) and an increase in heart rate. In spite of the fall in MAP (P less than .01), cardiac index actually was increased almost two-fold over Group 1 animals, due mainly to a fall in systemic vascular resistance index (P less than .01). There were no physiologically significant differences in ventricular filling pressures or stroke index between the two groups.

The effects of toxic concentrations of theophylline on oxygen consumption, ventricular work, acid base balance, and plasma catecholamine levels in the dog

Theophylline poisoning, characterized in part by tachyarrhythmias, hypokalemia, and a metabolic acidosis, is similar to that expected from excessive beta-adrenergic activity. Using a previously described canine model of theophylline poisoning, invasive cardiovascular parameters were determined along with oxygen consumption (VO2), arterial pH, base deficit, and plasma epinephrine (EPI) and norepinephrine (NEPI) concentrations in four control animals (Group 1) and in four animals receiving 140 mg/kg aminophylline intravenously (Group 2). Group 2 animals developed a significant rise in VO2 as compared to controls (P less than .01). Although left ventricular stroke work index was less in Group 2 animals (P less than .01), the sum of the total amount of ventricular work performed by both ventricles per minute did not differ between the two groups (P greater than .15). There was a marked increase in circulating levels of EPI (P less than .01) and NEPI (P less than .01) in Group 2 animals, along with the development of a metabolic acidosis. Catecholamines, which have been shown to produce tachyarrhythmias, increased VO2, hypokalemia, and a metabolic acidosis, may play an important role in the cardiovascular and metabolic effects seen in theophylline poisoning.

Optimal patient position for transport and initial management of toxic ingestions

STUDY OBJECTIVES Many factors influence the rate of gastric emptying and therefore the rate of drug absorption in the orally poisoned patient. Limited studies have evaluated the effect of body position on the rate of gastric emptying of radiographically marked foods and contrast media, but effects on drug absorption have not been studied previously. Our hypothesis was that body position would have an effect on the rate of drug absorption in an oral overdose model. DESIGN A blinded, within-subjects (crossover) design. PARTICIPANTS Six male and six female healthy, adult volunteer subjects with no concurrent drug use or medications affecting gastrointestinal function. INTERVENTIONS Five body positions commonly used in prehospital and emergency department settings were examined: left lateral decubitus, right lateral decubitus, supine, prone, and sitting. All were performed by all subjects in random order with a three-day washout phase between trials. To simulate an acute overdose, fasted subjects ingested 80 mg/kg acetaminophen in the form of 160-mg pediatric tablets. Each subject then remained in the body position for that trial for two hours. Acetaminophen levels were obtained at 15-minute intervals, and a two-hour area under the curve (AUC) was calculated for each subject trial to represent total drug absorption during each study period. Investigators were blinded to all results until all trials were completed. MEASUREMENTS AND MAIN RESULTS All subjects completed the study. Group mean drug absorption as represented by two-hour AUC (mg.L.min) was calculated for each body position. AUC for left lateral decubitus (6,006 +/- 2,614) was lowest but did not significantly differ from that for supine (6,649 +/- 2,761). Both were significantly less than those for prone (7,432 +/- 1,809), right lateral decubitus (8,950 +/- 1,405), and sitting (8,608 +/- 1,725) positions (P less than .05 by one-way analysis of variance and follow-up paired t tests). CONCLUSION Initial drug absorption as determined by two-hour AUC was lowest in the left lateral decubitus position. Although the difference between the left lateral decubitus and supine positions did not reach statistical significance, both left lateral decubitus and supine were significantly lower than three other common patient body positions tested. Because the left lateral decubitus position has other advantages (eg, prevention of aspiration) in addition to minimizing drug absorption, we recommend that orally poisoned patients be placed in the left lateral decubitus position for prehospital and initial ED management.