Lewis P. Singer

Effects of dantrolene on cooling times and cardiovascular parameters in an immature porcine model of heatstroke

OBJECTIVE To evaluate the effects of dantrolene on cooling times and cardiovascular parameters in an immature porcine model of heatstroke. DESIGN Prospective, randomized, controlled, multigroup study. SETTING Research animal laboratory. SUBJECTS Yorkshire piglets (n = 16), 4 to 5 wks of age, 3.5 to 4.5 kg of body weight. INTERVENTIONS Animals were slowly heated with a radiant heat source to 43 degrees C and then maintained at this temperature for 30 mins. The animals were then removed from the heat source and randomized into one of four groups to receive either conventional cooling methods consisting of fluid resuscitation with 0.9% sodium chloride solution, sponging with room temperature water, mechanical fanning, and gastric lavage with iced 0.9% sodium chloride solution (group 1), conventional cooling methods and dantrolene (group 2), conventional cooling methods and dantrolenes vehicle mannitol (group 3), or no treatment (group 4). Cooling times, defined as the time required to reach a core body temperature of 38.5 degrees C, and cardiovascular parameters for each group were then compared. MEASUREMENTS AND MAIN RESULTS Animals in groups 1, 2, and 3 had significantly (p < .05) lower core body temperatures than animals that received no treatment at the conclusion of the experiment. Piglets in groups 2 and 3 had faster cooling times than piglets in group 1 (p < .05). However, there was no statistically significant difference in cooling times between the animals in groups 2 and 3. There were no statistically significant differences in heart rate, mean arterial pressure, central venous pressure, pulmonary artery occlusion pressure, or systemic vascular resistance index between animals in groups 1, 2, or 3. Group 3 piglets had higher cardiac indices and stroke indices than the piglets in the other groups (p < .05). CONCLUSIONS Therapeutic interventions with conventional cooling or conventional cooling and dantrolene provided significant improvement in cardiovascular function in an immature porcine heatstroke model. Dantrolene, given with conventional cooling methods, offered no significant improvement in cardiovascular parameters compared with conventional cooling methods alone. Dantrolene significantly shortened the cooling time compared with conventional cooling but did not significantly shorten the cooling time compared with its vehicle, mannitol. Although dantrolene significantly shortened the cooling time, it did not appear to be superior compared with conventional cooling methods in treating heatstroke in this immature porcine heatstroke model.

Relationship between arterial, mixed venous, and internal jugular carboxyhemoglobin concentrations at low, medium, and high concentrations in a piglet model of carbon monoxide toxicity.

Objective This study tested the hypothesis that mixed venous carboxyhemoglobin concentrations (V-COHb) and internal jugular carboxyhemoglobin concentrations (I-COHb) accurately predict arterial carboxyhemoglobin concentrations (A-COHb). In addition, this study tested the hypothesis that there is a high correlation at low (COHb, 0% to 10%), moderate (COHb, >10% to 40%), and high (COHb, >40%) concentrations between V-COHb, I-COHb, and A-COHb. Design The study was a prospective comparison of A-COHb, V-COHb, and I-COHb concentrations in piglets exposed to increasing concentrations of carbon monoxide over 6 hrs to achieve a concentration of ≥60% COHb. Carboxyhemoglobin measurements were evaluated by analysis of variance and correlation analysis. Agreement between V-COHb and A-COHb concentrations was examined by using a plot of arteriovenous differences against the mean of the two measurements. Intervention We simultaneously sampled arterial, mixed venous, and internal jugular blood every 30 mins over the 6-hr study period. Results Two hundred fifty arterial and mixed venous COHb concentrations were obtained, and 214 internal jugular COHb concentrations were obtained. One hundred additional arterial, mixed venous, internal jugular, and peripheral COHb concentrations were obtained. Correlation between samples at each concentration revealed r2 ≥ .94. Conclusion Venous COHb concentrations predict arterial COHb concentrations with a high degree of accuracy and are correlated at low, moderate, and high concentrations of carbon monoxide exposure. Arterial or venous samples can be used to accurately measure COHb concentrations.

TOXIC SHOCK SYNDROME FOLLOWING INFLUENZA A IN A CHILD

Adult patients infected with influenza A and S. aureus developed a fulminant pneumonia, but no documented cases of TSS have been reported to date. Multisystem failure is seen in TSS and may be mediated by the enterotoxin TSST-1, which is produced by certain strains of S. aureus. We describe a 12-yr-old female with nonmenstrual TSS following infection with influenza A

The Effect of Dobutamine On Porcine Cardiovascular Function After Respiratory Arrest 213

In an effort to improve circulation in children post respiratory arrest(RA), we examined the effects of dobutamine (D) on the hemodynamic function of piglets.

OUTCOME OF PEDIATRIC (P) HIV PATIENTS REQUIRING ADMISSION TO THE PEDIATRIC CRITICAL CARE UNIT. 256

OUTCOME OF PEDIATRIC (P) HIV PATIENTS REQUIRING ADMISSION TO THE PEDIATRIC CRITICAL CARE UNIT. 256