Biomedical subjects
Robyn J Meyer
Publications and source records attributed to Robyn J Meyer.
Pediatric defibrillation doses often fail to terminate prolonged out-of-hospital ventricular fibrillation in children.
BACKGROUND: The recommended dose for pediatric defibrillation is 2 J/kg, based on animal studies of brief duration ventricular fibrillation (VF) and a single pediatric study of short duration in-hospital VF. In a piglet model of out-of-hospital (prolonged) cardiac arrest, this recommended dose was usually ineffective at terminating VF. We, therefore, hypothesized that pediatric dose defibrillation may be less effective for prolonged out-of-hospital pediatric VF. METHODS: We evaluated retrospectively all cardiac arrests in children less than 13 years old in Tucson from November 1998 to April 2003, with special attention to all children in ventricular fibrillation. We determined the rate of ventricular fibrillation termination after pediatric dose shocks in this cohort, and compared this rate with a published historical pediatric in-hospital defibrillation control group. A pediatric dose shock was defined as 2 J/kg (+/-10 J). All shocks in both groups were provided as monophasic damped sinusoidal waveforms. RESULTS: Thirteen of 151 (9%) children with out-of-hospital cardiac arrest had documented VF. Eleven children received a total of 14 pediatric dose shocks. The median minimum untreated dispatch-to-shock time in unwitnessed arrest or collapse-to-shock in witnessed arrest for those 11 children was 11 min (interquartile range 25-75%; 9-15.5 min). Seven of the 14 pediatric dose shocks terminated the VF (six to asystole, one to pulseless electrical activity). Nine children (68%) died in the emergency department and four (31%) in the pediatric intensive care unit; none survived to hospital discharge. Failure to terminate VF after a pediatric dose shock in this study group with prolonged out-of-hospital ventricular fibrillation was substantially more common than the previously reported in-hospital data (7/14 versus 5/57; OR 10.4; 95% CI 2.6-42; P=0.001). CONCLUSIONS: Termination of VF after a pediatric defibrillation dose is substantially worse for prolonged pediatric out-of-hospital VF cardiac arrest compared with in-hospital (short duration) ventricular fibrillation. The optimal pediatric defibrillation dose for prolonged VF is not known.
Evaluating hyperosmolar therapy for hyperosmolar disease.
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Post-resuscitation right ventricular dysfunction: delineation and treatment with dobutamine.
BACKGROUND: Left ventricular dysfunction after resuscitation from cardiac arrest has been well described. Treatment with dobutamine improves post-resuscitation left ventricular function. Right ventricular function following resuscitation has not been investigated. The purposes of this study were to examine right ventricular function following resuscitation and determine whether dobutamine would improve post-resuscitation right ventricular function. METHODS AND RESULTS: Right ventricular function was measured in 28 swine (29+/-1 kg) before and after resuscitation from 15 min of untreated ventricular fibrillation. Twelve animals received dobutamine at 10 mcg/kg/min while 16 animals served as untreated controls. Among controls, right ventricular dysfunction post-resuscitation was demonstrated by a decrease in right ventricular ejection fraction and an increase in right ventricular end-diastolic pressure. Among animals treated with dobutamine, there was a significant improvement in right ventricular function post-resuscitation compared to untreated controls. CONCLUSIONS: This study establishes that right ventricular systolic and diastolic dysfunction does occur after prolonged cardiac arrest from ventricular fibrillation. Dobutamine can ameliorate post-resuscitation right ventricular dysfunction.
Pediatric extracorporeal life support after high frequency ventilation: predictors of survival.
Previous studies of extracorporeal life support in pediatric patients have identified variables associated with survival. However, none of these studies focused on extracorporeal life support after failure of high frequency ventilation (HFV). In the present study, we determined variables associated with survival for pediatric respiratory failure patients who received HFV prior to extracorporeal life support, using data reported to the Extracorporeal Life Support Organization Registry from 1992 to 1998. Patients with neonatal diagnoses, immune compromising conditions, or congenital cardiac defects were excluded. The 243 patients who met inclusion criteria had a 58% survival rate (95% CI 48-66%). The mean age was 22 +/- 39 months. Mean duration of mechanical ventilation prior to extracorporeal life support was 6.6 +/- 5.8 days. Venoarterial extracorporeal life support was used in 72% of the patients; venovenous in 28%. The survival rate for the subset of patients with an oxygenation index greater than 42 cm H2O/torr on HFV (n = 122) was not significantly different from the overall sample. We determined that lower mean airway pressure, lower pressure amplitude, decreased oxygenation index, increased PaO2, and increased oxygen saturation on HFV were associated with increased survival in patients who were subsequently treated with extracorporeal life support.