Infant pertussis deaths and the management of cardiovascular compromise.

Infants infected with Bordetella pertussis in the first few weeks of life are at risk of death from 'overwhelming cardiovascular compromise despite intensive care support'. The mechanisms of this severe disease are not completely understood. Three case histories, including that of one infant who survived, are presented. Two of the patients died despite intensive therapy with pressors and, in one child, milrinone. The third child survived following treatment with nitric oxide and sildenafil. Hence, sildenafil in combination with nitric oxide shows promise as a therapy for the haemodynamic consequences of pertussis toxaemia and this should prompt clinical trials for their efficacy for this condition.

Energy expenditure in 100 ventilated, critically ill children: improving the accuracy of predictive equations.

OBJECTIVE: The purpose of this study was to evaluate current methods of predicting energy requirements and to develop and validate new equations derived from energy expenditure measurements of ventilated, critically ill children. DESIGN: Prospective, observational, sequential study. SETTING: Pediatric intensive care unit. PATIENTS: A total of 100 ventilated, critically ill children who fit the criteria of energy expenditure measurement. Additional patients (n = 25) were included in the validation study. INTERVENTION: An indirect calorimeter was used to measure energy expenditure for a period of 30 mins. MEASUREMENTS AND MAIN RESULTS: The mean measured energy expenditure was 185+/-51 kJ/kg per day. Predicted energy expenditure from standard equations was compared with measured energy expenditure by using the Bland and Altman "methods comparison procedure," and poor precision and accuracy were observed. Patient variables were collected at the time of measurement, and multiple regression analysis was performed to determine the independent contribution of each variable to measure energy expenditure. New predictive equations were formulated and validated with additional energy expenditure measurements. Patient variables that did not correlate significantly with energy expenditure were gender, Pediatric Risk of Mortality score, and commencement of nutritional support. An equation was derived from patient variables (age, weight, weight for age Z score, body temperature, number of days after intensive care admission, and primary reason for admission) that correlated significantly (r2 = .898) with measured energy expenditure. A second, simplified equation (energy expenditure kJ/day = ¿17 x age [months]¿ + ¿48 x weight [kg]¿ + ¿292 x body temperature degrees C¿ - 9,677) was produced (r2 = .867). Validation found no significant difference between measured and predicted energy expenditure by the new equations; however, the equations did not predict accurately for patients <2 months of age. CONCLUSION: The new equations provide a more accurate alternative to current predictive methods in assessing energy requirements of ventilated, critically ill children.

Energy expenditure measurements in ventilated critically ill children: within- and between-day variability.

BACKGROUND: Energy expenditure measurement (EEM) by indirect calorimetry is used as a research and clinical tool in pediatric intensive care units. The aims of the study were to determine if a 30-minute EEM is representative of a 24-hour EEM (within-day variation); to determine if there is any diurnal variation during the 24-hour period of EEM; and to determine if there is a clinically significant between day variation of EEMs. METHODS: To determine within-day variation, energy expenditure was measured for a period of 24 hours for each subject (n = 11). The 24-hour period was then divided into 30-minute periods. The 30-minute means were compared with the 24-hour means. To determine between-day variation, EEMs were made daily for 30 minutes. RESULTS: In the within-day study, the overall mean percent coefficient of variation of the 30-minute measurements was 7.2% +/- 4.5%. There was no significant difference between the 30-minute means and the 24-hour means for each patient (p < .691). In 8 subjects the 30-minute means did not differ from the 24-hour mean by more than 20%. No diurnal variation was observed. The mean percent variation of between day EEM was 21% +/- 16%; the range was 1% to 69%. CONCLUSION: In critically ill ventilated children, clinically relevant within-day variations in EEM are uncommon and a single 30-minute EEM gives an acceptable guide to the level of nutrition support required. Between-day variations can, however, be large and daily EEMs are required.

Supraventricular tachycardia associated with continuous furosemide infusion.

Three cases of supraventricular tachycardia (SVT) associated with the use of furosemide infusion (FI) in children following cardiac surgery are reported. The SVT occurred three to seven hours after starting an infusion at 1.0 mg.kg-1.hr-1. All three patients had a diuresis of 8-10 ml.kg-1.hr-1 compared with a mean average of 2.5 ml.kg-1.hr-1 in 22 other patients who had received a similar infusion. A rapid fluid shift was the most likely mechanism of the tachycardia. Sotalol was effective in controlling the tachycardia in the two patients in whom it was tried. We now recommend a starting dose of 0.3 mg.kg-1.hr-1 in using furosemide as a continuous infusion, with hourly increments of 0.1 mg.kg-1.hr-1 until the desired diuresis is obtained.