Biomedical subjects

M F el-Khatib

Publications and source records attributed to M F el-Khatib.

3 recordsLinked to original sources

PubMed1996

Inspiratory pressure/maximal inspiratory pressure: does it predict successful extubation in critically ill infants and children?

OBJECTIVE: To evaluate the accuracy of the initial negative inspiratory pressure (PI) to maximal negative inspiratory pressure (PImax) ratio in predicting extubation outcome for intubated infants and children. DESIGN: A prospective study. SETTING: Pediatric intensive care unit. PATIENTS: A sample of 50 stable intubated pediatric patients who were judged clinically ready for extubation. METHODS: Using a one-way valve, PI and PImax were measured in all patients, after which the < or = ratio PI/PImax was calculated and its accuracy in predicting extubation outcome evaluated. MEASUREMENTS AND RESULTS: A total of 39 patients (78%) were successfully extubated and 11 patients (22%) were not. The mean PI/PImax ratio was not significantly different between extubation successes (0.36 +/- 0.14) and failures (0.45 +/- 0.1) (P > 0.05). The cut-off value of 0.3 for PI/PImax identified in adult patients did not discriminate between extubation success and failure in children. Furthermore, a discriminatory cut-off value other than 0.3 could not be identified for infants and children. CONCLUSION: The PI/PImax ratio cannot be used to predict extubation outcome in pediatric patients. Indices that predict extubation outcome in adults should not be extrapolated to infants and children before testing and validation.

Adolescent↗

PubMed1994

Mechanical ventilators optimized for pediatric use decrease work of breathing and oxygen consumption during pressure-support ventilation.

OBJECTIVES: a) To investigate whether the patient work of breathing needed to trigger inspiration is affected by the type of ventilator delivering pressure-support ventilation for mechanically ventilated pediatric patients. b) To determine whether changes in oxygen consumption (VO2) trend with changes in work of breathing and would thus be helpful in tracking work of breathing. DESIGN: Prospective study. SETTING: Pediatric intensive care unit at a university hospital. PATIENTS: Nine mechanically ventilated patients (2 to 75 months of age). INTERVENTIONS: While maintaining a constant pressure-support ventilation level, patients were alternately supported with the Siemens Servo 900C, the Bird VIP, and the Newport Wave E200 ventilators in random order. MEASUREMENTS AND MAIN RESULTS: Work of breathing, defined as the integral of the pressure-volume curve corresponding to negative pressure, was calculated with a pulmonary monitoring system. VO2 was measured with a metabolic cart. Patient distress levels were assessed using the COMFORT scale, a behavioral scoring system. Mean values (20 breaths/patient) for measured variables with each ventilator were compared using analysis of variance and Scheffé tests, with p < .05 indicating statistical significance. The lowest VO2 (103 +/- 35 mL/min/m2) and work of breathing (24 +/- 15 g.cm/m2) were achieved with the Bird VIP ventilator and were significantly (p < .05) lower than those values obtained with either the Siemens Servo 900C (VO2 147 +/- 33 mL/min/m2; work of breathing 49 +/- 18 g.cm/m2) or the Newport Wave E200 (VO2 122 +/- 33 mL/min/m2; work of breathing 35 +/- 15 g.cm/m2). Also, the values of work of breathing and VO2 obtained using the Newport Wave E200 were significantly (p < .05) lower than those values obtained using the Servo 900C. No change in behavioral distress occurred when the ventilators were changed. In all patients, there was a clear similarity in the trends of VO2 and work of breathing. CONCLUSIONS: We conclude that VO2 and work of breathing may be reduced significantly using the latest generation of mechanical ventilators optimized for infant and pediatric use. Because work of breathing is less with the Bird VIP than the other two ventilators tested, leading to a corresponding decrease in VO2, we suggest that the Bird VIP better adapts the patient to the ventilator and may facilitate weaning from ventilatory support. We also suggest that changes in VO2 might be helpful in tracking changes in work of breathing.

Analysis of Variance↗

PubMed1993

PEEP does not improve pulmonary mechanics in infants with bronchiolitis.

Positive end-expiratory pressure (PEEP) may improve pulmonary mechanics, work of breathing, and gas exchange in some patients with respiratory failure. These beneficial effects do not occur consistently, however, and side effects, such as gas trapping due to expiratory flow limitation, may be exacerbated. We determined the effects of PEEP (0, 3, 6, and 9 cm H2O applied in random order) on the expiratory airway resistance and static compliance of nine infants mechanically ventilated for acute bronchiolitis. We also noted the presence of inadvertent PEEP (PEEPi) to determine its influence on the response to applied PEEP. Applied PEEP at any level failed to consistently improve passive expiratory airway resistance or increase compliance from baseline (PEEP = 0 cm H2O, resistance = 92 +/- 32 cm H2O/L/s; compliance = 0.71 +/- 0.19 ml/cm H2O/kg). Increases in end-expiratory lung volumes ranged from 18 to 40% of the tidal volume at maximal PEEP. Although all infants had PEEPi (5 +/- 2 cm H2O), PEEPi had no influence on the response of mechanics to applied PEEP other than that peak inspiratory pressures increased when PEEP > PEEPi. We conclude that the routine use of PEEP in infants with bronchiolitis does not consistently improve passive expiratory pulmonary mechanics and may increase the risk of barotrauma from gas trapping.

Airway Resistance↗