Elimination of ventilator dead space during synchronized ventilation in premature infants

BACKGROUND: Mainstream airflow sensors used in neonatal ventilators to synchronize mechanical breaths with spontaneous inspiration and measure ventilation increase dead space and may impair carbon dioxide (CO(2)) elimination. OBJECTIVE: To evaluate a technique consisting of a continuous gas leakage at the endotracheal tube (ETT) adapter to wash out the airflow sensor for synchronization and ventilation monitoring without CO(2) rebreathing in preterm infants. DESIGN: Minute ventilation (V'(E)) by respiratory inductance plethysmography, end-inspiratory and end-expiratory CO(2) by side-stream microcapnography, and transcutaneous CO(2) tension (TcPCO(2)) were measured in 10 infants (body weight, 835+/-244 g; gestational age, 26+/-2 weeks; age, 19+/-9 days; weight, 856+/-206 g; ventilator rate, 21+/-6 beats/min; PIP, 16+/-1 centimeters of water (cmH(2)O); PEEP, 4.2+/-0.4 cmH(2)O; fraction of inspired oxygen (FIo(2)), 0.26+/-0.6). The measurements were made during four 30-minute periods in random order: IMV (without airflow sensor), IMV+Sensor, SIMV (with airflow sensor), and SIMV+Leak (ETT adapter continuous leakage). RESULTS: Airflow sensor presence during SIMV and IMV+Sensor periods resulted in higher end-inspiratory and end-expiratory CO(2), Tcpco(2), and spontaneous V'(E) compared with IMV. These effects were not observed during SIMV+Leak. CONCLUSIONS: The significant physiologic effects of airflow sensor dead space during synchronized ventilation in preterm infants can be effectively prevented by the ETT adapter continuous leakage technique.     

Oxygen saturation in healthy infants immediately after birth

OBJECTIVE: Because the optimal concentration of oxygen (FiO2) required for stabilization of the newly born infant has not been established, the FiO2 is commonly adjusted according to the infant's oxygen saturation (SpO2). We aimed to determine the range of pre-ductal SpO2 in the first minutes of life in healthy newborn infants. STUDY DESIGN: We applied an oximetry sensor to the infant's right palm or wrist of term and preterm deliveries immediately after birth. Infants who received any resuscitation or supplemental oxygen were excluded. SpO2 was recorded at 60 second intervals for at least 5 minutes and until the SpO2 was >90%. RESULTS: A total of 205 deliveries were monitored; 30 infants were excluded from the study. SpO2 readings were obtained within 60 seconds of age from 92 of 175 infants (53%). The median (interquartile range) SpO2 at 1 minute was 63% (53%-68%). There was a gradual rise in SpO2 with time, with a median SpO2 at 5 minutes of 90% (79%-91%). CONCLUSION: Many newborns have an SpO2 <90% during the first 5 minutes of life. This should be considered when choosing SpO2 targets for infants treated with supplemental oxygen in the delivery room.     

Noninvasive therapy with helium-oxygen for severe bronchiolitis

OBJECTIVE: To determine whether noninvasive therapy using a helium-oxygen mixture reduces the use of positive-pressure ventilation in the treatment of respiratory failure caused by severe bronchiolitis. STUDY DESIGN: This was a multicenter, randomized, double-blind, placebo-controlled trial that recruited infants in 4 pediatric intensive care units (PICUs). A total of 39 nonintubated infants with severe bronchiolitis caused by respiratory syncytial virus (RSV) were randomly assigned within 8 hours of PICU admission to receive a helium-oxygen mixture (helium group) or an air-oxygen mixture (control group) through an inflatable head hood. The primary study outcome was the requirement for positive pressure mechanical ventilation. Results were compared using Fisher's exact test. RESULTS: No differences were noted between the control and helium groups with respect to age (1.0 vs 1.1 months), prematurity, or family history of asthma or smoking. Positive pressure ventilation was judged necessary for 4 of the 21 (19.0%) infants in the control group and in 4 of the 18 (22.2%) in the helium group (relative risk = 1.17; 95% confidence interval = 0.34 to 4.01). CONCLUSIONS: This study did not detect any differences between the patients in the helium group and the control group with respect to the rate of positive-pressure ventilation.     

Early versus late cord clamping: effects on peripheral blood flow and cardiac function in term infants

BACKGROUND: In the debate on the best cord clamping time in newborn infants, we hypothesized that late cord clamping enables an increased volemia due to blood transfer to the newborn from the placenta. AIM: To assess whether clamping time can affect limb perfusion and heart hemodynamics in a group of 22 healthy term newborn infants. STUDY DESIGN: A case-control study. SUBJECTS: Eleven early-clamped (at 30 s) vaginally-delivered newborn infants were compared with eleven late-clamped (at 4 min) newborns. OUTCOME MEASURES: The two groups were studied using near-infrared spectroscopy and M-mode echocardiography. RESULTS: Late cord clamping coincided with a higher hematocrit (median 62% versus 54%) and hemoglobin concentration (median 17.2 versus 15 g/dL), whilst there were no changes in bilirubin level. Echocardiography showed a larger end-diastolic left ventricle diameter (1.7 cm median value versus 1.5) coupled with unvaried shortening and ejection fraction values. There were no changes in calf blood flow, oxygen delivery, oxygen consumption or fractional oxygen extraction calculated from the NIRS measurements, or in foot perfusion index. CONCLUSIONS: Our results demonstrated that late cord clamping coincides with an increased placental transfusion, expressed by higher hematocrit and hemoglobin values, and larger left ventricle diameter at the end of the diastole, with no changes in peripheral perfusion or oxygen metabolism.