Cerebral oxygenation and desaturations in preterm infants - a longitudinal data analysis.

OBJECTIVE: Hypoxemic episodes commonly occur in very preterm infants and may be associated with several adverse effects. Cerebral tissue oxygen saturation (StO2) as measured by near infrared spectroscopy (NIRS) may be a useful measure to assess brain oxygenation. However, knowledge on variability of StO2 is limited in preterm infants at this time, so StO2 dependency on arterial oxygenation (SpO2) and heart rate (HR) was assessed in preterm infants using statistical methods of time series analysis. STUDY DESIGN: StO2, SpO2, and HR were recorded from 15 preterm infants every 2 seconds for six hours. Statistical methods of time series and longitudinal data analysis were applied to the data. RESULT: The mean StO2 level was found as 72% (95% confidence interval (CI) 55.5% -85.5%) based on a moving average process with a 5 minute order. Accordingly, longitudinal SpO2 measurements showed a mean level of 91% (95% CI 69% -98%). Generally, compensation strategies to cope with both StO2 and SpO2 desaturations were observed in the studied patients. SpO2 had a significant effect on cerebral oxygenation (p < 0.001), but HR did not, which led to inconclusive results considering different time intervals. CONCLUSION: In infants with intermittent hypoxemia and bradycardia, we found a mean StO2 level of 72% and a strong correlation with SpO2. We observed large differences between individuals in the ability to maintain StO2 at a stable level.

Permissive hypercapnia for severe acute respiratory distress syndrome in immunocompromised children: A single center experience.

BACKGROUND: Controlled hypoventilation while accepting hypercapnia has been advocated to reduce ventilator-induced lung injury. The aim of the study was to analyze outcomes of a cohort of immunocompromised children with acute respiratory distress syndrome (ARDS) ventilated with a strategy of stepwise increasing PCO2 targets up to 140 mm Hg. METHODS: Retrospective analysis of outcomes of a cohort of children with oncologic disease or after stem cell transplantation and severe respiratory failure in comparison with a historical control cohort. RESULTS: Out of 150 episodes of admission to the PICU 88 children underwent invasive mechanical ventilation for >24h (overall survival 75%). In a subgroup of 38 children with high ventilator requirements the PCO2 target ranges were increased stepwise. Fifteen children survived and were discharged from the PICU. Severe pulmonary hypertension was seen in two patients and no case of cerebral edema was observed. Long term outcome was available in 15 patients and 10 of these patients survived without adverse neurological sequelae. With introduction of this strategy survival of immunocompromised children undergoing mechanical ventilation for >24h increased to 48% compared to 32% prior to introduction (historical cohort). CONCLUSIONS: A ventilation strategy incorporating very high carbon dioxide levels to allow for low tidal volumes and limited inspiratory pressures is feasible in children. Even severe hypercapnia may be well tolerated. No severe side effects associated with hypercapnia were observed. This strategy could potentially increase survival in immunocompromised children with severe ARDS.

Cerebral oxygenation during intermittent hypoxemia and bradycardia in preterm infants.

BACKGROUND: Episodes of hypoxemia and bradycardia frequently occur with apnea of prematurity in preterm infants. Little is known about the impact of different event types on the brain. OBJECTIVES: To describe the influence of hypoxemia and bradycardia, either isolated or in combination, on cerebral oxygenation. METHODS: In 16 preterm infants with intermittent hypoxemia and/or bradycardia, cerebral tissue oxygen saturation (StO2, as measured by near-infrared spectroscopy), heart rate and pulse oximetric saturation (SpO2) were recorded simultaneously for 16 h. Events were classified as isolated bradycardia (type 1), isolated hypoxemia (type 2) or combined (simultaneous, type 3; bradycardia first, type 4; hypoxemia first, type 5). Primary outcome was a score representing the area below baseline for cerebral StO2 desaturation during an event. Secondary outcomes were duration and depth of cerebral desaturation. RESULTS: Patients had a median (range) gestational age of 25.9 (22.6-30.4) weeks and a postnatal age of 32.5 (7-58) days. The median (quartiles) number of events was 49 (34-58). Isolated hypoxemias were the most frequent events (24; 9-36) and isolated bradycardias the least common (0; 0-1). Cerebral StO2 baseline was not different between event types. Cerebral desaturation score, duration of event and depth of cerebral desaturation were smallest for isolated bradycardias and largest for combined events, especially for those starting with hypoxemia followed by bradycardia. Regardless of event type, 12/16 infants maintained cerebral StO2 >60% despite severe SpO2 desaturations. CONCLUSIONS: Isolated bradycardias had the lowest impact on cerebral desaturation, and combined events had the highest. Most infants preserved cerebral oxygenation >60% during events.

[Current concepts of weaning children from invasive ventilation]. / Respiratorentwöhnung--Definition und klinischer Kontext aus Sicht der Pädiatrie.

Timely weaning from invasive ventilation is of major importance to limit time of invasive ventilation and improve outcomes. However, in pediatrics only limited knowledge on the optimal weaning approach is available. In this review evidence from recent trials on weaning in pediatrics is summarized. Standardized daily evaluation of weaning readiness, daily interruption of sedation, use of pediatric sedation protocols, application of noninvasive ventilation and prophylactic treatment with steroids of patients with high risk for post-extubation upper airway obstruction have been shown to decrease duration of invasive ventilation or to decrease the risk of extubation failure. However, due to the heterogeneous patient population in pediatric intensive care units, an individual approach might be necessary for certain subgroups of pediatric patients.

Prospective risk factor monitoring reduces intracranial hemorrhage rates in preterm infants.

BACKGROUND: Intracranial hemorrhage occurs in 20% to 25% of neonates born before the 30th week of gestation or weighing less than 1500 grams at birth. These hemorrhages carry a risk of long-term neurocognitive damage. Measures for lowering the incidence of intracranial hemorrhage were evaluated. METHODS: A working group at the University of Ulm, Germany, developed a prospective monitoring program for risk factors and a bundle of measures including altered clinical approaches to delivery, initial care of the neonate in the delivery room immediately after birth, and intensive care in the first few days thereafter. Adherence to these measures was checked once per week. The evaluation was performed prospectively for a period of 23 months (August 2010 to July 2012) with a 31-month period of historical controls (January 2008 to July 2010). RESULTS: In the reference period before the intervention was introduced, 263 neonates weighing less than 1500 grams and with a median (quartile) gestational age at birth of 27.4 (25.4-29.9) weeks were treated. The incidence of intracranial hemorrhage was 22.1%, and that of high-grade hemorrhage was 9.1%. The mortality was 6.1%, and the rate of survival without brain hemorrhage was 74.5%. After the bundle of preventive measures was introduced, 191 neonates weighing less than 1500 grams and with a median (quartile) gestational age at birth of 28.0 (26.0, 30.3) weeks were treated. The incidence of intracranial hemorrhage dropped to 10.5% (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.25-0.73); the incidence of high-grade hemorrhage dropped to 3.7% (OR 0.36; 95% CI 0.14-0.89). The mortality was no different at 6.3%, and 85.3% of the children survived without a hemorrhage (OR 1.95, 95% CI 1.20-3.15). After statistical adjustment for higher gestational age, the OR for intracranial hemorrhage (IVH) was 0.49 (0.28-0.86) and the probability of survival without IVH improved (OR 1.68, 95% CI 1.01-2.81). CONCLUSION: The rate of brain hemorrhage in premature neonates can be considerably lowered by prospective monitoring of risk factors.

Cerebral desaturations in preterm infants: a crossover trial on influence of oxygen saturation target range.

OBJECTIVE: To test the hypothesis that a higher pulsoximetric arterial oxygen saturation (SpO2) target range is associated with reduced cerebral tissue oxygen desaturations from baseline during events of hypoxaemia or bradycardia. DESIGN: Randomised crossover trial. SETTING: Single tertiary care neonatal intensive care unit. PATIENTS: Sixteen preterm infants with severe intermittent hypoxaemia or bradycardia. INTERVENTIONS: SpO2 target was set to 80-92% and 85-96% for 4 h each in random sequence. On a subsequent day, the target sequence was reversed and the study was repeated. MAIN OUTCOME MEASURES: We simultaneously recorded cerebral tissue oxygen saturation (cerebral StO2), SpO2 and heart rate. Cerebral StO2 was measured by near infrared spectroscopy. The primary outcome was the cumulative cerebral StO2 desaturation score representing the area below a cerebral StO2 baseline value before onset of each hypoxaemic or bradycardic event. RESULTS: During low SpO2 target range the median (IQR) cumulative cerebral StO2 desaturation score was higher (27384 (15825-37396) vs 18103 (6964-32946), p=0.011) and the mean (±SD) number of events was higher (29.1 (±15.3) vs 21.1 (±11.4), p=0.001). More time was spent with SpO2 below 80% (57.2 (±24.8) min vs 34.0 (±29.6) min, p=0.006). Total time of hyperoxaemia (defined as SpO2 ≥97% and ≥99%, respectively) and total time with cerebral StO2 <60% and <55% were similar. CONCLUSIONS: A lower SpO2 target range was associated with a greater cumulative cerebral StO2 desaturation score, caused by more frequent SpO2 desaturations. However, time at very low cerebral StO2 was not affected. Episodes of hyperoxaemia were not reduced.

Cerebral near-infrared spectroscopy during transition of healthy term newborns.

BACKGROUND: Values of regional cerebral tissue oxygen saturation (cStO2) have been described during transition of term and preterm infants after birth. However, use of different devices precludes comparison of measurements. OBJECTIVE: To measure cStO2 during transition of term infants using a calibrated 4-wavelength laser light source near-infrared spectroscopy oximeter (FORE-SIGHT) to obtain data that allow comparison with cStO2 of very-low-birth-weight (VLBW) infants using this oximeter and with cStO2 of term infants using different oximeters. METHODS: cStO2 (FORE-SIGHT oximeter), preductal arterial oxygen saturation and heart rate were measured in 46 healthy term infants (n = 20 spontaneous delivery, n = 22 caesarean section, n = 4 assisted vaginal delivery) during the first 10 min after delivery. RESULTS: The median (interquartile range) cStO2 at 2 min after birth was 42% (39-46) after spontaneous delivery, 42% (30-52) after caesarean section and 36% (20-53) after assisted vaginal delivery (no difference between groups). In association with increasing arterial oxygen saturation and heart rate, cStO2 increased continuously and reached a steady state approximately 8 min after birth of 62-77% (interquartile range) in all three groups. CONCLUSIONS: Healthy term newborns had similar cStO2 changes from 2 min after birth regardless of the mode of delivery. cStO2 of healthy term infants was lower than cStO2 of VLBW infants during transition. cStO2 values as measured by the FORE-SIGHT oximeter seem in the range of values as measured by the NIRO 300 oximeter. They were lower than values as measured by the INVOS 5100 oximeter.