Oxygen saturation targeting in preterm infants receiving continuous positive airway pressure.

OBJECTIVE: The precision of oxygen saturation (SpO2) targeting in preterm infants on continuous positive airway pressure (CPAP) is incompletely characterized. We therefore evaluated SpO2 targeting in infants solely receiving CPAP, aiming to describe their SpO2 profile, to document the frequency of prolonged hyperoxia and hypoxia episodes and of fraction of inspired oxygen (FiO2) adjustments, and to explore the relationships with neonatal intensive care unit operational factors. STUDY DESIGN: Preterm infants <37 weeks' gestation in 2 neonatal intensive care units were studied if they were receiving CPAP and in supplemental oxygen at the beginning of each 24-hour recording. SpO2, heart rate, and FiO2 were recorded (sampling interval 1-2 seconds). We measured the proportion of time spent in predefined SpO2 ranges, the frequency of prolonged episodes (≥30 seconds) of SpO2 deviation, and the effect of operational factors including nurse-patient ratio. RESULTS: A total of 4034 usable hours of data were recorded from 45 infants of gestation 30 (27-32) weeks (median [IQR]). When requiring supplemental oxygen, infants were in the target SpO2 range (88%-92%) for only 31% (19%-39%) of total recording time, with 48 (6.9-90) episodes per 24 hours of severe hyperoxia (SpO2 ≥98%), and 9.0 (1.6-21) episodes per 24 hours of hypoxia (SpO2 <80%). An increased frequency of prolonged hyperoxia in supplemental oxygen was noted when nurses were each caring for more patients. Adjustments to FiO2 were made 25 (16-41) times per day. CONCLUSION: SpO2 targeting is challenging in preterm infants receiving CPAP support, with a high proportion of time spent outside the target range and frequent prolonged hypoxic and hyperoxic episodes.

Delayed antivenom for life-threatening tiger snake bite: Lessons learnt.

An adolescent victim of an urban snakebite developed respiratory failure, rhabdomyolysis and consumption procoagulopathy but recovered with two vials of tiger snake antivenom administered after a delay of 48 hours. The clinical significance of a post-bite collapse was not initially appreciated. Tiger snake (Notechis spp.) venom antigen was measurable in blood before antivenom but not after whereas antivenom was measurable in blood for nine ensuing days. This case adds to growing evidence that further pharmacokinetic research of venom-antivenom interaction is required to establish the correct dose and timing of tiger snake antivenom. Antivenom therapy, even when delayed, facilitates recovery from snake envenomation.

Impact of Minimally Invasive Surfactant Therapy in Preterm Infants at 29-32 Weeks Gestation.

BACKGROUND: Most preterm infants born at 29-32 weeks gestation now avoid intubation in early life, and thus lack the usual conduit through which exogenous surfactant is given if needed. OBJECTIVE: The aim of this work was to examine whether a technique of minimally invasive surfactant therapy used selectively at 29-32 weeks gestation would improve outcomes. METHODS: We studied the impact of selective administration of surfactant (poractant alfa 100-200 mg/kg) by thin catheter in infants with respiratory distress syndrome on continuous positive airway pressure (CPAP). The threshold for consideration of treatment was CPAP ≥7 cm H2O and FiO2 ≥0.35 prior to 24 h of life. In-hospital outcomes were compared before and after introducing minimally invasive surfactant therapy (epochs 1 and 2, respectively). RESULTS: During epoch 2, of 266 infants commencing CPAP, 51 (19%) reached the treatment threshold. Thirty-seven infants received surfactant via thin catheter, and CPAP failure was avoided in 34 of these (92%). For the overall cohort of infants at 29-32 weeks gestation, after the introduction of minimally invasive surfactant therapy, there were reductions in CPAP failure (epoch 1: 14%, epoch 2: 7.2%) and average days of intubation, with equivalent surfactant use and days of respiratory support (intubation + CPAP). Pneumothorax was substantially reduced (from 8.0 to 2.4%). These findings were mirrored within the subgroups reaching the severity threshold in each epoch. The incidence of bronchopulmonary dysplasia was low in both epochs. CONCLUSIONS: Selective use of minimally invasive surfactant therapy at 29-32 weeks gestation permits a primary CPAP strategy to be pursued with a high rate of success, and a low risk of pneumothorax.

Lost without trace: oximetry signal dropout in preterm infants.

Oxygen saturation (SpO2) signal dropout leaves caregivers without a reliable measure to guide oxygen therapy. We studied SpO2 dropout in preterm infants on continuous positive airway pressure, noting the SpO2 values at signal loss and recovery and thus the resultant change in SpO2, and the factors influencing this parameter. In 32 infants of median gestation 26 weeks, a total of 3932 SpO2 dropout episodes were identified (1.1 episodes/h). In the episodes overall, SpO2 decreased by 1.1%, with the SpO2 change influenced by starting SpO2 (negative correlation), but not dropout duration. For episodes starting in hypoxia (SpO2 <85%), SpO2 recovered at a median of 3.2% higher than at SpO2 dropout, with a downward trajectory in a quarter of cases. We conclude that after signal dropout SpO2 generally recovers in a relative normoxic range. Blind FiO2 adjustments are thus unlikely to be of benefit during most SpO2 dropout episodes.