Long QT and Hearing Loss in High-Risk Infants Prospective Study Registry.

The objective of this study is to determine the prevalence of an abnormal electrocardiogram showing a prolonged QTc greater than 450 ms in infants with unilateral or bilateral sensorineural hearing loss. We conducted a prospective study of healthy term infants (≥37 weeks gestational age) who failed their newborn auditory brainstem response hearing screen, were seen by an audiologist and diagnosed as having sensorineural hearing loss during follow-up to 1 year of age. In infants with a diagnosis of hearing loss, we collected a detailed family history and performed an ECG between 2 and 6 months of age. We obtained follow-up for 1 year by calling the parent requesting the hearing and cardiac status of their child. Two of the 40 infants with sensorineural hearing loss (5%) had a QTc greater than 450 ms. Both had mild bilateral hearing loss and genetic testing did not identify a known mutation for long QT syndrome. The remaining 38 infants had QTc intervals of ≤ 450 ms. One patient diagnosed with bilateral severe sensorineural hearing loss had a normal ECG (QTc = 417 ms). Several months after the ECG was performed, the infant's mother contacted the study cardiologist after she learned that the infant's maternal grandmother was diagnosed with a cardiomyopathy and arrhythmias. Genetic testing was recommended even though the child was asymptomatic and was positive for a pathogenic mutation in the KCNQ1 gene. We speculate that molecular genetic testing in infants with hearing loss may become the standard of care rather than targeted electrocardiograms.Clinical Trial Registration NCT02082431 https://www.clinicaltrials.gov/ct2/show/NCT02692521?cond=NCT02692521&rank=1 .

Evaluation of a lipid extract surfactant isolated from foam from adult sheep lung lavage

A simple and inexpensive method of isolating surfactant was devised. The in vivo function of surfactant isolated from saline alveolar washes of adult sheep lungs by foam formation using nitrogen gas was evaluated. The foam was organic solvent extracted with chloroform:methanol:saline (2:1:1 v/v) either once or twice. Part of each lipid extract surfactant (LES) was autoclaved. The total phosphorus (TP) and saturated phosphatidylcholine (sat PC) measurements were used to quantify these phospholipids in the LES. The mean sat PC:TP ratio was 0.54 and there were no changes with sterilization. to evaluate in vivo function, surfactant deficient preterm rabbits were treated intratracheally with either 100 mg/kg of the isolated sheep surfactant extracted twice with chloroform:methanol (LES-2), surfactant extracted only once (LES- 1), 4 ml/kg Survanta (S), or air (control, Cx). The rabbits were then ventilated with dital volumes of 8 ml/kg and 3 cm H20 positive and expiratory pressure (PEEP). Ventilation pressures (peak inspiratory pressure-PIP in cm H20, mean +/- SE) of animals treated with LES-2 (14.4 +/- 0.7) were lower (p 0.01) than Cx (22.8 + 0.5) and LES-1 (19.5 + 0.6), and not different from S (14.6 +/- 1.1). Dynamic compliances (ml/cmH20/kg) in animals treated with LES-2 (0.6 +/- 0.0) were higher (p 0.01) than Cx (0.4 +/- 0.0) and LES-1 (0.4 +/- 0.0), and not different from S (0.6 +/- 0.1). The initial inflation pressure from pressure-volume curve measurements was lowest for LES-2 treated animals (p0.01 at 20cm H20). Survanta and LES-2 treated animals retained more volume on deflation than Cx and LES-1 animals (p 0.01 at 0 cm H20). The ventilation and pressure-volume curve measurements for the autoclaved LES and non-autoclaved LES were similar. Based on the invivo performance of the LES, recommendations are made for improvements of the isolation procedure. (Author)