Short term evaluation of respiratory effort by premature infants supported with bubble nasal continuous airway pressure using Seattle-PAP and a standard bubble device.

BACKGROUND: Almost one million prematurely born infants die annually from respiratory insufficiency, predominantly in countries with limited access to respiratory support for neonates. The primary hypothesis tested in the present study was that a modified device for bubble nasal continuous positive airway pressure (Bn-CPAP) would provide lower work of spontaneous breathing, estimated by esophageal pressure-rate products. METHODS: Infants born <32 weeks gestation and stable on Bn-CPAP with FiO2 <0.30 were studied within 72 h following delivery. Esophageal pressures during spontaneous breathing were measured during 2 h on standard Bn-CPAP, then 2 h with Bn-CPAP using a modified bubble device presently termed Seattle-PAP, which produces a different pattern of pressure fluctuations and which provided greater respiratory support in preclinical studies, then 2 h on standard Bn-CPAP. RESULTS: All 40 infants enrolled completed the study and follow-up through 36 wks post menstrual age or hospital discharge, whichever came first. No infants were on supplemental oxygen at completion of follow-up. No infants developed pneumothoraces or nasal trauma, and no adverse events attributed to the study were observed. Pressure-rate products on the two devices were not different, but effort of breathing, assessed by areas under esophageal pressure-time curves, was lower with Seattle-PAP than with standard Bn-CPAP. CONCLUSION: Use of Seattle-PAP to implement Bn-CPAP lowers the effort of breathing exerted even by relatively healthy spontaneously breathing premature neonates. Whether the lower effort of breathing observed with Seattle-PAP translates to improvements in neonatal mortality or morbidity will need to be determined by studies in appropriate patient populations.

Transcatheter elimination of left-to-right shunts in infants with bronchopulmonary dysplasia is feasible and safe.

OBJECTIVE: To test the hypothesis that transcatheter elimination of left-to-right (L-R) cardiac shunts in former premature infants with bronchopulmonary dysplasia (BPD) is feasible, safe, and is associated with an improvement in respiratory status. DESIGN: Retrospective case review. PATIENTS: Twelve patients with BPD who underwent an attempt at transcatheter closure of an L-R shunt lesion within the first year of life at a single center. Median weight was 5.4 kg and median age was 6 months. Fifteen L-R shunt lesions included patent ductus arteriosus (n = 1), atrial septal defect (ASD) (n = 9), and aortopulmonary collaterals (n = 5). OUTCOME MEASURES: Echocardiographic and clinical markers were collected before and after intervention as well as procedural variables including successful elimination of the shunt and procedural complications. RESULTS: The L-R shunts were successfully occluded in 11/12 (91.6%) patients without any significant procedural adverse event. The ASD closure group demonstrated a decrease in right heart size after the procedure. All patients required respiratory support prior to, and 1 month after, the procedure while only 5/10 (50%) required respiratory support at 12 months of age (P = .0129). There was no change in the median weight percentile over time. CONCLUSION: Transcatheter occlusion of L-R shunts can be performed safely and effectively in children with BPD. Further studies may clarify the role of such therapy in improvement in respiratory physiology over time.

Myocardial tissue Doppler changes in patients with bronchopulmonary dysplasia.

OBJECTIVE: To determine whether tissue Doppler measurements provide sensitive measures of right ventricular function that correlate with the severity of bronchopulmonary dysplasia (BPD). STUDY DESIGN: 21 subjects (6 control subjects with no/mild BPD, 7 patients with moderate BPD, and 8 patients with severe BPD) underwent limited echocardiograms with standard M-mode, mitral and tricuspid inflow velocities, and tissue Doppler features measured. BPD severity was scored by using the NICHD/NHLBI/ORD workshop rating scale by physicians blinded to the echocardiogram results. Groups were compared by using 1-way analysis of variance with post-hoc testing and linear regression. RESULTS: Patients with moderate BPD had a higher early Doppler inflow velocity to the early tissue Doppler velocity ratio (E/E' ratio; P = .03), corresponding to increased end diastolic pressure, compared with patients with no/mild BPD. Patients with severe BPD had a higher E/E' ratio (P = .004) than patients with no/mild BPD. Linear regression demonstrated a correlation between BPD category and right ventricle E/E' (P = .007, R(2) = 0.33) and left ventricular myocardial performance index (P = .02, R(2) = 0.28). CONCLUSION: Increasing right ventricle E/E' ratio correlates with clinical severity of BPD. Abnormal left ventricular myocardial performance index was noted to correlate with the grade of BPD. Further longitudinal studies of tissue Doppler echocardiographic assessment of cardiac function in premature infants with BPD are needed.

Spatiotemporal characteristics of acid refluxate and relationship to symptoms in premature and term infants with chronic lung disease.

BACKGROUND AND OBJECTIVES: The prevalence of gastroesophageal reflux (GER) is high among infants with chronic lung disease (CLD), and the associated pathogenic mechanisms are not clear. The relationship of symptoms to the extent or duration of acid reflux events (AREs) is not well known in preterm or term infants. Our aim was to evaluate the relationship between spatial (height) and temporal (duration) characteristics of AREs (pH <4.0) with symptoms in CLD. We tested the hypothesis that in infants with CLD, AREs into the pharynx are associated with increased symptom occurrence and delayed clearance. METHODS: Nine infants born at 29.8 +/- 5.5 wk gestation (mean +/- SD, range 24.7-39.0 wk) with CLD were evaluated for GER at 49.7 +/- 8.0 wk postmenstrual age (mean +/- SD, range 39.9-67.4 wk). Esophageal manometry was first performed to determine the nares-lower esophageal sphincter (LES) distance. A pH-impedance probe was placed at 87% of the nares-LES distance, and a recording was performed for about 24 h at cribside. Symptoms (respiratory, sensory, and movement) were documented by nurses that were blinded to the pH-impedance recordings. A symptom was considered associated with an ARE if it occurred 2 min before, during, or 2 min after the ARE. The proximal extent and associated clearance mechanisms were correlated with symptom sensitivity index (SSI = number of AREs with symptoms/total AREs *100). Multiple logistic regression methods, analysis of variance (ANOVA) models, and chi(2) tests were performed. Data are described as median, mean +/- SD, or %. RESULTS: A total of 511 AREs, based on pH-Impedance methods, were analyzed from 203 h of recordings in the nine infants. The distal esophagus was the maximal height reached in 80% of AREs (P < 0.001, compared to other esophageal segments). Overall 33% of the AREs were associated with symptoms, and an SSI of 77% was noted with high AREs into the pharynx. The average acid clearance time was prolonged with symptomatic AREs versus nonsymptomatic AREs by 3.5-fold (P < 0.001). CONCLUSIONS: The occurrence and frequency of symptoms with AREs depend on the most proximal extent of the ARE and the acid clearance time.