SV40 seroprevalence in two Latin American countries involved in field trials of candidate oral poliovaccines.

OBJECTIVES: This study sought to determine SV40 seroprevalence in residents of two Latin American countries, Colombia and Nicaragua, which were sites of prelicensure oral poliovaccine (OPV) trials. METHODS: Archival sera were tested for SV40 neutralizing antibody using a virus-specific plaque-reduction assay. Samples included 517 sera from Colombia and 149 sera from Nicaragua. RESULTS: Overall SV40 seroprevalence was 22.8% for Colombian subjects and 12.8% for Nicaraguans. Subgroups of Colombian subjects ranged in frequency of SV40 seropositivity from 10.0% to 38.6%. Birth cohorts both older and younger than the age cohort that contained potential OPV vaccinees from both countries had SV40 antibodies. Gender and ethnicity had no significant effects on SV40 seropositivity. CONCLUSIONS: Inhabitants of both Colombia and Nicaragua had detectable SV40 neutralizing antibody, including those of ages presumably not recipients of potentially SV40-contaminated OPV. This observation provides support for the concept that transmission of SV40 human infections can occur. Frequency of SV40 antibody positivity was elevated over that reported for the US where there was limited use of contaminated OPV. This investigation indicates also that study results of SV40 infections in humans will reflect whether subject populations had probable exposures to contaminated poliovaccines and to environmental conditions favoring cycles of viral transmission.

Exhaled carbon dioxide in healthy term infants immediately after birth.

OBJECTIVE: To measure exhaled carbon dioxide (ECO2) in term infants immediately after birth. STUDY DESIGN: Infants >37 weeks gestation born at The Royal Women's Hospital, Melbourne, Australia were eligible. A combined flow sensor and mainstream carbon dioxide (CO2) analyzer was placed in series proximal to a facemask to measure ECO2 and tidal volumes in the first 120 seconds after birth. RESULTS: Term infants (n = 20) with a mean (SD) birth weight of 2976 (697) g and gestational age of 38 (2) weeks were included. Infants took a median (range) 3 (1-8) breaths before ECO2 was detected. The median (range) of maximum ECO2 was 51 (40-73) mm Hg at 70 (21-106) seconds after birth. Within the first 10 breaths, CO2 increased from 0-27 (22-34) mm Hg. The median (IQR) tidal volume during the breaths without CO2 was 1.2 (0.8-3.1) mL/kg compared with 7.3 (3.2-10.9) mL/kg during the first 10 breaths where CO2 was exhaled. CONCLUSIONS: The first breaths for an infant after birth did not contain ECO2. With aeration of the distal gas exchange regions, tidal volume and ECO2 significantly increased. ECO2 can be used to monitor lung aeration immediately after birth.

The effects of nasal continuous positive airway pressure on cardiac function in premature infants with minimal lung disease: a crossover randomized trial.

OBJECTIVE: To assess the effects of different nasal continuous positive airway pressure (nCPAP) pressures on cardiac performance in preterm infants with minimal lung disease, we conducted a randomized, blinded crossover study. STUDY DESIGN: We studied infants between 28 and 34 weeks' corrected gestational age, treated with nCPAP of 5 cm H2O, in air. Infants with significant cardiac shunts were excluded. Infants were randomly assigned to nCPAP levels of 4, 6, and 8 cm H2O for 15 minutes each. Right and left ventricular outputs and left pulmonary artery and superior vena cava flows were measured 15 minutes after each change. RESULTS: Thirty-four infants born at a mean gestational age of 29 weeks with a birth weight of 1.3 kg were studied. There were no significant differences in right and left ventricular outputs and left pulmonary artery and superior vena cava flows at different levels of nCPAP. CONCLUSION: We investigated the effect of increasing nCPAP levels on cardiac output. We conclude that nCPAP levels between 4 and 8 cm H2O did not have an effect on cardiac output in stable preterm infants with minimal lung disease.

Respiratory function monitor guidance of mask ventilation in the delivery room: a feasibility study.

OBJECTIVE: To investigate whether using a respiratory function monitor (RFM) during mask resuscitation of preterm infants reduces face mask leak and improves tidal volume (V(T)). STUDY DESIGN: Infants receiving mask resuscitation were randomized to have the display of an RFM (airway pressure, flow, and V(T) waves) either visible or masked. RESULT: Twenty-six infants had the RFM visible, and 23 had the RFM masked. The median mask leak was 37% (IQR, 21%-54%) in the visible RFM group and 54% (IQR, 37%-82%) in the masked RFM group (P = .01). Mask repositioning was done in 19 infants (73%) of the visible group and in 6 infants (26%) of the masked group (P = .001). The median expired V(T) was similar in the 2 groups. Oxygen was provided to 61% of the visible RFM group and 87% of the RFM masked group (P = .044). Continuous positive airway pressure use was greater in the visible RFM group (73% vs 43%; P = .035). Intubation in the delivery room was done in 21% of the visible group and in 57% of the masked group (P = .035). CONCLUSION: Using an RFM was associated with significantly less mask leak, more mask adjustments, and a lower rate of excessive V(T).

Identification of pneumothorax in very preterm infants.

OBJECTIVE: To compare respiratory and other morbidities between very preterm infants with and without a pneumothorax and to determine whether infants at higher risk of pneumothorax can be identified early in their course. STUDY DESIGN: Preterm infants at 23 to 28 weeks' gestation with pneumothorax were compared with matched control subjects. Demographic and clinical data from birth through the first 72 hours were compared. RESULTS: Sixty-two (9.2%) of 675 infants had pneumothorax. There were no significant differences in the baseline maternal and infant characteristics. Mortality was significantly higher in the pneumothorax group (43%) versus control subjects (13%). There was no significant difference in continuous positive airway pressure or surfactant treatment or rates of intraventricular hemorrhage or bronchopulmonary dysplasia. Infants treated with early continuous positive airway pressure in the delivery room typically had pneumothorax on day 2 of life. Those who had pneumothorax had higher inspired fraction of oxygen before its diagnosis and over the first 12 hours of life than did control subjects. CONCLUSIONS: Pneumothorax is associated with increased mortality and with severity of lung disease in the first day of life. It may be possible to identify babies at highest risk of pneumothorax on the basis of inspired fraction of oxygen in the first 12 hours of life.