Objectives To identify variables associated with successful elective extubation, and to determine neonatal morbidities associated with extubation failure in extremely preterm neonates. Study design This study was a secondary analysis of the National Institute of Child Health and Human Development Neonatal Research Network’s Surfactant, Positive Pressure, and Oxygenation Randomized Trial that included extremely preterm infants born at 240/7 to 276/7 weeks’ gestation. Patients were randomized either to a permissive ventilatory strategy (continuous positive airway pressure group) or intubation followed by early surfactant (surfactant group). There were prespecified intubation and extubation criteria. Extubation failure was defined as reintubation within 5 days of extubation. Results Of 1316 infants in the trial, 1071 were eligible; 926 infants had data available on extubation status; 538 were successful and 388 failed extubation. The rate of successful extubation was 50% (188/374) in the continuous positive airway pressure group and 63% (350/552) in the surfactant group. Successful extubation was associated with higher 5-minute Apgar score, and pH prior to extubation, lower peak fraction of inspired oxygen within the first 24 hours of age and prior to extubation, lower partial pressure of carbon dioxide prior to extubation, and non-small for gestational age status after adjustment for the randomization group assignment. Infants who failed extubation had higher adjusted rates of mortality (OR 2.89), bronchopulmonary dysplasia (OR 3.06), and death/bronchopulmonary dysplasia (OR 3.27). Conclusions Higher 5-minute Apgar score, and pH prior to extubation, lower peak fraction of inspired oxygen within first 24 hours of age, lower partial pressure of carbon dioxide and fraction of inspired oxygen prior to extubation, and nonsmall for gestational age status were associated with successful extubation. Failed extubation was associated with significantly higher likelihood of mortality and morbidities. Trial registration ClinicalTrials.gov: NCT00233324.

The present study was undertaken to determine if a synthetic peptide, KLLLLKLLLLKLLLLKLLLLK (KL4), in which K = lysine and L = leucine, in an aqueous dispersion of phospholipids (DPPC and POPG), would expand pulmonary alveoli and improve gas exchange in premature human infants with respiratory distress syndrome (RDS). The KL4 peptide was synthesized to resemble the amino acid pattern of surfactant protein B (SP-B). Forty-seven infants with RDS were treated within 4 h of birth with the KL4-peptide/phospholipid mixture, called KL4-Surfactant. The average arterial-to-alveolar oxygen tension ratios (a/A O2) of 39 patients included in efficacy analyses rose from pretreatment values of 0.14 +/- 0.02 (mean +/- SEM) to 0.40 +/- 0.04 (normal value > or = 0.40) by 12 h of age. Mean airway pressures and oxygenation index values fell concomitantly, and expansion of the lungs was observed on radiographs. The median duration of mechanical ventilation was 5.0 d. Of the 39 included infants, 29 required only a single dose. Radiographic data indicate that those patients requiring a second instillation of KL4-Surfactant but not showing a sustained rise in a/A O2 ratios did, in fact, exhibit expansion of alveoli in the lung. There were no RDS-related deaths; the incidence of complications was no higher than found in other comparable published studies. The data demonstrate that the synthetic peptide, KL4, which mimics the hydrophobic and hydrophilic pattern of SP-B, when formulated in an aqueous dispersion with the phospholipids DPPC and POPG, creates a strong and durable surfactant activity as judged by expansion of pulmonary alveoli and improvement of gas exchange in infants with RDS.

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Holstein cows (n = 64) ranging from peak to end lactation were restrained in self-locking stanchions (i.e., head locks) for approximately 4 h/d for four periods in a modified switchback design. Milk yield, milk fat percentage, somatic cell count, and dry matter intake and dry matter intake were unaffected by restraint. Milk protein percentage was significantly lower for cows that were restrained. Plasma cortisol concentrations and the ratio of neutrophils to mononuclear cells were not significantly different between restrained and unrestrained (control) cows. No difference in the incidence of mastitis or other health concerns was noted. Behaviorally, cows that were locked in the stanchions spent significantly more time lying after release from restraint. For cows that were locked up, eating frequency over 24 h was significantly reduced, but dry matter intake was not affected. Total rumination frequency over 24 h was not significantly different for cows that were restraubed; however, cows that were restrained ruminated less during the day following release. Grooming was considered to be a behavioral need and was significantly increased during all times when cows were not locked up. Grooming was also one of the first behaviors performed following release. Acts of aggression were elevated during all periods following restraint, but oral behaviors, such as tongue playing and chewing on objects, drinking behavior, and resting postures were not affected. The use of self-locking stanchions did not appear to affect substantially the overall well-being of the cow.

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