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Background: Previous randomised trials and meta-analyses have shown that nasal continuous positive airway pressure (NCPAP) is a useful method for providing respiratory support after extubation. However, this treatment sometimes 'fails' in infants, and they may require endotracheal re-intubation with its attendant risks and expense. Nasal intermittent positive pressure ventilation (NIPPV) can augment NCPAP by delivering ventilator breaths via nasal prongs. Older children and adults with chronic respiratory failure benefit from NIPPV, and the technique has been applied to neonates. However, serious side effects including gastric perforation have been reported with older methods of providing NIPPV., Objectives: Primary objective To compare effects of management with NIPPV versus NCPAP on the need for additional ventilatory support in preterm infants whose endotracheal tube was removed after a period of intermittent positive pressure ventilation. Secondary objectives To compare rates of gastric distension, gastrointestinal perforation, necrotising enterocolitis and chronic lung disease; duration of hospitalisation; and rates of apnoea, air leak and mortality for NIPPV and NCPAP., Search Methods: We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 9), MEDLINE via PubMed (1966 to 28 September 2015), Embase (1980 to 28 September 2015) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 28 September 2015). We also searched clinical trials databases, conference proceedings and reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials., Selection Criteria: We included randomised and quasi-randomised trials comparing use of NIPPV versus NCPAP in extubated preterm infants. NIPPV included non-invasive support delivered by a mechanical ventilator or a bilevel device in a synchronised or non-synchronised way. Participants included ventilated preterm infants who were ready to be extubated to non-invasive respiratory support. Interventions compared were NIPPV, delivered by short nasal prongs or nasopharyngeal tube, and NCPAP, delivered by the same methods.Types of outcomes measures included failure of therapy (respiratory failure, rates of endotracheal re-intubation); gastrointestinal complications (i.e. abdominal distension requiring cessation of feeds, gastrointestinal perforation or necrotising enterocolitis); pulmonary air leak; chronic lung disease (oxygen requirement at 36 weeks' postmenstrual age) and mortality., Data Collection and Analysis: Three review authors independently extracted data regarding clinical outcomes including extubation failure; endotracheal re-intubation; rates of apnoea, gastrointestinal perforation, feeding intolerance, necrotising enterocolitis, chronic lung disease and air leak; and duration of hospital stay. We analysed trials using risk ratio (RR), risk difference (RD) and the number needed to treat for an additional beneficial outcome (NNTB) or an additional harmful outcome (NNTH) for dichotomous outcomes, and mean difference (MD) for continuous outcomes. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence., Main Results: Through the search, we identified 10 trials enrolling a total of 1431 infants and comparing extubation of infants to NIPPV or NCPAP. Three trials had methodological limitations and possible selection bias.Five trials used the synchronised form of NIPPV, four used the non-synchronised form and one used both methods. Eight studies used NIPPV delivered by a ventilator, one used a bilevel device and one used both methods. When all studies were included, meta-analysis demonstrated a statistically and clinically significant reduction in the risk of meeting extubation failure criteria (typical RR 0.70, 95% CI 0.60 to 0.80; typical RD -0.13, 95% CI -0.17 to -0.08; NNTB 8, 95% CI 6 to 13; 10 trials, 1431 infants) and needing re-intubation (typical RR 0.76, 95% CI 0.65 to 0.88; typical RD -0.10, 95% CI -0.15 to -0.05; NNTB 10, 95% CI 7 to 20; 10 trials, 1431 infants). We graded evidence for these outcomes as moderate, as all trial interventions were unblinded. Although methods of synchronisation varied (Graseby capsule or pneumotachograph/flow-trigger), the five trials that synchronised NIPPV showed a statistically significant benefit for infants extubated to NIPPV in terms of prevention of extubation failure up to one week after extubation.Unsynchronised NIPPV also reduced extubation failure. NIPPV provided via a ventilator is more beneficial than that provided by bilevel devices in reducing extubation failure during the first week. When comparing interventions, investigators found no significant reduction in rates of chronic lung disease (typical RR 0.94, 95% CI 0.80 to 1.10; typical RD -0.02, 95% CI -0.08 to 0.03) or death, and no difference in the incidence of necrotising enterocolitis. Air leaks were reduced in infants randomised to NIPPV (typical RR 0.48, 95% CI 0.28 to 0.82; typical RD -0.03, 95% CI -0.05 to -0.01; NNTB 33, 95% CI 20 to 100). We graded evidence quality as moderate (unblinded studies) or low (imprecision) for secondary outcomes., Authors' Conclusions: Implications for practice NIPPV reduces the incidence of extubation failure and the need for re-intubation within 48 hours to one week more effectively than NCPAP; however, it has no effect on chronic lung disease nor on mortality. Synchronisation may be important in delivering effective NIPPV. The device used to deliver NIPPV may be important; however, data are insufficient to support strong conclusions. NIPPV does not appear to be associated with increased gastrointestinal side effects. Implications for research Large trials should establish the impact of synchronisation of NIPPV on safety and efficacy of the technique and should compare the efficacy of bilevel devices versus a ventilator for providing NIPPV.

Background: Respiratory distress syndrome (RDS) is the single most important cause of morbidity and mortality in preterm infants. In infants with progressive respiratory insufficiency, intermittent positive pressure ventilation (IPPV) with surfactant is the standard treatment for the condition, but it is invasive, potentially resulting in airway and lung injury. Continuous distending pressure (CDP) has been used for the prevention and treatment of RDS, as well as for the prevention of apnoea, and in weaning from IPPV. Its use in the treatment of RDS might reduce the need for IPPV and its sequelae., Objectives: To determine the effect of continuous distending pressure (CDP) on the need for IPPV and associated morbidity in spontaneously breathing preterm infants with respiratory distress.Subgroup analyses were planned on the basis of birth weight (> or < 1000 or 1500 g), gestational age (groups divided at about 28 weeks and 32 weeks), methods of application of CDP (i.e. CPAP and CNP), application early versus late in the course of respiratory distress and high versus low pressure CDP and application of CDP in tertiary compared with non-tertiary hospitals, with the need for sensitivity analysis determined by trial quality.At the 2008 update, the objectives were modified to include preterm infants with respiratory failure., Search Methods: We used the standard search strategy of the Neonatal Review Group. This included searches of the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, 2015 Issue 4), MEDLINE (1966 to 30 April 2015) and EMBASE (1980 to 30 April 2015) with no language restriction, as well as controlled-trials.com, clinicaltrials.gov and the International Clinical Trials Registry Platform of the World Health Organization (WHO)., Selection Criteria: All random or quasi-random trials of preterm infants with respiratory distress were eligible. Interventions were continuous distending pressure including continuous positive airway pressure (CPAP) by mask, nasal prong, nasopharyngeal tube or endotracheal tube, or continuous negative pressure (CNP) via a chamber enclosing the thorax and the lower body, compared with spontaneous breathing with oxygen added as necessary., Data Collection and Analysis: We used standard methods of The Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each review author., Main Results: We included six studies involving 355 infants - two using face mask CPAP, two CNP, one nasal CPAP and one both CNP (for less ill babies) and endotracheal CPAP (for sicker babies). For this update, we included no new trials.Continuous distending pressure (CDP) is associated with lower risk of treatment failure (death or use of assisted ventilation) (typical risk ratio (RR) 0.65, 95% confidence interval (CI) 0.52 to 0.81; typical risk difference (RD) -0.20, 95% CI -0.29 to -0.10; number needed to treat for an additional beneficial outcome (NNTB) 5, 95% CI 4 to 10; six studies; 355 infants), lower overall mortality (typical RR 0.52, 95% CI 0.32 to 0.87; typical RD -0.15, 95% CI -0.26 to -0.04; NNTB 7, 95% CI 4 to 25; six studies; 355 infants) and lower mortality in infants with birth weight above 1500 g (typical RR 0.24, 95% CI 0.07 to 0.84; typical RD -0.28, 95% CI -0.48 to -0.08; NNTB 4, 95% CI 2.00 to 13.00; two studies; 60 infants). Use of CDP is associated with increased risk of pneumothorax (typical RR 2.64, 95% CI 1.39 to 5.04; typical RD 0.10, 95% CI 0.04 to 0.17; number needed to treat for an additional harmful outcome (NNTH) 17, 95% CI 17.00 to 25.00; six studies; 355 infants). We found no difference in bronchopulmonary dysplasia (BPD), defined as oxygen dependency at 28 days (three studies, 260 infants), as well as no difference in outcome at nine to 14 years (one study, 37 infants)., Authors' Conclusions: In preterm infants with respiratory distress, the application of CDP as CPAP or CNP is associated with reduced respiratory failure and mortality and an increased rate of pneumothorax. Four out of six of these trials were done in the 1970s. Therefore, the applicability of these results to current practice is difficult to assess. Further research is required to determine the best mode of administration.

Background: Extremely preterm infants require assistance recruiting the lung to establish a functional residual capacity after birth. Sustained inflation (SI) combined with positive end expiratory pressure (PEEP) may be a superior method of aerating the lung compared with intermittent positive pressure ventilation (IPPV) with PEEP in extremely preterm infants. The Sustained Aeration of Infant Lungs (SAIL) trial was designed to study this question., Methods/design: This multisite prospective randomized controlled unblinded trial will recruit 600 infants of 23 to 26 weeks gestational age who require respiratory support at birth. Infants in both arms will be treated with PEEP 5 to 7 cm H2O throughout the resuscitation. The study intervention consists of performing an initial SI (20 cm H20 for 15 seconds) followed by a second SI (25 cm H2O for 15 seconds), and then PEEP with or without IPPV, as needed. The control group will be treated with initial IPPV with PEEP. The primary outcome is the combined endpoint of bronchopulmonary dysplasia or death at 36 weeks post-menstrual age., Trial Registration: www.clinicaltrials.gov , Trial identifier NCT02139800 , Registered 13 May 2014.

Background: Children with impending respiratory failure due to severe asthma may be treated with endotracheal intubation and mechanical ventilation. Barotrauma occurs in a significant number of these children. Non-invasive positive pressure ventilation (NPPV) has been used as an alternative intermediary therapy and potentially prevents intubation. However, the comparative risk of barotrauma associated with the use of NPPV has not been evaluated in this population., Objective: To determine if the mode of positive pressure delivery per se affects the likelihood of development of barotrauma., Methods: We retrospectively examined data from all children older than 2 years of age admitted to the Intensive Care Unit (ICU) with an asthma exacerbation between April 1997 and August 2006., Results: Of the 293 children admitted to the ICU with asthma, 45 (17%) received treatment with positive pressure ventilation: 11 received only NPPV, 29 were intubated and mechanically ventilated, and 7 children received both of these therapies. Compared with those not requiring positive pressure, children receiving positive pressure were significantly more likely to develop barotrauma during hospitalization (OR 8.9; 95% CI 2.4-32.7). However, the incidence of barotrauma did not significantly differ according to the mode of positive pressure delivery: 9% in those who received only NPPV, 14% in those who were intubated, and 14% in those who received both therapies (p = 0.92)., Conclusions: The use of positive pressure is associated with an increased risk of barotrauma in children with asthma, regardless of the mode of delivery.

Background: Respiratory distress syndrome (RDS) is the single most important cause of morbidity and mortality in preterm infants (Greenough 1998, Bancalari 1992). Intermittent positive pressure ventilation (IPPV) with surfactant is the standard treatment for the condition. The major difficulty with IPPV is that it is invasive, resulting in airway and lung injury and contributing to the development of chronic lung disease., Objectives: In spontaneously breathing preterm infants with RDS, to determine if continuous distending pressure (CDP) reduces the need for IPPV and associated morbidity without adverse effects., Search Strategy: The standard search strategy of the Neonatal Review group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2002), MEDLINE (1966-January 2002), and EMBASE (1980-January 2002), previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants, journal hand searching mainly in the English language., Selection Criteria: All trials using random or quasi-random allocation of preterm infants with RDS were eligible. Interventions were continuous distending pressure including continuous positive airway pressure (CPAP) by mask, nasal prong, nasopharyngeal tube, or endotracheal tube, or continuous negative pressure (CNP) via a chamber enclosing the thorax and lower body, compared with standard care., Data Collection and Analysis: Standard methods of the Cochrane Collaboration and its Neonatal Review Group were used, including independent assessment of trial quality and extraction of data by each author., Main Results: CDP is associated with a lower rate of failed treatment (death or use of assisted ventilation) [summary RR 0.70 (0.55, 0.88), RD -0.22 (-0.35, -0.09), NNT 5 (3, 11)], overall mortality [summary RR 0.52 (0.32, 0.87), RD -0.15 (-0.26, -0.04), NNT 7 (4, 25)], and mortality in infants with birthweights above 1500 g [summary RR 0.24 (0.07, 0.84), RD -0.281 (-0.483, -0.078), NNT 4 (2, 13)]. The use of CDP is associated with an increased rate of pneumothorax [summary RR 2.36 (1.25, 5.54), RD 0.14 (0.04, 0.23), NNH 7 (4, 24)]., Reviewer's Conclusions: In preterm infants with RDS the application of CDP either as CPAP or CNP is associated with benefits in terms of reduced respiratory failure and reduced mortality. CDP is associated with an increased rate of pneumothorax. The applicability of these results to current practice is difficult to assess, given the intensive care setting of the 1970s when four out of five of these trials were done. Where resources are limited, such as in developing countries, CPAP for RDS may have a clinical role. Further research is required to determine the best mode of administration and its role in modern intensive care settings

Unlabelled: In acute lung injury, airway pressure release ventilation (APRV) with superimposed spontaneous breathing improves gas exchange compared with controlled mechanical ventilation. However, the release of airway pressure below the continuous positive airway pressure (CPAP) level may provoke lung collapse. Therefore, we compared gas exchange and hemodynamics using a crossover design in nine pigs with oleic acid-induced lung injury during CPAP breathing and APRV with a release pressure level of 0 and 5 cm H(2)O. At an identical minute ventilation (V(E) 8 L/min) spontaneous breathing averaged 55%, 67%, and 100% of V(E) during the two APRV modes and CPAP, respectively. Because of the concept of APRV, mean airway pressure was highest during CPAP and lowest during APRV with a release pressure of 0 cm H(2)O. Shunt was reduced to almost half during CPAP (6.6% of Q(t)) compared with both APRV-modes (13.0% of Q(t)). Cardiac output and oxygen consumption, in contrast, were similar during all three ventilatory settings. Thus, in our lung injury model, CPAP was superior to partial ventilatory support using APRV with and without positive end-expiratory pressure. This may be attributable to beneficial effects of spontaneous breathing on gas exchange as well as to rapid lung collapse during the phases of airway pressure release below the CPAP level. These findings may suggest that the amount of mechanical ventilatory support using the APRV mode should be kept at the necessary minimum., Implications: Oxygenation is better with continuous positive airway pressure breathing than with partial mechanical ventilatory support using airway pressure release ventilation. Therefore, mechanical ventilatory support achieved by a cyclic release of airway pressure during APRV should be kept at the minimum level that enables enough ventilatory support for patients to avoid respiratory muscle fatigue.

Background: Respiratory distress syndrome (RDS) is the single most important cause of morbidity and mortality in preterm infants (Greenough 1998, Bancalari 1992). Intermittent positive pressure ventilation (IPPV) with surfactant is the standard treatment for the condition. The major difficulty with IPPV is that it is invasive, resulting in airway and lung injury and contributing to the development of chronic lung disease., Objectives: In spontaneously breathing preterm infants with RDS, to determine if continuous distending airway pressure (CDAP) reduces the need for IPPV and associated morbidity without adverse effects., Search Strategy: The standard search strategy of the Neonatal Review group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants, journal hand searching mainly in the English language., Selection Criteria: All trials using random or quasi-random patient allocation of newborn infants with RDS were eligible. Interventions were continuous distending airway pressure including continuous positive airway pressure (CPAP) by mask, nasal prong, nasopharnygeal tube, or endotracheal tube, or continuous negative pressure (CNDP) via a chamber enclosing the thorax and lower body, compared with standard care., Data Collection and Analysis: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used., Main Results: CDAP is associated with a lower rate of failed treatment (death or use of assisted ventilation), overall mortality, and mortality in infants with birthweights above 1500 g. The use of CDAP is associated with an increased rate of pneumothorax., Reviewer's Conclusions: In preterm infants with RDS the application of CDAP either as CPAP or CNDP is associated with some benefits, particularly in infants with birthweights over 1500 gms. The extent of this benefit is difficult to assess given the outdated methods to administer CDAP, low use of antenatal corticosteroids, non-availability of surfactant and the intensive care setting of the 1970's in which these trials were done. Where resources are limited, such as in developing countries, CPAP for RDS may have a clinical role. Further research is required to determine the best mode of administration and its role in modern intensive care settings

Background: Respiratory distress syndrome (RDS) is the single most important cause of morbidity and mortality in preterm infants (Greenough 1998, Bancalari 1992). Intermittent positive pressure ventilation (IPPV) with surfactant is the standard treatment for the condition. The major difficulty with IPPV is that it is invasive, resulting in airway and lung injury and contributing to the development of chronic lung disease., Objectives: In spontaneously breathing preterm infants with RDS, to determine if continuous distending pressure (CDP) reduces the need for IPPV and associated morbidity without adverse effects., Search Strategy: The standard search strategy of the Neonatal Review group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE (1966-Jan. 2000), previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants, journal hand searching mainly in the English language., Selection Criteria: All trials using random or quasi-random patient allocation of newborn infants with RDS were eligible. Interventions were continuous distending pressure including continuous positive airway pressure (CPAP) by mask, nasal prong, nasopharyngeal tube, or endotracheal tube, or continuous negative pressure (CNP) via a chamber enclosing the thorax and lower body, compared with standard care., Data Collection and Analysis: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used., Main Results: CDP is associated with a lower rate of failed treatment (death or use of assisted ventilation), overall mortality, and mortality in infants with birthweights above 1500 g. The use of CDP is associated with an increased rate of pneumothorax., Reviewer's Conclusions: In preterm infants with RDS the application of CDP either as CPAP or CNP is associated with some benefits in terms of reduced respiratory failure and reduced mortality. CDP is associated with an increased rate of pneumothorax. The applicability of these results to current practice is difficult to assess, given the outdated methods to administer CDP, low use of antenatal corticosteroids, non-availability of surfactant and the intensive care setting of the 1970s when these trials were done. Where resources are limited, such as in developing countries, CPAP for RDS may have a clinical role. Further research is required to determine the best mode of administration and its role in modern intensive care settings

Ninety neonates were ventilated over a period of 33 months of whom 50 (55.5%) survived. Fifty seven babies received IPPV while 33 CPAP. IPPV mode was being used more frequently recently and survival rates have steadily improved over past 3 years. Survival was cent per cent in babies above 1.5 kg on CPAP mode while 16/26 (57.7%) survived on IPPV mode. Of 22 extremely VLBW (< 1 kg) babies, six survived. HMD was the commonest indication of ventilation (50%), of which 53% (24/45) survived. The other important indications of ventilation were apnea in 13 and transient tachypnea in 11 babies. All babies requiring ventilation for transient tachypnea survived. Nosocomial infections were common in association with ventilation 34/90 (37.7%), out of which in 14 was responsible for about a third of deaths. Pulmonary air leaks developed in 12 babies of which 6 died. Two babies developed BPD and one ROP. Neonatal ventilation should be ventured in centres where basic facilities for level II care already exist. It may not be cost effective to ventilate extremely low birth weight neonates.

Objectives: To estimate the incidence of silent myocardial ischemia, its pattern over time and its relationship to the time and mode of weaning high-risk cardiac patients after noncardiac surgery., Design: Prospective study with random assignment to one of three weaning modes., Setting: A surgical intensive care unit in a university hospital and a Veterans Administration hospital., Patients: Sixty-two patients meeting standard criteria for extubation were randomized to one of three modes of weaning: synchronized intermittent mandatory ventilation (n = 19), T-Bar (n = 21) or continuous positive airway pressure (n = 22)., Methods: Ischemia was monitored with a continuous two-lead (V5, III) ST segment analyzer. Tracings were reviewed by a cardiologist. Ischemia was defined as greater than 1 mm ST segment depression 60 milliseconds after the J point. The monitoring period included a prewean (mean 654.0 minutes), wean (mean 46.5 minutes) and postwean (mean 1223.4 minutes) period., Results: Of 62 patients, 12 (19.3%) experienced ischemia at some time during the monitoring period, most often during the weaning period. Ischemia during weaning was detected in 3 of 21 (14.3%) T-Bar patients and 2 of 22 (9.1%) continuous positive airway pressure patients but in no synchronized intermittent mandatory ventilation patients., Conclusion: This study demonstrates that silent myocardial ischemia occurs frequently in high-risk postoperative patients, with the highest incidence during weaning.

We investigated the effects of hormonal changes on decreased urine output induced by IPPV with PEEP in 8 dogs anesthetized with nitrous oxide-oxygen-pentobarbital. The decreased urine output could be attributed to the hemodynamic changes as previously reported. The results of this investigation suggest that renin, angiotensin II and ADH do not have significant influences on the decreased urine output. However, the decrease in alpha-ANP which might have been caused by the compression of the atria and the decrease of venous return induced by IPPV with PEEP, may be the cause of the decrease in urine output.

A case is presented of severe barotrauma due to thoracoscopy with multiple lung biopsies and consecutive mechanical ventilation for pneumocystis carinii pneumonia. When tension subcutaneous emphysema developed, circulatory collapse occurred. Relief of pressure by a subcutaneous drain reversed the circulatory state.

Air embolism in neonates is usually fatal. We describe an infant who survived and discuss the pathogenesis and management of this condition.

Positive pressure ventilation is associated with a reduction and redistribution of cardiac output. Splanchnic blood flow is decreased. Blood supply of the liver is reduced exceeding the fall in cardiac output. As a result oxygen transport to the mesenteric bed and liver is curtailed. There is a concomitant impairment of hepatic venous outflow. These hemodynamic changes may cause functional, structural and metabolic disturbances in organs whose blood supply arises from splanchnic circulation.

Alveolar pressure can remain positive throughout the ventilatory cycle of mechanically-ventilated patients with airflow obstruction, even when positive end-expiratory pressure (PEEP) is not applied intentionally. The increase of intrathoracic pressure associated with this "auto-PEEP" phenomenon can severely depress cardiac output as well as elevate the end-expiratory pulmonary artery wedge pressure. Such effects may be exaggerated in patients with chronic obstructive pulmonary disease because abnormally compliant lungs transmit a high fraction of alveolar pressure to intrathoracic vessels. Failure to recognize the hemodynamic consequences of auto-PEEP may lead to inappropriate fluid restriction or unnecessary vasopressor therapy. Although not apparent during normal ventilator operation, the auto-PEEP effect can be detected and quantified by a simple bedside maneuver: expiratory port occlusion at the end of the set exhalation period.

Rabbit neonates delivered on day 27--30 of gestation were subjected to intermittent positive pressure ventilation (IPPV) for 60 min. Tidal volume was standardized to 10 ml/kg, and the insufflation pressure required to maintain this tidal volume was recorded. The quasistatic compliance of the lung-thorax system, corrected for variations in body weight, was significantly lower in animals delivered on day 27--28 than in those delivered on day 29--30. Immature animals with low lung-thorax compliance (less than 0.40 ml/cm H2O.kg) regularly developed widespread necrosis of bronchiolar epithelium following IPPV, whereas no such lesions were observed in mature animals. It seems probable that these lesions are secondary to overdistension of bronchioles during IPPV and that this abnormal expansion pattern is related to a deficiency of surfactant in the lungs of immature newborn animals.

Two newborn infants with respiratory distress syndrome developed massive systemic air embolisms and pneumoencephaly. These complications occurred during positive-pressure ventilation therapy. Intracranial gas was probably due to the rupture of cerebral vessels secondary to systemic gas embolism. The diagnostic features of plain radiographs, computed tomography, and ultrasonography in the evaluation of this unusual entity are described. The importance of early CT scans of the head is emphasized.

Lung function tests in 11 children aged 2.5--5.5 years who required intermittent positive pressure ventilation (1--624 hrs) in infancy were obtained. The conditions necessitating artificial ventilation were hyaline membrane disease, neonatal apneic spells, aspiration of milk, and birth asphyxia. On examination the probands were in a good healthy state and without any subjective signs of dyspnea. Lung volumes could be measured in all of the probands. They did not show any statistically significant deviation from standards for height and correlated with the age of the probands. Time related flow rates were sufficiently measurable in 7 probands only, who cooperated adequately. In 6 of them the expiratory flow showed a decrease of the effort independent portion with a slight increase in the total airway resistance. There was no correlation between the condition requiring artificial ventilation, the former therapeutic characteristics and the degree of the pathological lung function tests. The results of this investigation suggest damage of the smallest airways which could be the reason for the obstructively impaired expiratory patterns seen in 6 of the probands.

Sequential magnitude and the rate of change in tracheal mechanics after application of intermittent positive pressure (IPP), and the time constant, tau, of this deformation were determined in fetal (21 and 27 days gestation), neonatal (term, 31 days gestation) and adult rabbits. In vitro tracheal mechanics were determined by liquid plethysmography before and after IPP, (25 cm H2O at 30 cycles/min) of 20, 40, 60, and 120 min duration. A sequential decrease in tracheal compliance was documented at all ages. This was associated with increased values of tau as the maturational age advanced. Further, the rate of tracheal deformation was 0.008 cm H2O min-1 at 21 days gestation compared to 0.00025 cm H2O min-1 at adulthood. The decrease in rate of deformation was related to the gestational maturity and duration of IPP. The rate of deformation, as predicted by calculated deformation time constants, appears to be a function of structural elastic and viscoelastic properties of the trachea as well as the duration and magnitude of applied pressure. The deformation time constant may be defined as a useful index to predict the rate of airway deformation. Utilizing the rabbit model, this provides a measure of comparing barotrauma with different modes of ventilation in preterms.

Recent publications have suggested that in infants receiving artificial ventilatory support a particular pattern of interaction between spontaneous breaths and ventilator inflations (active expiration against each ventilator inflation) may be important in the production of pneumothoraces. We have looked at patterns of interaction from 47 preterm infants studied on 51 occasions. We found that active expiration against the ventilator occurred on a total of 16 occasions. This pattern was prevented on 14 occasions by altering the ventilator settings. In two other babies, the pattern persisted but neither baby developed a pneumothorax.

Chest X-ray, pulmonary mechanics, clinical lung disease and growth were studied in 48 low birthweight infants surviving after ventilator treatment in the neonatal period. Bronchopulmonary dysplasia (BPD) was present in 14 infants shortly after weaning off ventilator. At 4 to 6 years of age most patients had normal chest radiographs but 13 still showed signs of pulmonary fibrosis and hyperinflation. Most patients had low dynamic compliance and high pulmonary resistance shortly after ventilator treatment. All but 8, however, had normal findings at 1 to 1 1/2 years of age. Pneumonias and bronchitis were common during the first two years but thereafter declined in frequency. Weight and length development were retarded for BPD patients during the first two years and for non-BPD patients for the first year. Both groups had a complete catch-up.

44 premature newborn rabbits, removed by hysterotomy on day 27 of gestation, were ventilated with positive pressure under differing standardized conditions, with or without application of positive end-expiratory pressure (PEEP; 5 cm H2O). After 10 min ventilation, compliance of the lung-thorax system was significantly higher in fetuses ventilated with PEEP than in controls. The application of PEEP also resulted in a significantly lower maximal expiratory air flow compared to controls in groups ventilated with standardized tidal volume. Morphometric evaluation revealed bronchiolar epithelial lesions to be less prominent in fetuses treated with PEEP. Our findings show that application of PEEP has a beneficial effect on lung mechanics during artificial ventilation and that it reduces the risk of epithelial damage to the airways, presumably by promoting uniform expansion of the lung parenchyma.

Pulmonary mechanics, chest X-ray and the incidence of clinical lung disease were studied in 41 low birth weight infants treated with intermittent positive pressure ventilation (IPPV) in the neonatal period. Shortly after IPPV most patients, irrespective of X-ray findings, had signs of lung damage reflected in low dynamic compliance or high pulmonary resistance. Both parameters, however, had a strong tendency towards normalization during the first year of life. Overdistention on chest X-ray was common at 6--12 months of age. Pneumonia and bronchitis were common during the first two years of life but subsided later on. Development of BPD or later respiratory disease were not correlated to treatment with high inspired oxygen concentrations but commonest in patients with hyaline membrane disease. The combined findings of pulmonary mechanics and chest X-ray shortly after IPPV were correlated to later clinical lung disease.

The effect of positive pressure ventilation on the highly compliant fetal airways was evaluated utilizing fetal rabbit tracheal segments. The degree of mechanical and dimensional deformation was quantified to the pressure applied intermittently (IPP) or continuously (CPAP) for 60 min. Excised tracheal segments were obtained at 21, 27, and 31 days fetal rabbit gestation (term = 31 days) and from 18 +/- 6-month-old adults. Internal diameter, resting length, and volume of the tracheal segments were measured, and their pressure-volume relationships were determined by plethysmography. Tracheal specific compliance at deflation pressure of 0 to 10 cm H2O was calculated from these data. In all fetal groups, the application of positive pressure resulted in a decrease of both tracheal distensibility and the slope of the pressure-volume curves; in addition, a highly significant decrease in tracheal specific compliance was documented. At 21 days gestation, the tracheal specific compliance decreased from 0.089 to 0.034 cm H20-1 (P less than 0.001) after CPAP and to 0.025 cm H2O (P less than 0.001) after IPP. For the same group, the resting tracheal volume increased by a dramatic 89% (P less than 0.001) after CPAP and by 124% (P less than 0.001) after IPP. The magnitude of these alterations decreased as gestational age advanced; the changes were not significant by adulthood. These data indicate that significant pressure-induced deformation (barotrauma) is sustained by susceptible immature airways.

The incidence of bronchopulmonary dysplasia (BPD) and neuro-developmental sequelae in 135 infants surviving intermittent positive pressure ventilation (IPPV) in the newborn period were studied in relation to primary disorders requiring IPPV. The rate of BPD increased over the 6-year study period in hyaline membrane disease survivors from 14% to 28%, but decreased in infants with apnoea repetens from 38% to 13%. Immaturity seemed to be one important factor for development of BPD. The incidence of neuro-developmental sequelae in IPPV treated infants fell from 22% to 13% over the years. In infants with birth weight below 1501 g the rate of neurological handicaps was 11%.

The influence of intermittent positive pressure ventilation on gastro-oesophageal reflux in preterm infants is not known. In many neonatal units, however, concern that ventilation may increase gastro-oesophageal reflux (and therefore aspiration) leads to avoidance of enteral feeding during ventilation. We have therefore performed a crossover study of gastrooesophageal reflux by monitoring lower oesophageal pH in a group of nine enterally fed, very low birthweight infants both during assisted ventilation and normal breathing. All infants had less reflux during intermittent positive pressure ventilation (mean (SEM) reflux index 2.3 (0.6%)) than during normal breathing (mean (SEM) reflux index 6.1 (1.1%)). Assisted ventilation was associated with a significant reduction in the gastro-oesophageal pressure gradient, an effect which may be related to the use of positive and end expiratory pressure during ventilation. These data show that fear of gastro-oesophageal reflux should not preclude the use of enteral feeding in preterm infants receiving ventilation.

Case reports of all infants admitted to the NICU from 1971 to 1982, who developed a pneumopericardium (PPC) while receiving intermittent positive-pressure ventilation, were reviewed in order to determine those variables of assisted ventilation associated with the occurrence of PPC. Of 19 infants seen during the 11-yr period, 16 had respiratory distress syndrome (RDS) and 3 had other forms of severe pulmonary disease. Mean birth weight was 1720 g, gestational age 32 wk, and age at occurrence 59 h. Peak inspiratory pressure (PIP) (mean 32 cm H2O), inspiratory time (IT) (0.74 sec), and mean airway pressure (MAP) (mean 17 cm H2O) were significantly elevated just before occurrence of the PPC, compared with values 6 h previously. PEEP (mean 3.8 cm H2O), ventilator rate (mean 40/min), PaCO2 (mean 41 torr), P(A-a)O2 (mean 443 torr), and inspired oxygen concentration (FIO2, 0.77) were unchanged. MAP was significantly lower (mean 11 cm H2O) 6 h after the event compared with just before (mean 14 cm H2O) in infants who died, suggesting that lowering airway pressure does not improve survival. These data indicate that high PIP, prolonged IT and elevated MAP are associated with the development of PPC. MAP provides a composite of pressure transmitted to the airways and may be the more useful index in preventing barotrauma and pulmonary air leak.

Tracheal dimension, pressure-volume relationships and bulk modulus (K) were determined in excised fetal and adult rabbit tracheal segments before and after application of intermittent positive pressure (IPP) which was 0--25 cm H2O pressure, at 30 cycles/min, and for a duration of 60 min. Both tracheal elastic behavior and dimensions underwent dramatic changes following IPP. At 21, 27, 31 days gestation age, the bulk modulus, K, of the rabbit trachea approximated those of the adult control values. However, the adult values of K did not vary significantly after IPP. The associated increase in tracheal dimensions were also related to the maturity of the animal. Significant structural and functional barotrauma is thus sustained by immature airways, and may account for the tracheal deformation frequently observed as a result of IPP.

A prospective study was undertaken in 41 newborn infants receiving artificial respiration for evaluation of the incidence of respiratory infections. Clinical and radiologic evidence of pneumonia was compared with the appearance of serum antibodies against antigens prepared from microorganisms isolated from bronchial aspirates, and with serum and bronchial immunoglobulin M values. A significant specific immune response was documented in 24% of the patients studied. The data indicate that by correlating the clinical and radiographic findings with specific antibodies and IgM antibody responses, it is possible to document a significant number of respiratory infections. One implication of this study is that subclinical infections may not be uncommon. The significance of the presence and changes in concentration of IgM in bronchial aspirate requires further study.

The natural history and outcome of 20 asthmatics who required mechanical ventilation is reviewed. Seven of these patients died. The majority of the deaths could have been prevented if: (1) The patient had been followed-up in an asthma clinic and had been fully informed of the danger of an asthmatic attack. (2) The medical staff had been trained more fully in the evaluation and management of a severe asthma attack. Careful sequential assessment will enable timely transfer of patients with severe bronchial asthma to a unit experienced in their management.

Lung function tests were performed on 14 infants 22 to 67 wk following mechanical ventilation of 6 h to 51 days and on 5 infants of comparable age who had been treated with continuous positive airway pressure (CPAP). Airway resistance increased (P less than 0.01) and specific airway conductance decreased (P less than 0.001) in the ventilated infants compared with the CPAP-treated group who were normal. The airway resistance and specific airway conductance were normal in two ventilated infants and in one CPAP-treated infant who were studied earlier in the neonatal period. There were no significant differences in thoracic gas volume between groups of ventilated and nonventilated babies studied initially or at follow-up. There was no relationship between lung damage and the following: peak inspiratory pressure, the duration of high pressure ventilation, the level of CPAP or its duration, or the duration of greater than 60% oxygen administration. The degree of lung damage was not related to the maximum ventilatory frequency used, but there was a significant correlation with the duration of rapid frequency ventilation. This study supports the view that barotrauma is a major cause of lung disease following neonatal intensive care.

Review of the case notes of 373 admissions to a neonatal intensive care unit during one year revealed 30 babies with pulmonary air leak. These babies had the uniform characteristics of being between 26 and 34 weeks' gestation and receiving intermittent positive pressure ventilation during the course of respiratory distress. A control group was formed of the remaining 27 infants with these characteristics who did not sustain an air leak. No significant difference was found between the groups in any clinical factor, nor in any maximum ventilator setting other than a longer maximum inspiratory time in the study group. A more dynamic evaluation of variables was performed using standard deviation scoring, and the findings of slightly elevated peak inspiratory pressure and mean airway pressure in the study group prior to air leak were overshadowed by much greater prolongations of inspiratory time. Excessive prolongation of inspiratory time may be a major risk factor in the pathogenesis of pulmonary air leak.

We ventilated 10 healthy young rabbits with warm moist air at 20 cm H2O peak airway pressure and compared their pulmonary histology to that of 10 controls. The histological changes were analysed using the Leitz Texture Analysis System. Four hundred high-power fields (240 micrometers X 240 micrometers) were scanned from each section and the mean proportions of air space, interstitium and oedema determined. Calculated bicarbonate decreased significantly in both groups (P < 0.05); this was accompanied by a modest decrease in pHa in the ventilated group. The PaO2 and PaCO2 were maintained within the normal range. The blood pressure decreased in both groups. Seven of 10 ventilated rabbits had interstitial widening while only 1 of 10 controls had a similar lesion (chi 2 = 5.21, P = < 0.05). The area occupied by interstitium ranged from 26 to 46% (mean 37.6%) in controls and 18 to 81% (mean 45.4%) in ventilated rabbits. There was a lack of correlation between clinical and histopathological findings. While 6 of 10 ventilated rabbits had intra-alveolar oedema and a decrease in air space to less than 50% of total area, none developed hypoxaemia. Two of these 6 rabbits also had pHa less than 7.35 by the end of the study, yet all were clinically stable. These data indicate that intermittent partial-pressure ventilation with warm moist air may result in pulmonary parenchymal damage within 6 h in healthy rabbits.

A case is reported in which a young man undergoing exploratory thoracotomy following a gunshot wound had a cardiac arrest during reinflation of the collapsed lung. Systemic air embolism was suspected as the cause. Subsequent neurological examination and C.T. scan demonstrated a lesion ascribable to this. Discontinuation of nitrous oxide, aspiration of left heart chambers and a head-down position are recommended as immediate treatment if this diagnosis is made. In cases with piercing lung trauma high inflation pressures should be avoided to prevent embolism.

In order to evaluate long term effects of artificial ventilation, 27 children, who had been ventilated for more than five days in their neonatal period, were reinvestigated at school age. In 5 of them bronchopulmonary dysplasia had been diagnosed. Seven had more than 10 upper respiratory tract infections per year and 9 had recurrent obstructive airway disease. On pulmonary function testing (n = 23) 19% showed some airway obstruction, and in 43% bronchial hyperreactivity was found by bronchial provocation with histamine. There was a significant correlation (p less than 0.05) between bronchial hyperreactivity and the duration of neonatal ventilation. The degree of hyperreactivity (PC20, FEV1) also correlated with birth weight (p less than 0.005) and gestational age (p less than 0.02). It is concluded that prolonged neonatal ventilation might be followed by bronchial hyperreactivity, especially in the small and premature newborn.

The scope and impact of sustained assisted ventilation were investigated within a cohort of 11,061 babies born to a geographically defined community. 76 (0.7%) normally formed newborn infants and 3 with major anomalies had respiratory failure potentially treatable by mechanical ventilation. 31 (0.3%) weighed less than 1000 g. 28 infants underwent more than 8 hours' assisted ventilation, which was initiated as an emergency in 14 cases, as an elective measure to minimise the hazards of transport in 10, and as a therapeutic option for apnoea in 4. Pneumothorax requiring drainage complicated the ventilation of 10 infants, 7 of whom died and 2 were subsequently disabled. Of the 14 ventilated survivors examined at school age, 2 had serious persisting disabilities associated with the ventilation and 2 with other perinatal events; of the 10 considered normal, 5 had had emergency ventilation.