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Improvements in obstetrical and neonatal care during the last decades have led to a marked increase in survival rate of preterm and term infants. In order to study the short- and long-term outcome in infants who survived neonatal intensive care (NIC) and were born in the county of Uppsala between January 1st 1986 and April 30th 1989, a prospective long-term follow-up study was conducted. Epidemiological data on all infants born in the county during the study period and the short-term outcome, measured as overall neuromotor function at term and at 2, 4, 6 and 10 months of corrected age in 245 infants surviving NIC and 72 healthy control infants are presented. The infants' neuromotor function was evaluated with different clinical neurological methods. In the study population of NIC infants 85.9% survived the neonatal period. The early infant mortality was high in this group 11.6% compared to that of all infants born in the county of Uppsala (0.30%). Only a minority of the infants showed abnormal neuromotor function. A comparison of the results of the overall evaluation of neuromotor function at 10 months of age with those of the examinations made at an earlier age showed poor correspondence in individual infants, especially in preterm and very preterm infants.

In an experimental study we determined the response trigger delay time of three infant ventilators with a capacity to detect and support spontaneous breathing. We measured this in anaesthetized cats as the time between the start of phrenic nerve activity and the increase in airway pressure caused by the subsequent inflation. Two modes of ventilatory support were used, namely Assist/Control (A/C) and synchronised intermittent mandatory ventilation (SIMV). We found that ventilators equipped with flow sensors close to the free end of the endotracheal tube had a shorter trigger delay than a ventilator which detected breathing with an abdominal sensor. Further, the trigger delay was shorter in SIMV mode than in A/C mode of operation. A higher set sensitivity reduced the response time. We conclude that triggered ventilation may be used in infants, at least when the spontaneous breathing rate is below 60 breaths per minute. This mode of ventilation could be useful when infants are to be weaned off the ventilator.

This study was made to determine how oscillations superimposed on intermittent positive pressure ventilation (IPPV) influence the arterial blood gases, pH and the airway pressures during adequate alveolar ventilation i.e. at inhibition of inspiratory activity, before and after experimentally induced lung injury in the anaesthetized cat. Two IPPV frequencies were studied. The lung was injured by instillation of xanthine oxidase into the upper airways during IPPV. The peak, mean and end-expiratory intrapleural and airway (intratracheal) pressures at two levels were measured and the arterial blood gases and pH were determined at inhibition of inspiratory activity with and without superimposition of oscillations on the ventilatory pattern. Before lung injury, superimposed oscillations lowered the airway pressures only at an IPPV rate of 15 breaths per minute (b.p.m.). After lung injury, such oscillations increased the airway pressures only at 15 b.p.m. The airway pressures were always lower at 60 than at 15 b.p.m.

This study was undertaken to determine whether oscillations superimposed on a regular ventilatory pattern influence the arterial blood gases and pH and the airway pressures at adequate alveolar ventilation at the onset of inhibition of inspiratory activity. The peak, mean and end-expiratory airway pressures were therefore measured at inhibition of this activity with and without superimposition of oscillations on the ventilatory pattern. It was found that superimposed oscillations lowered the airway pressure only at a low ventilatory frequency, whereas inhibition occurred at almost equal arterial PCO2 and pH values with and without superimposed oscillations on the ventilatory pattern.

The effects of intra-arterial and intravenous injections of adenosine and hypoxanthine were investigated with special reference to respiratory variables in anesthetized young cats. Studies were made of the effects on inspiratory activity (phrenic nerve activity), heart rate, blood pressure and central venous pressure. To assess the risk of accumulation of adenosine degeneration products after several injections measurements were also made of hypoxanthine, xanthine and urate in plasma at intervals after the injections. It was found that intra-arterial and intravenous injections of adenosine increased central inspiratory activity during the first few breaths after the injection. The blood pressure and heart rate decreased slightly and central venous pressure increased slightly after the injection. Degradation of adenosine and its metabolites takes place rapidly and it is therefore unlikely that metabolites influence the results. It is concluded that adenosine causes brief stimulation of inspiratory activity.