A. D. Milner

Physiologic responses to prolonged and slow-rise inflation in the resuscitation of the asphyxiated newborn infant.

Measurements of thoracic volume, inflation pressure, and intrathoracic pressure have been recorded at the resuscitation of nine newborn babies. The initial inflation pressure was maintained for approximately five seconds which produced a twofold increase in inflation volume compared to standard resuscitation techniques and always led to formation of an FRC. When the inflation pressure was increased slowly over three to five seconds, the apparent opening pressure which occurred universally in square wave inflation was rarely seen.

Lung function abnormalities after acute bronchiolitis.

Measurements of thoracic gas volume, airways resistance, and total respiratory resistance were measured in a group of babies with acute severe bronchiolitis. Assessments were made at convalescence, three to four months later, and after 12 months. Clinical histories were also taken 12 months after the acute episode. Results at this time showed that 35% of the infants had coughing attacks, 50% episodes of wheezing, 50% had dry skin or eczema, and that over 75% had lung function abnormality.

Betamethasone 17 valerate aerosol and disodium cromoglygate in severe childhood asthma

Eleven children with severe perennial asthma and a poor clinical response to disodium cromoglycate were studied in a 4-month, double blind trial involving 1 months treatment with placebo, disodium cromoglycate, betamethasone 17 valerate, and both drugs combined according to a predetermined random design. Each drug apparently reduced symptoms and improved daily peak flow and fortnightly spirometric measurements compared with placebo, but the improvement after betamethasone 17 valerate was greater in part because of the way this group of patients was selected. There did not appear to be any additional benefit when both drugs were used together. Betamethasone 17 valerate was not compared with beclomethasone diproprionate aerosol and there is no reason to believe it may be superior. Corticosteroid aerosols have potential hazards which may prove to equal those of long-term systemic steroids, but they offer the prospect of satisfactory control of symptoms without the risk of growth suppression in children with severe asthma. Disodium cromoglycate remains the drug of choice in severe childhood asthma and the use of corticosteroid aerosols should be confined to those children who fail to respond satisfactorily to disodium cromoglycate.

The effect of changes in inspiratory time on neonatal triggered ventilation

Nine preterm infants with hyaline membrane disease were studied using a ventilator triggered from abdominal movement. It was possible to alter respiratory rate over a short space of time by adjustments of the inspiratory time setting. There was a marked inverse relationship between inspiratory time and both ventilator and babys respiratory rate-mean baby respiratory rate was 62 breaths/min at an inspiratory time of 0.2 s and 45 breaths/min at 0.8 s. This drop was statistically significant (P<0.005). Mean tidal volume changed little over this range. This interaction meant that mean minute ventilation was optimal at inspiratory times of 0.2 to 0.4 s, being 269 and 258 ml/kg per minute, respectively, but at 0.8 s fell to 213 ml/kg per minute (P<0.05).

RELATIONSHIP BETWEEN APNOEA AND BRADYCARDIA IN PRETERM INFANTS

Abstract. Vyas, H., Milner, A. D. and Hopkin. I. E. (Department of Child Health, Department of Neonatal Medicine and Surgery, City Hospital, Nottingham, England). Relationship between apnoea and bradycardia in preterm infants. Acta Paediatr Scand, 70: 785, 1981.‐Nine studies were carried out on seven babies who were having repeated episodes of bradycardias without any clinically obvious apnoea. Their mean gestational age was 31.7 weeks (range 29 to 36 weeks) and the mean birth weight was 1.56 kg (range 1.08 kg to 2.16 kg). Investigations were carried out in a total body plethysmograph. Face mask with a pneumotachograph attached to it measured flow. Tidal volume was obtained by integrating these signals. An oesophageal balloon measured intrathoracic pressure changes and the heart rate was measured from ECG chest electrodes. A total of 172 episodes of apnoea were observed. In 50 % of these apnoeas, the airway was closed as determined by the absence of cardiac artefact on the flow signals. Apnoea was associated with bradycardia in just over 25 % of all apnoea. It tended to occur early (11 to 14 sec). Whether the apnoea was central or obstructive had no effect on the pattern provided the baby did not make any inspiratory efforts. Inspiration against a closed airway produced bradycardia in over 50 % of obstructive apnoea, the heart rate falling precipitously within 1 to 2 sec. These findings indicate that often bradycardias occur too early‐in apnoea to be due to central hypoxia and must be due to a peripheral mechanism.

The bronchodilator effects of chlorpheniramine in childhood asthma.

Significant improvement in lung function has been demonstrated following the inhalation of chlorpheniramine. The doses which were used caused local irritation and are probably unsuitable for routine clinical use. Nevertheless, we believe that antihistamines deserve further investigation in the treatment of childhood asthma.

Thoracic gas volume, helium functional residual capacity and air-trapping in the first six hours of life: the effect of oxygen administration.

Abstract Within the first 6 hours of life a consistent difference can be demonstrated between the TGV measured plethysmographically and the FRC measured using a helium dilution technique. This difference persists despite oxygen administration which has little or no effect on the lung volumes in this group of babies.

Lung volumes and lung-mechanics in babies born vaginally and by elective and emergency lower segmental cesarean section

DURING PASSAGE down the birth canal, compression of the infants thoracic cage results in elimination of variable amounts fetal lung liquid. 1 Babies born by cesarean section are not subjected to this squeeze. Two studies have shown that the crying vital capacity is reduced in babies born by cesarean section compared with those born vaginally. 2. 3 Measurement of the thoracic gas volume by Milner et aP using the body plethysmograph has demonstrated a clear-cut difference between the lung volumes of vaginally born babies compared with those born by cesarean section in the first six hours after birth. There was, however, a suggestion that the differences may last only a few hours, although the time course for the resolution of transient tachypnea of the newborn, which is attributed to delayed clearing of lung fluid, is much longer. The present study was undertaken with two aims: (1) To determine for how long these differences in lung volumes and lung mechanics persist. (2) To determine whether the process of labor itself contributes to the clearance of liquid.

The effects of mid-trimester amniocentesis on lung function in the neonatal period

Lung function tests were carried out on 39 healthy full term babies born after pregnancies subjected to mid-trimester amniocentesis. The results were compared to 42 babies born after normal pregnancies. There were no significant differences in gestational age, birth weight, thoracic gas volume or crying vital capacity. Babies subjected to amniocentesis had a significantly lower dynamic compliance (6.96ml/cm H2O vs. 8.60ml/cm H2O) and tended to have higher resistence compared to controls (52.8 cm H2O/l/s vs. 37.3 cm H2O/l/s). This provides further evidence that mid-trimester amniocentesis does have an adverse effect on lung growth and development.

Continuous positive airway pressure via a single nasal catheter in preterm infants.

We present the results of giving continuous positive airway pressure (CPAP) via a single nasal catheter to 20 preterm infants. A beneficial effect in terms of reduced work of breathing (P less than or equal to 0.01) and improved pattern of respiration (P less than or equal to 0.05) are demonstrated. CPAP via a single nasal catheter does not seem to mediate effects inside the thorax unlike CPAP delivered by a tight fitting face mask. Gross variations in CPAP level may result from altering the infants position.