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A telephone survey of 20 English intensive care units (ICUs) confirmed that visual estimation of patient weight is often performed. Four experienced intensive care staff (three doctors and one nurse) estimated the weight and measured the height of 30 volunteers and the estimates were compared with accurate reference measurements. The estimates were shown to be significantly inaccurate for individual observers. We consider the degree of inaccuracy to be of clinical importance. However, pooling the individual estimates of weight as mean values improved accuracy. Recommendations are made concerning the performance of height and weight determination.

Desmopressin (DDAVP) may be used to augment the action of factor VIII in mild haemophilia. Its use has been associated with serious adverse effects. We report a case of a three-year-old child with a family history of haemophilia who suffered complications due to severe acute hyponatraemia following the administration of this drug for post-tonsillectomy bleeding.

Right-to-left shunt (Qs/Qt) was measured by the SF6 and oxygen methods in 13 anaesthetized closed-chest dogs intubated with a double-lumen endobronchial tube. Collapse of the left lung increased Qs/Qt from 10% to 23%, suggesting that blood flow to the left lung had been reduced by about 60%. Increasing right lung mean airway pressure by the alteration of the inspiratory:expiratory time ratio or the application of PEEP produced a small but non-significant increase in Qs/Qt with significant increases in arterial and mixed venous carbon dioxide tensions, and arterial to right lung end-tidal carbon dioxide tension difference. Fluid loading during collapse increased cardiac output and pulmonary vascular pressures, but Qs/Qt did not differ significantly from the normovolaemic collapsed state. Increasing the right mean airway pressure in this condition had no effect on Qs/Qt or carbon dioxide tensions.

Saline lavage of the lungs of eight anaesthetized New Zealand White rabbits was performed to produce a surfactant-depletion model of the neonatal respiratory distress syndrome. A characteristic change in the shape of the pressure-volume curve occurred, with the appearance of an inflection point on the inspiratory limb. The animals were treated with high frequency oscillation (HFO) at 15 Hz and the results compared with those of a previously studied group of eight similar rabbits treated with controlled mechanical ventilation (CMV) with end-expiratory pressure equal to the pressure at the inflection point, but with the same mean airway pressure of 15 mm Hg. The animals treated with HFO had significantly higher arterial oxygen tensions and end-expiratory lung volumes than those treated with CMV, but there was no significant difference between hyaline membrane scores. Although there was no significant difference in mean survival times, five of the HFO treated animals showed reversion of the shape of their pressure-volume curves towards the prelavage configuration, suggesting a recovery of surfactant function.

Sixteen rabbits were anaesthetized and subjected to saline lavage of the lungs to produce surfactant deficiency. This resulted in an arterial oxygen tension of less than 12 kPa on 100% inspired oxygen and an inflection point on the pressure-volume curve at a pressure of 8-12 mmHg. After lavage the animals were randomly assigned to receive either conventional mechanical ventilation (CMV) with a positive end-expiratory pressure (PEEP) of 1-2 mmHg (group I - low PEEP) or CMV with PEEP equal to the inflection point pressure (group II - high PEEP). Mean airway pressures were kept at 14-16 mmHg in both groups by increasing the inspiratory:expiratory time ratios in the low PEEP group. The 5-h protocol was completed by 4 animals in group I and 6 animals in group II, early death usually being associated with a metabolic acidosis. On 100% oxygen, the mean PaO2 at 2-h post-lavage was 15.2 +/- 8.3 kPa in group I and 39.6 +/- 21.8 kPa in group II. Group I had much lower end-expiratory lung volumes (3.0 +/- 1.5 ml above FRC) than group II (34.9 +/- 12.2 ml above FRC). Histological examination of the lungs revealed significantly less hyaline membrane formation in group II (p = 0.001). Thus, the prevention of alveolar collapse by the use of high PEEP levels appears to reduce lung damage in this preparation.

A study was undertaken to compare CPAP/IMV systems shown to be in common use in the U.K. The most frequently used system (Servo 900B) has characteristics which are likely to increase the work of breathing. Recommendations are made regarding the theoretically most acceptable systems.