Age and the onset of desaturation in apnoeic children.

Most patients undergoing general anaesthesia are apnoeic during laryngoscopy and tracheal intubation. This study determined the time until the onset of desaturation following pre-oxygenation in apnoeic infants, children, and adolescents. Fifty ASA physical status I patients, 2 days to 18 yr of age, were studied. The patients were stratified into one of five groups according to age: Group I, 0-6 mo; Group II, 7-23 mo; Group III, 2-5 yr; Group IV, 6-10 yr; and Group V, 11-18 yr. Following induction of anaesthesia with halothane via mask or intravenous barbiturates, the ability of the anaesthetist to ventilate the lungs via the mask was ascertained and paralysis was accomplished with vecuronium 0.1 mg.kg-1. Manual mask ventilation was maintained with oxygen and halothane. When end-tidal N2 decreased below 3% (minimum time two minutes), the face mask was removed. The time between the removal of the face mask and a decrease in oxygen saturation (SpO2) from 99-100% to 90% was measured. Manual ventilation was then resumed and the trachea intubated. Desaturation started earlier in infants than in two- to five-year-old children (96.5 +/- 12.7 sec vs 160.4 +/- 30.7 sec, P < 0.0001). Children became desaturated faster than adolescents (160.4 +/- 30.7 vs 382.4 +/- 79.9 sec, P < 0.0001). The time required to reach 90% saturation correlated well with age by linear regression analysis (r2 = 0.88, P < 0.0001). We conclude that the time to onset of desaturation following pre-oxygenation with mask ventilation increases with age in healthy apnoeic children.(ABSTRACT TRUNCATED AT 250 WORDS)

A quantitative densitometric method for the rapid separation and quantitation of the major lipids of tissues and lipoproteins by high-performance thin-layer chromatography. II. Reduction of the densitometric data.

A BASIC program is described for acquisition of data and data reduction for an automated densitometric system for quantitation of lipids separated by high-performance thin-layer chromatography. The program allows calculation of mass of samples from log/log calibration curves computed from standards. The calculated masses are reported as nmol/volume or nmol/mg protein. The program contains a flexible dialog system which permits its use for a variety of applications in addition to the system described for quantitation of lipids.