GAS EXCHANGE AND HAEMODYNAMICS DURING THORACOTOMY

Cardiac index, systemic and pulmonary arterial pressures, carbondioxide elimination and ventilation of each lung were studiedduring thoracotomy. Seventeen patients, placed in the full lateralposition, were ventilated mechanically through a Carlens’tube to moderate hypocapnia. Mean cardiac index increased by12% as the pleura was opened (P<0.05), with no further changeduring surgery on the still ventilated upper lung. Mean arterialpressure was unchanged after opening the pleura, but decreasedfrom 114±15 mm Hg (mean±1 SD) to 104±18mm Hg during surgery on the hing(P<0.01). Mean pulmonaryartery pressure was unchanged. There was a significant (P<0.01)increase in carbon dioxide elimination from the upper lung whenthe pleura was opened. In addition, the ventilation of thislung increased significantly (P<0.05). Mean end-tidal PCO₂of the lower lung increased from 4.1 to 4.2 kPa after openingthe pleura, while that of the upper lung increased from 3.0to3.6 kPa(P<0.01). VD/VT decreased from 43 to 38% as thepleura was opened (P<0.01). During surgical handling of thelung, marked decreases in ventilation, compliance, carbon dioxideelimination and end-tidal PCO₂ were observed in the upper lung.We conclude that ventilation-perfusion mismatch decreased onopening the pleura, and that neither opening the pleura northe subsequent lung surgery (both lungs being ventilated) causedany clinically important derangements in haemodynamics or oxygenation     

VENTRICULAR ARRHYTHMIA OR SUPRAVENTRICULAR ARRHYTHMIA WITH ABERRANT CONDUCTION? AN ELECTROCARDIOGRAPHIC STUDY IN HALOTHANE-ANAESTHETIZED CHILDREN UNDERGOING ADENOIDECTOMY

The electrocardiograph (ECG) was recorded continuously in 20children undergoing adenoidectomy during halotharie anaesthesia.Five surface ECG leads and an oesophageal lead were used. In11 children, there were QRS complexes which had a shape distinctlydifferent frord that of the ordinary sinus-evoked beats. Exceptin one child, these anomalous QRS complexes first made theirappearance during surgery, although the arrhythmia continueduntil 0–1 min after adenoidectomy in some children. Theseverity ranged from that of occasional anomalous QRS complexeswith uniform shape to that of a fast irregular rhythm with avariety of QRS shapes. Although the anomalous QRS complexeswere premature, P waves and P-P intervals were unchanged. Insome children, there appeared to be ventricular capture beatsand fusion beats. Because of this, and in view of evidence gatheredfrom studies in animal, by other authors, we considered it likelythat the anomalous beats were ventricular in origin.