Anaesthesia
-
Reports of two hypoxic episodes which occurred during the use of the East Radcliffe PNA 1 ventilator in the 'complete rebreathing' mode led to the study of the efficiency of the emergency air entrainment system. The inability of this system to maintain adequate oxygen concentrations during interruption of the fresh gas supply results in the development of a hypoxic gas mixture despite patency of the entrainment valve. The reasons for this, and their clinical implications during intermittent positive pressure ventilation in the 'complete rebreathing' mode, are discussed.
-
Age dependent variations in minute ventilation (VE), tidal volume (Vr), respiratory rate and dynamic compliance (Cdyn) as well as ventilatory response to inhalation of carbon dioxide (CO2) were investigated in 20 spontaneously breathing intubated infants and children during halothane anaesthesia. Ages ranged from 6 days to 5 years. Seven patients were younger than 6 months of age. ⋯ There was no ventilatory response in any patient to inhalation of 2.22% CO2. In the older group of children (greater than 6 months of age) VE increased by 34% during inhalation of 3.71% CO2 (p less than 0.025). In the younger patients (less than 6 months of age) no ventilatory response to inhalation of 3.71% of CO2 was found, indicating a more pronounced depression of ventilation in these infants.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Pre-operative intramuscular ranitidine and cimetidine. Double blind comparative trial, effect on gastric pH and volume.
A controlled trial was carried out on 120 healthy patients presenting for elective surgery. The patients were divided randomly into three groups, which received respectively, 50 mg ranitidine, 100 mg ranitidine, or 300 mg cimetidine intramuscularly at least 45 minutes before operation. Following induction of anaesthesia, a nasogastric tube was passed, the stomach contents aspirated and analysed for volume and pH. ⋯ No side effects attributable to the administration of either drug were observed. It is concluded that intramuscular administration of ranitidine or cimetidine is an effective method of reducing the number of patients at risk of acid aspiration during anaesthesia. However, neither drug eliminates the risk of acid aspiration in all patients, and thus careful anaesthetic technique to protect the airway remains essential.