Articles: general-anesthesia.
-
Pulmonary gas exchange is disturbed during general anaesthesia; both oxygenation and elimination of carbon dioxide are impaired. The shape of the chest wall alters after induction of anaesthesia-paralysis in recumbent subjects, and its motion during inspiration is also altered. The mechanical properties of lung and chest wall are also affected and FRC may be reduced. ⋯ These regions may progress into right-to-left shung during 100 per cent oxygen breathing. The low ventilation-to-perfusion regions and the shunt may both impair oxygenation. The development of lung regions with high ventilation-to-perfusion ratios after induction of anaesthesia-paralysis contributes to the inefficient elimination of carbon dioxide.
-
Comparative Study
Maternal blood-gas tensions (PAO2-PaO2), physiological shunt and Vd/Vt during general anaesthesia for Caesarean section.
Measurements of maternal blood-gas tensions, (PAO2-PaO2), calculated pulmonary venous admixture (physiological shunt) and deadspace/tidal volume ratio (VD/VT) were made in 14 patients undergoing Caesarean section. Measurements were carried out after induction of general anaesthesia, and before delivery, with the patient tilted to the left. With a mean inspired oxygen concentration of 67.5% mean PaO2 was 44.3 kPa, mean (PAO2-PaO2) 18.4 kPa, mean Vd/Vt 32% and mean physiological shunt 9.5%. The findings are compared with published values for non-anesthetized pregnant patients.
-
A case of unsuspected acute amphetamine abuse by a 22-year-old girl which led to serious intracranial hypertension during anaesthesia for a neurosurgical procedure is described. It was difficult to maintained anaesthesia with an intermittent positive-pressure ventilation technique using muscle relaxants, N2O and O2 and supplements of fentanyl despite large doses of pancuronium and fentanyl. The differing effects of chronic and acute amphetamine dosage on anaesthetic requirements are reviewed.
-
Hemodynamic monitoring and care of the patient at high risk for anesthesia require a careful and systematic approach. During preoperative evaluation the patient at increased risk must be identified and correctable problems must be solved. The patient's current medications must be reviewed because they may influence the choice of anesthetic approach and may alter the physiologic response to the stresses commonly associated with anesthesia. ⋯ The stresses during emergence from anesthesia contribute to lability of the cardiovascular status and hypoxemia. The period of risk does not conclude with immediate recovery from anesthesia but extends through the postoperative phase. Careful monitoring and attention to the control of pain, prevention of hypotension and hypertension, adequate oxygenation, early mobilization and resumption of the administration of cardiac medications are important factors in a successful outcome.