Articles: general-anesthesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of etomidate in combination with fentanyl or diazepam, with thiopentone as an induction agent for general anaesthesia.
In 104 premedicated patients undergoing general surgery, anaesthesia was induced either with etomidate 0.3 mg kg-1 preceded by fentanyl 1.25 or 2.5 microgram kg-1 i.v.or diazepam 0.0625 or 0.125 mg kg-1 i.v., or with thiopentone preceded by fentanyl 1.25 microgram kg-1 i.v. Despite the use of fentanyl or diazepam, the frequency of pain on injection in patients receiving etomidate was between 32% and 53%, being rated as severe in 5-20% of patients. ⋯ The frequency of both pain and involuntary muscle movements was least when fentanyl 2.5 microgram kg-1 preceded the administration of etomidate. There was no significant relationship between the pain and muscle movement; three of 10 patients given etomidate into a central vein had such movements.
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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.
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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.