Cerebral metabolic rate of oxygen, intracranial tension and blood flow equivalent during isoflurane or sevoflurane anaesthesia in brain surgery

This study included 28 patients of ASA physical status I-II, aged 18-55 years, subjected to craniotomies for supratentorial brain tumor. They were randomly allocated into two groups to receive either isoflurane [group I] or sevoflurane [group II] anesthesia. Cerebral venous monitoring through bulb catheterization to allow assessment of global oxygen delivery adequacy. A fiberoptic extradural sensor was inserted in extramural space to monitor the ICP. Anesthesia was induced by thiopentone/fentanyl/pepecurium/isoflurane in group I, and thiopentone/pepecurium/sevoflurane in group II. Anesthesia was maintained with 1.5 MAC [1.5%] isoflurane in group I and 1.5 MAC [3%] sevoflurane in group II in FiO2 100%. The patients were mechanically ventilated in such a rate to maintain PaCO2 between 32-35 mmHg. Mean arterial blood pressure [MAP], intracranial pressure, arterial and jugular venous blood gases, arterial and jugular venous lactate concentrations were measured and times of recovery parameters were recorded. Cerebral perfusion pressure [CPP], arterial oxygen content [CaO2], jugular venous oxygen content [VjvO2], arteriojugular venous oxygen content difference [AJVDO2], cerebral oxygen extraction ratio [OER], arteriojugular lactate difference [AJVLS], lactate oxygen index [LOI], cerebral blood flow equivalent [CBF equivalent] were calculated. Times elapsed, till recovery parameters occurred, were recorded

Pethidine as a regional intravenous anaesthetic agent

Pethidine hydrochloride [100 mg diluted in 30-40 ml saline] was compared with lidocaine hydrochloride [0.5 mg/kg in 5% solution 30-40 ml] for intravenous regional anaesthesia [IVRA] for upper limb surgery. The onset, degree of analgesia need for supplementary analgesia, cardiovascular respiratory changes and motorparalysis during and after release of the tourniquet, the need for post-operative analgesia and any complications due to its use for this procedure were determined. Pethidine hydrochloride provided excellent analgesia in 75.7% of cases comparable to 70% in case of lidocaine hydrochloride. The onset of analgesia was prolonged but of longer duration after release of tourniquet, no cardiovascular or respiratory complications were noticed with the two studied drugs. Poor analgesia was noticed in 9.1% of wrist and fingers operations, which Suggested that the mechanism of analgesia is due to blockage of small nerves or possibly sensory nerve endings and not major nerve trunks at the elbow as has been suggested previously for local anaesthetic. No motor paralysis was noticed. It also has the advantage of prolonged postoperative analgesia. So it could be used safely for the procedure of IVRA