ABSTRACT
Objective: This prospective randomized BIS controlled study was conducted to compare low-flow anesthesia [LFA] techniques with or without nitrous oxide [N[2]O] using remifentanil and sevoflurane, with respect to ventilation parameters and sevoflurane consumption
Methodology: Forty-five, ASA I/II women younger than 65-year-old, scheduled for gynecological surgery lasting nearly two hour under general anesthesia were enrolled. Electrocardiogram [ECG], pulse oximetry, non-invasive arterial pressure, train-of-four [TOF] and bispectral index [BIS] were monitored. Anesthesia was induced by inj propofol 2 mg/kg with increments of 10 mg until BIS was under 60 and rocuronium 0.6 mg/ kg. Patients were randomized to one of three groups, 15 patients in each, to receive either N[2]O [Group-N] or N[2]O-free anesthesia [Groups RI nd RII]. All groups received bolus remifentanil 0.5 microg/kg and then infusions @ 0.2 microg/kg/min [Group-R I], or 0.05 microg/kg/min [Group-R II] as maintenance. Anesthesia was maintained with sevoflurane in O[2] + N[2]O or air. Signs indicating adequate depth of anesthesia during maintenance phase of anesthesia were HR, arterial blood pressure and BIS. The goal was to obtain a BIS value between 40 and 60 and hemodynamic parameters within 20% of baseline values. Opioid infusions were constant as sevoflurane vaporizer dial setting was adjusted in +/- 0.5% volumes to maintain this goal. Systolic, diastolic and mean arterial pressures, HR, SpO[2], the inspired and expired gas partial pressure measurements of O[2], sevoflurane, N[2]O, and CO[2], BIS values sevoflurane vaporizer dial settings, and recovery times were recorded. Measuring points were at every 5 min during surgery. A minimum inspired oxygen concentration [FiO[2] ] of 0.3 was maintained. Consumption and costs for sevoflurane were calculated
Results: Demographic data, duration of surgery and anesthesia were similar between the groups. A significant decrease was observed in FiO[2] by time in all groups. For all recording times FiO[2] was statistically greater in Group-N. The difference between delivered O[2] and FiO[2] was the lowest in Group-N. The difference between inspired and expired fractions of sevoflurane [Fisevo and Fetsevo] reduced by time during the low flow period. It was lower in Group-N than in remifentanil groups. Total sevoflurane consumption was significantly greater in Group-R II than Group-N but there was no significant difference in sevoflurane consumption and costs per patient per minute between groups. Recovery times were comparable between the groups
Conclusions: We concluded that risk of hypoxia and volatile anesthetic consumption did not differ with or without N[2]O in remifentanil-sevoflurane, low flow anesthesia. Monitoring FiO[2] is essential in both air/ O[2] and N[2]O/O[2] mixtures. Both are safe to administer unless FiO[2] is lower than 30%. BIS-guided sevoflurane with its low solubility feature successfully adapts quickly to variable anesthetic depth levels during low-flow anesthesia
ABSTRACT
The management of an undetected pseudocholinesterase deficiency in a parturient who underwent urgent cesarean section has been presented. After rapid sequence induction with succinylcholine, rocuronium was used for maintenance of neuromuscular block. At the end of the operation neostigmine was given to antagonize the residual block. Upon persistent prolonged neuromuscular blockade sugammadex was administered. Probable reasons, drug interactions, the importance of suspecting pseudocholinesterase deficiency and the need of neuromuscular monitoring have been argued in this case report