This was a prospective randomised study comparing carboxyhaemoglobin concentrations between low-flow anaesthesia (fresh gas flow 1.0 L/min) and minimal-flow anaesthesia (0.5 L/min) using desflurane. Sixty (ASA 1 or 2) adult patients undergoing elective surgery under general anaesthesia were randomly allocated to receive either low-flow (Group 1) or minimal flow anaesthesia (Group 2). Venous blood samples for carboxyhaemoglobin levels were taken at baseline and at 10 mins intervals for 40 mins. Both groups showed significant increase in carboxyhaemoglobin concentrations within the first 10 mins when fresh gas flow of 4.0 L/min was used. Reduction in carboxyhemoglobin levels was seen after 20 mins of minimal or low flow anaesthesia. However, there was no significant difference in the magnitude of reduction of carboxyhemoglobin concentrations between the groups. The fractional inspired of oxygen (FiO2) showed no significant changes in either group. In conclusion, desflurane usage in anaesthesia with either low-flow or minimal-flow was not associated with increased carboxyhaemoglobin concentrations.
Supraglottic airway devices have been used as safe alternatives to endotracheal intubation in appropriate types of surgery. This was a prospective, randomised, single blind study comparing the use of LMA™ and SLIPA™ in terms of ease of insertion, haemodynamic changes and occurrence of adverse effects (e.g. blood stains on the device upon removal and sore throat). A total of 62 ASA I or II patients, aged between 18 to 70 years were recruited for this study. Patients were randomised into two groups; LMA™ and SLIPA™ group. Following induction of anaesthesia, an appropriate sized LMA™ or SLIPA™ was inserted after ensuring adequate depth of anaesthesia. Anaesthesia was maintained with oxygen, nitrous oxide and sevoflurane. The ease of insertion was graded and haemodynamic changes were recorded at 2 minute intervals up to 10 minutes after insertion of the airway devices. The presence of blood stains upon airway device removal at the end of surgery and incidence of sore throat was also recorded. No difficult insertion was experienced in either of these devices. Insertion was either easy [LMA™ 87.1% versus SLIPA™ 80.6% (p = 0.49)] or moderate [LMA™ 12.9% versus SLIPA™ 19.4% (p = 0.16)]. Throughout the study period, the haemodynamic changes that occurred in both groups were not statistically different. Traces of blood were noted on the surface of the device in 9.7% of patients in the SLIPA™ group versus 6.5% of patients in the LMA™ group. The incidence of sore throat was recorded in 12.9% versus 19.4% of patients in the SLIPA™ and the LMA™ groups respectively. These findings were not statistically significant. In conclusion, this study showed no significant differences between the use of LMA™ and SLIPA™ in terms of ease of insertion, haemodynamic changes and adverse effects in patients undergoing minor surgical procedures.
This was a prospective randomized study comparing the ease of insertion, haemodynamic changes, quality of airway seal, oxygenation and ventilation parameters and complications between Laryngeal Tube Suction II (LTS II) with Proseal Laryngeal Mask Airway (PLMA), both are supraglottic airway incorporated with gastric passage. Fifty-four ASA I and II patients were randomly allocated to receive either LTS II or PLMA. Both devices provided a secure airway even under conditions of elevated intra-abdominal pressure up to 17 mmHg. In this study, there were no differences concerning ease of insertion, haemodynamic changes, quality of airway seal, oxygenation and ventilation parameters and complications between LTS II and PLMA.