Methods: Sixty-four patients aged 18-60 years, American Society of Anaesthesiologists (ASA) class I-II who underwent elective surgery were randomised to a Marsh group (n= 32) or Schnider group (n= 32). All the patients received a 1 μg/kg loading dose of dexmedetomidine, followed by TCI anaesthesia with remifentanil at 2 ng/mL. After the effect-site concentration (Ce) of remifentanil reached 2 ng/mL, propofol TCI induction was started. Anaesthesia induction commenced in the Marsh group at a target plasma concentration (Cpt) of 2 μg/mL, whereas it started in the Schnider group at a target effect-site concentration (Cet) of 2 μg/mL. If induction was delayed after 3 min, the target concentration (Ct) was gradually increased to 0.5 μg/mL every 30 sec until successful induction. The Ct at successful induction, induction time, Ce at successful induction and haemodynamic parameters were recorded.
Results: The Ct for successful induction in the Schnider group was significantly lower than in the Marsh group (3.48 [0.90] versus 4.02 [0.67] μg/mL;P= 0.01). The induction time was also shorter in the Schnider group as compared with the Marsh group (134.96 [50.91] versus 161.59 [39.64]) sec;P= 0.02). There were no significant differences in haemodynamic parameters and Ce at successful induction.
Conclusion: In the between-group comparison, dexmedetomidine reduced the Ct requirement for induction and shortened the induction time in the Schnider group. The inclusion of baseline groups without dexmedetomidine in a four-arm comparison of the two models would enhance the validity of the findings.
CASE PRESENTATION: A 25-year-old super morbidly obese female (body mass index = 55 kg/meter2) presented with worsening shortness of breath. For MV, pairing of a 6 mm (mm) diameter ETT to accommodate the patient's vocal cord edema, with a CSS not designed to maintain a clean catheter tip, precipitated ETT blockage and respiratory acidosis. Replacement of these devices with a 6.5 mm ETT and a CSS designed to keep the catheter tip clean resolved the complications. After use of the different ETT and CSS for approximately one week, the patient was discharged to home.
DISCUSSION: The clean-tip catheter CSS enabled a more patent airway than its counterpart device that did not have this feature. Use of a clean-tip catheter CSS was an important care development for this patient, because this individual's super morbidly obese condition minimized tolerance for MV complications that would exacerbate her pre-existing tenuous respiratory health status.
CONCLUSION: Special attention should be given to the choices of ETT size and CSS to manage super morbidly obese patients who have a history of difficult airway access.
METHODS: A total of 93 patients with American Society of Anaesthesiologists (ASA) physical status I or II having lower limb orthopaedic surgery under spinal anaesthesia were randomised into two groups that received either Volulyte (n = 47) or Gelaspan (n = 46). Before the spinal anaesthesia, these patients were pre-loaded with 500 mL of the fluid of their respective group. Blood samples were taken before pre-loading and again after spinal anaesthesia and sent for venous blood gas and electrolyte level measurement. Baseline and intraoperative records of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR) and the requirement of ephedrine to treat hypotension were also recorded.
RESULTS: Both fluids could not prevent significant reductions in SBP (P = 0.011), DBP (P = 0.002) and MAP (P = 0.001). There was also significant reduction in HR over time (P < 0.001). There was no significant difference in terms of ephedrine usage between both groups. Neither Volulyte 6% nor Gelaspan 4% caused significant changes in acid-base status.
CONCLUSION: The use of 500 mL of either Gelaspan 4% or Volulyte 6% as pre-loading fluids did not significantly prevent the incidence of post-spinal anaesthesia hypotension following orthopaedic lower limb surgery; however, both were useful in the maintenance normal acid-base balance.