A randomised comparison of C-MAC™ and King Vision® videolaryngoscopes with direct laryngoscopy in 180 obstetric patients.

BACKGROUND: Current evidence suggests that there is uncertainty about which videolaryngoscope performs best in obstetric anaesthesia. The aim of this study was to compare C-MAC and King Vision® videolaryngoscopes and direct laryngoscopy for tracheal intubation of patients undergoing caesarean section. METHODS: One hundred and eighty women were randomly assigned. The primary outcome was the time to tracheal intubation. Secondary outcomes were the time to the best laryngeal view, grade of Cormack and Lehane view, overall and first-pass success, intubation difficulty, the number of intubation attempts and optimisation manoeuvres; and complications. RESULTS: The time to successful intubation, first-pass and overall success rates did not differ between the devices. The difficulty of intubation was less for C-MAC than King Vision® (P <0.001). No difference was observed between King Vision® and direct laryngoscopy (P=0.06) or C-MAC and direct laryngoscopy (P=0.05). King Vision® required the longest time to best laryngeal view (9 ±â€¯6 s, P=0.028), had the highest rate of grade 1 view (47 (80%) patients, P <0.001), and the highest need for optimisation manoeuvres (59 (100%) patients, P <0.0001). Five minor complications were recorded with King Vision® and one with direct laryngoscopy. CONCLUSIONS: Compared to direct laryngoscopy, C-MAC and King Vision® did not prolong the time to intubation, supporting these videolaryngoscopes as primary intubation devices in obstetric anaesthesia. The C-MAC was easier to use and needed fewer additional manoeuvres than the King Vision®. The C-MAC may be better suited for tracheal intubation of obstetric patients undergoing caesarean section.

Effect of epidural and intravenous clonidine on the neuro-endocrine and immune stress response in patients undergoing lung surgery.

The effects of intravenous and epidural clonidine, 4 microg kg-1, combined with epidural morphine, 40 microg kg-1, on the neuro-endocrine and immune stress responses to thoracic surgery are reported. A control group received only epidural morphine. Anaesthesia was induced and maintained with propofol. Catecholamines, vasopressin, cortisol, beta-endorphin concentrations and leucocyte counts were measured before drug administration, immediately after intubation of the trachea, after thoracotomy and at the end of surgery. Catecholamines did not change in any of the groups. The other stress hormones increased during surgery, the pattern being similar in the three groups. Total leucocyte and neutrophil counts were increased in all groups at the end of surgery, but the increase was least in the epidural clonidine group. The number of lymphocytes was reduced at the end of surgery in the epidural and intravenous group, compared with the control group in which the number of lymphocytes did not change. The effects are more pronounced with epidural than with intravenous administration. We conclude that clonidine can modulate the immune stress response to thoracic surgery.

Estimation of arterial CO2 partial pressure by measurement of tracheal CO2 during high-frequency jet ventilation in patients with a laryngectomy.

Tracheal and arterial CO2 partial pressures were measured simultaneously in 27 laryngectomized patients both while they were awake and during high-frequency jet ventilation. Tracheal gas was sampled during brief interruptions of high-frequency jet ventilation. Agreement between tracheal and arterial CO2 partial pressures was assessed using the Bland-Altman method. The tracheal-arterial CO2 partial pressures gradient during spontaneous breathing was significantly lower (P < 0.0002) than during high-frequency jet ventilation. During spontaneous ventilation, the bias was -0.77 kPa (95% CI = -0.99 to -0.55 kPa), and the upper and lower limits of agreement were 0.29 kPa (95% CI = -0.11 to -0.7 kPa) and -1.83 kPa (95% CI = -2.24 to -1.43 kPa). During high-frequency jet ventilation, the bias was -1.61 kPa (95% CI = -1.76 to -1.46 kPa), and the limits of agreement were -0.48 kPa (95% CI = -0.75 to -0.21 kPa) and -2.74 kPa (95% CI = -3.01 to -2.47 kPa). Despite the poor agreement between tracheal CO2 partial pressure and arterial CO2 partial pressure, it is sufficient to allow for adjustment of ventilator settings during jet ventilation.

A comparison of intravenous and inhalational maintenance anaesthesia for endoscopic procedures in the aspirin intolerance syndrome.

Intravenous (n = 21) and inhalational maintenance anaesthesia (n = 21) were compared by random allocation in patients with the aspirin intolerance syndrome undergoing endoscopic nasal procedures. Premedication was with oral midazolam and intravenous methylprednisolone sodium succinate 10 mg kg-1. Anaesthesia was induced in both groups with etomidate and alfentanil and ventilation was controlled. Anaesthesia was maintained in the intravenous group by infusion of alfentanil 1-1.5 micrograms kg-1 min-1 and injections of midazolam 2.5-5 mg h-1, and in the inhalational group by isoflurane up to 2%. Moderate arterial hypotension (70 mmHg) was achieved with nitroglycerine 0.5-5 micrograms kg-1 min-1 in the intravenous group, and with isoflurane up to 2% in the inhalational group. Adrenaline 1: 200 000 with 2% lignocaine was injected into the operative field. One patient in the inhalational group developed a resistant tachyarrhythmia but there was no overall significant difference (P = 0.34) in the frequency of dysrhythmias precipitated by adrenaline and lignocaine between the two groups. In one patient of each group methylprednisolone precipitated bronchospasm. On later challenge testing, 125 mg of intravenous methylprednisolone significantly reduced the peak expiratory flow (P < 0.05) in one of these patients. The results suggest that intravenous and inhalational maintenance anaesthesia are equally suitable for patients with aspirin intolerance syndrome. Corticosteroids during surgery should be given by the same route used pre-operatively (spray, oral, or spray plus oral) because intravenous injection may have adverse effects.