Effect of low dose phenylephrine infusion on shivering and hypothermia in patients undergoing cesarean section under spinal anesthesia: a randomized clinical trial.

BACKGROUND: Shivering is a common complication of spinal anesthesia. Phenylephrine, due to its peripheral vasoconstrictive effect, may limit the core to periphery redistribution of body temperature following spinal anesthesia, and reduce hypothermia and shivering. We hypothesized that prophylactic phenylephrine infusion would reduce shivering and hypothermia in women undergoing cesarean section under spinal anesthesia. METHODS: A two-arm randomized, double-blind, placebo-controlled trial in term pregnant patients undergoing cesarean section. In the phenylephrine group (n=75) prophylactic phenylephrine infusion was administered at 25 µg/min immediately after initiation of spinal anesthesia and continued until the end of the operative period. In the placebo group (n=75) a normal saline infusion was administered during the same period. The primary outcome was the incidence of shivering; secondary outcomes were severity of shivering, changes in nasopharyngeal (core) temperature, and incidence of hypotension and bradycardia. RESULTS: The incidence of shivering in the phenylephrine and control groups was 24.0% (95% CI 14.3% to 33.7%) and 53.3% (95% CI 42.0% to 64.6%), respectively. The severity of shivering was greater in the control group (P=0.002) and the mean (±SD) end of surgery core temperature was significantly higher in the phenylephrine group (35.84°C ±â€¯0.60) compared with controls (35.61°C ±â€¯0.48) (P=0.009). The incidence of hypotension was higher in controls (53.4% vs. 2.7%; P <0.001) but bradycardia more frequent in group P (P=0.023). CONCLUSION: The incidence of shivering and degree of hypothermia were significantly reduced by a prophylactic phenylephrine infusion during cesarean section under spinal anesthesia.

Comparison of laryngeal morbidities with modified reinforced silicone tube intubation guided over a bougie vs. a guidewire: novel assessment with voice analysis.

Semi-rigid flexible introducer-guided tracheal intubation is associated with pharyngolaryngeal morbidities. We compared the practice of railroading a newly described modified reinforced silicone tracheal tube with a built-in guide channel in its wall over a non-kinking guidewire with railroading the same tube over a disposable bougie, with respect to pharyngolaryngeal morbidities. One hundred and twenty-four ASA 1 and 2 adults were randomly assigned to undergo bougie-guided (n = 62) or wire-guided (n = 62) intubation under general anaesthesia. All patients were assessed for postoperative pharyngolaryngeal complaints. In addition, voice parameters (fundamental frequency, shimmer, jitter and harmonic noise ratio) with vowels 'a' and 'i' were analysed pre-operatively and 24 h postoperatively. The success of first-attempt intubation and the associated haemodynamic response were also recorded. A higher incidence of pharyngolaryngeal complaints was seen in the bougie group, 48.3%, 95%CI (35.9-60.9%) when compared with wire-guided group 28.3%, 95%CI (18.0-40.6%), p = 0.01. Postoperatively, all the voice parameters were significantly more affected when compared with their pre-operative value in the bougie-guided group (p < 0.05) but not in the wire-guided group. The success of first-attempt intubation was similar in both groups. Wire-guided orotracheal intubation was associated with a lower incidence of pharyngolaryngeal complaints and effect on voice when compared with bougie-guided intubation.