Impact of a prophylactic strategy on the incidence of nausea and vomiting after general surgery.

BACKGROUND: This study aimed to evaluate the implementation of a strategy to prevent postoperative nausea and vomiting (PONV) in patients undergoing general surgery. STUDY DESIGN: Prospective observational study. METHODS: A first period was observational. During a second period, a strategy to prevent PONV was based on five risk factors (RF) identified after the first phase. From two RF, antiemetic treatment was given according to the number of RF. The incidence of PONV was recorded in postoperative anaesthesic care unit (PACU) and at the 24th postoperative hour (24h). RESULTS: We prospectively enrolled 823 patients. Implementation of a prophylactic PONV strategy was associated with a decrease of nausea in PACU from 29.9 to 9.8% (P<0.001) and at 24h from 19 to 10.3% (P<0.001). Vomiting decreased from 12.4 to 2.3% (P<0.001) in PACU and from 5.6 to 3.7% at 24h (non-significant). CONCLUSION: Prophylaxis of PONV by the administration of antiemetic treatment according to a strategy based on a local risk score was efficient and associated with a significant decrease of PONV.

Analgesic efficacy of bilateral superficial cervical plexus block administered before thyroid surgery under general anaesthesia.

BACKGROUND: The use of regional anaesthesia in thyroid surgery remains controversial. This double-blind, randomized controlled study was conducted to evaluate the analgesic efficacy of bilateral superficial cervical plexus block (BSCPB) performed under general anaesthesia in patients undergoing total thyroidectomy. METHODS: Eighty-seven consecutive consenting patients were randomized to receive a BSCPB with saline (Group P, n = 29), ropivacaine 0.487% (Group R, n = 29), or ropivacaine 0.487% plus clonidine 5 microg ml(-1) (Group RC, n = 29). Sufentanil was given during the intraoperative period for a 20% increase in arterial mean pressure or heart rate in a patient with a bispectral index between 40 and 60. All patients received 4 g of acetaminophen during the first 24 h after operation. The pain score was checked every 4 h and nefopam was given for pain score >4 on a numeric pain scale. RESULTS: During surgery, the median sufentanil requirements were significantly reduced in Group RC compared with Groups R and P (0.32 vs 0.47 and 0.62 microg kg(-1); P < 0.0001). After surgery, the number of patients requiring nefopam within 24 h of surgery was significantly lower in Groups R and RC than in Group P (16 and 19 vs 25; P = 0.03). At post-anaesthetic care unit admission, median (range) pain scores were significantly lower in Groups R [3 (0-10)] and RC [3 (0-8)] than in Group P [5 (0-8), P = 0.03]. No major complications of BSCPB occurred during study. CONCLUSIONS: BSCPB with ropivacaine and clonidine improved intraoperative analgesia. BSCPB with ropivacaine or ropivaciane and clonidine was effective in reducing analgesic requirements after thyroid surgery.

Confidence intervals of evolutionary distances between sequences and comparison with usual approaches including the bootstrap method.

Two methods are commonly employed for evaluating the extent of the uncertainty of evolutionary distances between sequences: either some estimator of the variance of the distance estimator, or the bootstrap method. However, both approaches can be misleading, particularly when the evolutionary distance is small. We propose using another statistical method which does not have the same defect: interval estimation. We show how confidence intervals may be constructed for the Jukes and Cantor (1969) and Kimura two-parameter (1980) estimators. We compare the exact confidence intervals thus obtained with the approximate intervals derived by the two previous methods, using artificial and biological data. The results show that the usual methods clearly underestimate the variability when the substitution rate is low and when sequences are short. Moreover, our analysis suggests that similar results may be expected for other evolutionary distance estimators.