Timing of reversal with respect to three nerve stimulator end-points from cisatracurium-induced neuromuscular block.

After elective ear surgery with cisatracurium neuromuscular blockade, 48 adults were randomly assigned to receive neostigmine: (a) at appearance of the fourth twitch of a 'train-of-four'; (b) at loss of fade to train-of-four; or (c) at loss of fade to double-burst stimulation, all monitored using a TOF-Watch SX® on one arm. For each of these conditions, the recovery from train-of-four (TOF) ratio was measured in parallel objectively using a TOF-Watch SX placed on the contralateral arm. The median (IQR [range]) time from administration of reversal to a train-of-four ratio ≥ 0.9 was 11 (9-15.5 [2-28]) min, 8 (4-13.5 [1-25]) min and 7 (4-10 [2-15]) min in the three groups, respectively. This recovery time was significantly shorter when reversal was given at loss of fade to double-burst stimulation (c), than when given at the appearance of the fourth twitch (a), p = 0.046. However, the total time to extubation may be unaffected as it takes longer for fade to be lost after double-burst stimulation than for four twitches subjectively to appear.

Influence of a modified propofol equilibration rate constant (k(e0)) on the effect-site concentration at loss and recovery of consciousness with the Marsh model.

This study compared the predicted effect-site concentration of propofol at loss and recovery of consciousness when using target-controlled infusion devices with the same pharmacokinetic model (Marsh) but a different plasma effect-site equilibration rate constant (ke0 ), the Diprifusor(TM) (ke0 0.26 min(-1) ) and Base Primea™ (ke0 1.21 min(-1) ). We studied 60 female patients undergoing minor gynaecological surgery under general anaesthesia. Although the total dose of propofol and time until loss of consciousness were comparable, the effect-site concentration at loss of consciousness was significantly lower with the Diprifusor than with the Base Primea (1.2 (0.3) µg.ml(-1) vs 4.5 (0.9) µg.ml(-1) , respectively, p < 0.001). The effect-site concentration at recovery of consciousness was significantly higher with the Diprifusor than with the Base Primea (1.8 (0.4) µg.ml(-1) vs 1.5 (0.2) µg.ml(-1) , respectively, p = 0.01). In conclusion, the effect-site concentration of propofol differs depending on the ke0 , despite the use of the same pharmacokinetic model. Therefore, the ke0 should be considered when predicting loss and recovery of consciousness based on the effect-site concentration of propofol.

Emergence agitation in children undergoing adenotonsillectomy: a comparison of sevoflurane vs. sevoflurane-remifentanil administration.

BACKGROUND: Sevoflurane is widely used in paediatric anaesthesia but frequently causes emergence agitation (EA). This study evaluated whether limiting the sevoflurane concentration by combining remifentanil with sevoflurane reduced the incidence of EA. METHODS: Eighty-four preschool children scheduled for adenotonsillectomy were randomly assigned to either the remifentanil or sevoflurane group. In the remifentanil group, anaesthesia was induced with thiopental, rocuronium, and 1% sevoflurane. It was maintained with 1% sevoflurane, 60% nitrous oxide in oxygen, and a continuous infusion of remifentanil. For the sevoflurane group, anaesthesia was induced with thiopental, rocuronium, and 8% sevoflurane, and was maintained with 2-3% sevoflurane. Both groups received ketorolac 1 mg/kg and dexamethasone 0.15 mg/kg. EA was measured using the paediatric anaesthesia emergence delirium (PAED) scale and a four-point EA scale in the post-anaesthesia care unit. RESULTS: The scores on the PAED scales were significantly lower in the remifentanil group than in the sevoflurane group [median (interquartile range); 6 (4.25-10.25) vs. 11 (7.75-14.0), P = 0.007], and the proportion of patients with PAED scores ≥ 10 was significantly lower in the remifentanil group than in the sevoflurane group [15 (35.7%) vs. 27 (64.2%), P = 0.009]. The incidence of EA evaluated using the four-point scale was also lower in the remifentanil group [11 (26.1%) vs. 21 (50%), respectively, P = 0.025]. CONCLUSION: The incidence of EA was lower in children undergoing adenotonsillectomy who received a lower concentration of sevoflurane combined with remifentanil than in those given a higher concentration of sevoflurane without remifentanil.

Influence of a prolonged lateral position on induction of spinal anesthesia for cesarean delivery: a randomized controlled trial.

BACKGROUND: Maternal hypotension occurs commonly during cesarean delivery under spinal anesthesia. We evaluated whether hypotension due to aortocaval compression could be prevented by maintaining a lateral position after an intrathecal injection. METHODS: Eighty-six women undergoing elective cesarean delivery were enrolled. Spinal anesthesia was conducted in the right lateral position using 8 mg of hyperbaric bupivacaine and 15 µg of fentanyl. Patients were randomly assigned to maintain the right lateral position for 6 min before assuming the wedged supine position (group L), or to assume the wedged supine position immediately after the spinal injection (group S). Hypotension was defined as a decrease in mean arterial pressure to <80% of baseline. Ephedrine was given if blood pressure decreased to <70% of baseline. The incidence of hypotension and nausea, ephedrine requirement, maximal block height, and neonatal outcomes were evaluated. RESULTS: No significant between-group differences were observed in the lowest blood pressure, total ephedrine dose, or incidence of hypotension or nausea. Onset of hypotension was delayed (6 ± 2 vs. 10 ± 3 min, P<0.001), and the sensory block level was more cephalad in group L than in group S (T2 [C8-T5] vs. T4 [T1-T6], P=0.001). Apgar scores did not differ between the groups. CONCLUSION: During spinal anesthesia for elective cesarean delivery, maintaining the lateral position for 6 min after an intrathecal injection of hyperbaric bupivacaine resulted in a more gradual and higher cephalad sensory block, without an increase in the incidence of maternal hypotension.