Programmed intermittent epidural bolus vs. patient-controlled epidural analgesia for maintenance of labour analgesia: a two-centre, double-blind, randomised study†.

The programmed intermittent epidural bolus technique has shown superiority to continuous epidural infusion techniques, with or without patient-controlled epidural analgesia for pain relief, reduced motor block and patient satisfaction. Many institutions still use patient-controlled epidural analgesia without a background infusion, and a comparative study between programmed intermittent epidural bolus and patient-controlled epidural analgesia without a background infusion has not yet been performed. We performed a randomised, two-centre, double-blind, controlled trial of these two techniques. The primary outcome was the incidence of breakthrough pain requiring a top-up dose by an anaesthetist. Secondary outcomes included: motor block; pain scores; patient satisfaction; local anaesthetic consumption; and obstetric and neonatal outcomes. We recruited 130 nulliparous women who received initial spinal analgesia, and then epidural analgesia was initiated and maintained with either programmed intermittent epidural bolus or patient-controlled epidural analgesia using ropivacaine 0.12% with sufentanil 0.75 µg·ml-1 . The programmed intermittent epidural bolus group had a programmed bolus of 10 ml every hour, with on-demand patient-controlled epidural analgesia boluses of 5 ml with a 20 min lockout, and the patient-controlled epidural analgesia group had a 5 ml bolus with a 12 min lockout interval; the potential maximum volume per hour was the same in both groups. The patients in the programmed intermittent epidural bolus group had less frequent breakthrough pain compared with the patient-controlled epidural analgesia group, 7 (10.9%) vs. 38 (62.3%; p < 0.0001), respectively. There was a significant difference in motor block (modified Bromage score ≤ 4) frequency between groups, programmed intermittent epidural bolus group 1 (1.6%) vs. patient-controlled epidural analgesia group 8 (13.1%); p = 0.015. The programmed intermittent epidural bolus group had greater local anaesthetic consumption with fewer patient-controlled epidural analgesia boluses. Patient satisfaction scores and obstetric or neonatal outcomes were not different between groups. In conclusion, we found that a programmed intermittent epidural bolus technique using 10 ml programmed boluses and 5 ml patient-controlled epidural analgesia boluses was superior to a patient-controlled epidural analgesia technique using 5 ml boluses and no background infusion.

Effects of moderate acute isovolaemic haemodilution on myocardial function in patients undergoing coronary surgery under volatile inhalational anaesthesia.

When myocardial oxygen demand is increased by elevated heart rate in patients undergoing coronary artery surgery under total intravenous anaesthesia, acute isovolaemic haemodilution may be associated with a deterioration of cardiac function. We investigated the effects of acute isovolaemic haemodilution during volatile inhalational anaesthesia. Forty patients undergoing coronary surgery were randomly assigned to two groups according to the rate of atrioventricular pacing (Group 70 at 70.min(-1) and Group 90 at 90.min(-1)). While paced at the fixed heart rate, acute isovolaemic haemodilution was performed before the start of cardiopulmonary bypass. In both groups mean (SD) stroke volume increased with haemodilution (from 65 (9) to 83 (10) ml.min(-1) (p < 0.01) in Group 70 and from 65 (9) to 81 (9) ml.min(-1) (p < 0.01) in Group 90) as a result of a decrease in systemic vascular resistance (from 1175 (231) to 869 (164) dynes.s.cm(-5) (p < 0.01) and from 1060 (185) to 849 (146) dynes.s.cm(-5) (p < 0.01), respectively) and an increase in end-diastolic volume (from 1049 (234) to 1405 (211) ml (p < 0.01) and from 1078 (106) to 1438 (246) ml (p < 0.01), respectively). Left ventricular pressure-derived data remained unchanged with acute isovolaemic haemodilution in both groups.

Continuous cardiac output measurement: arterial pressure analysis versus thermodilution technique during cardiac surgery with cardiopulmonary bypass.

This study compared cardiac output measured with an arterial pressure-based cardiac output measurement system and a thermodilution cardiac output measurement system. We studied 36 patients undergoing cardiac surgery with cardiopulmonary bypass. Simultaneous arterial pressure-based and thermodilution cardiac output measurements were compared before and after cardiopulmonary bypass, and after phenylephrine administration. Bland-Altman analysis showed good overall agreement between the two methods. Bias (limits of agreement) before and after cardiopulmonary bypass were - 0.21 (- 2.97-2.55) lxmin(-1) and 0.01 (- 3.79-3.81) lxmin(-1), respectively. Phenylephrine administration decreased thermodilution cardiac output by a mean (SD) of 11 (16)% and increased arterial pressure-based cardiac output by 55 (34)%. We conclude that arterial pressure-based cardiac output and thermodilution cardiac output measurement systems yield comparable results during cardiac surgery with cardiopulmonary bypass. However, after phenylephrine administration, the two measurement systems provided opposing results.

Incidence of atrial fibrillation early after cardiac surgery: can choice of the anesthetic regimen influence the incidence?

Occurrence of atrial fibrillation is a common complication after coronary surgery. This study aimed to identify the perioperative factors that are associated with its occurrence with specific attention to the possible influence of the choice of the anesthetic regimen after elective coronary surgery. A retrospective chart analysis was performed in 460 patients who underwent elective coronary artery surgery with cardiopulmonary bypass using the standard institutional anesthetic, surgical and postoperative protocols. The only difference in management was the choice of the primary anesthetic regimen. 110 patients had a total intravenous anesthesia with propofol, 90 patients had a total intravenous anesthesia with midazolam, 150 patients were anesthetized with sevoflurane and 110 patients with desflurane. The primary outcome variable was the incidence of atrial fibrillation within the first 24 postoperative hours. Atrial fibrillation occurred in 64 of the 460 patients included (13.9%). Multiple logistic regression analysis identified increased age (> 70 years), EuroSCORE > 4, prolonged CPB time (> 100 min) and need for prolonged inotropic support (> 6 hours) as the significant independent risk factors for the occurrence of postoperative atrial fibrillation. The incidence of postoperative atrial fibrillation differed among the different anesthetic groups with the lowest incidence in the sevoflurane group (propofol: 17/110; midazolam: 15/90; sevoflurane: 9/150; desflurane: 23/110) (p = 0.004). This finding should be further confirmed in a prospective sufficiently powered multicenter study.