An inhalation bolus of sevoflurane versus an intravenous bolus of remifentanil for controlling hemodynamic responses to surgical stress during major surgery: a prospective randomized trial

Comparison of Haemodynamic Response to Inhalational Bolus with Desflurane in Normotensive and Hypertensive Patients Undergoing Laparoscopic Cholecystectomy

Objective

Desflurane causes sympathetic stimulation at high end-tidal concentrations. We conducted this study to compare the haemodynamic response to inhalational bolus with desflurane in normotensive and hypertensive patients undergoing laparoscopic cholecystectomy.

Methods

In this prospective, clinical trial, 40 patients aged 18-60 years and undergoing laparoscopic cholecystectomy were divided into normotensives (Group N; n=20) and hypertensives (Group H; n=20). Heart rate (HR), mean arterial pressure (MAP) and bispectral index (BIS) were measured at baseline and every 60 s for 5 min after induction, intubation, initiation and inhalational bolus of desflurane. The primary objective was to compare haemodynamic response, and the secondary objective was to assess the need for inhalational boluses and to compare the number of overcorrections and undercorrections in BIS value after each inhalational bolus. An independent t-test was used to compare the means of the study parameters between the groups, and a dependent t-test was used to compare the percentage change in the means of the study parameters within the same group. Statistical significance was defined as p<0.05.

Results

No statistically significant difference in the percentage of patients responding with a decrease, increase or no change of HR or MAP were seen between the two groups after inhalational bolus of desflurane. An overcorrection of BIS (value <45) was seen in 60% of the patients in Group H and 15% of the patients in Group N (p=0.003). None of the patients in either group had an undercorrection (BIS>55).

Conclusion

BIS-guided desflurane administration and BIS-triggered inhalational boluses of desflurane is safe, feasible and does not cause sympathetic stimulation in either normotensive or hypertensive patients.

Remifentanil in electroconvulsive therapy: a systematic review and meta-analysis of randomized controlled trials

In electroconvulsive therapy (ECT), remifentanil is often used concurrently with anesthetics. The objective of this study was to provide an up-to-date and comprehensive review on how the addition of remifentanil to anesthetics affects seizure duration and circulatory dynamics in mECT. We performed a meta-analysis of RCTs that investigated seizure duration and circulatory dynamics in patients treated with ECT using anesthetics alone (non-remifentanil group) and with anesthetics plus remifentanil (remifentanil group). A total of 13 RCTs (380 patients and 1024 ECT sessions) were included. The remifentanil group showed a significantly prolonged seizure duration during ECT compared to the non-remifentanil group [motor: 9 studies, SMD = 1.25, 95 % CI (0.21, 2.29), p = 0.02; electroencephalogram: 8 studies, SMD = 0.98, 95 % CI (0.14, 1.82), p = 0.02]. The maximum systolic blood pressure (SBP) was significantly reduced in the remifentanil group compared to the non-remifentanil group [7 studies, SMD = -0.36, 95 % CI (-0.65, 0.07), p = 0.02]. Substantial heterogeneity was observed for meta-analyses for seizure durations, but a pre-planned subgroup analysis revealed that seizure duration was prolonged only when the use of the anesthetic dose was reduced in the remifentanil group. The results of our study suggest that addition of remifentanil to anesthesia in ECT may lead to prolonged seizure duration when it allows the use of reduced anesthetic doses. Further, the addition of remifentanil was associated with reduced maximum SBP.

Evaluation of recovery and anesthetic gas consumption using remifentanil combined with low-flow sevoflurane anesthesia in tympanoplasty

BACKGROUND

The aim of this study was to compare the effects of low-flow sevoflurane and low-flow sevoflurane supplemented with remifentanil anesthesia on the recovery time, consumption amount of the anesthetic drugs and hemodynamic differences.

MATERIALS AND METHODS

A prospective, randomized and double-blinded study with 50 patients was designed. Following intubation, group S received sevoflurane 1.8 vol%, oxygen, nitrous oxide at 4 l · min(-1) and normal saline continuous infusion; group SR received sevoflurane 1.2 vol%, oxygen, nitrous oxide at 4 l · min(-1) and 0.25 μg · kg(-1) · min(-1) remifentanil continuous infusions. Ten minutes after intubation the flow rates decreased to 1 l · min(-1). Consumption of each drug, postoperative recovery characteristics and visual analog scale (VAS) scores for pain were recorded.

RESULT

There were no significant differences in hemodynamic parameters, tramadol consumption and VAS scores for pain. The patients in group SR showed faster early recovery as compared to group S. The mean consumption of sevoflurane was 18 ml in group SR, while it was 25 ml in group S.

CONCLUSIONS

Low-flow sevoflurane anesthesia combined with remifentanil regimen in patients undergoing tympanoplasty surgery resulted in a faster early recovery and decreased sevoflurane consumption.

Low-dose remifentanil to suppress haemodynamic responses to noxious stimuli in cardiac surgery: a dose-finding study

BACKGROUND

High-dose remifentanil (1-5 microg kg-1 min-1), commonly used for cardiac surgery, has been associated with muscle rigidity, hypotension, bradycardia, and reduced cardiac output. The aim of this study was to determine an optimal lower remifentanil dose, which should be accompanied by fewer adverse events, that still effectively suppresses haemodynamic responses to typical stressful stimuli (i.e. intubation, skin incision, and sternotomy).

METHODS

Total i.v. anaesthesia consisted of a target-controlled propofol (2 microg ml-1) and a remifentanil infusion. Forty patients were allocated to receive either a constant infusion of remifentanil at 0.1 microg kg-1 min-1 or up-titrations to 0.2, 0.3, or 0.4 microg kg-1 min-1, respectively, 5 min before each stimulus. Subsequently, changes in heart rate and mean arterial blood pressure were recorded for 8 min. Increases exceeding 20% of baseline were considered to be of clinical relevance. Patients who exhibited these alterations were termed responders.

RESULTS

The number of responders was less with the two higher remifentanil dosages (P<0.05) while propofol target doses could either be kept at the same level or even be reduced without affecting the plane of anaesthesia. Although single phenylephrine bolus had to be applied more frequently in these two groups (P<0.05), no severe haemodynamic depression was observed.

CONCLUSIONS

Remifentanil at 0.3 and 0.4 microg kg-1 min-1 in combination with a target-controlled propofol infusion in the pre-bypass period is well tolerated. It appears to mitigate potentially hazardous haemodynamic responses from stressful stimuli equally well as higher doses when compared with data from the literature.

The effect of adding two target-controlled concentrations (1–3 ng mL−1) of remifentanil on MACBAR of desflurane*

BACKGROUND AND OBJECTIVES

The aim of this prospective, randomized, double-blind study was to determine the effects of adding two different target-controlled concentrations of remifentanil (1 and 3 ng mL(-1)) on the desflurane requirement for blunting sympathetic responses after surgical incision (minimum anaesthetic concentration (MAC(BAR)).

METHODS

67 patients, aged 20-50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive no remifentanil infusion (n = 21) or a target-controlled effect-site concentration of 1 ng mL(-1) (n = 24) or 3 ng mL(-1) remifentanil (n = 22). All patients were anaesthetized with propofol, cisatracurium and desflurane with a mixture of 60% nitrous oxide in oxygen. Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal desflurane and target-controlled remifentanil concentrations. Predetermined end-tidal desflurane concentrations and the MAC(BAR) for each group were determined using an up-and-down sequential-allocation technique.

RESULTS

The MAC(BAR) of desflurane was higher in the group receiving no remifentanil (6.25% [95% confidence interval: 5.9-6.5%]) as compared with patients of the groups receiving 1 ng mL(-1) (2.7% [2.6-2.8%]; P < 0.001) and 3 ng mL(-1) remifentanil (2% [1.9-2.2%]; P < 0.01). When considering a MAC value in this age population and the contribution of 60% nitrous oxide (0.55 MAC), the combined MAC(BAR) values, expressed as multiples of the MAC, were 1.9, 0.8 and 0.6 MAC, in the three groups, respectively.

CONCLUSION

A target-controlled concentration of 1 ng mL(-1) remifentanil results in a 57% decrease in the MAC(BAR) of desflurane combined with 60% nitrous oxide. Increasing the target concentration of remifentanil to 3 ng mL(-1) produces a further 26% decrease in the MAC(BAR) values of desflurane.

The effect of adding nitrous oxide on MAC of sevoflurane combined with two target-controlled concentrations of remifentanil in women

BACKGROUND AND OBJECTIVE

The aim of this prospective, randomized, double-blind study was to determine the effects of adding nitrous oxide on sevoflurane requirement for blunting sympathetic responses after surgical incision combined with two different target-controlled concentrations of remifentanil (1 and 3 ng mL(-1)) in female.

METHODS

102 female patients, aged 20-50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive sevoflurane anaesthesia alone (Group A, n=53), or with the addition of 60% nitrous oxide (Group N, n=49). Patients of both groups were further assigned to receive a target-controlled remifentanil infusion with an effect-site concentration of either 1 ng mL(-1) (Group N1, n=27; Group A1, n=30), or 3 ng mL(-1) (Group N3, n=22; Group A3, n=23). Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal sevoflurane and target-controlled remifentanil concentrations. Predetermined end-tidal sevoflurane concentrations and minimum alveolar concentration (MAC) for each group were determined using an up-and-down sequential allocation technique.

RESULTS

The MAC of sevoflurane was 3.96% (95% confidence interval, CI95: 3.69-4.23%) in Group A1 and 1.2% (CI95: 0.9-1.3%) in Group N1 (P < 0.01), while in Groups A3 and N3 the MAC of sevoflurane was 0.36% (CI95: 0.24-0.47%) and 0.18% (CI95: 0.1-0.3%), respectively (P < 0.05).

CONCLUSION

Adding 60% nitrous oxide reduces the MAC of sevoflurane by 70% when using a remifentanil concentration of 1 ng mL(-1) and 50% when using a remifentanil concentration of 3 ng mL(-1).

Blood Glucose Control During Selective Arterial Stimulation and Venous Sampling for Localization of Focal Hyperinsulinism Lesions in Anesthetized Children

Surgical management of congenital hyperinsulinism is improved by accurate localization of small, focal dysregulated pancreatic lesions using the arterial stimulation and venous sampling (ASVS) test, which can demonstrate increased hepatic venous insulin concentrations after selective arterial injections of calcium. However, anesthesia-related increases in blood glucose can induce insulin secretion, making it difficult to interpret ASVS test data. In this retrospective study, we examined the effect of anesthetic interventions on blood glucose concentrations in 68 children undergoing ASVS testing. We considered only the glucose concentrations observed before calcium stimulation in the final analysis. The choice of drugs for induction (sevoflurane, propofol, or thiopentone), maintenance inhaled anesthetics (sevoflurane, desflurane, or isoflurane), and the use of caudal epidural bupivacaine were not associated with significant differences in the mean blood glucose concentration before ASVS. However, patients receiving remifentanil infusions had smaller mean glucose concentrations (80 +/- 18 versus 100 +/- 44 mg x dl(-1), P = 0.01). These concentrations were also significantly smaller if tracheal intubation was delayed for at least 10 min after induction while patients received inhaled anesthetics via a face mask along with remifentanil infusions (79 +/- 14 for delayed intubation versus 95 +/- 39 mg x dl(-1) for early intubation, respectively, P = 0.03). The percentage increase in glucose concentrations from preintubation values was significantly smaller in these subjects (3.7% +/- 21.9% for delayed intubation versus 31.7% +/- 60.4% for early intubation, P = 0.02). We conclude that the anesthetic management protocol for these patients should include the use of remifentanil infusions and the administration of inhaled anesthetics and remifentanil infusions for a minimum of 10 min to establish a deep plane of anesthesia before tracheal intubation.

Effects of propofol and sevoflurane on the excitability of rat spinal motoneurones and nociceptive reflexes in vitro

BACKGROUND

Spinal actions of halogenated ethers are widely recognized, whereas spinal actions of intravenous anaesthetics like propofol are less clear. The aim of this study was to compare the spinal effects of propofol and sevoflurane.

METHODS

We used an isolated spinal cord in vitro preparation from rat pups and superfused the anaesthetics at known concentrations. Responses of motoneurones to single and repetitive C-fibre intensity stimulation (trains of 20 stimuli at 1 Hz) of a lumbar dorsal root were recorded from the corresponding ventral root via a suction electrode.

RESULTS

Stimulation trains produced a wind-up of action potentials in motoneurones. Both propofol and sevoflurane produced a significant concentration-dependent depression of the evoked wind-up, although at clinically relevant concentrations sevoflurane exhibited a larger intrinsic efficacy. Applied at anaesthetic concentrations, sevoflurane 250 micro M abolished action potentials whereas propofol 1 micro M only produced a reduction close to 50%. At these concentrations, sevoflurane produced a large depressant effect on the monosynaptic reflex whereas propofol was ineffective.

CONCLUSIONS

Sevoflurane produces large inhibitory effects on nociceptive and non-nociceptive reflexes which are likely to contribute to immobility during surgery. Compared with sevoflurane, propofol appears to have much weaker effects on spinal reflexes such as those recorded in an isolated preparation.

Optimization of desflurane administration in morbidly obese patients: a comparison with sevoflurane using an ‘inhalation bolus’ technique

BACKGROUND

The concept of an 'inhalation bolus' can be used to optimize inhaled drug administration. We investigated the depth of anaesthesia, haemodynamic stability, and recovery time in morbidly obese patients resulting from bispectral index (BIS)-guided sevoflurane or desflurane administration and BIS-triggered inhalation boluses of sevoflurane or desflurane combined with titration of remifentanil.

METHODS

Fifty morbidly obese patients undergoing laparoscopic gastroplasty received either BIS-guided sevoflurane or desflurane anaesthesia in combination with a remifentanil target-controlled infusion. Intraoperative haemodynamic stability and BIS control were measured. Immediate recovery was recorded.

RESULTS

Intraoperatively, the BIS was between 40 and 60 for a greater percentage of time in the sevoflurane (78 (13)% of case time) than in the desflurane patients (64 (14)% of case time), owing to too profound anaesthesia in the desflurane patients at the start of the procedure. However, fewer episodes of hypotension were found in the desflurane group, without the occurrence of more hypertensive episodes. During immediate recovery, eye opening, extubation, airway maintenance, and orientation occurred sooner in the desflurane group.

CONCLUSIONS

Immediate recovery was significantly faster in the desflurane group. Overall hypnotic controllability measured by BIS was less accurate with desflurane. Overall haemodynamic controllability was better when using desflurane. Fewer episodes of hypotension were found in the desflurane group. The use of the inhalation bolus was found to be appropriate in both groups without causing severe haemodynamic side effects. Minimal BIS values were significantly lower after a desflurane bolus.

Sevoflurane: an ideal agent for adult day-case anesthesia?

Sevoflurane has several properties which make it potentially useful as a day case anaesthetic. Following induction of anaesthesia with propofol, awakening from sevoflurane is faster compared to isoflurane, faster or similar compared to propofol and comparable (in the majority of studies) to desflurane. Subsequent recovery and discharge is generally similar following all agents. Sevoflurane may also be used to induce anaesthesia, which is generally well-received and causes less hypotension and apnoea compared to propofol. When used as a maintenance anaesthetic, the incidence of postoperative nausea and vomiting after sevoflurane is comparable to other inhaled anaesthetics, but this complication appears more common after inhaled inductions. The tolerability and low solubility of sevoflurane facilitate titration of anaesthesia and may reduce the need for opioid analgesia, which in turn may limit the occurrence of nausea and vomiting.