The continuous recording of blood pressure in patients undergoing carotid surgery under remifentanil versus sufentanil analgesia

Bolus dose remifentanil and sufentanil blunting cardiovascular intubation responses in children: a randomized, double-blind comparison

BACKGROUND AND OBJECTIVE

The present randomized controlled study was designed to compare the efficacy of remifentanil 2 microg kg(-1) and sufentanil 0.2 microg kg(-1) by bolus injection on the cardiovascular response to intubation in healthy children.

METHODS

One hundred and five children, ASA 1-2 and scheduled for elective plastic surgery under general anaesthesia, were randomly divided into one of two study groups to receive the following treatments in a double-blind manner: remifentanil 2 microg kg(-1) (group R) and sufentanil 0.2 microg kg(-1) (group S). Blood pressure and heart rate (HR) were recorded before anaesthesia induction (baseline values), immediately before intubation (postinduction values), at intubation and every minute for 5 min after intubation. The percentage changes in systolic blood pressure (SBP) and HR relative to baseline values were calculated. The incidences of SBP and HR percentage changes of more than 30% of baseline values during the observation were recorded.

RESULTS

As compared with baseline values, blood pressure and HR at intubation and their maximum values during the observation increased significantly in group S, but decreased significantly in group R. Blood pressure and HR at intubation and their maximum values during the observation were significantly different between the groups. There were significant differences between the groups in the percentage changes of SBP and HR relative to baseline values and their maximum percentage changes during the observation. The incidences of SBP and HR percentage increases of more than 30% of baseline values were not significantly different between the groups, but the incidences of SBP and HR percentage decreases of more than 30% of baseline values were significantly higher in group R than in group S.

CONCLUSION

In combination with propofol for anaesthesia induction in children, sufentanil 0.2 microg kg(-1) by bolus injection fails to depress the cardiovascular intubation response. Remifentanil 2 microg kg(-1) by bolus injection can completely abolish the cardiovascular intubation response, but causes more adverse cardiovascular depression.

Remifentanil for general anaesthesia: a systematic review

We performed a quantitative systematic review of randomised, controlled trials that compared remifentanil to short-acting opioids (fentanyl, alfentanil, or sufentanil) for general anaesthesia. Eighty-five trials were identified and these included a total of 13 057 patients. Intra-operatively, remifentanil was associated with clinical signs of deeper analgesia and anaesthesia, such as fewer responses to noxious stimuli (relative risk 0.65, 95% CI 0.48-0.87), more frequent episodes of bradycardia (1.46, 1.04-2.05), more hypotension (1.68, 1.36-2.07) and less hypertension (0.60, 0.46-0.78). Postoperatively, remifentanil was associated with faster recovery (difference in extubation time of -2.03, 9.5% CI, -2.92 to -1.14 min), more frequent postoperative analgesic requirements (1.36, 1.21-1.53) and fewer respiratory events requiring naloxone (0.25, 0.14-0.47). Remifentanil had no overall impact on postoperative nausea (1.03, 0.97-1.09) or vomiting (1.06, 0.96-1.17), but was associated with twice as much shivering (2.15, 1.73-2.69). Remifentanil does not seem to offer any advantage for lengthy, major interventions, but may be useful for selected patients, e.g. when postoperative respiratory depression is a concern.

[Remifentanil and conventional laryngoscopy and tracheal intubation]

INTRODUCTION

Laryngoscopy and tracheal intubation in patients undergoing surgical procedures under balanced general endotracheal anesthesia may provoke a sympathetic response with tachycardia and hypertension.

MATERIAL AND METHODS

Various pharmacological agents, such as anesthetics, analgesics, adrenergic blockers, can modify the hemodynamic response. This investigation evaluated the effects of three different doses of remifentanil on the cardiovascular response to laryngoscopy and orotracheal intubation. The study included 100 patients of both sexes, aged between 21 and 64 years, undergoing various types of surgical procedures under general anesthesia. Patients received remifentanil just before the initiation of anesthesia, and thiopental was used for induction of anesthesia.

RESULTS AND CONCLUSION

The results of this investigation indicate that intravenous bolus dose of remifentanil of 0.5 microg/kg, combined with thiopental, reduces the cardiovascular response to laryngoscopy and tracheal intubation, whereas bolus doses of remifentanil, 1 and 1.5 microg/kg, provide cardiovascular stability, as well as safe and efficient induction of anesthesia.

Effects of clonidine and superficial cervical plexus block on hemodynamic stability after carotid endarterectomy

OBJECTIVES

To evaluate the effects of 2 interventions (intravenous clonidine and superficial cervical block) on hemodynamic stability after carotid endarterectomy and to identify variables associated with hemodynamic instability.

DESIGN

Prospective, observational study, sequential enrollment.

SETTING

University hospital.

PARTICIPANTS

Two hundred seventy-five patients undergoing elective carotid endarterectomy under general anesthesia.

INTERVENTIONS

Group NN (n = 50) received no intervention. In group CN (n = 85), 3 mug/kg of clonidine were administered intravenously 30 minutes before the end of the operation. Group CB (n = 140) additionally received a superficial cervical plexus block (SCB) with 20 mL of naropine 0.5% before the induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Clonidine alone (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.45-3.76) and clonidine combined with an SCB (OR, 4.99; 95% CI, 3.19-7.82) resulted in a significant increase in hemodynamic stability after CEA (p < 0.001) from 53.3% (NN) to 70.0% (CN) and 83.3% (CB), respectively. The need for rescue medication decreased from 40.0% to 17.6% and 13.6% (p < 0.001). Both interventions significantly reduced the need for postoperative opioid analgesics (p < 0.01). Logistic regression analysis showed preoperative systolic blood pressure values greater than 170 mmHg (OR, 3.23; 95% CI, 1.76-5.93), previous cardiac interventions (OR, 3.3; 95% CI, 1.54-7.11), and the need for rescue medication in the awakening period (OR, 5.8; 95% CI, 2.88-11.52) to be independent risk factors for postoperative hemodynamic instability (p < or = 0.002).

CONCLUSIONS

Intravenous clonidine and superficial cervical block significantly improve cardiovascular stability after carotid endarterectomy. Patients with pre-existing excessive hypertension and previous coronary interventions must be considered a high-risk group.

Surgical stress index reflects surgical stress in gynaecological laparoscopic day-case surgery

BACKGROUND

Monitoring of analgesia remains a challenge during general anaesthesia. The surgical stress index (SSI) is derived from the photoplethysmographic waveform amplitude and the heart beat-to-beat interval. We evaluated the ability of SSI to measure surgical stress in patients undergoing gynaecological laparoscopy. Our hypothesis was that while keeping State Entropy (SE) at a predetermined level, SSI would be higher in patients receiving a beta-blocking agent (esmolol) than in those receiving an opioid (remifentanil) during laparoscopy.

METHODS

Thirty women undergoing gynaecological laparoscopy were assigned randomly to receive esmolol (n = 15) or remifentanil (n = 15). Anaesthesia was induced with propofol and fentanyl and maintained with desflurane and nitrous oxide 50% in oxygen to keep SE at 50(5). The infusion of esmolol or remifentanil was started before laparoscopy and adjusted to keep the systolic blood pressure at -20 to +10% from the preoperative value.

RESULTS

During the fentanyl phase, before surgery, both groups behaved similarly, with an increase in SSI after intubation. In the patients receiving esmolol, the SSI reacted to the initial incision (P < 0.05), and remained high after trocar insertion (P < 0.05). In patients receiving remifentanil, it did not react to the initial incision, but increased after trocar insertion (P < 0.05), and it remained lower both after incision (P < 0.05) and after trocar insertion (P < 0.05).

CONCLUSION

SSI was higher in patients receiving esmolol. The index seems to reflect the level of surgical stress and may help guide the use of opioids during general anaesthesia.

Remifentanil update: clinical science and utility

The anilidopiperidine opioid remifentanil has pharmacodynamic properties similar to all opioids; however, its pharmacokinetic characteristics are unique. Favourable pharmacokinetic properties, minimally altered by extremes of age or renal or hepatic dysfunction, enable easy titration and rapid dissipation of clinical effect of this agent, even after prolonged infusion. Remifentanil is metabolised by esterases that are widespread throughout the plasma, red blood cells, and interstitial tissues, whereas other anilidopiperidine opioids (e.g. fentanyl, alfentanil and sufentanil) depend upon hepatic biotransformation and renal excretion for elimination. Consequently, remifentanil is cleared considerably more rapidly than other anilidopiperidine opioids. In addition, its pKa (the pH at which the drug is 50% ionised) is less than physiological pH; thus, remifentanil circulates primarily in the non-ionised moiety, which quickly penetrates the lipid blood-brain barrier and rapidly equilibrates across the plasma/effect site interface. By virtue of these distinctive pharmacokinetic properties, the context-sensitive half-time (i.e. the time required for the drug's plasma concentration to decrease by 50% after cessation of an infusion) of remifentanil remains consistently short (3.2 minutes), even following an infusion of long duration (> or =8 hours). Remifentanil, a clinically versatile opioid, is useful for intravenous analgesia and sedation in spontaneously breathing patients undergoing painful procedures. Profound analgesia may be achieved with minimal effect on cognitive function. Remifentanil may also provide sedation and analgesia during placement of regional anaesthetic blocks, and in conjunction with topical anaesthesia and airway nerve blocks, it may be useful for blunting reflex responses and facilitating 'awake' fibreoptic intubation. Compared with fentanyl and alfentanil in a day-surgery setting, remifentanil supplementation of general anaesthesia may improve intraoperative haemodynamic control. Both emergence time and the incidence of respiratory depression during post-anaesthetic recovery may be reduced. However, outcomes such as home discharge time, post-emergence adverse effect profile, and patient and provider satisfaction are not significantly improved, and the incidence of intraoperative hypotension and bradycardia is greater. In addition, drug acquisition costs for remifentanil are higher and clinicians may need extra time to familiarise themselves with the drug's unique pharmacokinetics.Ironically, the quick dissipation of opioid analgesic effect following remifentanil discontinuation may be a significant clinical disadvantage. Unless little or no postoperative pain is anticipated, the clinician may wish to treat prospectively using local or regional anaesthesia, non-opioid analgesics, or longer-acting opioid analgesics.

Intraoperative management: carotid endarterectomies

The management of anesthesia for patients undergoing carotid endarterectomy is challenging and dynamic. Effective management and good outcome requires the anesthesiologist's understanding of cerebral physiology, knowledge of neck anatomy, and understanding of the rapid pathophysiologic changes that occur during carotid artery manipulations. The anesthesiologist must be flexible in the management of patients, who frequently have underlying multiorgan pathology and cardiovascular compromise. Good communication between the anesthetic and surgical teams is needed to avoid irreversible debilitating consequences for the patient.

Anaesthesia for carotid endarterectomy: comparison of hypnotic- and opioid-based techniques †

BACKGROUND

Although the synergistic interaction between hypnotics and opioids for total i.v. anaesthesia has been repeatedly demonstrated, questions about different dose combinations of hypnotics and opioids remain. The optimal combination would be based on maximal synergy, using the lowest dose of both drugs and having the lowest incidence of side-effects.

METHODS

The major goal of this prospective randomized study was to compare two different dose combinations of propofol and remifentanil (both administered by target controlled infusion (TCI)) in respect of haemodynamics during surgery and recovery, and the need for cardiovascular treatment in the recovery room. A secondary goal was to compare pain scores (VAS) and morphine consumption in the recovery room. Anaesthesia was induced in both groups using TCI propofol, adjusted to obtain a bispectral index score (BIS) value between 40 and 60. TCI for remifentanil commenced at an initial effect-site concentration of 0.5 ng ml(-1), and was adjusted according to haemodynamics. Patients were divided into one of two groups during anaesthesia: (i). Group H, hypnotic anaesthesia (n=23), propofol effect-site concentration maintained at 2.4 microg x ml(-1); and (ii). Group O, opioid anaesthesia (n=23), propofol effect-site concentration maintained at 1.2 microg x ml(-1). In both groups, remifentanil effect-site concentration was adjusted according to haemodynamics and changes in BIS value.

RESULTS

In Group O, more episodes of intraoperative hypotension (P<0.02) and hypertension (P<0.01), and fewer episodes of tachycardia were observed. More patients in Group O required nicardipine administration for postoperative hypertension (8 patients in Group H vs 15 patients in Group O, P<0.04). During recovery, morphine titration was necessary in approximately 50% of patients. No significant difference between groups was observed concerning pain scores or requirement for morphine titration.

CONCLUSIONS

Maintenance of anaesthesia predominantly with propofol and a low dose of remifentanil, both administered using TCI, is associated with greater stability in perioperative haemodynamics than anaesthesia predominantly with remifentanil alone. Postoperative pain was identical in both groups of patients who underwent relatively short duration, and relatively painless surgery.

Target-controlled infusion for remifentanil in vascular patients improves hemodynamics and decreases remifentanil requirement

Remifentanil is a potent ultra-short-acting opioid, which permits rapid emergence. However, remifentanil is expensive and may have detrimental effects on hemodynamics in case of overdose. Target-controlled infusion (TCI) permits adapting infusion to pharmacokinetic models. In this prospective randomized study, we compared intra- and postoperative hemodynamics, remifentanil requirement during anesthesia, and postoperative morphine requirement in patients scheduled for carotid surgery, and receiving either continuous IV weight-adjusted infusion of remifentanil (RIVA) or TCI for remifentanil (TCIR). Forty-six patients were enrolled in this study: all were anesthetized by using TCI for propofol. Twenty-three received RIVA (0.5 micro g. kg(-1) x min(-1)) for the induction of anesthesia and endotracheal intubation, with the infusion rate decreased to 0.25 micro g x kg(-1) x min(-1) after intubation, then adapted by step of 0.05 micro g x kg(-1) x min(-1) according to hemodynamics. Twenty-three patients received TCIR (Minto model, Rugloop), with an effect-site concentration at 4 ng/mL during induction, then adapted by step of 1 ng/mL according to hemodynamics. All patients received atracurium and a 50% mixture of N(2)O/O(2). Hemodynamic variables were recorded each minute. The number and duration of hemodynamic events were collected, and total doses of anesthetics (remifentanil and propofol) and vasoactive drugs were noted in both groups of patients. Data were analyzed by using unpaired t-tests. RIVA was significantly associated with more frequent episodes of intraoperative hypotension (16 versus 6, P < 0.001) and more frequent episodes of postoperative hypertension and/or tachycardia requiring more frequent administration of beta-adrenergic blockers (16 vs 10, P < 0.04) in comparison with TCIR. The need for morphine titration was not significantly different between groups. TCIR led to a significantly smaller requirement of remifentanil (700 +/- 290 versus 1390 +/- 555 micro g, P < 0.001) without difference in propofol requirement. This prospective randomized study demonstrated that, during carotid endarterectomy, in comparison with patients receiving remifentanil using continuous RIVA, TCI results in less hypotensive episodes during the induction of anesthesia, in fewer episodes of tachycardia and/or hypertension and a smaller beta-adrenergic blocker requirement during recovery, and a decrease in remifentanil requirement. Recommendations to prefer TCI for remifentanil administration during carotid endarterectomy may be justified.

IMPLICATIONS

Remifentanil for intraoperative analgesia in carotid artery surgery is associated with a better stability in perioperative hemodynamics when administered in target-controlled infusion compared with continuous weight-adjusted infusion. This may be related to a smaller requirement of this drug when using target-controlled infusion, as well as a smooth mode of administration.