Remifentanil-based anesthesia versus a propofol technique for otologic surgical procedures

A New Robotic Endoscope Holder for Ear and Sinus Surgery with an Integrated Safety Device

In the field of sinus and ear surgery, and more generally in microsurgery, the surgeon is faced with several challenges. The operations are traditionally carried out under binocular loupes, which allows for the surgeon to use both hands for a microinstrument and an aspiration tool. More recently, the development of endoscopic otological surgery allowed for seeing areas that are difficult to access. However, the need to handle the endoscope reduces the surgeon’s ability to use only one instrument at a time. Thus, despite anaesthesia, patient motions during surgery can be very risky and are not that rare. Because the insertion zone in the middle ear or in the sinus cavity is very small, the mobility of the endoscope is limited to a rotation around a virtual point and a translation for the insertion of the camera. A mechanism with remote center motion (RCM) is a good candidate to achieve this movement and allow for the surgeon to access the ear or sinus. Since only the translational motion along the main insertion axis is enabled, the ejection motion along the same axis is safe for the patient. A specific mechanism allows for inserting and ejecting the endoscope. In a sense, the position is controlled, and the velocity is limited. In the opposite sense, the energy stored in the spring allows for very quick ejection if the patient moves. A prototype robot is presented using these new concepts. Commercially available components are used to enable initial tests to be carried out on synthetic bones to validate the mobility of the robot and its safety functions.

The Effect of Dexmedetomidine on Middle Ear Pressure

OBJECTIVE: Dexmedetomidine is a preferred anesthetic agent in otological surgery because it provides controlled hypotension and good surgical field visibility. The aim of this study was to evaluate the influence of this novel agent on middle ear pressure.

STUDY DESIGN AND SETTING: This prospective clinical trial was performed in 60 patients who were scheduled for elective surgery. They received dexmedetomidine or saline infusion for 20 minutes before induction of anesthesia. Tympanometric measurements were recorded for both ears at preoperative, intraoperative, and postoperative states.

RESULTS: Mean difference of tympanometric peak pressure from baseline was statistically significant between dexmedetomidine and control group at the 30th minute of operation (24.8 daPa, P = 0.003 for right ear; 20.5 daPa, P = 0.02 for left ear) and at the end of the operation (25.8 daPa, P = 0.01 for right ear; 28.1 daPa, P = 0.004 for left ear).

CONCLUSIONS: Dexmedetomidine anesthesia raises the tympanometric parameters, but they never exceed the limits of normal.

Anaesthetic interventions for prevention of awareness during surgery

BACKGROUND

General anaesthesia is usually associated with unconsciousness. 'Awareness' is when patients have postoperative recall of events or experiences during surgery. 'Wakefulness' is when patients become conscious during surgery, but have no postoperative recollection of the period of consciousness.

OBJECTIVES

To evaluate the efficacy of two types of anaesthetic interventions in reducing clinically significant awareness:- anaesthetic drug regimens; and- intraoperative anaesthetic depth monitors.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, ISSUE 4 2016); PubMed from 1950 to April 2016; MEDLINE from 1950 to April 2016; and Embase from 1980 to April 2016. We contacted experts to identify additional studies. We performed a handsearch of the citations in the review. We did not search trial registries.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of either anaesthetic regimens or anaesthetic depth monitors. We excluded volunteer studies, studies of patients prior to skin incision, intensive care unit studies, and studies that only randomized different word presentations for memory tests (not anaesthetic interventions).Anaesthetic drug regimens included studies of induction or maintenance, or both. Anaesthetic depth monitors included the Bispectral Index monitor, M-Entropy, Narcotrend monitor, cerebral function monitor, cerebral state monitor, patient state index, and lower oesophageal contractility monitor. The use of anaesthetic depth monitors allows the titration of anaesthetic drugs to maintain unconsciousness.

DATA COLLECTION AND ANALYSIS

At least two authors independently scanned abstracts, extracted data from the studies, and evaluated studies for risk of bias. We made attempts to contact all authors for additional clarification. We performed meta-analysis statistics in packages of the R language.

MAIN RESULTS

We included 160 studies with 54,109 enrolled participants; 53,713 participants started the studies and 50,034 completed the studies or data analysis (or both). We could not use 115 RCTs in meta-analytic comparisons because they had zero awareness events. We did not merge 27 of the remaining 45 studies because they had excessive clinical and methodological heterogeneity. We pooled the remaining 18 eligible RCTs in meta-analysis. There are 10 studies awaiting classification which we will process when we update the review.The meta-analyses included 18 trials with 36,034 participants. In the analysis of anaesthetic depth monitoring (either Bispectral Index or M-entropy) versus standard clinical and electronic monitoring, there were nine trials with 34,744 participants. The overall event rate was 0.5%. The effect favoured neither anaesthetic depth monitoring nor standard clinical and electronic monitoring, with little precision in the odds ratio (OR) estimate (OR 0.98, 95% confidence interval (CI) 0.59 to 1.62).In a five-study subset of Bispectral Index monitoring versus standard clinical and electronic monitoring, with 34,181 participants, 503 participants gave awareness reports to a blinded, expert panel who adjudicated or judged the outcome for each patient after reviewing the questionnaires: no awareness, possible awareness, or definite awareness. Experts judged 351 patient awareness reports to have no awareness, 87 to have possible awareness, and 65 to have definite awareness. The effect size favoured neither Bispectral Index monitoring nor standard clinical and electronic monitoring, with little precision in the OR estimate for the combination of definite and possible awareness (OR 0.96, 95% CI 0.35 to 2.65). The effect size favoured Bispectral Index monitoring for definite awareness, but with little precision in the OR estimate (OR 0.60, 95% CI 0.13 to 2.75).We performed three smaller meta-analyses of anaesthetic drugs. There were nine studies with 1290 participants. Wakefulness was reduced by ketamine and etomidate compared to thiopental. Wakefulness was more frequent than awareness. Benzodiazepines reduces awareness compared to thiopental, ketamine, and placebo., Also, higher doses of inhaled anaesthetics versus lower doses reduced the risk of awareness.We graded the quality of the evidence as low or very low in the 'Summary of findings' tables for the five comparisons.Most of the secondary outcomes in this review were not reported in the included RCTs.

AUTHORS' CONCLUSIONS

Anaesthetic depth monitors may have similar effects to standard clinical and electrical monitoring on the risk of awareness during surgery. In older studies comparing anaesthetics in a smaller portion of the patient sample, wakefulness occurred more frequently than awareness. Use of etomidate and ketamine lowered the risk of wakefulness compared to thiopental. Benzodiazepines compared to thiopental and ketamine, or higher doses of inhaled anaesthetics versus lower doses, reduced the risk of awareness.

Standard Anesthetic Technique for Middle Ear Surgical Procedures: A Comparison of Desflurane and Sevoflurane

Objective:

This study was designed to compare desflurane and sevoflurane anesthesia for middle ear microsurgery.

Study Design:

One hundred healthy adults undergoing middle ear surgery were assigned to receive either desflurane or sevoflurane as their anesthetic. Intraoperative hemodynamics and BIS numbers were recorded. Hemodynamics, pain, nausea/vomiting, discharge readiness, and other parameters were compared postoperatively and 24 hours later.

Results:

No intraoperative differences were noted except in BIS scores which trended lower with desflurane. PACU blood pressures were higher after desflurane but pain scores, nausea/vomiting, rescue anti-emetics, recovery scores, and discharge times were similar. A significant difference was noted in anesthetic costs (desflurane > sevoflurane), and in patients with the lowest BIS scores associated with more nausea/vomiting.

Conclusions:

Both anesthetics may be used for ototic surgery but propofol anesthesia should still be considered in patients with a history of emetic sequelae.

Significance:

Short-acting inhalational anesthetics produce excellent operating conditions and reduce costs for otologic surgery.

Remifentanil, fentanyl, or the combination in surgical procedures in the United States: predictors of use in patients with organ impairment or obesity

Introduction

Remifentanil has a rapid onset and short duration of action, predictable pharmacokinetic/pharmacodynamic profile, and unlike fentanyl, does not accumulate with repeated or prolonged administration. This study evaluated predictors of remifentanil use in surgical patients with renal or hepatic impairment, or obesity in the United States who received remifentanil, fentanyl, or the combination.

Methods

Data (2010) from the US Healthcare National Inpatient Database, State Inpatient Database, State Ambulatory Surgery Database, and private hospital and Medicaid databases were used in this analysis. Patients included had presence of hepatic or renal disease, and/or obesity and were >5 and ≤80 years of age.

Results

In 2010, 9,274 patients with renal impairment, 1,896 with hepatic impairment, and 6,278 with obesity were identified. The percentage of surgical patients diagnosed with renal disease, hepatic disease, or obesity who received remifentanil was 41, 28, and 35 %, respectively; 29, 17, and 22 % received both remifentanil and fentanyl, and 30, 55, and 43 % received fentanyl alone, respectively. In patients with renal or hepatic disease the probability of remifentanil use was greater for persons aged >50 years, with Medicare as primary payer, or who were diagnosed with obesity (p < 0.05 all comparisons). In obese patients, the probability of remifentanil use was greater for persons aged >50 years or female (both p < 0.05). For all 3 disease states, the probability of remifentanil use was lower for those receiving epidural anesthesia or with Medicaid as primary payer (p < 0.05 all comparisons).

Conclusion

Remifentanil in combination with fentanyl is used less than fentanyl in surgical patients with hepatic impairment or obesity. This is inconsistent with the fact that the pharmacokinetic/pharmacodynamic features of remifentanil suggest it is the preferred intraoperative opioid in these patients. Predictors of remifentanil use in patients with renal or hepatic impairment, or obesity include older age, obesity, and Medicare as primary payer. Remifentanil in combination with fentanyl was significantly less utilized than fentanyl in persons with Medicaid as primary payer even though there was a disproportionate enrollment of beneficiaries with renal or hepatic disease, or obesity in state Medicaid programs.

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.

Bispectral index values during elective rigid bronchoscopy: a prospective observational pilot study

Rigid bronchoscopy is associated with a high incidence of haemodynamic disturbance and awareness under anaesthesia. Anaesthetic agents are given both to attenuate the sympathetic response to bronchoscopy and to prevent awareness. Use of the Bispectral index to guide anaesthesia has shown to reduce awareness and improve recovery times from general anaesthesia. We undertook a prospective observational study of BIS values in 50 patients during routine anaesthesia for rigid bronchoscopy. BIS values were found to be between 40-60 during bronchoscopy for only 0.5% of the time (0-11.5%[0-98.7%]), median (interquartile range [range]). Patients had a BIS < 40 for 99.6% (87.9-100%[0-100%]) of the duration of bronchoscopy. We identified one case of possible awareness. Few of our patients undergoing general anaesthesia for rigid bronchoscopy had BIS scores in the suggested range of between 40 and 60. BIS < 40 was more frequent than in previous studies of different surgical populations. There was no difference in the BIS values of patients anaesthetised with intermittent boluses or target controlled infusions of propofol.

Less postoperative nausea and vomiting after propofol + remifentanil versus propofol + fentanyl anaesthesia during plastic surgery

BACKGROUND

The effect of different opioids on postoperative nausea and vomiting (PONV) has not been conclusively determined yet, thus the aim of this study was to compare the incidence of PONV in propofol-anaesthetized patients receiving either fentanyl or remifentanil as opioid supplement.

METHODS

Sixty ASA physical status I and II patients scheduled for plastic surgery gave their written informed consent for this prospective, randomized, double-blind study. Anaesthesia was induced with propofol, rocuronium and fentanyl (n = 30; 2 microg kg(-1)) or remifentanil (n = 30; 1 microg kg(-1)). After tracheal intubation, anaesthesia was maintained with propofol, oxygen in air and an infusion of the opioid studied, which was modified according to clinical criteria. Baseline postoperative analgesia was achieved with intravenous propacetamol + metamizol. Intravenous morphine was given if visual analogic scale (VAS) for pain was > or = 4 (scale 0-10) and metoclopramide was administered if a patient presented > or = 2 PONV episodes (nausea or vomiting) in less than 30 min. Postoperatively (2, 12 and 24 h), we registered VAS, rescue morphine consumption, number of patients with episodes of PONV and number of patients requiring metoclopramide. P < 0.05 was considered significant.

RESULTS

There were no significant differences between groups in the demographic parameters, ASA physical status, propofol dose, VAS, and rescue morphine requirements. Fourteen patients in the fentanyl group and four in the remifentanil group presented PONV episodes 2-12 h postoperative hours' interval; (P < 0.05). Ten patients in the fentanyl group and four in the remifentanil group presented vomiting episodes in the same period (P < 0.05); and eight patients in the fentanyl group and one in the remifentanil group required metoclopramide; (P < 0.05). The number of postoperative PONV episodes were low, both in the 0-2-h period (n = 2 vs. n = 1, fentanyl and remifentanil, respectively) and in the 12-24-h period (n = 3 vs. n = 1).

CONCLUSION

Propofol + fentanyl anaesthesia resulted in a higher incidence of PONV and requirements of antiemetic drugs in the period between 2 and 12 postoperative hours compared with propofol + remifentanil, in patients undergoing plastic surgery.

Cost analyses of remifentanil, mivacurium and ropivacaine - a systematic review

Remifentanil, mivacurium and ropivacaine are the latest innovations in clinical anaesthesia and have gained increasing importance in daily practise due to their unique pharmacodynamic and pharmacokinetic properties. However, drug acquisition costs for these agents are considerably higher in most countries than for comparable substances. This review provides a systematic, critical appraisal of pharmacoeconomic studies with remifentanil, mivacurium and ropivacaine, primarily based on prospective, randomised trials. Results from analyses using cost-minimising techniques stress the issue of the higher drug acquisition costs. However, studies using a more sophisticated method (e.g., cost-effectiveness analysis) indicate comparable costs or even financial advantage in favour of the newer investigative drugs remifentanil, mivacurium and ropivacaine.

Hemodynamic stability, myocardial ischemia, and perioperative outcome after carotid surgery with remifentanil/propofol or isoflurane/fentanyl anesthesia

This study compares remifentanil/propofol (remi/prop) with isoflurane/fentanyl (iso/fen) anesthesia to determine which provides the greater hemodynamic stability, lesser myocardial ischemia, and morbidity with better postoperative outcomes after carotid endarterectomy. Sixty patients undergoing unilateral carotid endarterectomy were randomized to receive either a remi/prop or iso/fen anesthetic. Hemodynamic variables were recorded during the surgical procedure. In addition, transesophageal echocardiography was used to assess evidence of intraoperative regional wall motion abnormalities suggestive of cardiac ischemia. Emergence and extubation times, recovery from anesthesia, hemodynamic instability, nausea, vomiting, and pain in post anesthesia recovery, discharge delays, ICU admittance, hospital discharge, and preoperative and postoperative troponin levels were compared using appropriate statistical methods with P < 0.05 considered significant. The groups were demographically alike. Hemodynamic variables were similar during intubation and throughout surgery. Twenty-two percent of patients receiving iso/fen developed intraoperative regional wall motion abnormalities suggestive of ischemia, whereas no remi/prop patients had changes (P < 0.05). There was no difference in ST-T wave changes after surgery, and no patient had an elevation in troponin I levels. Postoperative variables were similar except that patients who received iso/fen had lower Stewart recovery scores during the first 15 minutes after post anesthesia care unit admission and a higher incidence of nausea and vomiting the day after surgery, whereas patients receiving remi/prop had discharge delays secondary to hypertension. ICU admittance, time to first void, oral intake, and time to hospital discharge were similar between the groups. At 9 times the cost of an iso/fen anesthesia technique, remi/prop offers little advantage over inhalational anesthesia for carotid endarterectomy.

A comparison of four intravenous sedation techniques and Bispectral Index monitoring in sinonasal surgery

This study was performed to investigate the quality of different intravenous sedation techniques, and the correlation between the Bispectral Index (BIS) values and the Observer's Assessment of Alertness/Sedation (OAA/S) scores. Eighty patients undergoing sinonasal surgery were randomly assigned to one of four groups. Group MF received midazolam and fentanyl, group PF received propofol and fentanyl, group MR received midazolam and remifentanil, and group PR received propofol and remifentanil. Heart rate and mean arterial pressure values were not different among the groups. SpO2 decreased only after intravenous medication in groups MF and MR (P < 0.017). Emesis was less common with propofol. A positive relationship existed between the BIS values and OAA/S scores during the operation in all groups and the strongest correlation was observed in group PR (r = 0.565 and P < 0.001). In conclusion, these four intravenous sedation techniques did not change mean arterial pressure, heart rate or SpO2 clinically and produced a similar level of light sedation. The BIS was useful for monitoring of sedation during sinonasal surgery under local anaesthesia with intravenous sedation.

Cost considerations in the use of anaesthetic drugs

Measuring the direct drug costs of an anaesthetic is relatively easy, but assessing increased expenditure in relation to clinical benefits and indirect costs is not. This review examines a number of papers that have attempted just such a task and tries to illustrate some of the difficulties inherent in this important area of cost-effective analyses.

Pharmacokinetics and pharmacodynamics of remifentanil: an update in the year 2000

Remifentanil is still in its infancy in terms of postmarketing development. Its appropriate role in modern anesthesia care is still being defined and reports of novel clinical applications for remifentanil are frequently appearing in the anesthesia literature. This review will focus on selected advances in our understanding of remifentanil pharmacokinetics and pharmacodynamics and on newly proposed clinical applications for remifentanil.