Influence of intraoperative opioid on postoperative pain and pulmonary function after laparoscopic gastric banding: remifentanil TCI vs sufentanil TCI in morbid obesity

Implementation of a Bayesian based advisory tool for target-controlled infusion of propofol using qCON as control variable

This single blinded randomized controlled trial aims to assess whether the application of a Bayesian-adjusted CePROP (effect-site of propofol) advisory tool leads towards a more stringent control of the cerebral drug effect during anaesthesia, using qCON as control variable. 100 patients scheduled for elective surgery were included and randomized into a control or intervention group (1:1 ratio). In the intervention group the advisory screen was made available to the clinician, whereas it was blinded in the control group. The settings of the target-controlled infusion pumps could be adjusted at any time by the clinician. Cerebral drug effect was quantified using processed EEG (CONOX monitor, Fresenius Kabi, Bad Homburg, Germany). The time of qCON between the desired range (35-55) during anaesthesia maintenance was defined as our primary end point. Induction parameters and recovery times were considered secondary end points and coefficient of variance of qCON and CePROP was calculated in order to survey the extent of control towards the mean of the population. The desired range of qCON between 35 and 55 was maintained in 84% vs. 90% (p = 0.15) of the case time in the control versus intervention group, respectively. Secondary endpoints showed similar results in both groups. The coefficient of variation for CePROP was higher in the intervention group. The application of the Bayesian-based CePROP advisory system in this trial did not result in a different time of qCON between 35 and 55 (84 [21] vs. 90 [18] percent of the case time). Significant differences between groups were hard to establish, most likely due to a very high performance level in the control group. More extensive control efforts were found in the intervention group. We believe that this advisory tool could be a useful educational tool for novices to titrate propofol effect-site concentrations.

Intravenous Lidocaine Decreased the Median Effective Concentration of Sufentanil for Tracheal Intubation in Obese Patients

Purpose

Sufentanil has been widely used to inhibit the hemodynamic responses caused by tracheal intubation. Using intravenous lidocaine may reduce the dose of sufentanil and better maintain the hemodynamics. This study aimed to determine the effects of intravenous lidocaine on the median effective concentration (EC50) of sufentanil for endotracheal intubation in obese patients.

Patients and Methods

This is a randomized, double-blind, up-and-down sequential allocation study. Fifty obese patients undergoing bariatric surgery were randomly allocated in a 1:1 ratio into the lidocaine group and the saline group. Anesthesia was induced using a target-controlled infusion of propofol and sufentanil. The effect-site concentration (Ce) of propofol was 3.5 μg/mL. The Ce of sufentanil for the first patient was 0.4 ng/mL, and the sufentanil dose for the next patient was determined according to the responses of the previous patient, using Dixon's up-and-down sequential method with an interval of 0.05 ng/mL. When the target concentration of propofol and sufentanil was reached, lidocaine 1.5 mg/kg or the same volume of normal saline was infused over 3 min. Tracheal intubation was performed 3 min after the end of the lidocaine or normal saline infusion. Probit regression was used to calculate the EC50 and 95% confidence interval (CI) of sufentanil.

Results

Thirty-eight patients completed this study. The EC50 of sufentanil was 0.36 ng/mL (95% CI: 0.31-0.41 ng/mL) in the lidocaine group, which was significantly lower than 0.50 ng/mL (95% CI: 0.43-0.62 ng/mL) in the saline group. In addition, compared with saline group, the dosage of sufentanil in lidocaine group decreased significantly during the test. The hemodynamics of the two groups were stable during the study period.

Conclusion

Intravenous lidocaine 1.5 mg/kg decreased the EC50 of sufentanil required for tracheal intubation in obese patients undergoing bariatric surgery.

Pain Therapy Guided by Purpose and Perspective in Light of the Opioid Epidemic

Prescription opioid misuse is an ongoing and escalating epidemic. Although these pharmacological agents are highly effective analgesics prescribed for different types of pain, opioids also induce euphoria, leading to increasing diversion and misuse. Opioid use and related mortalities have developed in spite of initial claims that OxyContin, one of the first opioids prescribed in the USA, was not addictive in the presence of pain. These claims allayed the fears of clinicians and contributed to an increase in the number of prescriptions, quantity of drugs manufactured, and the unforeseen diversion of these drugs for non-medical uses. Understanding the history of opioid drug development, the widespread marketing campaign for opioids, the immense financial incentive behind the treatment of pain, and vulnerable socioeconomic and physical demographics for opioid misuse give perspective on the current epidemic as an American-born problem that has expanded to global significance. In light of the current worldwide opioid epidemic, it is imperative that novel opioids are developed to treat pain without inducing the euphoria that fosters physical dependence and addiction. We describe insights from preclinical findings on the properties of opioid drugs that offer insights into improving abuse-deterrent formulations. One finding is that the ability of some agonists to activate one pathway over another, or agonist bias, can predict whether several novel opioid compounds bear promise in treating pain without causing reward among other off-target effects. In addition, we outline how the pharmacokinetic profile of each opioid contributes to their potential for misuse and discuss the emergence of mixed agonists as a promising pipeline of opioid-based analgesics. These insights from preclinical findings can be used to more effectively identify opioids that treat pain without causing physical dependence and subsequent opioid abuse.

Remifentanil-induced postoperative hyperalgesia: current perspectives on mechanisms and therapeutic strategies

The use of remifentanil in clinical practice offers several advantages and it is used for a wide range of procedures, ranging from day-surgery anesthesia to more complex procedures. Nonetheless, remifentanil has been consistently linked with development of opioid-induced hyperalgesia (OIH), which is described as a paradoxical increase in sensitivity to painful stimuli that develops after exposure to opioid treatment. The development of OIH may cause several issues, delaying recovery after surgery and preventing timely patient's discharge. Moreover, it causes patient's discomfort with higher pain scores, greater use of analgesics, and associated side effects. Remifentanil is the opioid most convincingly associated with OIH, and hereby we provide a review of remifentanil-induced hyperalgesia, describing both the underlying mechanisms involved and the available studies investigating experimental and clinical pharmacologic approaches aiming at reducing its incidence and degree.

Comparison of effects of intraoperative nefopam and ketamine infusion on managing postoperative pain after laparoscopic cholecystectomy administered remifentanil

BACKGROUND

Although intraoperative opioids provide more comfortable anesthesia and reduce the use of postoperative analgesics, it may cause opioid induced hyperalgesia (OIH). OIH is an increased pain response to opioids and it may be associated with N-methyl-D-aspartate (NMDA) receptor. This study aimed to determine whether intraoperative nefopam or ketamine, known being related on NMDA receptor, affects postoperative pain and OIH after continuous infusion of intraoperative remifentanil.

METHODS

Fifty-four patients undergoing laparoscopic cholecystectomy were randomized into three groups. In the nefopam group (N group), patients received nefopam 0.3 mg/kg at the induction of anesthesia followed by a continuous infusion of 0.065 mg/kg/h. In the ketamine group (K group), patients received ketamine 0.3 mg/kg at the induction of anesthesia followed by a continuous infusion of 3 µg/kg/min. The control group did not received any other agents except for the standard anesthetic regimen. Postoperative pain score, first time and number of demanding rescue analgesia, OIH and degrees of drowsiness/sedation scale were examined.

RESULTS

Co-administrated nefopam or ketamine significantly reduced the total amount of intraoperative remifentanil and postoperative supplemental morphine. Nefopam group showed superior property over control and ketamine group in the postoperative VAS score and recovery index (alertness and respiratory drive), respectively. Nefopam group showed lower morphine consumption than ketamine group, but not significant.

CONCLUSIONS

Both nefopam and ketamine infusion may be useful in managing in postoperative pain control under concomitant infusion of remifentanil. However, nefopam may be preferred to ketamine in terms of sedation.

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.

Gender-related difference in postoperative pain after laparoscopic Roux-En-Y gastric bypass in morbidly obese patients

Some evidence exist to suggest that women experience more pain and require more medication than men to achieve a similar state of analgesia. However, this was not studied in morbidly obese patients. The study evaluates the effect of gender on postoperative pain and analgesic consumption in the first 24 h in morbidly obese patients who undergo laparoscopic Roux-En-Y gastric bypass surgery (RYNGPB). One hundred thirty obese adult patients who underwent elective RYNGPB were included in the study. Postoperative pain scores were compared using a numeric rating scale, at intervals (0, 15, 30, 45, 60, 90, and 120 min), and following discharge from the postanesthesia care unit (PACU) at 6, 12, and 24 h. Titrated morphine dose during the 2-h PACU stay and pethidine consumption in the subsequent 24 h were measured. One hundred fourteen patients completed the study (59 females and 55 males). Female patients had higher initial pain scores and higher morphine consumption (10.1 ± 3.1 mg) than male patients (7.2 ± 4.5 mg), P = 0.0001. Following PACU discharge, there was no gender difference in pain scores or analgesic consumption. Pethidine consumption in male patients during the first day was 97.8 ± 35.1 versus 98.1 ± 61.6 mg among female patients, P = 0.9729. Female patients had higher initial pain score and morphine consumption than men in the immediate postoperative period, but that difference disappeared after discharge from PACU.

Challenges in the optimisation of post-operative pain management with opioids in obese patients: a literature review

An increasing number of obese patients are undergoing surgery, particularly bariatric and orthopaedic surgery. The physiological differences between obese and normal-weight subjects may modify not only anaesthetic requirements during surgery but also post-operative analgesic management, raising a number of challenges in a critical period. In this review, we analyse studies of post-operative pain management with opioids in obese subjects. We discuss the genetic factors common to pain and obesity and the factors potentially modifying opioid pharmacokinetics and pharmacodynamics in obese patients, and we analyse the overall efficacy and safety of opioids for pain management during the post-operative period in obese patients. Both modifications to surgical methods and additional analgesic treatments to decrease the requirement for opioids may improve early rehabilitation and quality of care and reduce adverse effects in obese patients.

Anesthetic Pharmacology and the Morbidly Obese Patient

Anesthesiologists are increasingly being faced with treating obese patients. Physiologic and anthropometric associated with obesity-most notably increases in cardiac output, changes in tissue perfusion and increases in total body weight (TBW), lean body weight (LBW), and fat mass affect the pharmacokinetics (PK) of anesthetic agents. In addition, redundancy of airway tissue, obstructive and central sleep apnea and CO2 retention affect the pharmacodynamics (PD) of anesthetics and narrow the therapeutic window of numerous anesthetic drugs. Safe and effective pharmacologic management of the obese patient requires a thorough understanding of how obesity affects the PK and PD of anesthetics.

Comparison of propofol-remifentanil versus propofol-ketamine deep sedation for third molar surgery

This study aimed to compare continuous intravenous infusion combinations of propofol-remifentanil and propofol-ketamine for deep sedation for surgical extraction of all 4 third molars. In a prospective, randomized, double-blinded controlled study, participants received 1 of 2 sedative combinations for deep sedation for the surgery. Both groups initially received midazolam 0.03 mg/kg for baseline sedation. The control group then received a combination of propofol-remifentanil in a ratio of 10 mg propofol to 5 μg of remifentanil per milliliter, and the experimental group received a combination of propofol-ketamine in a ratio of 10 mg of propofol to 2.5 mg of ketamine per milliliter; both were given at an initial propofol infusion rate of 100 μg/kg/min. Each group received an induction loading bolus of 500 μg/kg of the assigned propofol combination along with the appropriate continuous infusion combination . Measured outcomes included emergence and recovery times, various sedation parameters, hemodynamic and respiratory stability, patient and surgeon satisfaction, postoperative course, and associated drug costs. Thirty-seven participants were enrolled in the study. Both groups demonstrated similar sedation parameters and hemodynamic and respiratory stability; however, the ketamine group had prolonged emergence (13.6 ± 6.6 versus 7.1 ± 3.7 minutes, P = .0009) and recovery (42.9 ± 18.7 versus 24.7 ± 7.6 minutes, P = .0004) times. The prolonged recovery profile of continuously infused propofol-ketamine may limit its effectiveness as an alternative to propofol-remifentanil for deep sedation for third molar extraction and perhaps other short oral surgical procedures, especially in the ambulatory dental setting.

A randomised trial comparing sufentanil versus remifentanil for laparoscopic gastroplasty in the morbidly obese patient

BACKGROUND AND OBJECTIVE

This prospective, randomised double-blind study compared the effects of target control infusion (TCI) of sufentanil and remifentanil on the quality of recovery and post-operative pain control in morbidly obese patients undergoing laparoscopic gastroplasty.

METHODS

Following institutional Ethics Committee approval and written informed consent, 100 morbidly obese patients were randomised to receive either TCI sufentanil (0.3 ng ml⁻¹; S-group; N = 50) or TCI remifentanil (3 ng ml⁻¹; R-group; N = 50) in combination with desflurane (O₂/air mixture: FiO₂, 50%). Quality of recovery was estimated by means of the modified Aldrete score and by the ability to perform psychomotor tests with the same competence post-operatively as pre-operatively. Post-operative pain was evaluated by the quantity of piritramide needed to achieve a visual analogue scale (VAS) less than 3. Statistical analysis was performed using an unpaired Student's t-test, Mann-Whitney U-test and χ² test, as appropriate.

RESULTS

Patient and surgical characteristics were similar among groups. In the R-group, time to extubation was significantly shorter, but VAS significantly higher than that in the S-group (P < 0.01). Quality of recovery and duration of post-anaesthesia care unit stay were comparable between groups (S-group: 119 ± 27 min and R-group: 119 ± 35 min). Piritramide consumption during the first 4 post-operative hours was higher in the R-group than in the S-group [S-group (median, range): 11.5 mg, 5.5-16.0; R-group: 18.0 mg, 14-22, P < 0.01], but not later on.

CONCLUSION

In the conditions of the present study, although TCI sufentanil resulted in slower awakening than TCI remifentanil, it was associated with a better quality of recovery.

Lung function after total intravenous anaesthesia or balanced anaesthesia with sevoflurane

BACKGROUND

We investigated the effects of total i.v. anaesthesia (TIVA) and balanced anaesthesia (BAL) with sevoflurane on postoperative lung function in patients undergoing surgery in the prone position.

METHODS

Sixty patients, aged 21-60 yr, undergoing elective lumbar disc surgery in the prone position were randomly allocated to undergo TIVA (propofol-remifentanil) or BAL (fentanyl-nitrous oxide-sevoflurane). Forced vital capacity (FVC), forced expiratory volume in 1 s, mid-expiratory flow (MEF 25-75), and peak expiratory flow were measured before and after general anaesthesia.

RESULTS

Both groups were similar with respect to patient characteristic data and preoperative lung function parameters. Irrespective of the type of anaesthesia administered, lung function parameters decreased after operation, with the decrease in FVC being greater after TIVA than after BAL with sevoflurane.

CONCLUSIONS

In patients emerging from general anaesthesia, postoperative reduction in FVC is greater after TIVA than after BAL with sevoflurane.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.