Effects of remifentanil with or without midazolam pretreatment on the 95% effective dose of propofol for loss of consciousness during induction: A randomized, clinical trial

Hemodynamic effects of a low versus a high dose of propofol during induction of anesthesia. A randomized trial

BACKGROUND

Hypotension is common after anesthesia induction with propofol and is associated with increased morbidity. It is important to examine the effects of the proposed interventions to limit preventable hypotension, as suggested by the reduction in the dose of propofol. Our objective was to investigate whether a high dose of propofol is inferior to a low dose with respect to changes in systolic arterial blood pressure (SAP).

METHODS

This randomized, double-blind, dose-controlled, non-inferiority study included 68 healthy women scheduled for gynecological surgery at the Day Surgery Unit, Haugesund Hospital, Norway. The patients were randomly allocated 1:1 to a low or high dose (1.4 mg/kg total body weight (TBW) versus 2.7 mg/kg TBW of propofol corresponding to maximal effect site concentrations (Ce) of 2.0 μg/mL versus 4.0 μg/mL. The dose of remifentanil was 1.9-2.0 μg/kg TBW, with maximal Ce of 5.0 ng/mL. The patients were observed for 450 s from the start of the infusions. The first 150 s was the sedation period, after which a bolus of propofol and remifentanil was administered. Baseline was defined as 55-5 s before the bolus doses. LiDCOplus was used for invasive beat-to-beat hemodynamic monitoring of changes in SAP, heart rate (HR), cardiac output (CO), stroke volume (SV), and systemic vascular resistance (SVR). A difference of 10 mmHg in the change in SAP was considered to be clinically important.

RESULTS

The SAP change difference for low versus high dose was -2.9 mmHg (95% CI -9.0-3.1). The relative changes for low versus high dose were SAP -31% versus -36%, (p < .01); HR -24% versus -20%, (p = .09); SVR -20% versus -31%, (p < .001); SV -16% versus -20%, (p = .04); and CO -35% versus -32%, (p = .33).

CONCLUSION

A high dose of propofol was not inferior to a low dose, and a reduction in the dose of propofol did not result in clinically important attenuation of major hemodynamic changes during induction in healthy women.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT03861364, January 3, 2019.

Effective dose of remimazolam co-administered with remifentanil to facilitate I-gel insertion without neuromuscular blocking agents: an up-and-down sequential allocation trial

BACKGROUND

Remimazolam is a new anesthetic drug developed and is an ultra-short-acting agent with rapid onset and offset. The pharmacology of this drug seems to be ideal for short surgeries eligible for I-gel insertion. Therefore, this study aimed to determine the optimal bolus dose of remimazolam for I-gel insertion when co-administered with remifentanil without neuromuscular blocking agents (NMBAs).

METHODS

Patients aged 19-65 years with American Society of Anesthesiologists physical status I or II scheduled for general anesthesia were enrolled. The first dose of remimazolam was 0.15 mg/kg and remifentanil was co-administered at an effect-site concentration (Ce) of 3.0 ng/mL. The dose of remimazolam for the following patient was decreased or increased by 0.05 mg/kg depending on the success or failure of I-gel insertion in the previous patient.

RESULTS

The remimazolam bolus dose required for successful I-gel insertion in 50% of adult patients using modified Dixon's up-and-down method with remifentanil Ce 3.0 ng/mL and no NMBAs was 0.280 ± 0.048 mg/kg. Isotonic regression analysis showed that the 50% and 95% effective doses were 0.244 (83% confidence interval [CI] 0.213-0.313) mg/kg and 0.444 (95% CI 0.436-0.448) mg/kg, respectively. The mean time to loss of consciousness (Modified Observer's Assessment of Alertness/Sedation score < 2) was 52.2 s. Three patients (12.0%) showed a reduction in systolic blood pressure of more than 30% from baseline.

CONCLUSIONS

Selecting the appropriate dose of remimazolam/remifentanil without NMBAs makes it feasible to insert the I-gel.

TRIAL REGISTRATION

This study protocol was registered at http://cris.nih.go.kr (KCT0007801, 12th, October, 2022).

The effect of preoperative sleep quality on the target plasma concentration of propofol and postoperative sleep in patients undergoing painless gastroscopy

BACKGROUND

This study aims to investigate the effect of preoperative sleep quality on the target plasma concentration of propofol and postoperative sleep in patients undergoing painless gastroscopy.

METHODS

Ninety-three outpatients aged 45 to 64 years with body mass index (BMI) of 18.5-30 kg/m² and ASA grades of I or II, who underwent painless gastroscopy, were selected. All patients were evaluated by the Athens insomnia scale (AIS) before the painless gastroscopy. The patients were divided into two groups according to the AIS score evaluated before painless gastroscopy: normal sleep group (group N, AIS score < 4 points, 47 cases) and sleep disorder group (group D, AIS score > 6 points, 46 cases). The target-controlled infusion (TCI) of propofol (Marsh model) was used for general anesthesia, the Bispectral index (BIS) was used to monitor the depth of anesthesia, and the BIS was maintained between 50 and 65 during the painless gastroscopy. The target plasma concentration (Cp) of propofol was recorded when the patient's eyelash reflex disappeared (T1), before the painless gastroscopy (T2), at the time of advancing the gastroscope (T3) and during the painless gastroscopy (T4), and the infusion rate per body surface area of propofol was calculated. The patient's AIS score was followed up by telephone at day 1, day 3, 1 week, and 1 month after the painless gastroscopy to assess the postoperative sleep of the patient. The occurrence of adverse reactions during the painless gastroscopy was recorded; the patient's satisfaction and the endoscopist's satisfaction with the anesthesia effect were compared between the two groups.

RESULTS

Compared with group N, the Cp at each time point and the infusion rate per body surface area of propofol in group D was increased significantly (P < 0.05); compared with the AIS scores before the painless gastroscopy, the AIS scores of the two groups of patients were significantly increased day 1 after the painless gastroscopy (P < 0.05); there were no significant differences in the AIS scores of the two groups at day 3, 1 week, and 1 month after the painless gastroscopy (P > 0.05). There were no statistically significant differences in the occurrence of adverse reactions and the patient's satisfaction and the endoscopist's satisfaction with the anesthesia effect between the two groups (P > 0.05).

CONCLUSION

The preoperative sleep disturbance will increase the Cp and the infusion rate per body surface area of propofol in patients undergoing painless gastroscopy. Propofol only affects the patients' sleep for day 1 after the painless gastroscopy.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2100045332) on 12/04/2021.

The Impact of Age on Propofol Requirement for Inducing Loss of Consciousness in Elderly Surgical Patients

It is generally accepted that geriatric patients are more sensitive to propofol than adults; thus, a dose-adjusted propofol is recommended for these patients during the induction of anesthesia. However, for patients aged 75 years and over, established guidelines for propofol induction doses do not provide dose references. To this end, we observed 80 surgical patients (female 39, male 41, American Society of Anesthesiologists physical status score I ∼ II) to access the appropriate dose of propofol for inducing loss of consciousness (LOC). Accordingly, patients were subdivided into group A (20 patients, 45–64 years), group B (20 patients, 65–74 years), group C (20 patients, 75–84 years), and group D (20 patients, ≥ 85 years). All patients received propofol (at a rate of 0.3 mg/kg/min) alone for inducing LOC, which was defined by loss of both eyelash reflex and verbal response. Compared with group A, the propofol requirement for LOC in Group B, C and D decreased by 14.8, 25.2 and 38.5%, respectively. Bivariate linear correlation analysis showed that propofol requirement was negatively correlated with age. After adjusting for potential confounders, age was still an independent factor affecting propofol requirement. In conclusion, the propofol requirement for inducing LOC decreased significantly in elderly patients. We demonstrated that age was an independent factor impacting propofol requirement for LOC during the induction of general anesthesia, implying that the propofol dose for anesthesia induction should be further reduced in elderly surgical patients, especially those aged 75 years and over.

[Effects of remifentanil on awakening of propofol sedated patients submitted to upper gastrointestinal endoscopy: a randomized clinical trial]

BACKGROUND AND OBJECTIVES

Sedation for endoscopic procedures aims to provide high quality sedation, lower risks, short recovery time, superior recovery quality and absence of side effects, seeking high patient level of satisfaction. The goal of the study was to assess administration of remifentanil combined with propofol regarding the effects of the drug association during sedation and recovery for patients submitted to upper GI diagnostic endoscopy.

METHOD

One hundred and five patients were assessed, randomly divided into three groups of 35 patients. The Control Group was sedated with propofol alone. Study Group 1 was sedated with a fixed dose of 0.2 μg.kg^-1 remifentanil combined with propofol. Study Group 2 was sedated with 0.3 μg.kg^-1 remifentanil combined with propofol. We assessed the quality of sedation, hemodynamic parameters, incidence of significant hypoxemia, time for spontaneous eye opening, post-anesthetic recovery time, quality of post-anesthetic recovery, presence of side effects and patient satisfaction.

RESULTS

Study Group 1 showed better quality of sedation. The groups in which remifentanil was administered combined with propofol showed shorter eye-opening time and shorter post-anesthetic recovery time compared to the control group. The three groups presented hemodynamic changes at some of the moments assessed. The incidence of significant hypoxemia, the quality of post-anesthetic recovery, the incidence of side effects and patient satisfaction were similar in the three groups.

CONCLUSIONS

The combination of propofol with remifentanil at a dose of 0.2 μg.kg^-1 was effective in improving the quality of sedation, and at doses of 0.2 μg.kg^-1 and 0.3 μg.kg^-1 reduced the time to spontaneous eye opening and post-anesthetic recovery in comparison to sedation with propofol administered alone.

Effect of remifentanil and midazolam on ED95 of propofol for loss of consciousness in elderly patients: A randomized, clinical trial

BACKGROUND

Older people are more vulnerable to hemodynamic instability caused by propofol due to their decreased initial distribution volume and increased sensitivity to propofol. Midazolam or remifentanil can often be coadministered because of their synergistic or additive effects with propofol as well as amnesic properties and the blockade of sympathetic stimulation. However, no study has confirmed the appropriate dose of propofol for loss of consciousness in aged patients when administered with other drugs, including opioids or benzodiazepines.

METHODS

Patients >65 years scheduled for general anesthesia were enrolled. The patients were randomized into 3 groups using a computer-generated randomization table. Patients in group P (propofol) received only propofol for loss of consciousness, those in group PR (propofol-remifentanil) received remifentanil before propofol, and those in group PMR (propofol-midazolam-remifentanil) received remifentanil and midazolam before propofol. After propofol administration, loss of both eyelash reflex and verbal response represented success. The 95% effective dose of propofol for loss of consciousness in each group, which was the primary outcome, was determined using a modified biased coin up-and-down method.

RESULTS

In total, 120 patients were randomized into the 3 groups (n = 40). The 95% effective dose of propofol for loss of consciousness was 1.13, 0.87, and 0.72 mg/kg in groups P, PR, and PMR, respectively. The mean blood pressure (MBP) in group PMR was more significantly decreased before propofol injection (P = .041) as well as 2 minutes (P = .005) and 3 minutes after propofol administration (P<.001), compared with group P, but there were no intergroup differences at other time points.

CONCLUSIONS

The effective dose of propofol for loss of consciousness in elderly patients could be decreased by 23% and 36% when remifentanil pretreatment was used without and with midazolam, respectively. However, the decrease in MBP was greater with remifentanil and midazolam pretreatment than with propofol alone. These findings suggest that pretreatment with midazolam for propofol infusions with remifentanil in elderly patients should be cautiously used, due to hemodynamic instability during induction.

Efficacy and Safety of Sufentanil-Propofol Versus Remifentanil-Propofol as Anesthesia in Patients Undergoing Craniotomy: A Meta-Analysis

OBJECTIVE

In this study, we aimed to evaluate the efficacy and safety of sufentanil-propofol (SF) versus remifentanil-propofol (RF) as maintenance therapy for anesthesia in patients undergoing craniotomy.

METHODS

Randomized controlled studies on SF and RF as anesthesia for craniotomy were searched in electronic databases such as PubMed, Web of Science, Cochrane Library, Embase, CNKI, and Wanfang Data. All studies were published up to December 31, 2017. The primary outcomes were wake-up time, extubation time, and pain score. The secondary outcomes were heart rate, mean arterial pressure (MAP), and adverse reactions.

RESULTS

In this meta-analysis, 14 studies involving 927 patients were investigated. Compared with the SF group, RF could significantly reduce the wake-up time and extubation time after craniotomy (P = 0.02, standardized mean difference [SMD], 1.19; 95% confidence interval [CI], 0.21-2.18; P = 0.0001; SMD, 1.87; 95% CI, 0.90-2.83, respectively). Meanwhile, SF had better efficacy to alleviate postoperative pain than RF (P = 0.001; SMD, 2.10; 95% CI, -3.37 to -0.82). However, there were no obvious differences in improving heart rate and MAP between the 2 groups (P = 0.46; SMD, 0.17; 95% CI, -0.28 to 0.62; P = 0.43; SMD, 0.16; 95% CI, -0.54 to 0.23, respectively). Moreover, there were no significant differences in the incidents of nausea and vomiting, shivering, fidgeting, and respiratory depression between the SF and RF groups.

CONCLUSIONS

RF as anesthesia for craniotomy had better effects in reducing the time of postoperative wake-up and extubation and significantly alleviating pain. Moreover, there were no significant differences in the incidence of adverse reactions between the 2 groups. The findings will prove beneficial for the rational use of clinical anesthetic drugs in the future.