Interactions of Midazolam and Propofol on α1β2γ2L and α1β2γ2S Gamma Aminobutyric Acid Type A Receptors Expressed in Human Embryonic Kidney Cells

Cardiorespiratory Response to Sedative Premedication in Preschool Children: A Randomized Controlled Trial Comparing Midazolam, Clonidine, and Dexmedetomidine

PURPOSE

Sedative premedication in children may negatively impact their cardiorespiratory status during the perioperative course, and no clear consensus exists on the optimal premedication treatment for pediatric patients. The objective was to compare the perioperative cardiorespiratory responses to sedation using three different sedative premedication regimens in preschool children scheduled for surgery with total intravenous anesthesia.

DESIGN

A single-center randomized controlled trial.

METHODS

This is a planned secondary analysis of a study conducted at a 200-bed tertiary referral hospital. Ninety children participated in the study. They were aged 2-6 years and scheduled for ear, nose, and throat surgery with propofol/remifentanil anesthesia. Participants were randomly assigned to receive oral midazolam 0.5 mg/kg^-1 (MID), oral clonidine 4 mcg/kg^-1 (CLO), or intranasal dexmedetomidine 2 mcg/kg^-1 (DEX). The main outcome measures were the sedation level, based on the Ramsay Sedation Scale (RSS), and cardiorespiratory status, monitored during the perioperative period.

FINDINGS

The final cohort had 83 children (MID, n=27; CLO, n=26; DEX, n=30), with similar intergroup patient characteristics. RSS scores were lower in the MID group than in the CLO and DEX groups before induction and within 30 min postsurgery (P<0.001 and P=0.006, respectively). A negative correlation existed between the RSS and heart rate (HR) (r=-0.570, P<0.001). Before anesthesia induction, the respiratory rate was lowest in the DEX group (MID 21.5±1.7 min^-1, CLO 20.6±2.6 min^-1, DEX 20.2±1.7 min^-1; P=0.042). The HR was lower in the CLO and DEX groups than in the MID group (MID, 102.8±10.0 min^-1; CLO, 87.4±9.6 min^-1; DEX, 87.6±7.9 min^-1; P<0.001). The HR was lower immediately after induction (P=0.009) and intraoperatively (P=0.025) in the CLO and DEX groups than in the MID group.

CONCLUSIONS

When used as premedication before propofol/remifentanil anesthesia, clonidine and dexmedetomidine provided deeper preoperative sedation compared to midazolam. From a clinical perspective, all three study drugs provided essentially stable cardiovascular and respiratory conditions during the entire perioperative period.

A Review of Agents for Palliative Sedation/Continuous Deep Sedation: Pharmacology and Practical Applications

Continuous deep sedation at the end of life is a specific form of palliative sedation requiring a care plan that essentially places and maintains the patient in an unresponsive state because their symptoms are refractory to any other interventions. Because this application is uncommon, many providers may lack practical experience in this specialized area and resources they can access are outdated, nonspecific, and/or not comprehensive. The purpose of this review is to provide an evidence- and experience-based reference that specifically addresses those medications and regimens and their practical applications for this very narrow, but vital, aspect of hospice care. Patient goals in a hospital and hospice environments are different, so the manner in which widely used sedatives are dosed and applied can differ greatly as well. Parameters applied in end-of-life care that are based on experience and a thorough understanding of the pharmacology of those medications will differ from those applied in an intensive care unit or other medical environments. By recognizing these different goals and applying well-founded regimens geared specifically for end-of-life sedation, we can address our patients' symptoms in a more timely and efficacious manner.

Comparison of the Effect of Electrical Stimulations on the Chin Skin on Autonomic Nervous Activities During Propofol Sedation With or Without Midazolam

PURPOSE

The aim of this study was to compare the effect of electrical stimulations on the chin skin on autonomic nervous activities evaluated by use of power spectrum analysis of heart rate (HR) variability during intravenous sedation using propofol with or without midazolam.

MATERIALS AND METHODS

Thirty-eight healthy adult male volunteers underwent intravenous sedation with midazolam and propofol (group MP) and with propofol alone (group P) in a randomized crossover manner. In group MP, the participants received midazolam (0.04 mg/kg) and a target-controlled infusion of propofol with a predicted blood concentration of 1.0 μg/mL. In group P, the predicted blood concentration of propofol was maintained at 1.5 μg/mL. The observed variables were bispectral index value, systolic blood pressure, HR, high-frequency component (HF), low-frequency component (LF), and LF/HF ratio. Measurements were conducted over 100-second periods and carried out before, during, and after emergence from sedation by administering 0.2 mg of flumazenil. The paired t test, Wilcoxon t test, repeated-measures analysis of variance, and Friedman χ(2) r test were used for statistical analyses.

RESULTS

The mean age and body weight of the participants were 24.6 ± 2.8 years and 67.0 ± 7.9 kg, respectively. Bispectral index values, systolic blood pressure, and HR showed similar changes in both groups. The LF/HF ratio in group MP during sedation was lower than that before sedation; it also was lower than that in group P during sedation.

CONCLUSIONS

Intravenous sedation with a combination of midazolam and propofol inhibited sympathetic nervous activation induced by electrical stimulations to a greater extent than that with propofol alone.

Propofol Increases Host Susceptibility to Microbial Infection by Reducing Subpopulations of Mature Immune Effector Cells at Sites of Infection

Anesthetics are known to modulate host immune responses, but separating the variables of surgery from anesthesia when analyzing hospital acquired infections is often difficult. Here, the bacterial pathogen Listeria monocytogenes (Lm) was used to assess the impact of the common anesthetic propofol on host susceptibility to infection. Brief sedation of mice with physiologically relevant concentrations of propofol increased bacterial burdens in target organs by more than 10,000-fold relative to infected control animals. The adverse effects of propofol sedation on immune clearance of Lm persisted after recovery from sedation, as animals given the drug remained susceptible to infection for days following anesthesia. In contrast to propofol, sedation with alternative anesthetics such as ketamine/xylazine or pentobarbital did not increase susceptibility to systemic Lm infection. Propofol altered systemic cytokine and chemokine expression during infection, and prevented effective bacterial clearance by inhibiting the recruitment and/or activity of immune effector cells at sites of infection. Propofol exposure induced a marked reduction in marginal zone macrophages in the spleens of Lm infected mice, resulting in bacterial dissemination into deep tissue. Propofol also significantly increased mouse kidney abscess formation following infection with the common nosocomial pathogen Staphylococcus aureus. Taken together, these data indicate that even brief exposure to propofol severely compromises host resistance to microbial infection for days after recovery from sedation.