Pharmacokinetic and pharmacodynamics of intravenous dexmedetomidine in morbidly obese patients undergoing laparoscopic surgery

Evaluation of the Safety of Dexmedetomidine Dosing Utilizing Adjusted Body Weight in Obese Critically Ill Patients: A Retrospective Study

The purpose of this study was to evaluate the safety of dexmedetomidine dosing, utilizing adjusted body weight (AdjBW) in obese, critically ill patients. This was a retrospective cohort study of patients who received dexmedetomidine from March 2020 to April 2021. Participants received dexmedetomidine as the sole agent for sedation for ≥8 hours, were ≥18 years old, had a level of care listed as "critical care," and had an actual body weight (ABW) of at least 120% of their ideal body weight (IBW). A total of 225 participants were included. Results demonstrated that the incidence of hypotension and bradycardia was lower in the AdjBW group compared to the ABW group, but this did not reach statistical significance. Dosing dexmedetomidine based on AdjBW, instead of ABW, resulted in a statistically significant difference in the lowest recorded heart rate, with 61.2 ± 11.8 bpm in the ABW group and 65.2 ± 14.7 bpm in the AdjBW group (p = 0.027). Dosing dexmedetomidine based on AdjBW did not show statistically significant differences in the lowest recorded mean arterial pressure (MAP). Using AdjBW to dose dexmedetomidine appears to be safe in this patient population.

Dexmedetomidine as a Short-Use Analgesia for the Immature Nervous System

Pain management in neonates continues to be a challenge. Diverse therapies are available that cause loss of pain sensitivity. However, because of side effects, the search for better options remains open. Dexmedetomidine is a promising drug; it has shown high efficacy with a good safety profile in sedation and analgesia in the immature nervous system. Though dexmedetomidine is already in use for pain control in neonates (including premature neonates) and infants as an adjunct to other anesthetics, the question remains whether it affects the neuronal activity patterning that is critical for development of the immature nervous system. In this study, using the neonatal rat as a model, the pharmacodynamic effects of dexmedetomidine on the nervous and cardiorespiratory systems were studied. Our results showed that dexmedetomidine has pronounced analgesic effects in the neonatal rat pups, and also weakly modified both the immature network patterns of cortical and hippocampal activity and the physiology of sleep cycles. Though the respiration and heart rates were slightly reduced after dexmedetomidine administration, it might be considered as the preferential independent short-term therapy for pain management in the immature and developing brain.

Effect of dexmedetomidine on pulmonary function in obese patients undergoing laparoscopic surgery

OBJECTIVE

This research aimed to ascertain the effect of dexmedetomidine on pulmonary function in obese patients undergoing laparoscopic surgery.

METHODS

Obese patients undergoing laparoscopic surgery under general anesthesia were separated into the control group (group C) and the dexmedetomidine group (group D) (n = 30). Patients in group D were infused with dexmedetomidine (1 μg/kg) intravenously for 10 min and then at a rate of 0.5 mg/kg h until 30 min before the end of the surgery, and those in group C were infused with an equal volume of saline. The surgery time points were divided into: before anesthesia induction (T0), 5 min after intubation (T1), 30 min after pneumoperitoneum (T2), 10 min after pneumoperitoneum release (T3), at the time of extubation (T4), 3 min after extubation (T5), and 24 h after surgery (T6). Arterial blood was collected for blood gas analysis to record arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2). Dynamic lung compliance (Cdyn), oxygenation index (OI), alveolar-arterial oxygen partial pressure difference (A-aDO2), and respiratory index (RI) were calculated. The time of surgery, anesthesia, CO2 pneumoperitoneum, eye-opening, and time from the end of surgery to extubation were recorded. Plasma IL-8 and IL-10 levels were measured from T0 to T6.

RESULTS

The time of surgery, anesthesia, CO2 pneumoperitoneum, eye-opening, and time from the end of surgery to extubation in group D were not statistically significant when compared with those in group C. Versus at the T1 time point, A-aDO2 and RI were higher and Cdyn and OI were lower in both groups at T2 and T3 time points. Versus group C, group D had higher Cdyn and OI and lower A-aDO2 and RI at T2 and T3 time points. Versus at the T0 time point, at each time point from T1 to T6, IL-8 and IL-10 levels were higher in both groups. Versus group C, group D had lower IL-8 and higher IL-10 levels at each time point from T1 to T6.

CONCLUSION

In obese patients undergoing laparoscopic surgery under general anesthesia, the use of dexmedetomidine can improve the lung compliance and OI of the patients, inhibit the inflammatory response of the lungs of the patients and thus have a certain protective effect on the lung function.

Opioid-sparing effect of erector spinae plane block and intravenous dexmedetomidine for obese patients with obstructive sleep apnea: A randomized controlled trial

OBJECTIVE

This study assessed the impact of erector spinae plane block (ESPB) and intravenous (IV) dexmedetomidine in reduction of perioperative opioid consumption following bariatric surgery and their impact on post-operative recovery, analgesia, and pulmonary functions.

DESIGN

A randomized controlled trial.

SETTING

Tanta University Hospitals, Tanta, Gharboa, Egypt.

PATIENTS

Forty obese patients with obstructive sleep apnea syndrome (OSAS), aged 20-55 years, and eligible for bariatric surgery were included.

INTERVENTIONS

Patients randomized into group I (received general anesthesia [GA] with opioid, sham ESPB, and IV normal saline) or group II (received GA [without opioid], ESPB [at T7 level] using 20 mL bupivacaine 0.25 percent and bolus IV dexmedetomidine 1 µg/kg and then 0.25 µg/kg/h).

MAIN OUTCOME MEASURES

Fentanyl consumption (primary outcome), sevoflurane consumption, recovery time, Visual Analog Scale (VAS), and pulmonary functions (secondary outcomes) were recorded.

RESULTS

Perioperative fentanyl (intraoperative, post-operative, and total) consumption and sevoflurane consumption were substantially lower in group II compared to group I (p = 0.010, <0.001, <0.001, and <0.001, respectively). Moreover, recovery time was shorter in group II (p < 0.001). At 2, 4, 8, and 24 hours after surgery, group I patients had VAS values considerably higher. Relative to preoperative values, pulmonary function did not significantly alter after surgery. Oxygen desaturation was significantly lower in group II (p = 0.001).

CONCLUSIONS

The ESPB with IV dexmedetomidine is advantageous for OSAS patients having bariatric surgery as it provides anesthesia and opioid-sparing effect with short recovery, adequate analgesia, and nonsignificant complications. Yet, it had no effect on post-operative pulmonary function.

Predictors for Dexmedetomidine Requirement for Sedation under Regional Anesthesia

(1) Background: This prospective observational study aimed to investigate the predictors affecting DMT requirements for sedation during regional anesthesia. (2) Method: A total of 108 patients who received regional anesthesia with intravenous DMT administration for orthopedic upper- or lower-extremity surgery were enrolled. Following successful regional anesthesia, DMT was administered at a rate of 4 µg/kg/h until reaching loss of consciousness (LOC). The administered dose of DMT per body weight until LOC (DMTLOC; µg/kg) was evaluated. The infusion was maintained at a rate of 0.2-0.7 µg/kg/h during the surgery. At the end of surgery, the elapsed time to a BIS value of 90 (TBIS90; s) was recorded. Linear regression models were used to identify potential predictors of DMTLOC and TBIS90. (3) Results: One hundred patients were analyzed. There were negative relationships between DMTLOC and age (r = -0.297, p = 0.003) and DMTLOC and body mass index (BMI) (r = -0.425, p < 0.001), respectively. Multiple linear regression models revealed that both increasing age and BMI were significantly related to DMTLOC (r2 = 0.259, p < 0.001), but those variables showed no association with TBIS90. (4) Conclusions: The results of this study suggest that initial loading of DMT should be carefully titrated to minimize risk in elderly and obese surgical populations.

Adherence to Sedation Targets With Weight-Based Propofol and Dexmedetomidine in Patients With Morbid Obesity

BACKGROUND

Propofol and dexmedetomidine are routinely used in intensive care units (ICUs). Both are lipophilic, potentially leading to accumulation in adipose tissue. Limited evidence exists on what body weight to utilize in patients with morbid obesity.

OBJECTIVE

The purpose of this research was to evaluate the safety and efficacy of weight-based sedation with propofol and dexmedetomidine in ICU patients with morbid obesity.

METHODS

Retrospective review of ICU patients admitted from January 2018 to January 2020 who were sedated for ≥48 hours was performed. The primary outcome was the percentage of time within target sedation during the first 48 hours, stratified by body mass index (BMI) <40 or ≥40 kg/m². Additional outcomes included adverse events and the infusion rate to achieve target sedation. Data were evaluated using descriptive statistics.

RESULTS

A total of 80 patients were analyzed. Patients on propofol with a BMI <40 kg/m² were in their target Richmond Agitation-Sedation Scale (RASS) 11.7% versus 16.1% with a BMI ≥40 kg/m² (P = .580). Patients with a BMI <40 kg/m² on dexmedetomidine were in their target RASS 27.6% versus 10.7% with a BMI ≥40 kg/m² (P = .053).

CONCLUSION AND RELEVANCE

Body mass index did not significantly alter propofol target sedation attainment. However, patients with morbid obesity on dexmedetomidine demonstrated significantly less time in target sedation. An actual body weight dosing strategy of these drugs did not achieve desired target sedation for those with a BMI ≥40 versus BMI <40 kg/m². These findings support future research on the optimal sedation dosing strategy in this patient population.

Evaluation of Dexmedetomidine Dosing in Obese Critically Ill Patients

BACKGROUND

Dexmedetomidine is a highly selective α₂-adrenoreceptor agonist that produces dose-dependent sedation, anxiolysis, and analgesia without respiratory depression. Due to these ideal sedative properties, there has been increased interest in utilizing dexmedetomidine as a first-line sedative for critically ill patients requiring light sedation.

OBJECTIVE

To evaluate the ability to achieve goal intensive care unit (ICU) sedation before and after an institutional change of dosing from actual (ABW) to adjusted (AdjBW) body weight in obese patients on dexmedetomidine.

METHODS

This study included patients ≥ 18 years old, admitted to a surgical or medical ICU, required dexmedetomidine for at least 8 hours as a single continuous infusion sedative, and weighed ≥ 120% of ideal body weight. Percentage of RASS measurements within goal range (-1 to +1) during the first 48 hours after initiation of dexmedetomidine as the sole sedative agent or until discontinuation dosed on ABW compared to AdjBW was evaluated.

RESULTS

100 patients were included in the ABW cohort and 100 in the AdjBW cohort. The median dosing weight was significantly higher in the ABW group (95.9 [78.9-119.5] vs 82.2 [72.1-89.8] kg; p = 0.001). There was no statistical difference in percent of RASS measurements in goal range (61.5% vs 69.6%, p = 0.267) in patients that received dexmedetomidine dosed based on ABW versus AdjBW.

CONCLUSION

Dosing dexmedetomidine using AdjBW in obese critically ill patients for ongoing ICU sedation resulted in no statistical difference in the percent of RASS measurements within goal when compared to ABW dosing. Further studies are warranted.

BIS-guided sedation prevents the cough reaction of patients under general anaesthesia caused by extubation: a randomized controlled trial

Background

The multiple modes of SARS-CoV-2 transmission including airborne, droplet, contact and faecal–oral transmissions that cause coronavirus disease 2019 (COVID-19) contribute to a public threat to the lives of people worldwide. Heavy aerosol production by coughing and the big peak expiratory flow in patients with respiratory infections (especially SARS-CoV-2) during recovery from general anaesthesia are the highest risk factors for infection in healthcare workers. To perform sedation before extubation significantly reduced the incidence of coughing during recovery from general anaesthesia. However, there are few studies on endotracheal tube removal under BIS-guided sedation in postanaesthesia care unit (PACU). We speculated that the BIS-guided sedation with dexmedetomidine and propofol would better prevent coughing caused by tracheal extubation and reducing peak expiratory flow.

Methods

Patients with general anaesthesia were randomly assigned to Group S (dexmedetomidine was infused in the operating room for 30 min, and the bispectral index (BIS) value was maintained 60–70 by infusion propofol at 0.5~1.5 μg/ml in the PACU until the endotracheal tubes were pulled out) and Group C (no dexmedetomidine and propofol treatment, replaced with the saline treatment). The incidence of coughing, agitation and active extubation, endotracheal tube tolerance and the peak expiratory flow at spontaneous breathing and at extubation were assessed.

Results

A total of 101 patients were randomly assigned to Group S (51 cases) and Group C (50 cases). The incidence of coughing, agitation and active extubation was significantly lower (1(51), 0(51) and 0(51), respectively) in Group S than (11(50), 8(50) and 5(50), respectively) in Group C (p < 0.05 or p < 0.01, respectively); the scores of cough were significantly reduced (1(1, 1)) in Group S than (1(1, 2)) in Group C (p < 0.01); and the endotracheal tube tolerance was significantly improved (0(0, 1)) in Group S than (1(1, 3)) in Group C (p < 0.001). The peak expiratory flow at spontaneous breathing and at extubation was significantly reduced (5(5, 7) and 6.5(6, 8), respectively) in Group S than (8(5, 10) and 21(9, 32)) in Group C (p < 0.001).

Conclusions

BIS-guided sedation with dexmedetomidine and propofol significantly prevented coughing and reduced peak expiratory flow during recovery from general anaesthesia, which may play an important role in preventing medical staff from contracting COVID-19.

Trial registration

Chinese Clinical Trial Registry: ChiCTR2200058429 (registration date: 09-04-2022) “retrospectively registered”.

Comparison of Ketamine, Dexmedetomidine and Lidocaine in Multimodal Analgesia Management Following Sleeve Gastrectomy Surgery: A Randomized Double-Blind Trial

PURPOSE

The aim of this study was to compare the effects of ketamine, dexmedetomidine, and lidocaine infusions added to the multimodal analgesia regimen on pain scores and analgesic requirement in laparoscopic sleeve gastrectomy.

DESIGN

A prospective randomized double-blind trial. Seventy-three patients aged 18 to 65 years (ASA II-III) undergoing laparoscopic sleeve gastrectomy were included. The patients were divided into 3 groups. Intravenous (IV) ketamine (0.5 mg/kg/h), dexmedetomidine (0.5 mcg/kg/h), and lidocaine (2 mg/kg/h) were administered to Groups K, D and L, respectively. Postoperative infusions were continued for 12 hours.

METHODS

Visual Analog Scale (VAS) scores (during rest and movement) in the admission to postanesthesia care unit, 1, 3, 6, 12, 24, 48 hours, and on day 15 were assessed postoperatively. Rescue analgesia requirement, the number of patients with nausea, retching, and vomiting, time to mobilization, and hospital length of stay (LOS) were recorded.

FINDINGS

VAS_rest values during all measurements in the first 24 hours, and VAS_movement values in the first 6 hours and at 24 hours were lower in Group L when compared to Group K and Group D (P < .001, P < .001, P = .008, respectively). VAS_rest at 48 hours and VAS_movement at 12 and 48 hours were lower in Group L when compared to Group K (P = .044, P = .001 and P = .011, respectively). There was no statistically significant difference between Group D compared to the other two groups at these times (P > .05). The requirement of rescue analgesia on postoperative day 1 was significantly higher in Group K (P < .001). Hospital LOS was shorter in Group L than in the other groups (P = .002).

CONCLUSIONS

IV lidocaine added to multimodal analgesia provided better pain control in the early postoperative period compared to dexmedetomidine and ketamine and decreased the hospital LOS.

Drug pharmacokinetics in the obese population: challenging common assumptions on predictors of obesity-related parameter changes

INTRODUCTION

Obesity is associated with many physiological changes. We review available evidence regarding five commonly accepted assumptions to a priori predict the impact of obesity on drug pharmacokinetics (PK).

AREAS COVERED

The investigated assumptions are: 1) lean body weight is the preferred descriptor of clearance and dose adjustments; 2) volume of distribution increases for lipophilic, but not for hydrophilic drugs; 3) CYP-3A4 activity is suppressed and UGT activity is increased, implying decreased and increased dose requirements for substrates of these enzyme systems, respectively; 4) glomerular filtration rate is enhanced, necessitating higher doses for drugs cleared through glomerular filtration; 5) drug dosing information from obese adults can be extrapolated to obese adolescents.

EXPERT OPINION

Available literature contradicts, or at least limits the generalizability, of all five assumptions. Clinical studies should focus on quantifying the impact of duration and severity of obesity on drug PK in adults and adolescents, and also include oral bioavailability and pharmacodynamics in these studies. Physiologically-based PK approaches can be used to predict PK changes for individual drugs, but can also be used to define in general terms based on patient characteristics and drug properties, when certain assumptions can or cannot be expected to be systematically accurate.

A Response Surface Analysis of the Combination of Dexmedetomidine and Sufentanil for Attenuating the Haemodynamic Response to Endotracheal Intubation

Purpose

Dexmedetomidine combined with opioids has been extensively used to blunt cardiovascular responses to endotracheal intubation. To determine their interaction, we aimed to develop a response surface model between dexmedetomidine and sufentanil.

Methods

One hundred and twenty patients undergoing scheduled gynaecological surgery were recruited. According to a simulation of slice design, patients received different dose pairs of dexmedetomidine (0 to 1.1 μg/kg) and sufentanil (.1 to .5 μg/kg). The mean arterial blood pressure and heart rate of patients were recorded just before endotracheal intubation, immediately after intubation, and during the first 3 min after intubation. The primary outcomes were haemodynamic changes. The full dose–response relationship between dexmedetomidine and sufentanil was analysed using a logit model.

Results

This response surface model revealed that the interaction between dexmedetomidine and sufentanil was additive. The dose pairs that could effectively attenuate the haemodynamic response to endotracheal intubation primarily ranged from .3 to .4 μg/kg and .5 to 1.1 μg/kg for sufentanil and dexmedetomidine, respectively.

Conclusion

When used propofol as the main hypnotic drug during anaesthesia induction, dexmedetomidine could effectively reduce the requirement of sufentanil in an additive manner. However, it is not an effective drug for ablating the cardiovascular response to endotracheal intubation when used alone. The clinical trial registry. The trial registry name: Chinese Clinical Trial Registry. Registration number: ChiCTR1800015273. URL: http://www.chictr.org.cn

Dexmedetomidine-induced hemodynamic instability in patients undergoing orthopedic upper limb surgery under brachial plexus block: a retrospective study

Background

Hemodynamic instability is a frequent adverse effect following administration of dexmedetomidine (DMED). In this study, we evaluated the incidence of DMED-induced hemodynamic instability and its predictive factors in clinical regional anesthesia practice.

Methods

One hundred sixteen patients who underwent orthopedic upper limb surgery under brachial plexus block with intravenous DMED administration were retrospectively identified. The primary outcome was the incidence of DMED-induced hemodynamic instability. The participants were allocated to a stable or unstable group by their hemodynamic instability status. Patients’ characteristics were compared between the groups. The relationship between the potential risk factors and development of DMED-induced hemodynamic instability was analyzed with a logistic regression model.

Results

DMED-induced hemodynamic instability was observed in 14.7% of patients (17/116). The unstable group had more women than the stable group (76.5% vs. 39.4%, P = 0.010). When patients were classified into four subgroup according to body mass index (underweight, normal weight, overweight, and obesity), there was significant difference in the composition of the subgroups in the two groups (P = 0.008). In univariate analysis, female sex, obesity, and pre-existing hypertension were significant predictors of DMED-induced hemodynamic instability. Multivariate analysis demonstrated that female sex (adjusted OR 3.86, CI 1.09; 13.59, P = 0.036) and obesity (adjusted OR 6.41, CI 1.22; 33.57, P = 0.028) were independent predictors of DMED-induced hemodynamic instability.

Conclusions

Female and obese patients are more likely to have hemodynamic instability following intravenous DMED administration in clinical regional anesthesia practice. This study suggests that DMED dose may be diminished to prevent hypotensive risk in these populations.

Trial registration

This article was retrospectively registered at WHO clinical trial registry platform (Trial number: KCT0005977).

Drug dosing in the critically ill obese patient-a focus on sedation, analgesia, and delirium

Practice guidelines provide clear evidence-based recommendations for the use of drug therapy to manage pain, agitation, and delirium associated with critical illness. Dosing recommendations however are often based on strategies used in patients with normal body habitus. Recommendations specific to critically ill patients with extreme obesity are lacking. Nonetheless, clinicians must craft dosing regimens for this population. This paper is intended to help clinicians design initial dosing regimens for medications commonly used in the management of pain, agitation, and delirium in critically ill patients with extreme obesity. A detailed literature search was conducted with an emphasis on obesity, pharmacokinetics, and dosing. Relevant manuscripts were reviewed and strategies for dosing are provided.