The Effects of Liver and Renal Dysfunction on the Pharmacokinetics of Sedatives and Analgesics in the Critically Ill Patient

Differential Effects of Gamma-Aminobutyric Acidergic Sedatives on Risk of Post-Extubation Delirium in the ICU: A Retrospective Cohort Study From a New England Health Care Network

OBJECTIVES

To evaluate whether different gamma-aminobutyric acidergic (GABAergic) sedatives such as propofol and benzodiazepines carry differential risks of post-extubation delirium in the ICU.

DESIGN

Retrospective cohort study.

SETTING

Seven ICUs in an academic hospital network, Beth Israel Deaconess Medical Center (Boston, MA).

PATIENTS

Ten thousand five hundred and one adult patients mechanically ventilated for over 24 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We tested the hypothesis that benzodiazepine versus propofol-based sedation is associated with fewer delirium-free days within 14 days after extubation. Further, we hypothesized that the measured sedation level evoked by GABAergic drugs is a better predictor of delirium than the drug dose administered. The proportion of GABAergic drug-induced deep sedation was defined as the ratio of days with a mean Richmond Agitation-Sedation Scale of less than or equal to -3 during mechanical ventilation. Multivariable regression and effect modification analyses were used. Delirium-free days were lower in patients who received a high proportion of deep sedation using benzodiazepine compared with propofol-based sedation (adjusted absolute difference, -1.17 d; 95% CI, -0.64 to -1.69; p < 0.001). This differential effect was magnified in elderly patients (age > 65) and in patients with liver or kidney failure (p-for-interaction < 0.001) but not observed in patients who received a low proportion of deep sedation (p = 0.95). GABAergic-induced deep sedation days during mechanical ventilation was a better predictor of post-extubation delirium than the GABAergic daily average effective dose (area under the curve 0.76 vs 0.69; p < 0.001).

CONCLUSIONS

Deep sedation during mechanical ventilation with benzodiazepines compared with propofol is associated with increased risk of post-extubation delirium. Our data do not support the view that benzodiazepine-based compared with propofol-based sedation in the ICU is an independent risk factor of delirium, as long as deep sedation can be avoided in these patients.

Special considerations in the assessment of catastrophic brain injury and determination of brain death in patients with SARS-CoV-2

INTRODUCTION

The coronavirus disease 2019 (Covid-19) pandemic has led to challenges in provision of care, clinical assessment and communication with families. The unique considerations associated with evaluation of catastrophic brain injury and death by neurologic criteria in patients with Covid-19 infection have not been examined.

METHODS

We describe the evaluation of six patients hospitalized at a health network in New York City in April 2020 who had Covid-19, were comatose and had absent brainstem reflexes.

RESULTS

Four males and two females with a median age of 58.5 (IQR 47-68) were evaluated for catastrophic brain injury due to stroke and/or global anoxic injury at a median of 14 days (IQR 13-18) after admission for acute respiratory failure due to Covid-19. All patients had hypotension requiring vasopressors and had been treated with sedative/narcotic drips for ventilator dyssynchrony. Among these patients, 5 had received paralytics. Apnea testing was performed for 1 patient due to the decision to withdraw treatment (n = 2), concern for inability to tolerate testing (n = 2) and observation of spontaneous respirations (n = 1). The apnea test was aborted due to hypoxia and hypotension. After ancillary testing, death was declared in three patients based on neurologic criteria and in three patients based on cardiopulmonary criteria (after withdrawal of support (n = 2) or cardiopulmonary arrest (n = 1)). A family member was able to visit 5/6 patients prior to cardiopulmonary arrest/discontinuation of organ support.

CONCLUSION

It is feasible to evaluate patients with catastrophic brain injury and declare brain death despite the Covid-19 pandemic, but this requires unique considerations.

Prevalence and Implications of Abnormal Laboratory Results in Patients in the Terminal Phase of Life

BACKGROUND

Pathophysiological changes at the end of life may affect pharmacokinetics of drugs. However, caregivers typically do not extensively monitor patients' laboratory parameters at the end of life.

OBJECTIVE

Our aim was to describe laboratory parameters of hospice patients in the week before death.

METHODS

A cohort study was conducted on available laboratory results in the week before death, including clinical chemistry and hematology tests.

RESULTS

Laboratory data of 125 patients in a palliative care center were included, assessed at a median of 3 days before death. Eighty percent of patients had anemia and almost all had hypoalbuminemia (97%). Elevated levels of gamma-glutamyl transferase (gGT) were found in 75%, of alkaline phosphatase (ALP) in 60%, of aspartate aminotransferase (ASAT) in 60%, and of calcium (Ca) in 68%. Alanine aminotransferase (ALAT), bilirubin, sodium (Na), and potassium (K) were abnormal in from 8.8% to 36.0% of patients. A previous unknown poor kidney function was found in 60% of patients. Thirteen patients (22%) with a regular morphine prescription and one patient treated with a non-steroidal anti-inflammatory drug (NSAID) had severe kidney failure.

CONCLUSIONS

Abnormal laboratory results were expected due to the pathophysiological changes that occur during the last phase of life. Remarkably, however, electrolytes (Na and K) were balanced even shortly before death. Estimated glomerular filtration rate (eGFR), reflecting the kidney function, seems the most clinically relevant laboratory parameter, because it may guide drug choice and dosing.

The Impact of Liver and Renal Dysfunction on the Pharmacokinetics and Pharmacodynamics of Sedative and Analgesic Drugs in Critically Ill Adult Patients

The use of sedative and analgesic drug therapy is often necessary for the care of critically ill patients. Renal and hepatic dysfunction, which occurs frequently in this patient population, can significantly alter drugs' pharmacokinetic and pharmacodynamics properties. By anticipating how these medications may be affected by liver or kidney dysfunction, health care practitioners may be able to provide tailored dosing regimens that ensure optimal comfort while minimizing the risk of adverse events.

Relevance of Liver Failure for Anti-Infective Agents: From Pharmacokinetic Alterations to Dosage Adjustments

The liver is a complex organ with great ability to influence drug pharmacokinetics. Due to its wide array of function, its impairment has the potential to affect bioavailability, enterohepatic circulation, drug distribution, metabolism, clearance, and biliary elimination. These alterations differ widely depending on the cause of the liver failure, if it is acute or chronic in nature, the extent of impairment, and comorbid conditions. In addition, effects on liver functions do not occur in a proportional or predictable manner for escalating degrees of liver impairment. The ability of hepatic alterations to influence PK is also dependent on drug characteristics, such as administration route, chemical properties, protein binding, and extraction ratio, among others. This complexity makes it difficult to predict what these effects have on drugs. Unlike certain classes of agents, efficacy of anti-infectives is most often dependent on fulfilling pharmacokinetic/pharmacodynamic targets, such as C_max/MIC, AUC/MIC, T_>MIC, IC₅₀/EC₅₀, or T>EC₉₅. Loss of efficacy, or conversely, increased risk of toxicity may occur in certain circumstances of liver injury. Although important to consider these potential alterations and their effects on specific anti-infectives, many lack data to constitute specific dosing adjustments, making it important to monitor patients for effectiveness and toxicities of therapy.

Nursing Challenges in the Administration of Oral Antidepressant Medications in Gastric Bypass Patients

More than half of gastric bypass patients take antidepressants preoperatively, presenting some unique considerations with this patient population. The challenges associated with antidepressant medications are experienced both preoperatively and postoperatively. As the gastric bypass option becomes more readily used in the treatment of obesity, the requirement for understanding the effect of this procedure on any alteration of medications will become more clinically important. The purpose of this paper is to present an overview of the potential challenges in providing optimal patient care for the gastric bypass patient who is taking antidepressant medications.