The effect of cimetidine and ranitidine on cognitive function in postoperative cardiac surgical patients

Delirium and its Pharmacological Causes in Older People, Part Two

Delirium is a syndrome that can arise from many causes or underlying conditions, and though it has been reported in younger patients, it is more prevalent in older people, though it can occur in other age groups as well. Identifying delirium is challenging in older people because of the coexistence of underlying dementia or depression, which may further complicate the presentation. Drug-induced delirium is one of the major causes of delirium, and evaluation of this potential cause or contribution is an important component of the evaluation process, since it can lead to poor patient outcomes. Part one of this three part series reviewed the epidemiology, pathophysiology, evaluation, diagnostic process, and causes of delirium in older people, with a focus on the pharmacological causes. Part two of this series continues to review drugs and drug classes that can cause or contribute to delirium in older people.

Association of Histamine-2 Blockers and Proton-Pump Inhibitors With Delirium Development in Critically Ill Adults: A Retrospective Cohort Study

Supplemental Digital Content is available in the text.

OBJECTIVES:

Histamine-2 receptor antagonists are commonly administered for stress ulcer prophylaxis in critically ill adults and may be associated with delirium development. We aimed to determine differential associations of histamine-2 receptor antagonist or proton-pump inhibitor administration with delirium development in patients admitted to a medical ICU.

DESIGN:

Retrospective observational study using a deidentified database sourced from the University of North Carolina Health Care system. Participants were identified as having delirium utilizing an International Classification of Diseases-based algorithm. Associations among histamine-2 receptor antagonist, proton-pump inhibitor, or no medication administration and delirium were identified using relative risk. Multiple logistic regression was used to control for potential confounders including mechanical ventilation and age.

SETTING:

Academic tertiary care medical ICU in the United States.

PATIENTS:

Adults admitted to the University of North Carolina medical ICU from January 2015 to December 2019, excluding those on concurrent histamine-2 receptor antagonists and proton-pump inhibitors in the same encounter.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

We identified 6,645 critically ill patients, of whom 29% (n = 1,899) received mechanical ventilation, 45% (n = 3,022) were 65 or older, and 22% (n = 1,487) died during their medical ICU encounter. Of the 6,645 patients, 31% (n = 2,057) received an histamine-2 receptor antagonist and no proton-pump inhibitors, 40% (n = 2,648) received a proton-pump inhibitor and no histamine-2 receptor antagonists, and 46% (n = 3,076) had delirium. The histamine-2 receptor antagonist group had a greater association with delirium than the proton-pump inhibitor group compared with controls receiving neither medication, after controlling for mechanical ventilation and age (risk ratio, 1.36; 1.25–1.47; p < 0.001) and (risk ratio, 1.15; 1.07–1.24; p < 0.001, respectively).

CONCLUSIONS:

Histamine-2 receptor antagonists are more strongly associated with increased delirium than proton-pump inhibitors. Prospective studies are necessary to further elucidate this association and to determine if replacement of histamine-2 receptor antagonists with proton-pump inhibitors in ICUs decreases the burden of delirium in critically ill patients.

Rational Use of Second-Generation Antipsychotics for the Treatment of ICU Delirium

Delirium, described as an acute neuropsychiatric syndrome, occurs commonly in critically ill patients and leads to many negative outcomes including increased mortality and long-term cognitive deficits. Despite the lack of clinical data supporting the use of antipsychotics for the management of intensive care unit (ICU) delirium, pharmacological interventions are often needed to control acutely agitated patients. Given that the most current guidelines do not advocate the use of haloperidol for either the prevention or treatment of ICU delirium due to a lack of evidence, second-generation antipsychotics (SGAs) have been commonly used as alternatives to haloperidol for ICU patients with delirium. Nonetheless, the evidence supporting the use of SGAs to treat ICU delirium remains limited. This review is designed to assess the available clinical evidence and highlights the different neuropharmacological and safety properties of SGAs in order to guide the rational use of SGAs for the treatment of ICU delirium.

Underrepresentation of patients with pre-existing cognitive impairment in pharmaceutical trials on prophylactic or therapeutic treatments for delirium: a systematic review

OBJECTIVE

Representation of hospitalized patients with pre-existing cognitive impairment in pharmaceutical delirium trials is important because these patients are at high risk for developing delirium. The aim of this systematic review is to investigate whether patients with cognitive impairment were included in studies on pharmacological prophylaxis or treatment of delirium and to explore the motivations for their exclusion (if they were excluded).

STUDY DESIGN

This study was a systematic review. A MEDLINE search was performed for publications dated from 1 January 1985 to 15 November 2012. Randomized and non-randomized controlled trials that investigated medication to prevent or treat delirium were included. The number of patients with cognitive impairment was counted, and if they were excluded, motivations were noted.

RESULTS

The search yielded 4293 hits, ultimately resulting in 31 studies that met the inclusion criteria. Of these, five studies explicitly mentioned the percentage of patients with cognitive impairment that were included. These patients comprised a total of 8% (n = 279 patients) of the 3476 patients included in all 31 studies. Ten studies might have included cognitively impaired patients but did not mention the exact percentage, and sixteen studies excluded all patients with cognitive impairment. The motivations for exclusion varied, but most were related to the influence of dementia on delirium.

CONCLUSION

The exclusion of patients with pre-existing cognitive impairment hampers the generalizability of the results of these trials and leaves clinicians with limited evidence about the pharmacological treatment of this group of vulnerable patients who have an increased risk of side effects.

Strategies for prevention of postoperative delirium: a systematic review and meta-analysis of randomized trials

INTRODUCTION

The ideal measures to prevent postoperative delirium remain unestablished. We conducted this systematic review and meta-analysis to clarify the significance of potential interventions.

METHODS

The PRISMA statement guidelines were followed. Two researchers searched MEDLINE, EMBASE, CINAHL and the Cochrane Library for articles published in English before August 2012. Additional sources included reference lists from reviews and related articles from 'Google Scholar'. Randomized clinical trials (RCTs) on interventions seeking to prevent postoperative delirium in adult patients were included. Data extraction and methodological quality assessment were performed using predefined data fields and scoring system. Meta-analysis was accomplished for studies that used similar strategies. The primary outcome measure was the incidence of postoperative delirium. We further tested whether interventions effective in preventing postoperative delirium shortened the length of hospital stay.

RESULTS

We identified 38 RCTs with interventions ranging from perioperative managements to pharmacological, psychological or multicomponent interventions. Meta-analysis showed dexmedetomidine sedation was associated with less delirium compared to sedation produced by other drugs (two RCTs with 415 patients, pooled risk ratio (RR)=0.39; 95% confidence interval (CI)=0.16 to 0.95). Both typical (three RCTs with 965 patients, RR=0.71; 95% CI=0.54 to 0.93) and atypical antipsychotics (three RCTs with 627 patients, RR=0.36; 95% CI=0.26 to 0.50) decreased delirium occurrence when compared to placebos. Multicomponent interventions (two RCTs with 325 patients, RR=0.71; 95% CI=0.58 to 0.86) were effective in preventing delirium. No difference in the incidences of delirium was found between: neuraxial and general anesthesia (four RCTs with 511 patients, RR=0.99; 95% CI=0.65 to 1.50); epidural and intravenous analgesia (three RCTs with 167 patients, RR=0.93; 95% CI=0.61 to 1.43) or acetylcholinesterase inhibitors and placebo (four RCTs with 242 patients, RR=0.95; 95% CI=0.63 to 1.44). Effective prevention of postoperative delirium did not shorten the length of hospital stay (10 RCTs with 1,636 patients, pooled SMD (standard mean difference)=-0.06; 95% CI=-0.16 to 0.04).

CONCLUSIONS

The included studies showed great inconsistencies in definition, incidence, severity and duration of postoperative delirium. Meta-analysis supported dexmedetomidine sedation, multicomponent interventions and antipsychotics were useful in preventing postoperative delirium.

Which medications to avoid in people at risk of delirium: a systematic review

BACKGROUND

delirium is a common clinical problem and is associated with adverse health outcomes. Many medications have been associated with the development of delirium, but the strength of the associations is uncertain and it is unclear which medications should be avoided in people at risk of delirium.

METHODS

we conducted a systematic review to identify prospective studies that investigated the association between medications and risk of delirium. A sensitivity analysis was performed to construct an evidence hierarchy for the risk of delirium with individual agents.

RESULTS

a total of 18,767 studies were identified by the search strategy. Fourteen studies met the inclusion criteria. Delirium risk appears to be increased with opioids (odds ratio [OR] 2.5, 95% CI 1.2-5.2), benzodiazepines (3.0, 1.3-6.8), dihydropyridines (2.4, 1.0-5.8) and possibly antihistamines (1.8, 0.7-4.5). There appears to be no increased risk with neuroleptics (0.9, 0.6-1.3) or digoxin (0.5, 0.3-0.9). There is uncertainty regarding H(2) antagonists, tricyclic antidepressants, antiparkinson medications, steroids, non-steroidal anti-inflammatory drugs and antimuscarinics.

CONCLUSION

for people at risk of delirium, avoid new prescriptions of benzodiazepines or consider reducing or stopping these medications where possible. Opioids should be prescribed with caution in people at risk of delirium, but this should be tempered by the observation that untreated severe pain can itself trigger delirium. Caution is also required when prescribing dihydropyridines and antihistamine H1 antagonists for people at risk of delirium and considered individual patient assessment is advocated.

Critical care sedation for neuroscience patients

In 2000, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) introduced the mandate for the implementation of standards for both pain assessment and need for therapy in hospitalized patients. The need for the appropriate titration of sedation and analgesia is particularly poignant in an intensive care unit (ICU) setting where iatrogenic discomfort often complicates patient management. Neurologically ill patients in ICUs present particularly complex sedation issues, owing to the need to monitor these patients with serial neurological exams. Hence, maximal comfort without diminishing neurological responsiveness is desirable. Here, we review the frequently applied methods of evaluating levels of pain and agitation in critically ill patients as well as discuss the appropriate classes of pharmaceutical agents common to this population, with particular emphasis on the potential neurophysiological impact of such therapy.