Association between Use of Angiotensin-converting Enzyme Inhibitors or Angiotensin Receptor Blockers and Postoperative Delirium

Pharmacological Prevention of Postoperative Delirium in Adults: A Review of Recent Literature

PURPOSE OF REVIEW

Postoperative delirium (POD) is a common complication that has important implications for surgical patients, often leading to both short- and long-term cognitive deficits, worse outcomes, and increased healthcare costs. Given these implications, there may be a benefit in reducing the incidence of POD. Pharmacologic interventions may have the potential to reduce the risk of a patient developing POD.

RECENT FINDINGS

Recently studied therapies include dexmedetomidine, propofol, haloperidol, ketamine, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, acetaminophen, melatonin/ramelteon, corticosteroids, midazolam, physostigmine, and neostigmine. In addition, the implementation of regional anesthesia and reduction of overall anesthetic depth have been examined. Of these therapies, dexmedetomidine has been studied the most and has the most supporting evidence for prevention of POD, but current studies lack clarity on optimal dosing and timing of dexmedetomidine administration. Acetaminophen, corticosteroids, and melatonin/ramelteon are other plausible medications that have potential for reducing POD incidence, but they all require further investigation. Reduction of anesthetic depth and regional anesthetics are options for anesthetic management that show promise but still lack enough supporting evidence in recent literature to receive a strong recommendation. Future research should focus on identifying optimal strategies for the implementation of the pharmacological options listed, including doses and timing of administration. Attention should be given to dexmedetomidine given its promise demonstrated by recent literature.

Relationship between in-hospital angiotensin converting enzyme inhibitors and Angiotensin receptor blockers administration and delirium in the cardiac ICU

OBJECTIVES

Delirium may be associated with neuroinflammation and reduced blood-brain barrier (BBB) stability. ACE Inhibitors (ACEIs) and Angiotensin Receptor Blockers (ARBs) reduce neuroinflammation and stabilize the BBB, thus slowing the progression of memory loss in patients with dementia. This study evaluated the effect of these medications on delirium prevalence.

METHODS

This was a retrospective study of data from all patients admitted to a Cardiac ICU between 1 January 2020-31 December 2020. The presence of delirium was determined based on the International Classification of Diseases (ICD) 10 codes and nurse delirium screening.

RESULTS

Of the 1684 unique patients, almost half developed delirium. Delirious patients who did not receive either ACEI or ARB had higher odds (odds ratio [OR] 5.88, 95% CI 3.7-9.09, P < .001) of in-hospital death and experienced significantly shorter ICU lengths of stay (LOS) (P = .01). There was no significant effect of medication exposure on the time to delirium onset.

CONCLUSIONS

While ACEIs and ARBs have been shown to slow the progression of memory loss for patients with Alzheimer's disease, we did not observe a difference in time to delirium onset.

Relationship between angiotensin-converting enzyme inhibitors and angiotensin receptor blockers prescribing and delirium in the ICU-A secondary analysis

BACKGROUND

Studies suggest Angiotensin-Converting Enzyme inhibitors (ACEI) and Angiotensin Receptor Blockers (ARB) may slow the decline of memory function in individuals with mild to moderate Alzheimer's disease by regulating migroglial activation and oxidative stress within the brain's reticular activating system. Therefore, we evaluated the relationship between delirium prevalence and being prescribed ACEI and ARB in participants admitted to the intensive care units (ICU).

METHODS

A secondary analysis of data from two parallel pragmatic randomized controlled trials was performed. ACEI and ARB exposure was defined as being prescribed an ACEI or an ARB within six months prior to the ICU admission. The primary endpoint was the first positive delirium assessment based on Confusion Assessment Method for the ICU (CAM-ICU) for up to thirty days.

RESULTS

A total of 4791 patients admitted to the medical, surgical, and progressive ICU and screened for eligibility for the parent studies between February 2009 and January 2015 from two level 1 trauma and one safety net hospital in a large urban academic health system were included. Delirium rates in the ICU were not significantly different among participants with no exposure to ACEI/ARB (12.6%), or exposure to ACEI (14.4%), ARB (11.8%), or ACEI and ARB in combination (15.4%) in six months prior to the ICU admission. Exposure to ACEI (OR = 0.97[0.77, 1.22]), ARB (OR = 0.70 [0.47, 1.05]), or both (OR = 0.97 [0.33, 2.89]) in six months prior to ICU admission was not significantly associated with odds of delirium during the ICU admission after adjusting for age, gender, race, co-morbidities, and insurance status.

CONCLUSIONS

While the impact of ACEI and ARB exposure prior to the ICU admission was not associated with the prevalence of delirium in this study, further research is needed to fully understand the impact of antihypertensive medications on delirium.

Influence of Renin-Angiotensin System Inhibitors on Postoperative Delirium in Patients With Pulmonary Arterial Hypertension: A Secondary Analysis of a Retrospective Cohort Study

OBJECTIVE

To investigate the correlation between preoperative use of ACEIs/ARBs and postoperative delirium (POD) in surgical patients with pulmonary arterial hypertension (PAH).

METHODS

The present study is a secondary analysis of a retrospective cohort study conducted at the University of Washington Medical Center from April 2007 to September 2013. Patients with PAH who underwent non-cardiac, non-obstetric surgery were enrolled in the original research. We further excluded stroke, sepsis, and craniotomy patients from interfering with POD evaluation. The univariate regression analysis and multivariate-adjusted model were used to explore the influence of preoperative ACEIs/ARBs use on the occurrence of POD.

RESULTS

A total of 539 patients were included in this study. The incidence of POD in these patients was 3.0%. Following the adjustment of potential confounders (age, BMI, smoking status, pulmonary arterial systolic pressure, length of surgery, vascular surgery, asthma, obstructive sleep apnea, renal failure, atrial fibrillation, coronary artery disease, hydrochlorothiazide, alpha-blocker, calcium channel blocker, antiplatelet, steroids, statin, isoflurane), a negative relationship was found between preoperative use of ACEIs/ARBs and occurrence of POD (OR = 0.15, 95%CI: 0.03 to 0.80, P = 0.0266).

CONCLUSION

Preoperative use of ACEIs/ARBs in patients with PAH reduces the risk of POD. ACEIs/ARBs may be more recommended for patients with PAH in the future.

Heterogeneous impact of hypotension on organ perfusion and outcomes: a narrative review

Arterial blood pressure is the driving force for organ perfusion. Although hypotension is common in acute care, there is a lack of accepted criteria for its definition. Most practitioners regard hypotension as undesirable even in situations that pose no immediate threat to life, but hypotension does not always lead to unfavourable outcomes based on experience and evidence. Thus efforts are needed to better understand the causes, consequences, and treatments of hypotension. This narrative review focuses on the heterogeneous underlying pathophysiological bases of hypotension and their impact on organ perfusion and patient outcomes. We propose the iso-pressure curve with hypotension and hypertension zones as a way to visualize changes in blood pressure. We also propose a haemodynamic pyramid and a pressure-output-resistance triangle to facilitate understanding of why hypotension can have different pathophysiological mechanisms and end-organ effects. We emphasise that hypotension does not always lead to organ hypoperfusion; to the contrary, hypotension may preserve or even increase organ perfusion depending on the relative changes in perfusion pressure and regional vascular resistance and the status of blood pressure autoregulation. Evidence from RCTs does not support the notion that a higher arterial blood pressure target always leads to improved outcomes. Management of blood pressure is not about maintaining a prespecified value, but rather involves ensuring organ perfusion without undue stress on the cardiovascular system.

Factors affecting hallucinations in patients with delirium

Delirium develops through a multifactorial process and include multiple subtypes with different pathological factors. To refine the treatment and care for delirium, a more detailed examination of these subtypes is needed. Therefore, this study aimed to explore the factors affecting delirium in cases in which hallucinations are conspicuous. In total, 602 delirium cases referred to the psychiatry department at a general hospital between May 2015 and August 2020 were enrolled. The Delirium Rating Scale-revised-98 was used to assess perceptual disturbances and hallucinations in patients with delirium. Multiple regression analysis was applied to determine whether individual factors were associated with the hallucinations. A total of 156 patients with delirium (25.9%) experienced hallucinations, with visual hallucinations being the most common subtype. Alcohol drinking (p < 0.0005), benzodiazepine withdrawal (p = 0.004), and the use of angiotensin II receptor blockers (p = 0.007) or dopamine receptor agonists (p = 0.014) were found to be significantly associated with hallucinations in patients with delirium. The four factors detected in this study could all be reversible contributing factors derived from the use of or withdrawal from exogenous substances.

Neuroanesthesiology Update

This review summarizes the literature published in 2020 that is relevant to the perioperative care of neurosurgical patients and patients with neurological diseases as well as critically ill patients with neurological diseases. Broad topics include general perioperative neuroscientific considerations, stroke, traumatic brain injury, monitoring, anesthetic neurotoxicity, and perioperative disorders of cognitive function.