Chronic Renin–Angiotensin System (RAS) Blockade May Not Induce Hypotension During Anaesthesia for Bariatric Surgery

Hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers on the day of prone positioning spinal surgery in elderly patients

Introduction

The hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers (ARBs) before surgery in elderly patients undergoing spinal surgery in a prone position during anesthesia induction to skin incision are still unknown.

Methods

In this prospective study, 80 patients undergoing spinal surgery in a prone position with general anesthesia, aged 60-79 years, American Society of Anesthesiologists (ASA) II or III, were enrolled. Patients who had ARBs only in their preoperative medication list were randomly divided into two groups at a 1:1 ratio: In Group A, ARBs were continued on the morning of surgery, while in Group B, they were withhold. Norepinephrine was infused to maintain the blood pressure at the baseline level of ±20% during anesthesia induction in all patients. The primary outcome was the consumption of norepinephrine in each group from anesthesia induction to skin incision. The secondary outcomes include changes in invasive arterial blood pressure and heart rate, the fluid infusion volumes, the amounts of anesthetic drugs, and the total time from induction to skin incision.

Results

There were no significant differences in the demographics, the fluid infusion volumes, the amounts of anesthetic drugs, the total time from induction to skin incision, and hemodynamics at different time points (p > 0.05), while significant differences were found in norepinephrine consumption between the two groups (p < 0.001). Compared with Group B, the consumption of norepinephrine increased significantly in Group A (93.3 ± 29.8 vs. 124.1 ± 38.7 μg, p = 0.000). In addition, the same trend was illustrated in the pumping rate of norepinephrine between Group B (0.04 ± 0.01 μg·kg-1·min-1) and Group A (0.06 ± 0.02 μg·kg-1·min-1) (p = 0.004).

Conclusion

Our study conducted in elderly patients with hypotension undergoing prone spinal surgery demonstrated a greater pumping rate of norepinephrine during anesthesia induction in patients with ARBs continuing before surgery than those withholding, indicating that it was more difficult to maintain hemodynamic stability.Clinical Trial Registration: https://www.chictr.org.cn/showproj.html?proj=141081, ChiCTR2100053583.

Obesity, metabolic syndrome, and inflammation: an update for anaesthetists caring for patients with obesity

Our understanding of chronic inflammation in obesity is evolving. Suggested mechanisms include hypoxia of adipose tissue and a subsequent increase in circulating cytokines. It is now known that adipose tissue, far from being an inert tissue, produces and secretes multiple peptides that influence inflammation and metabolism, including substrates of the renin-angiotensin-aldosterone system (RAAS). RAAS blocking antihypertensive medication and cholesterol-lowering agents are now being evaluated for their metabolic and inflammation-modulating effects. Surgery also has pro-inflammatory effects, which may be exacerbated in patients with obesity. This narrative review will summarise the recent literature surrounding obesity, metabolic syndrome, inflammation, and interplay with the RAAS, with evidence-based recommendations for the optimisation of patients with obesity, prior to surgery and anaesthesia.

Refractory Hypotension During General Anesthesia Despite Withholding Telmisartan

Angiotensin receptor blockers (ARBs) are commonly used to treat hypertension. However, similar to angiotensin-converting enzyme inhibitors, ARBs can also cause refractory hypotension during general anesthesia. Therefore, it has been recommended that ARBs be withheld for 24 hours prior to the induction of anesthesia. This is a case report of refractory hypotension requiring the administration of potent vasopressors after the induction of general anesthesia despite withholding telmisartan for 24 hours. In the same patient undergoing a subsequent general anesthetic, telmisartan was withheld for 5 days before induction, leading to mild intraoperative hypotension that responded adequately to phenylephrine. The primary cause of refractory hypotension during the first general anesthetic was suspected to be an insufficient telmisartan washout period. Telmisartan's half-life of 24 hours is notably the longest of all ARBs in current use. This case report demonstrates that refractory hypotension during general anesthesia cannot always be avoided by withholding telmisartan for 24 hours before the induction of anesthesia. Therefore, a washout period greater than 24 hours is preferable for patients taking telmisartan.

Continuation of Angiotensin-Converting Enzyme Inhibitors on the Day of Surgery Is Not Associated With Increased Risk of Hypotension Upon Induction of General Anesthesia in Elective Noncardiac Surgeries

OBJECTIVE

The aim of this study was to find out whether the preoperative continuation of angiotensin-converting enzyme inhibitor (ACE-I) or angiotensin II receptor blocker (ARB) treatment is associated with intraoperative hypotension immediately after induction of general anesthesia in elective noncardiac surgeries.

DESIGN

Retrospective cohort study.

SETTING

Single institutional university hospital.

PARTICIPANTS

Four hundred patients who underwent elective noncardiac surgery under general anesthesia, with ACE-I or ARB on their list of preoperative home medications, were included.

INTERVENTION

Preoperative ACE-I and ARB use was evaluated, and patients were divided into an ACE-I/ARB group versus non-ACE-I/ARB group.

MEASUREMENTS

The primary outcome measure was intraoperative hypotension after induction of general anesthesia. The secondary outcome measure was preoperative medication use, medications taken the morning of surgery, induction medication and dosage, and vasopressor medication use during induction.

RESULTS

Three hundred forty-nine patients were included for final analysis. The mean admission American Society of Anesthesiologists status was 2.7 ± 0.5, age 65 ± 11 years, and body mass index 31 ± 6.9 kg/m². There were no statistically significant changes between the no ACE-I/ARB group and the ACE-I/ARB group in systolic blood pressure (p = 0.853), diastolic blood pressure (p = 0.357), and heart rate (p = 0.220) change over the 15 minutes. There was no statistical difference in induction medication dose (propofol, fentanyl, and rocuronium) and pressor use (p = 0.137) for hypotension between the 2 groups. Statistically significant hypotension (p < 0.001) occurred in both groups equally over 15 minutes.

CONCLUSION

Continuation of ACE-I/ARB on the day of surgery was not associated with increased risk of intraoperative hypotension upon induction and within 15 minutes of general anesthesia in elective noncardiac surgeries.

Consequences of continuing renin angiotensin aldosterone system antagonists in the preoperative period: a systematic review and meta-analysis

Background

Patients who use angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin II receptor blockers (ARBs) are prone to developing side effects like hypotension and even refractory hypotension during anesthesia use, and whether ACEIs/ARBs should be continued or discontinued in such patients remains debatable. The present systematic review and meta-analysis was conducted to clarify the consequences of continuing or withholding these drugs, especially with regards to the incidence of intraoperative hypotension, in patients who continue to use ACEIs/ARBs on the day of their scheduled surgery.

Methods

Studies with data pertinent to the incidence of intraoperative hypotension during anesthesia use in patients who continued the use of ACEIs/ARBs on the day of their scheduled surgery were considered for inclusion.

Results

Thirteen studies reporting on the incidences of intraoperative hypotension between patients who continued receiving ACEIs/ARBs and those who did not on the day of their surgical procedure were included. The pooled effects showed that hypotension during anesthesia was more likely to develop in patients who continued to take ACEIs/ARBs when compared to those who did not (RR = 1.41, 95% CI: 1.21–1.64). However, there were no significant differences between these groups of patients with regards to postoperative complications including ST-T abnormalities, myocardial injury, myocardial infarction, stroke, major adverse cardiac events, acute kidney injury, or death (RR = 1.25, 95% CI: 0.76–2.04). The differences remained similar in subgroup analyses and sensitivity analyses.

Conclusions

No sufficient available evidence to recommend discontinuing ACEIs/ARBs on the day of surgery was found in this literature review and meta-analysis. However, anesthetists should be cautious about the risk for intraoperative hypotension in patients chronically receiving ACEIs/ARBs, and should know how to treat it effectively.

Perioperative use of angiotensin-converting-enzyme inhibitors and angiotensin receptor antagonists

STUDY OBJECTIVE

Clinical repercussions of perioperative treatment with ACEIs/ARBs.

DESIGN

Systematic review according to PRISMA statement.

SETTING

Perioperative period.

PATIENTS

29 studies 11 cases/cases series, 12 observational studies and 6 randomized studies.

MEASUREMENTS

Arterial blood pressure differences, refractory hypotension, other comorbidities.

MAIN RESULTS

The studies show different results regarding the topics measured. They are divided in the results regarding blood pressure, long term morbidities and effects in neuraxial anesthesia.

CONCLUSIONS

Withholding AECI/ARBs on the morning prior to surgery could be recommended as a potentially effective measure, with a low level of evidence, in order to reduce the appearance of hypotension in the perioperative period of non-cardiac surgery.

Anaesthetic Preparation of Obese Patients: Current Status on Optimal Work-up

PURPOSE OF REVIEW

With the prevalence of obesity rapidly growing, bariatric anaesthesia becomes everyday anaesthesia rather than a subspecialty. In this review, we are aiming to draw attention to this complex group of patients and their comorbidities, relevant to everyday practice for contemporary anaesthetists.

RECENT FINDINGS

We wanted to focus greatly on sleep-related breathing disorders, because preoperative screening, diagnosis and treatment of the aforementioned make a huge impact in the improvement of preoperative morbidity and mortality, including positive effects on the cardiovascular system. The overview is touching on main obesity-related comorbidities and guides the anaesthetist and associated health professionals on how to approach and manage them. A multidisciplinary approach widely used in bariatric care may be adopted in the care of obese patients in order to reduce preoperative morbidity and mortality. We advocate the early involvement of the anaesthetic team in the preoperative assessment of obese patients in order to achieve appropriate risk stratification and optimise the care.