Perioperative Renin-Angiotensin Blockade

Preoperative N-terminal pro-B-type natriuretic peptide and myocardial injury after stopping or continuing renin-angiotensin system inhibitors in noncardiac surgery: a prespecified analysis of a phase 2 randomised controlled multicentre trial

BACKGROUND

Patients with elevated preoperative plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP >100 pg ml-1) experience more complications after noncardiac surgery. Individuals prescribed renin-angiotensin system (RAS) inhibitors for cardiometabolic disease are at particular risk of perioperative myocardial injury and complications. We hypothesised that stopping RAS inhibitors before surgery increases the risk of perioperative myocardial injury, depending on preoperative risk stratified by plasma NT-proBNP concentrations.

METHODS

In a preplanned analysis of a phase 2a trial in six UK centres, patients ≥60 yr old undergoing elective noncardiac surgery were randomly assigned either to stop or continue RAS inhibitors before surgery. The pharmacokinetic profile of individual RAS inhibitors determined for how long they were stopped before surgery. The primary outcome, masked to investigators, clinicians, and patients, was myocardial injury (plasma high-sensitivity troponin-T ≥15 ng L-1 or a ≥5 ng L-1 increase, when preoperative high-sensitivity troponin-T ≥15 ng L-1) within 48 h after surgery. The co-exposures of interest were preoperative plasma NT-proBNP (< or >100 pg ml -1) and stopping or continuing RAS inhibitors.

RESULTS

Of 241 participants, 101 (41.9%; mean age 71 [7] yr; 48% females) had preoperative NT-proBNP >100 pg ml -1 (median 339 [160-833] pg ml-1), of whom 9/101 (8.9%) had a formal diagnosis of cardiac failure. Myocardial injury occurred in 63/101 (62.4%) subjects with NT-proBNP >100 pg ml-1, compared with 45/140 (32.1%) subjects with NT-proBNP <100 pg ml -1 {odds ratio (OR) 3.50 (95% confidence interval [CI] 2.05-5.99); P<0.0001}. For subjects with preoperative NT-proBNP <100 pg ml-1, 30/75 (40%) who stopped RAS inhibitors had myocardial injury, compared with 15/65 (23.1%) who continued RAS inhibitors (OR for stopping 2.22 [95% CI 1.06-4.65]; P=0.03). For preoperative NT-proBNP >100 pg ml-1, myocardial injury rates were similar regardless of stopping (62.2%) or continuing (62.5%) RAS inhibitors (OR for stopping 0.98 [95% CI 0.44-2.22]).

CONCLUSIONS

Stopping renin-angiotensin system inhibitors in lower-risk patients (preoperative NT-proBNP <100 pg ml -1) increased the likelihood of myocardial injury before noncardiac surgery.

Discontinuation vs. continuation of renin-angiotensin system inhibition before non-cardiac surgery: the SPACE trial

BACKGROUND AND AIMS

Haemodynamic instability is associated with peri-operative myocardial injury, particularly in patients receiving renin-angiotensin system (RAS) inhibitors (angiotensin-converting-enzyme inhibitors/angiotensin II receptor blockers). Whether stopping RAS inhibitors to minimise hypotension, or continuing RAS inhibitors to avoid hypertension, reduces peri-operative myocardial injury remains unclear.

METHODS

From 31 July 2017 to 1 October 2021, patients aged ≥60 years undergoing elective non-cardiac surgery were randomly assigned to either discontinue or continue RAS inhibitors prescribed for existing medical conditions in six UK centres. Renin-angiotensin system inhibitors were withheld for different durations (2-3 days) before surgery, according to their pharmacokinetic profile. The primary outcome, masked to investigators, clinicians, and patients, was myocardial injury [plasma high-sensitivity troponin-T (hs-TnT) ≥ 15 ng/L within 48 h after surgery, or ≥5 ng/L increase when pre-operative hs-TnT ≥15 ng/L]. Pre-specified adverse haemodynamic events occurring within 48 h of surgery included acute hypertension (>180 mmHg) and hypotension requiring vasoactive therapy.

RESULTS

Two hundred and sixty-two participants were randomized to continue (n = 132) or stop (n = 130) RAS inhibitors. Myocardial injury occurred in 58 (48.3%) patients randomized to discontinue, compared with 50 (41.3%) patients who continued, RAS inhibitors [odds ratio (for continuing): 0.77; 95% confidence interval (CI) 0.45-1.31]. Hypertensive adverse events were more frequent when RAS inhibitors were stopped [16 (12.4%)], compared with 7 (5.3%) who continued RAS inhibitors [odds ratio (for continuing): 0.4; 95% CI 0.16-1.00]. Hypotension rates were similar when RAS inhibitors were stopped [12 (9.3%)] or continued [11 (8.4%)].

CONCLUSIONS

Discontinuing RAS inhibitors before non-cardiac surgery did not reduce myocardial injury, and could increase the risk of clinically significant acute hypertension. These findings require confirmation in future studies.

Arterial Stiffness Predicts General Anesthesia-Induced Vasopressor-Resistant Hypotension in Patients Taking Angiotensin-Converting Enzyme Inhibitors

OBJECTIVES

Patients chronically treated with angiotensin-converting enzyme inhibitors (ACEIs) may develop hypotension after induction of general anesthesia. A fraction of these patients are resistant to therapeutic doses of vasopressors, which poses serious concerns for hemodynamic management. The authors hypothesized that the patients who develop refractory hypotension, compared with those who do not, show lower central arterial stiffness due to the profound effect of ACEIs.

DESIGN

Prospective observational study.

SETTING

Single tertiary center.

INTERVENTIONS

Fifty surgical patients chronically treated with ACEIs were enrolled. Prior to surgery, all the patients had central arterial stiffness assessment measured by carotid-femoral pulse-wave velocity. Patients were categorized into 2 groups according to the systolic blood pressure response during the first 10 minutes after induction of general anesthesia: a vasopressor-resistant hypotension group requiring more than 200 µg phenylephrine, or a control group requiring no more than 200 µg of phenylephrine to maintain systolic blood pressure above 90 mmHg during the study period.

MEASUREMENTS AND MAIN RESULTS

Carotid-femoral pulse-wave velocity was significantly lower in the vasopressor-resistant hypotension group compared to the control group (7.6 [7.2-8.3] m/s v 9.9 [8.7-12.0] m/s, p = 0.001 [Hodges-Lehman median difference 2.2, 95% confidence interval = 1.1-4.4]).

CONCLUSION

These findings suggested that preoperative measurement of carotid-femoral pulse-wave velocity in patients chronically treated with ACEIs could help identify patients at increased risk of developing hypotension refractory to vasopressors after induction of general anesthesia.

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.

Predictors of Perioperative Acute Kidney Injury in Obese Patients Undergoing Laparoscopic Bariatric Surgery: a Single-Centre Retrospective Cohort Study

BACKGROUND

Obesity has been associated with increased risk of perioperative acute kidney injury (AKI). We aim to establish the incidence of AKI among patients undergoing laparoscopic bariatric surgery and identify potential risk factors.

METHODS

Records of 1230 patients who underwent laparoscopic bariatric surgery in a tertiary centre from 1 December 2009 to 31 January 2014 were retrospectively studied. AKI diagnosis was made by comparing the baseline and post-operative serum creatinine to determine the presence of predefined significant change based on the Kidney Disease: Improving Global Outcomes (KDIGO) definition. Univariate analyses were performed to determine significant clinical factors, and multiple logistic regression analysis was subsequently done to determine independent predictors of AKI.

RESULTS

Thirty-five (2.9 %) patients developed AKI during the first 72 h post-surgery. Multivariate logistic regression analysis revealed impaired renal function (OR 10.429, 95 % CI 3.560 to 30.552), use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (OR 3.038, 95 % CI 1.352 to 6.824), and body mass index (OR 1.048, 95 % CI 1.005 to 1.093) as independent predictors of perioperative acute kidney injury in the obese patients who underwent laparoscopic bariatric surgery.

CONCLUSIONS

We found that the incidence of perioperative AKI among patients who underwent laparoscopic bariatric surgery is at 2.9 %. Impaired renal function, use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and raised body mass index were found to be independent predictors of AKI. Patients with these risk factors could be considered at risk for developing perioperative AKI, and extra perioperative vigilance should be undertaken.

Effect of discontinuing morning dose of antihypertensive for renal transplant surgery on haemodynamic and early graft functioning: A prospective, double-blind, randomised study

BACKGROUND AND AIMS

Antihypertensive drugs are continued until the day of renal transplant surgery. These are associated with increased incidence of hypotension and bradycardia. Hence, this study was designed to evaluate perioperative haemodynamic and early graft functioning in renal recipients with discontinuation of antihypertensive drugs on the morning of surgery.

METHODS

This prospective, randomised, double-blind study recruited 120 patients. Group 1 patients received placebo tablet while Group 2 patients received usual antihypertensive drugs on the day of surgery. Perioperative haemodynamics and time for reinstitution of antihypertensives were the primary outcome measures. The secondary outcome measures were need for inotropic support and graft function. Perioperative haemodynamics were analysed using ANOVA and Student's t-tests with Bonferroni correction. Fischer's exact test was used for analysis.

RESULTS

Systolic blood pressure (SBP) declined, which was more in Group 2. Forty-one patients developed significant hypotension; a correlation was found between the maximum observed hypotension and number of antihypertensive medications (P = 0.003). Four cases had slow graft function (one in Group 1 and three in Group 2). Twenty-eight patients in Group 2 required mephentermine boluses to maintain their SBP compared to 13 patients in Group 1 (P < 0.001). Two patients in Group 2 required dopamine to maintain SBP above 90 mmHg after the establishment of reperfusion as compared to none in Group 1.

CONCLUSION

Single dose of long-acting antihypertensive drugs can be omitted on the morning of surgery without any haemodynamic fluctuations and graft function in controlled hypertensive end-stage renal disease renal transplant patients receiving a combined epidural and general anaesthesia.

Short-Term Angiotensin Subtype 1 Receptor Blockade Does Not Alter the Circulatory Responses to Sympathetic Nervous System Modulation in Healthy Volunteers Before and During Sevoflurane Anesthesia: Results of a Pilot Study

OBJECTIVE

The mechanism of perioperative hypotension in patients taking an angiotensin-receptor blocker up to the time of surgery remains unclear. This study tested the hypothesis that short-term angiotensin-receptor blocker treatment attenuated the sympathetic and vascular responses to autonomic stimuli in volunteers undergoing anesthesia.

DESIGN

Randomized, crossover, blinded, pilot design.

SETTING

Zablocki Veterans Affairs Medical Center, Milwaukee, WI.

PARTICIPANTS

The study comprised 8 male and 6 female healthy, young volunteers (age 23±1.2 years [mean±standard error of the mean]).

INTERVENTIONS

Volunteers were studied after receiving oral placebo or 50 mg of losartan (angiotensin-receptor blocker) for 3 days before each test day. The effectiveness of angiotensin-receptor blocker treatment was confirmed using the mean arterial blood pressure response to intravenous angiotensin II (1-µg bolus). Eight volunteers underwent direct mean arterial pressure and forearm bloodflow measurements during conscious baseline, a cold pressor test, induction of anesthesia, tracheal intubation, maintenance of anesthesia with 1 minimum alveolar concentration of sevoflurane, and airway irritation with 12% desflurane. Six volunteers experienced mean arterial pressure responses to 0.1 mg of phenylephrine at baseline and during 1 minimum alveolar concentration of sevoflurane.

MEASUREMENTS AND MAIN RESULTS

Comparisons were made over time and across groups. Angiotensin-receptor blocker treatment significantly reduced-mean arterial pressure and forearm vascular resistance (forearm blood flow/mean arterial pressure) over time and blocked the mean arterial pressure response to angiotensin-II challenge. The changes in mean arterial pressure and forearm vascular resistance in response to all stressors did not differ between treatments. Mean arterial pressure increases from phenylephrine were preserved.

CONCLUSIONS

In healthy, young volunteers, sympathetically-mediated responses from the short-term use of an angiotensin-receptor blocker were not altered and most likely did not contribute to perioperative hypotension during the intraoperative period.