Renin-angiotensin blockade is associated with increased mortality after vascular surgery

Perioperative Renin-Angiotensin System Inhibitors Improve Major Outcomes of Heart Failure Patients Undergoing Cardiac Surgery: A Propensity-Adjusted Cohort Study

OBJECTIVE

The aim of this study was to study the association of perioperative administration of renin angiotensin system inhibitors (RASi) and clinical outcomes of patients with heart failure (HF) undergoing cardiac surgery.

SUMMARY BACKGROUND DATA

It is controversial whether the perioperative RASi should be administered in HF patients undergoing cardiac surgery.

METHODS

A total of 2338 patients with HF and undergoing CABG and/or valve surgeries at multiple hospitals from 2001 to 2015 were identified from STS database. After adjustment using propensity score and instrumental variable, logistic regression was conducted to analyze the influence of preoperative continuation of RASi (PreRASi) on short-term in-hospital outcomes. Independent risk factors of 30-day mortality, major adverse cardiovascular events (MACE), and renal failure were analyzed by use of stepwise logistic regression. The effects of pre- and postoperative use of RASi (PostRASi) on long-term mortality were analyzed using survival analyses. Stepwise Cox regression was conducted to analyze the independent risk factors of 6-year mortality. The relationships of HF status and surgery type with perioperative RASi, as well as PreRASi-PostRASi, were also evaluated by subgroup analyses.

RESULTS

PreRASi was associated with lower incidences of 30-day mortality [ P < 0.0001, odds ratio (OR): 0.556, 95% confidence interval (CI) 0.405-0.763], stroke ( P =0.035, OR: 0.585, 95% CI: 0.355-0.962), renal failure ( P =0.007, OR: 0.663, 95% CI: 0.493-0.894). Both PreRASi ( P =0.0137) and PostRASi ( P =0.007) reduced 6-year mortality compared with the No-RASi groups.

CONCLUSIONS

Pre- and postoperative use of RASi was associated with better outcomes for the patients who have HF and undergo CABG and/or valve surgeries. Preoperative continuation and postoperative restoration are warranted in these patients.

Preoperative evaluation and perioperative management of patients undergoing major vascular surgery

Patients undergoing major vascular surgery have an increased risk of perioperative major adverse cardiovascular events (MACE). Accordingly, in this population, it is of particular importance to appropriately risk stratify patients' risk for these complications and optimize risk factors prior to surgical intervention. Comorbidities that portend a higher risk of perioperative MACE include coronary artery disease, heart failure, left-sided valvular heart disease, and significant arrhythmic burden. In this review, we provide a current approach to risk stratification prior to major vascular surgery and describe the strengths and weaknesses of different cardiac risk indices; discuss the role of noninvasive and invasive cardiac testing; and review perioperative pharmacotherapies.

Management of renin-angiotensin-aldosterone inhibitors and other antihypertensives and their clinical effects on pre-anesthesia blood pressure

Background

Blood pressure fluctuations appear more significant in patients with poorly controlled hypertension and are known to be associated with adverse perioperative morbidity. In the present study, we aimed to determine the effects of antihypertensive drug treatment strategies on preanesthetic operating room blood pressure measurements.

Methods

A total of 717 patients participated in our study; 383 patients who were normotensive based on baseline measurements and not under antihypertensive therapy were excluded from the analysis. The remaining 334 patients were divided into six groups according to the antihypertensive drug treatment. These six groups were examined in terms of preoperative baseline and pre-anesthesia blood pressure measurements.

Results

As a result of the study, it was observed that 24% of patients had high blood pressure precluding surgery, and patients using renin-angiotensin-aldosterone system inhibitors (RAASI) had higher pre-anesthesia systolic blood pressure than patients using other antihypertensive drugs. Patients who received beta-blockers were also observed to have the lowest pre-anesthesia systolic blood pressure, diastolic blood pressure, and mean blood pressure, compared to others.

Conclusions

Recently, whether RAASI should be continued preoperatively remains controversial. Our study shows that RAASI cannot provide optimal pre-anesthesia blood pressure and lead to an increase in the number of postponed surgeries, probably due to withdrawal of medication before the operation. Therefore, the preoperative discontinuation of RAASI should be reevaluated 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.

The Year in Vascular Anesthesia: Selected Highlights From 2018

This special article is the second in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia that is specifically dedicated to highlights in vascular anesthesiology published in 2018. This review begins with 2 updates in preoperative medicine in the vascular surgery population, including recent publications regarding the management of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and antiplatelet medications in the perioperative period. The next section focuses on complications related to thoracic endovascular aortic surgery, particularly as technology advances allow for endovascular repair of more complex anatomy. The final section focuses on quality in vascular surgery and evaluates recent publications that examine the safety and feasibility of fast-track endovascular aortic surgery. Even though this is only a sampling of the literature published in 2018 relevant to the cardiovascular anesthesiologist, these themes represent some of the topics most clinically relevant to the perioperative period.

Pathophisiology of abdominal aortic aneurysm: biomarkers and novel therapeutic targets

Abdominal aortic aneurysm (AAA) is a vascular pathology with a high rate of morbidity and mortality and a prevalence that, in men over 65 years, can reach around 8%. In this disease, usually asymptomatic, there is a progressive dilatation of the vascular wall that can lead to its rupture, a fatal phenomenon in more than 80% of cases. The treatment of patients with asymptomatic aneurysms is limited to periodic monitoring with imaging tests, control of cardiovascular risk factors and treatment with statins and antiplatelet therapy. There is no effective pharmacological treatment capable of limiting AAA progression or avoiding their rupture. At present, the aortic diameter is the only marker of risk of rupture and determines the need for surgical repair when it reaches values greater than 5.5cm. This review addresses the main aspects related to epidemiology, risk factors, diagnosis and clinical management of AAA, exposes the difficulties to have good biomarkers of this pathology and describes the strategies for the identification of new therapeutic targets and biomarkers in AAA.

Association of renin angiotensin antagonists with adverse perioperative events in patients undergoing elective orthopaedic surgery: a case-control study

BACKGROUND

Renin angiotensin antagonists (RAA) may block protective vasopressor responses during surgery. Evidence linking RAA with intraoperative hypotension and perioperative adverse events is conflicting.

AIM

To compare the incidence of intraoperative hypotension and adverse events between patients receiving or not receiving RAA.

METHODS

This is a retrospective case-control study of 258 consecutive patients who underwent elective total knee or hip replacement between 1 January 2013 and 31 August 2016 and who were chronically prescribed a single blood pressure-lowering agent up to the time of surgery. Primary outcome measures were differences between patients receiving RAA (cases; n = 129) and patients receiving non-RAA medications (controls; n = 129) in incidence of intraoperative hypotension (systolic blood pressure <90 mmHg), perioperative acute kidney injury (AKI, >30% increase in serum creatinine from baseline on Day 1 post-operatively) and new onset major adverse cardiac or cerebrovascular events (MACCE) or in-hospital death over 72 h post-operatively.

RESULTS

Patients receiving RAA had significantly higher preoperative systolic blood pressure, greater prevalence of hypertension and chronic kidney disease, lower prevalence of ischaemic heart disease and lower cardiac risk compared to controls. Age, gender, type of operation, operative fitness, mode and duration of anaesthesia and prevalence of other types of cardiovascular disease, dyslipidaemia and diabetes were similar between groups. Compared to controls, patients receiving RAA had higher incidence of intraoperative hypotension (76.0 vs 45.9%, P < 0.001), AKI (11.6 vs 1.6%, P = 0.002) and MACCE (6.2 vs 0%, P = 0.007), with all adverse events associated with intraoperative hypotension.

CONCLUSION

This study provides further observational evidence of RAA-induced harm in patients undergoing elective surgery, although determining benefits and harms of preoperative withdrawal of RRA requires prospective randomised trials.

Perioperative management of patients with coronary artery disease undergoing non-cardiac surgery: Summary from the French Society of Anaesthesia and Intensive Care Medicine 2017 convention

This review summarises the specific stakes of preoperative, intraoperative, and postoperative periods of patients with coronary artery disease undergoing non-cardiac surgery. All practitioners involved in the perioperative management of such high cardiac risk patients should be aware of the modern concepts expected to decrease major adverse cardiac events and improve short- and long-term outcomes. A multidisciplinary approach via a functional heart team including anaesthesiologists, cardiologists and surgeons must be encouraged. Rational and algorithm-guided management of those patients should be known and implemented from preoperative to postoperative period.

Angiotensin converting enzyme inhibitors enhance the hypotensive effects of propofol by increasing nitric oxide production

Propofol anesthesia is usually accompanied by hypotension. Studies have shown that the hypotensive effects of propofol increase in patients treated with angiotensin-converting enzyme inhibitors (ACEi). Given that both propofol and ACEi affect nitric oxide (NO) signaling, the present study tested the hypothesis that ACEi treatment induces pronounced hypotensive responses to propofol by increasing NO bioavailability. In this study we evaluated 65 patients, divided into three groups: hypertensive patients chronically treated with ACEi (HT-ACEi; n = 21), hypertensive patients treated with other antihypertensive drugs instead of ACEi, such as angiotensin II receptor blockers, β-blockers or diuretics (HT; n = 21) and healthy normotensive subjects (NT; n = 23). Venous blood samples were collected at baseline and after 10min of anesthesia with propofol 2mg/kg administrated intravenously by bolus injection. Hemodynamic parameters were recorded at each blood sample collection. Nitrite levels were determined by using an ozone-based chemiluminescence assay, while NOx (nitrites+nitrates) levels were measured by using the Griess reaction. Additionally, experimental approaches were used to validate our clinical findings. Higher decreases in blood pressure after propofol anesthesia were observed in HT-ACEi group as compared with those found in NT and HT groups. Consistently, rats treated with the ACEi enalapril showed more intense hypotensive responses to propofol. The hypotensive effects of propofol were associated with increased NO production in both clinical and experimental approaches. Enhanced increases in nitrite levels after propofol anesthesia were observed in HT-ACEi patients compared with NT and HT groups. Accordingly, rats treated with enalapril showed increased vascular NO formation after propofol anesthesia compared with rats receiving vehicle. Our data show that ACEi enhance the hypotensive responses to propofol anesthesia and increase nitrite concentrations. These findings suggest that increased NO bioavailability may account for the enhanced hypotensive effects of propofol in ACEi-treated patients.

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.

Perioperative Management of Patients Treated with Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers: A Quality Improvement Audit

Previous studies have shown that patients continuing angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers on the day of surgery are more likely to have significant intraoperative hypotension, higher rates of postoperative acute kidney injury and lower incidences of postoperative atrial fibrillation. However, many of these studies were prone to bias and confounding, and questions remain over the validity of these outcomes. This observational, before-and-after quality mprovement audit aimed to assess the effect of withholding these medications on the morning of surgery. We recruited 323 participants, with 83 (26%) having their preoperative angiotensin-converting enzyme inhibitor (ACEi) or angiotensin II receptor blocker (ARB) withheld on the day of surgery. There were only very small Spearman rank-order correlations between time since last dose of these medications (rho −0.12, P=0.057) and intraoperative and recovery room intravenous fluid administration (rho −0.11, P=0.042). There was no statistically significant difference between the continued or withheld groups in vasopressor (metaraminol use 3.5 [1.5–8.3] mg versus 3.5 [1.5–8.5] mg, P=0.67) or intravenous fluid administration (1000 ml [800–1500] ml versus 1000 [800–1500] ml, P=0.096), nor rates of postoperative acute kidney injury (13% vs 18%, P=0.25) or atrial fibrillation (15% versus 18%, P=0.71). This audit found no significant differences in measured outcomes between the continued or withheld ACEi/ARB groups. This finding should be interpreted with caution due to the possibility of confounding and an insufficient sample size. However, as the finding is in contrast to many previous studies, future prospective randomised clinical trials are required to answer this important question.

Association between Withholding Angiotensin Receptor Blockers in the Early Postoperative Period and 30-day Mortality

Background:

Despite widespread use, there is limited information to guide perioperative management of angiotensin receptor blockers (ARBs).

Methods:

In this retrospective cohort study, the authors evaluated the patterns of postoperative ARB use in veterans regularly prescribed ARBs admitted for noncardiac surgery at the Veterans Affairs Healthcare system between 1999 and 2011. Multivariable and propensity score–matched Cox proportional hazards models were used to determine the independent effect of failure to resume ARB by postoperative day 2 on the primary outcome of all-cause 30-day mortality.

Results:

Out of 1,167,482 surgical admissions, 30,173 inpatient surgical admissions met inclusion criteria. Approximately 10,205 patients (33.8%) in the cohort did not resume ARB by day 2. Those that resumed ARB had a 30-day mortality rate of 1.3% (260 of 19,968), whereas 3.2% (323 of 10,205) died in the group that withheld ARB. The unadjusted hazard ratio (HR) for 30-day mortality was 2.45 (95% CI, 2.08 to 2.89; P &lt; 0.001) for those that withheld ARB compared with those that resumed, whereas the multivariable adjusted HR was 1.74 (95% CI, 1.47 to 2.06; P &lt; 0.001). When restricted to a propensity score–matched subset of 19,490, the HR was similar (1.47; 95% CI, 1.22 to 1.78; P &lt; 0.001). Withholding ARB in younger patients increased mortality risk (HR = 2.52; 95% CI, 1.69 to 3.76; P &lt; 0.001 for age &lt;60 yr) compared with older patients (HR = 1.42; 95% CI, 1.09 to 1.85; P = 0.01 for age &gt;75 yr).

Conclusions:

Postoperative delay in resuming ARB is common, particularly in patients who are frail after surgery. Withholding ARB is strongly associated with increased 30-day mortality, especially in younger patients, although residual confounding may be present.

Angiotensin-converting enzyme 2 decreases formation and severity of angiotensin II-induced abdominal aortic aneurysms

OBJECTIVE

Angiotensin-converting enzyme 2 (ACE2) cleaves angiotensin II (AngII) to form angiotensin-(1-7) (Ang-(1-7)), which generally opposes effects of AngII. AngII infusion into hypercholesterolemic male mice induces formation of abdominal aortic aneurysms (AAAs). This study tests the hypothesis that deficiency of ACE2 promotes AngII-induced AAAs, whereas ACE2 activation suppresses aneurysm formation.

APPROACH AND RESULTS

ACE2 protein was detectable by immunostaining in mice and human AAAs. Whole-body deficiency of ACE2 significantly increased aortic lumen diameters and external diameters of suprarenal aortas from AngII-infused mice. Conversely, ACE2 deficiency in bone marrow-derived cells had no effect on AngII-induced AAAs. In contrast to AngII-induced AAAs, ACE2 deficiency had no significant effect on external aortic diameters of elastase-induced AAAs. Because ACE2 deficiency promoted AAA formation in AngII-infused mice, we determined whether ACE2 activation suppressed AAAs. ACE2 activation by administration of diminazene aceturate (30 mg/kg per day) to Ldlr(-/-) mice increased kidney ACE2 mRNA abundance and activity and elevated plasma Ang-(1-7) concentrations. Unexpectedly, administration of diminazene aceturate significantly reduced total sera cholesterol and very low-density lipoprotein-cholesterol concentrations. Notably, diminazene aceturate significantly decreased aortic lumen diameters and aortic external diameters of AngII-infused mice resulting in a marked reduction in AAA incidence (from 73% to 29%). None of these effects of diminazene aceturate were observed in the Ace2(-/y) mice.

CONCLUSIONS

These results demonstrate that ACE2 exerts a modulatory role in AngII-induced AAA formation, and that therapeutic stimulation of ACE2 could be a benefit to reduce AAA expansion and rupture in patients with an activated renin-angiotensin system.

Optimal perioperative medical management of the vascular surgery patient

Perioperative medical management of patients undergoing vascular surgery can be challenging because they represent the surgical population at highest risk. β-Blockers should be continued perioperatively in patients already taking them preoperatively. Statins may be used in the perioperative period in patients who are not on statin therapy preoperatively. Institutional guidelines should be used to guide insulin replacement. Recent research suggests that measurement of troponins may provide some risk stratification in clinically stable patients following vascular surgery. Multimodal pain therapy including nonopioid strategies is necessary to improve the efficacy of pain relief and decrease the risk of side effects and complications.

Angiotensin axis blockade, hypotension, and acute kidney injury in elective major orthopedic surgery

BACKGROUND

Patients presenting for surgery with angiotensin axis blockade (AAB) from therapy with either angiotensin-converting enzyme inhibitors or angiotensin receptor blockers experience an increased incidence of perioperative hypotension. Acute kidney injury (AKI) in patients receiving preoperative AAB has been demonstrated after lung, vascular, and cardiac surgery. However, there is little literature evaluating the hypotensive and renal effects of preoperative AAB and major orthopedic surgery.

METHODS

We performed a retrospective chart review of 1154 patients who underwent spinal fusion, total knee arthroplasty, or total hip arthroplasty during the 2010 calendar year in our academic medical center.

RESULTS

A total of 922 patients met inclusion criteria, 343 (37%) received preoperative AAB. Postinduction hypotension (systolic blood pressure ≤80 mm Hg for 5 minutes) was significantly higher in patients receiving AAB when compared to those not so treated (12.2% vs 6.7%; odds ratio [OR]: 1.93, P = 0.005). Of the 922 patients, 798 had documented measurements of both preoperative and postoperative creatinine. Postoperative AKI was significantly higher in patients receiving AAB therapy (8.3% vs 1.7%; OR: 5.40, P < 0.001), remaining significant after adjusting for covariates including hypotension (OR: 2.60, P = 0.042). Developing AKI resulted in a significantly higher mean length of stay (5.76 vs 3.28 days, P < 0.001) but no difference in 2-year mortality.

CONCLUSIONS

Patients undergoing major elective orthopedic surgery who receive preoperative AAB therapy,have an associated increased risk of postinduction hypotension and postoperative acute kidney injury resulting in a greater hospital length of stay.

Association between angiotensin converting enzyme inhibitor or angiotensin receptor blocker use prior to major elective surgery and the risk of acute dialysis

Background

Some studies but not others suggest angiotensin converting enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB) use prior to major surgery associates with a higher risk of postoperative acute kidney injury (AKI) and death.

Methods

We conducted a large population-based retrospective cohort study of patients aged 66 years or older who received major elective surgery in 118 hospitals in Ontario, Canada from 1995 to 2010 (n = 237,208). We grouped the cohort into ACEi/ARB users (n = 101,494) and non-users (n = 135,714) according to whether the patient filled at least one prescription for an ACEi or ARB (or not) in the 120 days prior to surgery. Our study outcomes were acute kidney injury treated with dialysis (AKI-D) within 14 days of surgery and all-cause mortality within 90 days of surgery.

Results

After adjusting for potential confounders, preoperative ACEi/ARB use versus non-use was associated with 17% lower risk of post-operative AKI-D (adjusted relative risk (RR): 0.83; 95% confidence interval (CI): 0.71 to 0.98) and 9% lower risk of all-cause mortality (adjusted RR: 0.91; 95% CI: 0.87 to 0.95). Propensity score matched analyses provided similar results. The association between ACEi/ARB and AKI-D was significantly modified by the presence of preoperative chronic kidney disease (CKD) (P value for interaction < 0.001) with the observed association evident only in patients with CKD (CKD - adjusted RR: 0.62; 95% CI: 0.50 to 0.78 versus No CKD: adjusted RR: 1.00; 95% CI: 0.81 to 1.24).

Conclusions

In this cohort study, preoperative ACEi/ARB use versus non-use was associated with a lower risk of AKI-D, and the association was primarily evident in patients with CKD. Large, multi-centre randomized trials are needed to inform optimal ACEi/ARB use in the peri-operative setting.

Preoperative angiotensin-converting enzyme inhibitors and angiotensin receptor blocker use and acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

Using either an angiotensin-converting enzyme inhibitor (ACEi) or an angiotensin receptor blocker (ARB) the morning of surgery may lead to 'functional' postoperative acute kidney injury (AKI), measured by an abrupt increase in serum creatinine. Whether the same is true for 'structural' AKI, measured with new urinary biomarkers, is unknown.

METHODS

The TRIBE-AKI study was a prospective cohort study of 1594 adults undergoing cardiac surgery at six hospitals between July 2007 and December 2010. We classified the degree of exposure to ACEi/ARB into three categories: 'none' (no exposure prior to surgery), 'held' (on chronic ACEi/ARB but held on the morning of surgery) or 'continued' (on chronic ACEi/ARB and taken the morning of surgery). The co-primary outcomes were 'functional' AKI based upon changes in pre- to postoperative serum creatinine, and 'structural AKI', based upon peak postoperative levels of four urinary biomarkers of kidney injury.

RESULTS

Across the three levels (none, held and continued) of ACEi/ARB exposure there was a graded increase in functional AKI, as defined by AKI stage 1 or worse; (31, 34 and 42%, P for trend 0.03) and by percentage change in serum creatinine from pre- to postoperative (25, 26 and 30%, P for trend 0.03). In contrast, there were no differences in structural AKI across the strata of ACEi/ARB exposure, as assessed by four structural AKI biomarkers (neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, interleukin-18 or liver-fatty acid-binding protein).

CONCLUSIONS

Preoperative ACEi/ARB usage was associated with functional but not structural acute kidney injury. As AKI from ACEi/ARB in this setting is unclear, interventional studies testing different strategies of perioperative ACEi/ARB use are warranted.

Preoperative angiotensin system inhibitor use attenuates heparin-induced hypotension in patients undergoing cardiac surgery

OBJECTIVE

Both angiotensin system inhibitor (ASI) use and heparin are associated with hypotension. This study attempted to determine whether preoperative ASI therapy affected the hemodynamic response to heparin administered to patients undergoing cardiac surgery.

DESIGN

Sixty-two patients undergoing elective cardiac surgery requiring full (300 units/kg) systemic heparinization were studied prospectively. Thirty-three patients were receiving preoperative ASI therapy, whereas 29 patients were not. Anesthetic technique and mechanical ventilation parameters were standardized. Hemodynamics were recorded at 3 time points: baseline (just before the administration of heparin), 1-minute post-heparin administration, and 4-minute post-heparin administration.

SETTING

Single university hospital.

PARTICIPANTS

Patients undergoing elective cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The 2 groups were similar regarding preoperative demographics and baseline hemodynamics. Baseline mean arterial pressure (MAP) in non-ASI patients was 82.0 mmHg, and it decreased significantly to 76.3 mmHg (1 min; p<0.05) and 70.7 mmHg (4 min; p<0.05) following heparin administration. MAP values in ASI patients were 81.9 mmHg, 81.8 mmHg, and 76.8 mmHg at baseline, 1-minute post-heparin, and 4-minute post-heparin administration, respectively (changes not significant).Within-group analysis revealed that non-ASI patients experienced significant decrease in MAP at 1-minute (-6.6%, p = 0.01) and 4-minute (-13.0%, p = 0.0011) post-heparin administration, whereas ASI patients did not (+1.9%, p = 0.52; -3.8%, p = 0.16, respectively). Between-group analysis revealed that differences in MAP values at 1 minute were significant (p = 0.03), whereas differences at 4 minutes were not significant (p = 0.05).

CONCLUSIONS

This prospective clinical study indicated that preoperative ASI therapy until the day before surgery may attenuate heparin-induced hypotension. Definitive mechanistic insight requires further clinical study.

Propofol increases vascular relaxation in aging rats chronically treated with the angiotensin-converting enzyme inhibitor captopril

BACKGROUND

Both propofol use and advanced age are predictors of intraoperative hypotension. We previously demonstrated that propofol enhances vasodilation in mesenteric arteries from aged rats, partly due to increased nitric oxide (NO) bioavailability. Patients chronically treated with angiotensin-converting enzyme (ACE) inhibitors may exhibit refractory hypotension under general anesthesia. We hypothesized that propofol enhances NO-mediated vasodilation in arteries from aged rats chronically treated with ACE inhibitors.

METHODS

Sprague-Dawley rats aged 12 to 13 months were treated with or without captopril for 7 to 8 weeks, yielding a final age of 14 to 15 months at the time of experimentation. Before euthanasia, arterial blood pressures were obtained through carotid artery cannulation. Concentration-response curves to propofol (0.1-100 µM) or methacholine (MCh) (0.01-3 µM) were then assessed on isolated resistance mesenteric arteries (100-200 μm diameter) from both treatment (captopril) and control rats. MCh relaxation was also assessed after propofol pretreatment (1 and 10 µM). N(G)-nitro-l-arginine methyl ester (l-NAME) (100 µM) and meclofenamate (10 µM) were used to inhibit NO and prostaglandin synthesis, respectively. Concentration-response data were summarized as 50% of the maximum relaxation response or area under the curve.

RESULTS

Mean arterial blood pressure in the captopril-treated rats was lower than in untreated rats (P = 0.049). When comparing relaxation in arteries from captopril-treated versus untreated rats, concentration-response curves revealed that captopril-treated rats display greater direct propofol relaxation (P = 0.018). MCh relaxation in the absence of propofol, however, was not different between captopril-treated and untreated rats (P = 0.80). Propofol pretreatment increased MCh relaxation in arteries from captopril-treated compared with untreated rats (P = 0.029 for 1 µM and P = 0.020 for 10 µM). Meclofenamate did not have an effect in this response (P = 0.22). l-NAME-dependent inhibition of MCh relaxation, however, was greater in arteries from control compared with captopril-treated rats (P = 0.0077). However, propofol increased the proportion of NO-dependent vasodilation to MCh similarly in both groups. This suggests that other vasodilatory pathways are involved in the differential response to MCh in the presence of propofol in captopril-treated rats.

CONCLUSIONS

Our results show that mesenteric arterial relaxation in response to propofol, both by direct stimulation and through modulation of endothelium-dependent mechanisms, is, in part, NO-dependent. In captopril-treated rats, propofol further increased arterial relaxation through a non-NO-dependent vasodilating pathway (e.g., endothelium-derived hyperpolarizing factor), which may account for enhanced vasodilation during propofol exposure in patients treated with ACE inhibitors.

Cardiac Arrest during Total Hip Arthroplasty in a Patient on an Angiotensin Receptor Antagonist

Angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor antagonists (ARA) are effective and well-tolerated first-line drugs in the therapy of hypertension and, therefore, are frequently encountered in the perioperative setting. Hemodynamic compensation for volume depletion seen in the perioperative period is normally mediated by the renin-angiotensin system, which is blocked by ACEI/ARA. These drugs may contribute to severe hypotension during anesthesia induction and may have contributed to the cardiac arrest seen in this patient. Additional factors such as increased intra-abdominal pressures and respiratory obstructive episodes leading to diminished venous return, as well diuretic use and the fasting state, common in the perioperative orthopedic patient, are likely to have contributed as well. Medication use may be an easily modifiable risk factor for severe hypotension and possible cardiac arrest in the perioperative setting.

Cardiovascular predictors for long-term mortality after EVAR for AAA

The aim of this study was to assess cardiovascular predictors for all-cause long-term mortality in patients undergoing standard endovascular aneurysm repair (EVAR) for infrarenal abdominal aortic aneurysm (AAA). Consecutive patients treated with EVAR (Zenith® stent grafts; Cook) between May 1998 and February 2006 were prospectively enrolled in a computerized database, together with retrospectively collected data on medication, and electrocardiographic and echocardiographic variables. Mortality was assessed on 1 December 2010. The median follow-up time was 68 months and the median age was 74 years (range 53–89) for the 304 patients. Mortality at the end of follow-up was 54.3% (165/304). The proportion of deaths caused by vascular diseases was 61% (101/165). In the univariate analysis, low preoperative ejection fraction (EF) ( p = 0.004), absence of statin medication ( p = 0.007), and medication with diuretics ( p = 0.028) or digitalis ( p = 0.016) were associated with an increased long-term mortality rate. Myocardial ischemia on electrocardiogram (ECG) (hazard ratio (HR) 1.6 [95% CI 1.1–2.4]) and anemia (HR 1.5 [95% CI 1.0–2.1]) were found to be independent predictors for long-term mortality after Cox regression analysis. There was a trend that chronic kidney disease, stage ≥ 3 (HR 1.5 [95% CI 1.0–2.2]), and age 80 years and above (HR 1.5 [95% CI 1.0–2.4]) were independently associated with long-term mortality. In conclusion, ischemia on ECG and anemia were independently related to an increased long-term mortality rate after EVAR, and these predictive factors seem to be most important for critical assessment in the preoperative medical work-up.

[Perioperative management of long-term medication]

Anesthesiologists and surgeons are increasingly faced with patients who are under long-term medication. Some of these drugs can interact with anaesthetics or anaesthesia and/or surgical interventions. As a result, patients may experience complications such as bleeding, ischemia, infection or severe circulatory reactions. On the other hand, perioperative discontinuation of medication is often more dangerous. The proportion of outpatient operations has increased dramatically in recent years and will probably continue to increase. Since the implementation of DRGs (pending in Switzerland, introduced in Germany for some time), the patient enters the hospital the day before operation. This means that the referring physician as well as anesthesiologists and surgeons at an early stage must deal with issues of perioperative pharmacotherapy. This review article is about the management of the major drug classes during the perioperative period. In addition to cardiac and centrally acting drugs and drugs that act on hemostasis and the endocrine system, special cases such as immunosuppressants and herbal remedies are mentioned.