Patient’s Own Risk Factors

RCRI

MACE rate

Risk

0.4% (0.1–0.8)

Low

1% (0.4–1.5)

Low-elevated^a

2.4% (1.3–3.5)

Elevated

5.4% (2.8–7.9)

Elevated

MACE indicates major adverse cardiac event

^aLow risk is <1% per ACC/AHA 2014 guidelines

Functional status is also imperative to cardiac risk assessment and is a prognostic determinant in the decision for further cardiac risk stratification [8, 9]. It is quantified by the use of metabolic equivalents (METS) . One MET is equal to the resting/basal oxygen consumption of a 40-year-old, 70 kg man. Functional status is classified as excellent (>10 METS), good (7–10 METS), moderate (4–6 METS), poor (<4 METS), or unknown. Patients with METS >4 are able to climb a flight of stairs or walk up a hill, walk on level ground at 4 miles per hour (MPH), or perform heavy work around the house. Activities requiring METS <4 include slow ballroom dancing, golfing with a cart, playing a musical instrument, or walking at approximately 2–3 MPH.

Patients with poor functional status have been shown to have an increased risk for perioperative morbidity and mortality [10]. These patients, in addition to those with elevated cardiac risk, may benefit from further risk stratification with cardiac stress testing [11]. The decision to pursue further evaluation depends on whether this testing will impact the decision-making or care of the patient perioperatively (i.e., perform original surgery or undergo cardiac intervention). If stress testing will change management, then the patient should undergo further cardiac testing with well-validated stress-testing modalities, such as dobutamine stress echocardiogram (DSE) or myocardial perfusion imaging (MPI) [12–14]. Currently, there are no randomized controlled trials comparing the two stress test modalities; therefore, which test to pursue should be based on local expertise performing the test, in addition to patient characteristics [2].

Patients with a moderate to large area of myocardial ischemia noted on stress test imaging are at increased risk for perioperative MI and/or death. They may be considered for preoperative revascularization if they are deemed to have unstable angina and/or left main disease and would otherwise need to undergo emergent/urgent revascularization [15, 16]. Patients who require revascularization secondary to an ST elevation MI or non-ST elevation MI usually benefit from percutaneous coronary intervention (PCI). Due to the shorter need for ongoing dual antiplatelet therapy (DAPT), bare-metal stent (BMS) may be preferred over a drug-eluting stent (DES) if surgery is time sensitive [16]. The Coronary Artery Revascularization Prophylaxis (CARP) trial – the largest randomized trial of its kind – showed that there was no mortality benefit to coronary artery revascularization, either with PCI or coronary artery bypass grafting (CABG), prior to elective vascular surgery, in patients with known stable coronary artery disease [17]. Only patients with left main disease showed a benefit to preoperative coronary artery revascularization [18].

Patients who undergo PCI should have surgery delayed by 14 days after balloon angioplasty and 30 days after BMS implantation. Those who undergo DES placement should have surgery delayed by at least 365 days, though surgery may be considered after 180 days if the risks of delaying the surgery further are greater than the risk of stent thrombosis [2, 19–21].

Perioperative Cardiac Medications

Beta-Blocker Therapy

Patients currently on beta-blockers should be continued on these medications throughout the perioperative period. Studies [22, 23] have shown that sudden withdrawal of beta-blocker may be harmful. However, they may need to be decreased in dose or temporarily discontinued due to hypotension, bradycardia, or bleeding.

There is conflicting data however on the benefits versus risks of initiating beta-blocker therapy. Initial data supported the use of beta-blockers to prevent postoperative cardiac complications; however, these trials were limited by small sample sizes with low power [2]. A favorable outcome has been observed in patients who preoperatively are at intermediate or high risk for myocardial ischemia, as determined by pharmacological stress test [24], or if the patient has an RCRI of ≥3 [25]. The POISE trial showed that beta-blockers had a potentially harmful effect, including increased risk of stroke and death. Criticism of the POISE trial included use of high-dose long-acting beta-blockers, initiating beta-blocker immediately before surgery, and lack of a titration protocol before or after surgery [26].

A risk-benefit analysis should be performed before deciding if a beta-blocker should be initiated. If a decision is made to start a beta-blocker, it should be initiated at least 1 day prior to surgery and titrated safely to lower the resting heart rate [2].

Statin Therapy

Patients currently taking a statin should be continued on the statin throughout the perioperative period. Further, patients may be started on statins if deemed to be higher risk (i.e., history of diabetes, hypertension, coronary artery disease). Data from statin trials suggests there is a reduction in cardiovascular events in the perioperative period in high-risk patients [27, 28]. The general recommendation is to start statin therapy 1 week prior to surgery and to continue for 30 days after, if not already indicated. Regardless, patients who meet criteria for initiation of a statin may benefit long term from its introduction.

Angiotensin-Converting Enzyme Inhibitor (ACEI) /Angiotensin Receptor Blocker (ARB) Therapy

ACEI/ARB may be continued throughout the perioperative period; however, there is increased risk for transient intraoperative hypotension [29]. If they are held preoperatively, they may be restarted postoperatively when the blood pressure is able to tolerate the addition of the medication.

Anticoagulants and Antiplatelet Therapy

See anticoagulation/antiplatelet section for further details.

Perioperative Pulmonary Assessment

The frequency of postoperative pulmonary complications (PPCs) varies from 5% to 70%, with the wide discrepancy explained by the definition used in each study, patient selection, and procedure-related risk factors [30].

PPCs include atelectasis, cough, dyspnea, bronchospasm, hypoxemia, hypercapnia, adverse reaction to pulmonary medication, pleural effusion, pneumonia, pneumothorax, and ventilatory failure. Those that are particularly at increased risk are persons with preexisting lung disease, medical comorbidities, poor nutritional status, overall poor health, and current smokers. PPCs are not only detrimental to the patient (account for about 25% of deaths occurring within 6 days of surgery [30]), but they are also costly to the hospital (i.e., can increase length of stay by 1–2 weeks). Similar to cardiac complications, the patient’s own risk factors, as well as the procedure itself, may increase the risk for pulmonary complications.

Patient Risk Factors

There are several patient-related risk factors that are associated with increased risk for PPCs. Age has been shown to be an independent risk factor for PPCs, specifically, in patients greater than age 50 [31]. The general health status is usually predicted by the American Society of Anesthesiology (ASA) classification system, and class two or higher is associated with an increased pulmonary risk [31]. In addition, patients with poor functional status, as well as those with low albumin (<3.5 g/dL) and weight loss, are at increased risk for PPCs [32].

Patients with at least a 20 pack-year smoking history are at increased risk for PPCs, compared to those with a lesser smoking history. Risk for PPCs is reduced when patients stop smoking at least 4 weeks prior to surgery [33]; however, data has shown that even briefer durations of smoking cessation have been associated with a reduction in PPCs [34, 35].

Chronic obstructive pulmonary disease (COPD) is an important risk factor for PPCs. Patients with severe COPD have an increased risk for pneumonia, unplanned intubation, and prolonged ventilatory support [36]. Similar to COPD, patients with asthma are at increased risk for PPCs when it is not well controlled [37, 38]. Patients should be medically optimized prior to surgery (Table 1.2).

Table 1.2

General perioperative strategies in reduction of postoperative pulmonary complications

Preoperative	Postoperative
Immediate smoking cessation	Incentive spirometer and deep breathing
Optimization of underlying lung disease	Early mobilization
Optimization of nutrition	Pain control in thoracic/abdominal surgeries
–	Nasogastric decompression when indicated

Obesity causes decreased lung volumes, ventilation-perfusion mismatch, and relative hypoxemia, which one would expect to increase the risk for PPCs. However, available data is inconsistent regarding this matter, and the consensus currently is that obesity is not a predictor of PPCs [38, 39]. Patients with suspected obstructive sleep apnea (OSA) should undergo screening with one of the available screening tools such as the STOP-BANG questionnaire. Early identification of these patients will allow for possible intraoperative and postoperative modifications to be made, such as minimizing the use of sedatives and opioid analgesics [40, 41]. An arterial blood gas should be considered in patients with suspected or known OSA and suspicion for obesity hypoventilation syndrome [40].

Procedure Risk Factors

Procedure risk factors include surgical site (the closer the incision site is to the diaphragm, the greater the risk for PPCs) [31], duration of surgery (longer than 3–4 h) [38], type of anesthesia, and type of neuromuscular blockade. Patients undergoing intra-abdominal surgeries are at an increased risk for pulmonary complications. While robotic urologic procedures are minimally invasive, they have been associated with a decrease in pulmonary compliance and tidal volume due to pneumoperitoneum and steep Trendelenburg position. Further, these patients are also at increased risk for facial, pharyngeal , and laryngeal edema leading to re-intubation [1].

Preoperative Testing

A complete history and physical exam are important in evaluating a patient’s risk for PPCs. These elements should be directed toward eliciting any findings that may be concerning for underlying lung or cardiac disease. Based on the history and physical exam, further preoperative testing may be warranted which may include pulmonary function testing, an arterial blood gas, and a chest radiograph.

Pulmonary Function Tests (PFTs)

Patients typically do not require PFTs to be performed prior to surgery, unless they have an unexplained history of dyspnea or exercise intolerance. PFTs do not predict the risk for pulmonary complications, and therefore patients should not have surgery withheld based on PFTs only. If a patient has a history of COPD/asthma and it is unclear if the patient is at their baseline, PFTs may be beneficial in determining whether the patient requires more aggressive treatment for optimization prior to surgery [42].

Arterial Blood Gas (ABG)

Although patients with hypercapnia are at increased risk for PPCs and mortality, there is no strong evidence to suggest that patients should have an ABG performed prior to surgery; however, this can be considered if obesity hypoventilation syndrome is suspected [42, 43].

Chest Radiographs

Despite routine ordering of chest radiographs prior to surgery, they have been shown to add little clinical significance in predicting PPCs [44]. It is therefore suggested that chest radiographs not be obtained in low-risk patients, unless the patient is over the age of 50 years with known history of cardiopulmonary disease undergoing a high-risk surgery involving the upper abdomen, esophagus, thoracic cavity, or aorta [45].

Postoperative Strategies to Reduce Pulmonary Complications

Strategies to reduce postoperative pulmonary complications include lung expansion maneuvers, early mobilization, adequate pain control, use of nasogastric decompression, and venous thromboembolism prophylaxis (Table 1.2).

Lung Expansion Maneuvers

Lung expansion maneuvers include incentive spirometry (IS), deep breathing exercises, chest physical therapy, intermittent positive pressure breathing, and continuous positive airway pressure (CPAP) . IS is widely used postoperatively given its cost-effectiveness and safety. However, whether there is benefit to preventing PPCs is controversial. In a meta-analysis by Overend et al. [46], there was no reduction in PPCs in patients using IS who had undergone cardiac or upper abdominal surgery. Conversely, in a systemic review by Ireland et al. [47], it was suggested that CPAP may reduce PPCs; however, the quality of the evidence was low.

Early Mobilization

The sooner the patient is able to ambulate after surgery, the less risk they have for PPCs [48]. Minimize bedrest orders and tethers that discourage mobility. Physical therapy and occupational therapy can be consulted soon after surgery to help aid in early mobilization of the patient.

Adequate Pain Control

Ensuring good pain control for the patient postoperatively helps reduce PPCs. Patients are able to take deeper breaths, as well as ambulate earlier [42, 49].

Nasogastric Decompression

Patients who have undergone abdominal surgery with subsequent routine placement of a nasogastric tube (NGT) for prophylactic reasons have an increased risk for PPCs [49]. NGTs should only be used when indicated (i.e., unable to tolerate oral intake due to nausea and vomiting, postoperative ileus).

Venous Thromboembolism (VTE) Prophylaxis

Surgery is a known risk factor for deep vein thrombosis (DVT) and subsequent pulmonary embolism (PE). Patients should be started on adequate prophylactic anticoagulation postoperatively, once deemed safe to do so.

Perioperative Anticoagulation Assessment

As the patient population continues to age, more patients are taking oral anticoagulants and antiplatelet agents. Patients requiring anticoagulation include patients with atrial fibrillation , prosthetic valves, and DVT/PE, while those requiring antiplatelet therapy include patients with cardiovascular, cerebrovascular, or peripheral arterial disease. The goal is to balance the risk for a thromboembolic event against the excess risk of bleeding. Data is limited regarding the risks and benefits of interrupting anticoagulation and/or antiplatelet therapy. As such, each patient should be evaluated separately in regard to when to hold or continue these therapies.

In general, patients undergoing invasive procedures should discontinue their anticoagulation in a timeframe that allows the drug effect to wear off prior to surgery – generally five half-lives of the medication. If the patient is at high risk for thromboembolic events , then the interruption period should be as short as possible (e.g., restart after hemostasis is established and the bleeding risk is acceptable). Those undergoing low bleeding risk procedures may be able to continue anticoagulation throughout the procedure though this is usually at the discretion of the operator.

Commonly used antiplatelet agents include aspirin (ASA) and the P2Y₁₂ inhibitors (clopidogrel, prasugrel, and ticagrelor). Despite its short half-life, ASA irreversibly inhibits thromboxane A1 and prostacyclin synthesis, thereby preventing platelet aggregation for the life of the platelet. These effects are maintained up to 5–7 days after cessation of ASA. P2Y₁₂ inhibitor also prevents platelet aggregation through the inhibition of the adenosine diphosphate receptor, which returns to normal after 5–7 days of cessation of the P2Y₁₂ inhibitor.

For decades, warfarin was the most commonly used anticoagulant; however, the development of direct oral anticoagulants (DOACs) has led to their increased use in many conditions in lieu of warfarin. DOACs include dabigatran (direct thrombin inhibitor) and the factor Xa inhibitors apixaban, edoxaban, and rivaroxaban.

Management of Anticoagulation (AC)/Antiplatelet (AP) Therapy

Robotic urologic surgery is associated with decreased bleeding and decreased transfusion rates compared to traditional open urologic surgery [50]. However, data is limited regarding the management of AC/AP therapy in the perioperative period for robotic surgeries. Decisions regarding AC/AP management have been based on prior studies involving other surgical procedures, including traditional urologic surgery [51].

Anticoagulant Therapy

Patients with mechanical valves at high risk for thromboembolism (Table 1.3) should stop warfarin 5 days prior to surgery and be bridged with either low molecular weight heparin (LMWH) or unfractionated heparin (UFH) once the INR falls below 2 [52]. LMWH may be stopped 24 h prior to surgery, while UFH may be stopped 6 h beforehand (Fig. 1.1) [52–54]. Once surgery is completed and hemostasis has been achieved, the patient should be restarted on LMWH or UFH, as a bridge to warfarin. Similarly, patients with atrial fibrillation and at high risk for thromboembolism (Table 1.3) should be restarted on warfarin after surgery, with a LMWH/UFH bridge, as soon as possible once the bleeding risk and hemostasis have been addressed (Fig. 1.1) [52].

Table 1.3

Thromboembolic risk conditions

	Low thromboembolic risk (Bridging generally not required)	High thromboembolic risk (Bridging generally required)
Mechanical valves	Bileaflet aortic valves (most common)	All right-sided valves (rare) All mitral valves Certain aortic valves Tilting disc Caged ball Other risk factors for thromboembolism^a
Atrial fibrillation	Low CHA₂DS₂-VASc score	High CHA₂DS₂-VASc score^b Prior stroke
DVT/PE	Remote	Recent (<3 months)

^aRisk factors include: previous thromboembolic event, concurrent atrial fibrillation, hypercoagulable condition, left ventricular systolic dysfunction (ejection fraction <30%), or more than one mechanical valve

^bNot well defined in the literature

Fig. 1.1

Warfarin dosing in setting of high thromboembolism risk

Patients with low-risk mechanical valves or atrial fibrillation with low- or intermediate-risk CHA₂DS₂-VASc score (Table 1.3) should consider stopping warfarin 5 days before surgery and be restarted on anticoagulation after surgery, with no need for full-dose bridging with LMWH or UFH (Fig. 1.2) [55]. Note that VTE prophylaxis is still indicated in these patients.

Fig. 1.2

Warfarin dosing in setting of low thromboembolism risk

Patients on a DOAC undergoing robotic urologic procedure should have their last dose of the drug held 2–5 days prior to surgery, based on the DOAC used and their creatinine clearance (CrCl). Patients on dabigatran and CrCl >50 ml/min should stop the drug 2–3 days before surgery, while those with a CrCl of 30–50 mL/min should stop the drug 3–5 days prior to surgery, depending on bleeding risk [56]. Similarly, patients on apixaban and rivaroxaban should stop the drug 2–3 days before surgery, with the longer duration for those undergoing high bleeding risk procedures. Patients with high risk for thromboembolism may benefit from bridging with LMWH or UFH; however, there is an associated increased risk of bleeding [57, 58]. If the patient has a low thromboembolic risk with low bleeding risk, DOACs may be restarted 24 h postoperatively; if there is a high bleeding risk, it may be restarted with a delay: 48–72 h postoperatively (Table 1.4).

Table 1.4

Direct oral anticoagulants and interval dosing