**2.2 Cardiovascular disease**

According to the guidelines of the American College of Cardiology (ACA)/ American Heart Association (AHA) Task Force, surgical interventions can be classified into three categories according to the risk associated with the procedure itself [11]:


Similarly, patients can be stratified in three categories based on the presence of risk factors for perioperative complications:


The recommendations provided by the AHA/ACC and the ESAIC can be schematically summarized for patients undergoing elective hip replacement as follows: patients with major risk factors require immediate cardiological evaluation, which, in most cases, will lead to myocardial revascularization, valve surgery, or modification of current medical therapy. In this case, the surgery can only be postponed unless it is considered an emergency and, therefore, undelayable. Patients with intermediate risk factors can undergo elective surgery without additional investigations if their functional reserve is at least moderate, and the proposed intervention is at (low or) intermediate risk such as hip replacement. The use of the risk calculator of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a recommended tool for cardiac perioperative risk stratification. In addition, the assessment of high-sensitivity cardiac troponins in high-risk patients 48 hours before

and 72 hours after major surgery is recommended to detect preexisting or postoperative cardiac failure [12]. Therapy with beta blockers should be continued throughout the perioperative period, mostly in patients who have known ischemic heart disease or myocardial ischemia. In patients treated with acetylsalicylic acid, the discontinuation of the therapy should be considered in the perioperative period and should be balanced among the risk of bleeding and the risk of thrombotic complications. For patients undergoing hip replacement, the execution of a baseline electrocardiogram (ECG) in the preoperative period should be mandatory. In the case of patients belonging to the minor-risk class of cardiovascular risk (i.e., elderly patients and patients with a traumatic femur or pelvis fracture) with indication for hip replacement, prolonged monitoring outside the operating room (recovery room/ICU) is strongly recommended, as a good clinical practice to reduce the overall postoperative risk.

## **2.3 Respiratory disorders**

Since chest radiograph rarely alters the perioperative management, it should not be included among the routine investigations. Similarly, spirometry is not recommended as a preoperative routine examination in all patients affected by respiratory problems. On the contrary, patients with obstructive sleep apnea syndrome (OSAS) should be evaluated carefully for potentially difficult airway in the need of ventilatory support or endotracheal intubation. History of previous surgical procedures and referred difficult airway should be investigated especially in patients with diagnosed or suspected OSAS. The use of specific questionnaires to screen for patients with OSAS is recommended when polysomnography (gold standard) is not available. In particularly, among others, the STOP-BANG questionnaire is the most sensitive, specific, and best validated score [13]. Perioperative continuous positive airway pressure (CPAP) must be continued in patients with OSAS to reduce hypoxic events. Moreover, patients with suspected or diagnosed OSAS receiving sedative or general anesthesia during or before surgery should be monitored in the immediate postoperative phase. Of note, stop smoking at least 4 weeks prior to surgery reduces postoperative complications [14].

### **2.4 Management of antiplatelets/anticoagulant drugs**

The perioperative management of anticoagulant therapy is cumbersome due to the complexity of the issue, as well as the simultaneous need to balance the risk of bleeding and the risk of thromboembolic events. On the one hand, surgery should be performed when coagulation is almost normalized to limit the risk of bleeding complications from excessive anticoagulation both during surgery and in the postoperative period. On the other hand, it is necessary to limit as much as possible the interval between the suspension and the restoration of the anticoagulant therapy in order to avoid thromboembolic complications.

A rational approach to the management of anticoagulant therapy should be multidisciplinary and involves the other specialists aiming to carefully evaluate the rationale of the ongoing therapy, the risk of bleeding related to the specific surgical procedure, and the risk of the patient to develop thromboembolic or hemorrhagic events during the complete or suboptimal anticoagulation therapy in the perioperative phase. Taken all together, the final decision should also consider all the therapeutic tools available that are able to modify the coagulation cascade in relation to the specific clinical context [15–18]. Many patients undergoing total hip replacement are on antiplatelet therapy, generally, with low-dose acetylsalicylic acid, ticlopidine, or

### *Anesthesia for Hip Replacement DOI: http://dx.doi.org/10.5772/intechopen.104666*

clopidogrel, more rarely with dipyridamole, indobuphene, or picotamide monohydrate. As for beta blockers, acetylsalicylic acid should be continued in the perioperative period, and its use is associated with a lower incidence of myocardial ischemia in the absence of a substantial increase in surgical bleeding [15]. In general, for mediumand high-risk procedures, clopidogrel should be routinely stopped 7 days before surgery with an exception for patients at high risk of thromboembolic events in whom an interval of 5 days before surgery is recommended and, if available, a platelet function test should be performed to evaluate an adequate platelet function. However, the ACC/AHA Task Force suggests that hip replacement surgery can be safely performed without stopping clopidogrel perioperatively [19]. Ticlopidine is the antiaggregant of choice in patients that are intolerant and/or allergic to acetylsalicylic acid. The antiplatelet effect persists for over 8 days after stopping the drug. The management of ticlopidine therapy in the perioperative period is not codified. For elective hip surgery, it is recommended to discontinue ticlopidine therapy, whereas for emergency procedures, in the case of significant bleeding risk, it would be preferable to perform a platelet transfusion of platelet concentrates [20, 21]. In view of the limited number of relevant publications, it is difficult to release recommendation regarding the perioperative management of antiplatelet therapy with dipyridamole, indobufen, and picotamide. Although some cases of epidural hematoma after locoregional anesthesia have been described in patients receiving acetylsalicylic acid or nonsteroidal anti-inflammatory drugs, the incidence of this complication does not appear to be significantly increased in patients treated with antiplatelet drugs [22, 23]. According to the existing knowledge, locoregional anesthesia is considered suitable for patients on antiplatelet therapy [15, 24]. Similar conclusions may not be drawn for ticlopidine because there is not yet sufficient evidence in the literature. Regarding patients treated with low-molecular-weight heparin (LMWH), heparin should be suspended based on the dosage administered depending on its use as prophylaxis or therapeutic of thromboembolic events. For hip replacement surgery, a 12-hour interval before surgery is recommended when LMWH is used at prophylactic dose. Noteworthy, when a therapeutic dose of enoxaparin (1 mg/kg) is used, a 24-hour interval is recommended. The LMWH can be generally resumed at least 12 hours after hip replacement surgery. The new oral anticoagulants (NAO or DOAC) are a recent class of drugs that act by selectively inhibiting a single coagulation factor, either II or X (**Table 1**), unlike the antivitamin K antagonists (AVK) Warfarin and Acenocoumarol, which act on several factors at the same time (VII, II, IX, and X). DOACs have been introduced


*Abbreviation: Tmax, time to peak drug concentration after dose.*

*\*Half-life varies with renal function, with increasing half-life, with increased renal impairment.*

#### **Table 1.**

*Mechanisms of action and characteristics of new oral anticoagulants.*


#### **Table 2.**

*Summary of withdrawal time of new oral anticoagulant stratified by renal clearance and type low versus high risk surgery.*

into clinical practice for the prevention of stroke and systemic thromboembolism in patients with atrial fibrillation and for the prevention and treatment of venous thromboembolism. Currently, the DOACs approved by the European Medicines Agency (EMA) on the market are the following:


**Table 1** summarizes the mechanisms of action of DOACs. **Table 2** reports the withdrawal times in relation to surgery and renal function.
