Fig. 5.1
Cardiac evaluation and treatment algorithm for noncardiac surgery based on active clinical conditions, known cardiovascular diseases, or cardiac risk factors for patients >50 years (Fleischer et al. [1]. Reprinted with permission)
Patient risk factors include “Active Cardiac Conditions” and “Clinical Risk Factors.” “Active Cardiac Conditions” include unstable coronary syndromes (recent myocardial infarction, unstable or severe angina), decompensated heart failure, significant arrhythmias, and severe valvular disease [1]. If the patient has “Active Cardiac Conditions” and is scheduled for elective surgery, the patient should be evaluated and treated prior to the operation or procedure. “Clinical Risk Factors” include ischemic heart disease, cerebrovascular disease, compensated heart failure, diabetes mellitus, and renal insufficiency [1].
In addition to patient risk factors, the risk of the surgical procedure is another component of cardiac risk stratification to consider in the evaluation of patients for noncardiac surgery. High–risk surgeries (cardiac risk >5 %) include emergency procedures, aortic and other major vascular surgeries, and peripheral vascular surgeries [1]. Intermediate–risk surgeries (cardiac risk 1–5 %) include carotid endarterectomy, head and neck surgery, abdominal and thoracic surgery, orthopedic surgery, prostate surgery, and endovascular aortic aneurysm repair [1]. Low–risk surgeries (cardiac risk <1 %) include endoscopic procedures, cataract surgery, and breast surgery [1].
Lastly, one needs to determine the patient’s functional capacity. A patient has good functional capacity when he or she is able to perform a Metabolic Equivalent Task (MET) of greater than or equal to four without chest pain or shortness of breath. Activities involving METs of four include climbing stairs or walking at a brisk pace (4 miles per hour).
Electrocardiogram (ECG)
Per ACC/AHA Guidelines, a preoperative 12-lead ECG is recommended for patients with at least one clinical risk factor who are undergoing vascular procedures and for patients with known coronary heart disease, peripheral arterial disease, or cerebrovascular disease who are undergoing intermediate-risk surgery [1]. If the preoperative ECG is abnormal, the ECG should be compared to a previous ECG to assess if the change is old or new. In addition, patients with pacemakers and/or implantable cardioverter-defibrillators should have a preoperative ECG.
Hypertension
Hypertension is known to cause end-organ disease including coronary artery disease, congestive heart failure, renal, and cerebrovascular disease. To address the association of hypertension and perioperative cardiac risk in the perioperative period, Howell et al. showed that postponing anesthesia and surgery in patients with hypertension does not reduce perioperative risk [2]. Thus, for patients with a systolic blood pressure ≥180 mmHg and a diastolic blood pressure ≥110 mmHg, the risks of performing an operation or a procedure must be weighed against the benefits of delaying it for a period of time required to medically optimize the patient’s blood pressure [1].
Angioplasty
Patients who had balloon angioplasty should have their elective surgery or procedure delayed for at least 2–4 weeks [3].
Coronary Stents
Patients with coronary stents scheduled for esophageal operations or procedures need to have prior to surgery a note in their medical record from the cardiologist stating whether the patient has a bare-metal stent or drug-eluting stent, when the coronary stent was placed, the type of stent, the results of any cardiac testing completed since the stent was placed, and the cardiologist’s recommendations of when it is safe to discontinue thienopyridine (Clopidogrel) and aspirin therapy. It is the prescribing physician’s decision when it is safe to stop thienopyridine and aspirin therapy. The patient should be asked what symptoms he or she had prior to the stent placement and if those symptoms have returned since the coronary stent was placed. If the patient’s symptoms have returned since the coronary stent was placed, this may be a sign that the patient is having coronary ischemia. This change in symptoms should be communicated to the cardiologist prior to proceeding with an elective operation or procedure.
Bare-Metal Stents
Patients with bare-metal stents are at increased risk of stent thrombosis in the first 2 weeks, which can result in a myocardial infarction or death [1]. Four to six weeks after stent placement, endothelialization of the stent occurs, after which the risk of thrombosis decreases [1]. It is thus recommended to delay elective surgery 4–6 weeks after bare-metal stent placement [1]. Thienopyridine and aspirin are administered for 4 weeks after bare-metal stent placement to reduce the risk of stent thrombosis. Aspirin therapy is often continued perioperatively unless the risk of bleeding outweighs the benefits of continued therapy.
Drug-Eluting Stents
For patients with drug-eluting stents, thienopyridine therapy and aspirin are continued for at least 1 year after stent placement to prevent stent thrombosis that can result in a myocardial infarction or death [1]. Elective surgeries or procedures should be delayed at least 12 months after the initiation of thienopyridine and aspirin therapy [1].
Cardiac Implantable Electronic Devices (CIED): Pacemakers, Implantable Cardioverter-Defibrillators (ICD)
During the preoperative evaluation, information from patients with CIEDs needs to be obtained to avoid untoward events in the perioperative period including abnormal rhythms, electromagnetic interference, and pulseless-electrical activity. It is essential to inquire about the type of device (pacemaker, ICD), if the patient is CIED dependent, when the device was last interrogated, when the battery was last changed, and the functioning of the device. A comprehensive evaluation of the device should be completed by a cardiologist or a CIED service preoperatively. Stone et al. recommend that in general pacemakers be evaluated within the last 12 months and ICDs be checked within the last 6 months [4]. Perioperative recommendations for the management of the CIED are obtained from the cardiologist or CIED service including whether or not reprogramming of the device is required.
Pulmonary Evaluation
Chest X-Ray (CXR)
Patients with esophageal disease may have a smoking history or a history of aspiration. A preoperative CXR may reveal aspiration and pulmonary or cardiac disease. The clinical indications for a preoperative CXR include cardiac or thoracic surgery, assessment of a possible mass compressing the trachea, active chest disease, decompensated heart failure, intrathoracic malignancy, radiation to the thoracic region, and pulmonary or mediastinal masses [5].
Pulmonary Function Tests (PFTs)
There usually are no routine clinical indications to obtain preoperative PFTs. However, preoperative PFTs can reveal potential pulmonary function in patients undergoing surgical resection of the lung [5]. Baseline PFTs for patients with severely compromised pulmonary function, such as patients with bronchiolitis obliterans syndrome related to GERD after lung transplantation surgery scheduled for laparoscopic antireflux surgery, can aid in the assessment of weaning from mechanical ventilation and extubation [6].
Smoking
Smokers have an increased risk of postoperative wound infections [7], pulmonary complications, anastomotic leaks [8], a higher rate of intensive care unit admissions postoperatively [9], and prolonged mechanical ventilation [10]. For those patients offered a program to stop smoking with an assumed 25 % cessation rate, Mills et al. estimate two million less postoperative complications [11]. Ideally it is recommended to have patients stop smoking at least 8 weeks prior to surgery [12].
Obstructive Sleep Apnea Syndrome (OSAS)
OSAS affects over 20 million Americans [13]. By the year 2050, it is estimated that nearly 100 million Americans will have a sleep disorder [13]. The prevalence of OSAS is 1–9 % for patients presenting for surgery [14]. However, approximately 80–90 % of adults with OSAS are undiagnosed [15]. This means that patients may present for surgery and anesthesia without a known diagnosis of OSAS. OSAS that goes undiagnosed is associated with increased perioperative morbidity and mortality [16, 17]. It is therefore important to screen patients at risk for OSAS preoperatively. Chung et al. developed and validated a screening tool, “STOP-BANG” [18, 19]. Patients are considered high risk for OSA if they have three or more of the items shown in Table 5.1 [18, 19]. Vasu et al. showed that a high score (3 or greater) of the STOP-BANG questionnaire revealed an approximate tenfold risk for postoperative complications [20].
Patients with OSAS are at increased risk for airway collapse and thus are more sensitive to the effects of narcotics, benzodiazepines, and inhaled anesthetics both intra- and postoperatively. Furthermore, these patients may have a potentially difficult airway, may experience exacerbation of hypoxemia and hypercarbia, cardiac arrhythmias and ischemia, hypertension, and increased postoperative wound infections [17] as well as progression to right heart failure from resulting pulmonary hypertension. Complications and the length of hospital stay can be reduced if patients with OSAS use their continuous positive airway pressure (CPAP) mask prior to surgery [17]. In addition, preoperative polysomnography should be scheduled for those at risk for OSAS without CPAP therapy and patients with OSAS should be encouraged to bring their CPAP machine the day of surgery for possible use after extubation.
Pulmonary Aspiration
When patients are unconscious, they lose their normal ability to protect their airway reflexes and are then at risk for aspiration. Virtually all patients with esophageal diseases are at increased risk for aspiration during anesthesia and surgery. Patients with gastroesophageal reflux disease (GERD), achalasia, large hiatal and paraesophageal hernias, gastrointestinal motility disorders, pregnancy, obesity, and patients who have eaten prior to surgery outside of the American Society of Anesthesiologists (ASA) Guidelines [21] (Table 5.2) are at increased risk for pulmonary aspiration and its consequences. Aspiration can occur at the induction of anesthesia, at extubation, or in the postoperative period.
Clear liquidsa | 2 h |
Breast milk | 4 h |
Infant formula | 6 h |
Light meal | 6 h |
Fried, fatty foods | 8 h |
Aspiration has significant physiological consequences. The clinical effects of aspiration can range from cough and laryngospasm to a chemical pneumonitis and death. Chronic aspiration can lead to pneumonia, sepsis, hypoxemia, and restrictive lung disease. Sakai et al. conducted a 4-year retrospective analysis of the incidence and outcome of perioperative pulmonary complications (PPA) and found that from 99,441 anesthetic procedures, 14 patients had PPA [22]. Interestingly, 50 % occurred during gastroesophageal procedures [22]. Out of the 14 cases, 10 occurred under general anesthesia and 4 occurred under monitored anesthesia care [22]. Six patients with PPA developed pulmonary complications and one of these six patients died [22]. The current incidence, morbidity, and mortality of PPA were therefore 1/7,103, 1/16,573, and 1/99,441, respectively [22].
To reduce the risk of and consequences of aspiration, one should follow these preoperative strategies:
1.
Initial assessment that includes the identification of risk factors for aspiration.
2.
3.
Preoperative Pharmacologic Management . The ASA Committee on Standards and Practice Parameters states that there is insufficient literature to evaluate the effects of gastrointestinal prokinetics, histamine-2 receptor antagonists, non-particulate antacids, and proton pump inhibitors on the incidence of pulmonary aspiration in the perioperative period [21]. Yet, in clinical practice, these agents are utilized to reduce gastric volume and gastric pH and increase gastric emptying preoperatively in selected patients at risk for aspiration [21].
The routine use of these agents is not recommended in patients not apparently at increased risk for pulmonary aspiration [21].
4.
Airway Protection. Various techniques, including an awake intubation, are utilized to secure the airway and reduce the risk of pulmonary aspiration. For example, an awake fiberoptic intubation may be used in patients who have a difficult airway and are at high risk of pulmonary aspiration. A rapid sequence induction is another technique utilized to induce general anesthesia in patients at high risk for aspiration despite few objective data supporting the efficacy of this technique [23]. A rapid sequence induction involves preoxygenating the patient, the application of cricoid pressure (Sellick maneuver), intravenous medications to induce anesthesia, the administration of a rapid-acting neuromuscular blocking agent, and the immediate intubation of the trachea without mask ventilation. Cricoid pressure is contraindicated in patients with tracheal injury, active vomiting, and an unstable cervical spine injury. Should alternative airway devices be used, a laryngeal mask airway offers less protection against aspiration than cuffed endotracheal tubes [24].
Nasogastric Tubes
Suctioning nasogastric tubes preoperatively and prior to extubation are strategies that minimize the risk of aspiration. These are especially indicated preoperatively in patients with achalasia with a dilated esophagus filled with food contents and in patients with large hiatal hernias. Moreover, the blind placement of a nasogastric tube is not indicated in patients with epiphrenic diverticula as it may perforate the diverticulum.
Intraoperative Monitoring
The decision of which monitors to utilize for esophageal surgery and procedures is based on the planned procedure and the extent of the patient’s comorbidities. ASA standard monitors of noninvasive blood pressure, electrocardiogram, pulse oximeter, and capnography are utilized for endoscopic procedures and minimally invasive procedures [25]. Per ASA Guidelines, significant changes in body temperature should be monitored when these changes are intended, anticipated, or suspected [25]. Invasive monitoring (arterial line) to continuously monitor blood pressure is utilized in transthoracic surgeries, surgeries involving one-lung ventilation, and in patients with significant cardiac or pulmonary comorbidities. Central venous lines are placed in those patients with poor peripheral intravenous access, those patients requiring vasopressors and inotropic support, and septic patients. Bladder catheterization should be considered for those surgeries of long duration, involving significant blood loss, and with extensive fluid shifts.
One-Lung Ventilation (OLV)
OLV facilitates the surgical approach for transthoracic approaches to the esophagus and for thoracoscopic esophageal surgery. The practitioner must become familiar with the airway anatomy, be aware if the patient had any prior radiation therapy to the head/neck, and be aware of existing compression of the trachea. Patients with severe pulmonary disease may not tolerate OLV secondary to the inability to oxygenate and ventilate.
Methods to achieve lung separation include double-lumen endobronchial tubes, bronchial blockers, uninvent tubes, or advancing a single-lumen endotracheal tube into the main stem bronchus.
Double-Lumen Endobronchial Tube (DLT)
One method of achieving OLV requires the use of a DLT with one lumen reaching a main stem bronchus and a second lumen ending in the distal trachea. Two cuffs, a proximal tracheal cuff and a distal bronchial cuff, allow achieving lung separation. There are two types of DLTs, right sided and left sided. Since the right main stem bronchus is shorter than the left main stem bronchus and the right upper lobe bronchus begins 1.5–2 cm from the carina, the right-sided DLTs have a slot on the endobronchial side of the tube to facilitate ventilation of the right upper lobe. Although left-sided DLTs are more commonly utilized, there are specific indications for right-sided DLTs. These include abnormal anatomy at the entrance of the left mainstem bronchus and operations involving the left mainstem bronchus [26]. The position of a DLT can be confirmed by auscultation, fiberoptic bronchoscopy, fluoroscopy, chest radiography, selective capnography, and use of an underwater seal. Problems associated with the use of a DLT are airway trauma, incorrect positioning of the endobronchial tube [26], and tension pneumothorax in the dependent, ventilated lung [27]. Patients with a difficult airway requiring OLV can undergo an awake fiberoptic intubation with a single-lumen endotracheal tube with the use of a tube exchanger to place a DLT once the patient is under general anesthesia. The position of the DLT is confirmed with auscultation and a fiberoptic bronchoscope. Consideration of exchanging a DLT to a single-lumen endotracheal tube at the end of the operation should be made for those patients requiring prolonged postoperative ventilation.
Bronchial Blockers
Bronchial blockers are an alternative method to achieve lung separation. Bronchial blockers allow the collapse of a lung distal to the occlusion and are placed through the lumen of a single-lumen endotracheal tube, alongside a single-lumen endotracheal tube, or through the glottis or tracheostomy. For an adult, nine French blockers are adequate. Conditions that may give a preferential use to bronchial blockers include a potentially difficult airway, an awake intubation, and postoperative ventilation. After prolonged ventilation, bronchial blockers avoid switching from a double-lumen to a single-lumen tube for postoperative ventilation thus potentially preventing airway compromise [26]. Patients with a difficult airway requiring OLV can undergo an awake fiberoptic intubation with a single-lumen endotracheal tube after the airway is anesthetized. Once the position of the endotracheal tube in the trachea is confirmed, a bronchial blocker is then placed.
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