Management: Patients should be admitted to the ICU for at least 24 hours of observation. An ECG should be obtained in most patients. Invasive hemodynamic monitoring, including an arterial line, central venous, or possibly pulmonary artery catheter, may be needed. All causes of tachycardia, hypertension, hypotension, anemia, and pain should be treated aggressively. Heart rate control is of paramount importance in acute ischemia. Six-month mortality and troponin levels are reduced by administration of β-blockers and optimization of the oxygen supply–demand ratio.[7] Reduced heart rate improves myocardial perfusion time during diastole. However, care must be taken to maintain adequate blood pressure with intravenous fluids while optimizing the heart rate. Nitroglycerin can be administered in the absence of hypotension. Nitroglycerin reduces ventricular wall tension by decreasing preload via venodilation, and may vasodilate coronary arteries. Morphine can be used to treat chest pain unresponsive to nitroglycerin. Morphine relieves anxiety and decreases heart rate, thereby reducing myocardial oxygen demand. Among medical patients experiencing MI, orally administered aspirin contributes substantial reduction (23%) to mortality.[8] With aspirin administration for the surgical patient one must weigh the risk of postoperative bleeding against the potential survival benefits. For most surgical patients, the benefits of aspirin will outweigh the risks when the clinical suspicion for MI is high. Patients for whom small quantities of bleeding may be devastating, including patients with recent intracranial, spinal, or ocular procedures, require special attention before a decision to administer aspirin is made. For patients who may benefit from aspirin but are not yet able to take oral medications, aspirin may be administered per rectum. Emergent coronary intervention, anticoagulants, or glycoprotein IIb/IIIa antagonists are rarely indicated owing to the risk of bleeding unless ST-segment elevation or intractable cardiogenic shock ensues.[9] In the perioperative setting, the use of these agents must be individualized based upon risk–benefit analysis, taking into account the risk of bleeding posed by the recent surgery.
Pulmonary embolism
Although surgical patients are a diverse group, there are characteristics that put this population at high risk of deep venous thrombosis (DVT) and thus pulmonary embolism (PE). These factors include total hip and knee replacement, surgery for hip fracture, surgery for cancer, trauma patients, following spinal cord injury, and immobilization.[10] Pleuritic chest pain is seen in 44% of patients experiencing acute pulmonary embolism.[11] Other symptoms include dyspnea, cough, orthopnea, lower extremity pain or swelling, and wheezing. Signs include tachypnea, tachycardia, rales, decreased breath sounds, an accentuated pulmonic component of the second heart sound, and jugular venous distension. Circulatory collapse is uncommon, but massive PE may be accompanied by acute right heart failure. It is important to keep in mind that many of these symptoms, including chest pain, may be masked in the acute postoperative period.
Evaluation: Many tests can be used to contribute to the diagnosis of PE. However, in 2006, The Christopher Study proposed a simplified algorithm for evaluating the patient suspected of having a PE.[12] Here, patients were first evaluated by the modified Wells criteria and categorized as PE unlikely (score ≤4) or PE likely (score >4). Scoring for the modified Wells criteria can be found in Table 6.1. If PE was unlikely by these criteria, the diagnosis was excluded if the D-dimer level was normal. All other patients underwent CT-pulmonary angiography (CT-PA). The application of these criteria in immediately postoperative patients can be difficult, and many postoperative patients will have a positive D-dimer due to surgical trauma. Therefore, most patients clinically suspected of having PE in the PACU should be evaluated by CT-PA as soon as possible. If CT-PA is inconclusive, pulmonary angiography is recommended.
| Clinical symptoms of DVT (leg swelling, pain with palpation) | 3.0 |
| Other diagnosis less likely than (PE) | 3.0 |
| Heart rate >100 bpm | 1.5 |
| Immobilization (>3 days) or surgery in the previous 4 weeks | 1.5 |
| Previous DVT/PE | 1.5 |
| Hemoptysis | 1.5 |
| Malignancy | 1.0 |
| Probability | Score |
| Traditional clinical probability assessment (Wells criteria) | |
| High | >6.0 |
| Moderate | 2.0 to 6.0 |
| Low | <2.0 |
| Simplified clinical probability assessment (modified Wells criteria) | |
| PE likely | >4.0 |
| PE unlikely | ≤4.0 |
Management: The initial management of suspected PE should focus on respiratory and hemodynamic support. Severe hypoxemia and respiratory failure should be treated with intubation and mechanical ventilation, keeping in mind that patients with right heart failure are prone to hypotension. Hypotension should be managed initially with intravenous fluid administration. One study found that administration of 500 ml of dextran significantly improves cardiac index in patients with PE.[13] If hemodynamic status does not improve, vasopressors may be required; however, an optimal agent has yet to be determined. Beyond supportive therapy, anticoagulation with unfractionated heparin is the next step of therapy for acute PE. Patients in the immediate postoperative period are likely to be at high risk for excessive bleeding; thus anticoagulation and thrombolytic therapy may not be possible after many procedures. In these cases, placement of an inferior vena cava filter is an acceptable alternative to prevent further embolism. Percutaneous or open surgical embolectomy may be considered in cases with severe hypotension or hypoxemia despite supportive therapy.
Pneumothorax
Pneumothorax (PTX) may occur in the perioperative patient because of complications of central venous access placement, barotrauma from positive pressure ventilation, or direct surgical trauma. PTX usually presents in the mechanically ventilated patient shortly after the inciting event. In the intubated patient, PTX may be suspected following the onset of high peak inspiratory pressures and possibly hypotension. However, the presentation may be delayed until PACU admission. Signs and symptoms of PTX include chest pain, dyspnea, tachypnea, unequal or unilaterally absent breath sounds, and hyperresonance to percussion on the affected side. Suspicion of PTX should be increased in the setting of recent subclavian central line placement, intercostal nerve blocks, chest trauma, or surgery at or near the diaphragm (liver resection, nephrectomy, splenectomy, hiatal hernia repair, gastric or esophageal resection).
Evaluation: Tension PTX can lead to rapid hemodynamic collapse and therefore requires rapid diagnosis and treatment. Signs include hypotension, tachycardia, tracheal deviation, completely absent breath sounds on the affected side, and jugular venous distension. PTX is often evaluated initially by chest X-ray. This evaluation can be performed in upright, supine, or lateral decubitus positions. Frequently, portable anteroposterior chest X-ray in the semi-upright position is the most quickly obtained exam in the PACU. However, the lateral decubitus position is most sensitive and is able to detect as little as 5 ml of pleural gas.[14] CT scanning is the most accurate diagnostic modality. Bedside ultrasound has also been used to screen for evidence of PTX in emergent situations. A systematic review has demonstrated that this modality is more sensitive and specific than the supine chest X-ray.[15] Although bedside ultrasound may be useful to the anesthesiologist in diagnosing PTX in the PACU, its use has not been well-documented in this setting.
Management: Small pneumothoraces (<15% of the hemithorax) may be observed for spontaneous reabsorption by serial chest radiographs. Suspected tension PTX should be treated with immediate tube thoracostomy or needle decompression. For the latter, a 14-gauge angiocatheter can be used. A length of up to 7 cm may be needed. Acceptable puncture sites include the second or third intercostal space in the midclavicular line or the fifth intercostal space in the midaxillary line. Needle decompression should produce an audible rush of air, and be followed by chest tube placement as soon as possible.
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