Thoracic Surgical Patient

Chapter 94


Thoracic Surgical Patient image



This chapter focuses on the perioperative care of patients undergoing thoracic surgical procedures and emphasizes key issues surrounding the management of these patients in the intensive care unit (ICU).



Preoperative


The preoperative evaluation of patients undergoing lung or esophageal surgery is often complex, and the decision to operate is heavily influenced by comorbid conditions and the urgency of the procedure. Although a comprehensive discussion of this topic is beyond the scope of this chapter, important elements to consider in all patients undergoing thoracic surgery include optimal imaging; evaluation for metastatic disease; and evaluation of pulmonary function, cardiac risk stratification, and management of comorbid conditions.


It is imperative to emphasize to patients the importance of smoking cessation several weeks prior to surgery. Although the optimal time interval between smoking cessation and lung resection remains poorly defined, a minimum of 2 to 3 weeks is advised. Quitting tobacco closer to the date of surgery has been shown to invoke a hypersecretory response in the airways. Additionally, patients should be encouraged to start an exercise program when appropriate. This serves as the foundation for mobilization and exercise after discharge. In patients with evidence of reactive airway disease, bronchodilator therapy should be optimized while minimizing the use of systemic steroids. Finally, all medications should be carefully reviewed with specific attention to whether the patient takes antiplatelet or anticoagulation agents. If the patient requires ongoing anticoagulation, a plan for postoperative anticoagulation should be developed.



Intraoperative


Critical elements of care during the thoracic procedure include patient positioning, analgesia strategies, ventilator and acid-base management, fluid replacement, and extubation considerations. For most thoracic procedures epidural analgesia, typically placed prior to the induction of general anesthesia, is appropriate. If placement of an epidural catheter is anticipated, the American Society of Regional Anesthesia and Pain Medicine has made specific recommendations regarding anticoagulation surrounding the time of the procedure (Table 94.1). The narcotic sparing effects of epidural analgesia combined with the excellent pain coverage make epidural analgesia optimal for thoracic surgical procedures. When this is not an option, however, intercostal nerve blockade with long-acting local anesthetic agents or placement of extrapleural or paravertebral infusion catheters may be a viable alternative (Chapter 87). image



The positioning for thoracic surgical procedures can have profound implications on the conduct of the operation as well as the anesthetic management. Most pulmonary resections are conducted in the lateral decubitus position, and a beanbag or other support device can be used to maintain this position. During positioning, it is imperative to pay close attention to axillary and arm position to avoid injury to the brachial plexus or other peripheral nerves. Adequate intravenous access, typically without the requirement for central access or monitoring, is usually established prior to positioning. Radial arterial cannulation and bladder catheterization are also typically employed. As with any surgical procedure that is anticipated to last several hours, appropriate padding and cushioning to prevent rhabdomyolysis and skin breakdown are important.


Most thoracic procedures require the institution of single lung ventilation. Careful monitoring of airway pressures during the operation is critical to avoid barotrauma. The relationship between fluid management and barotrauma continues to be an active area of investigation, but barotrauma seems to predispose to capillary leak and the development of postoperative pulmonary edema. This is particularly important during lung resection or pneumonectomy. The development of postpneumonectomy pulmonary edema or acute respiratory distress syndrome (ARDS) in the remaining lung remains a vexing clinical problem that is mitigated by attention to these intraoperative factors.



Postoperative


These patients should generally be cared for in units where the nursing and ancillary staffs are familiar with the salient issues. Information that should be discussed during daily rounds includes vital signs, oxygenation, urine output, chest tube output, telemetry for arrhythmia detection, respiratory patterns and lung exam, status of air leaks, ambulation, and bowel function. The remainder of this chapter focuses on specific issues that are particularly relevant to the thoracic surgical patient in the postoperative period.



Initiating Enteral Feeding


Most patients who undergo pulmonary resection can eat the next day or, rarely, the same day of surgery. It is critical, however, to minimize the risk of aspiration. Aspiration is a common occurrence following thoracic surgery, in part related to laryngeal dysfunction resulting from double lumen endotracheal tube placement. One of the most effective methods to minimize aspiration is to ensure the patient is not in the recumbent or semirecumbent position while eating. Formal swallow evaluations have not been found effective when performed routinely on all patients, but informal supervision during the early phase of recovery to detect cough and to emphasize the importance of careful mastication and swallowing is helpful. Thin liquids are usually difficult for patients with a compromised larynx to swallow properly, and thickening agents or delayed introduction of thin liquids should be considered. Patients who have undergone esophageal procedures are at even higher risk of aspiration likely related to neurapraxia and muscle dysfunction from cervical dissection. In these patients, introduction of oral nutrition or medications is typically delayed to permit esophageal anastomoses to heal. Hoarseness, often indicative of recurrent laryngeal nerve dysfunction, can also last for several days because of vocal cord edema.



Fluid and Electrolyte Management


Avoidance of hypervolemia is critical in patients undergoing thoracic surgical procedures. There are several mechanisms by which lung resection is thought to increase the risk of perioperative pulmonary edema. These include direct lung injury during intraoperative lung manipulation, disruption of lymphatic drainage by mediastinal lymphadenectomy, and alveolar hyperinflation (so-called volutrauma or ventilator-associated lung injury [VALI]) during single lung ventilation. Additionally, extensive lung resection decreases the total cross-sectional area of the pulmonary vasculature resulting in increased blood flow to the remaining lung, typically at higher pressure. This increased blood flow leads to increased pulmonary capillary pressures and increased transcapillary fluid flux caused by Starling forces. As a result, patients who undergo pneumonectomy are at especially high risk for postoperative respiratory decompensation, known as postpneumonectomy ARDS (despite being unilateral), and volume restriction is particularly important in these patients. Interestingly, studies that have evaluated the pleural fluid in patients with new effusions postoperatively have found the effluent to be exudative rather than transudative. This has led many to believe that the etiologies of effusion and edema are more complex than simply “fluid overload.”


In general, most patients who are postoperative from thoracic surgery should be maintained on a low rate (0.5 mL/kg/h) of intravenous fluids. These can be discontinued once the patient is able to tolerate oral intake. A urine output of 0.5 mL/kg/h is usually acceptable. Diuresis should be augmented as tolerated to wean off supplemental oxygen. image


Electrolyte abnormalities are common in the perioperative setting. Hypokalemia should be aggressively corrected to reduce the risk of arrhythmias. Hyperkalemia should typically be treated first with diuretic administration. Hyponatremia, often from syndrome of inappropriate antidiuretic hormone (SIADH), is also common and should be treated with free water restriction, added dietary salt, and attention to other electrolyte abnormalities, particularly potassium (Chapters 39 and 84). Serum sodium concentrations in the 131 to 135 mEq/L range are common and can be managed without aggressive therapy.

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Jul 7, 2016 | Posted by in CRITICAL CARE | Comments Off on Thoracic Surgical Patient

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