Postoperative Care of the Critically Ill

Key Points

1.
Cerebrovascular accidents are some of the most significant perioperative complications because they increase long-term disability, hospital length of stay, and mortality.
2.
Recent stroke is associated with a 1.8-fold increased risk of death in noncardiac surgery.
3.
There are a broad spectrum of critical care issues involving the pulmonary system, ranging from chronic diseases to surgical and anesthesia complications.
4.
Postoperative respiratory failure can be defined as unplanned intubation and mechanical ventilation within 48 hours of noncardiac surgery.
5.
Postoperative pulmonary edema can be either cardiogenic (e.g., heart failure) or noncardiogenic (e.g., negative pressure–induced) in origin.
6.
Massive transfusion in the perioperative period is still a significant cause of morbidity and mortality. The exact ratio of plasma to platelets to red blood cells has yet to be delineated.
7.
High-risk patients may have up to a 6% risk of developing venous thromboemboli in the postoperative period. Both deep venous thrombosis and pulmonary emboli require anticoagulation if it is not contraindicated by surgery.
8.
The initial treatment of sepsis revolves around three concepts: source control of infection, antibiotics, and early goal-directed resuscitation.

This chapter focuses on postoperative care of critically ill surgical patients and complications from surgery. It is organized by organ system and is intended to be an introduction to the topics that it covers. This is not an exhaustive review of critical illness. The Suggested Reading section is provided for a more in-depth review of the topics that are covered. Consultation with a specialist should be considered when clinically appropriate.

Neurologic System

Perioperative Cerebrovascular Accident

Cerebrovascular accident (CVA) is one of the most significant perioperative complications. The incidence of perioperative CVA in the general surgical population depends on the type of procedure and associated perioperative risk factors, but it remains low at approximately less than 0.7%. CVA, however, is responsible for a substantial increase in long-term disability, longer intensive care unit (ICU) and hospital stay, and mortality. The etiology is primarily embolic, and it is far more common than those related to hypoperfusion. Noncardiac surgery induces a hypercoagulable state, and tissue trauma enhances formation of thrombus and inflammation. Surgical stress is marked by decreased levels of tissue plasminogen activator (tPA), increased fibrinogen degradation products, increased thrombin-antithrombin complexes, and increased d -dimers. These prothrombotic changes coupled with dehydration, bed rest, general anesthesia, and cessation of anticoagulants increase the risk for postoperative CVA. The majority of CVAs occur on the second postoperative day and are typically related to the development of atrial fibrillation or myocardial ischemia.

Common perioperative risk factors are listed in Tables 21.1 and 21.2 . Modifiable risk factors may be addressed in the preoperative period to reduce morbidity and mortality.

Table 21.1

Modifiable Factors Affecting Cerebrovascular Accident Risk

Preventive	Therapeutic
Decreased surgical time Carotid artery revascularization in symptomatic patient β-Blockers Statins Glycemic control Continuation of anticoagulants when safe Consider delaying elective surgery for >9 months after cerebrovascular accident	Intravenous tissue plasminogen activator: higher risk of bleeding Supportive care: intubation for airway protection and mechanical ventilation Intraarterial thrombolysis: questionable efficacy Endovascular mechanical clot disruption: questionable efficacy

Table 21.2

Cerebrovascular Accident Risk Factors

Preoperative	Intraoperative	Postoperative
Patient age >70 years Female sex History of cerebrovascular accident or transient ischemic attack History of symptomatic carotid artery stenosis Atherosclerosis of the ascending aorta History of hypertension Diabetes Creatinine >2 mg/dL History of cardiac disease Peripheral vascular disease Ejection fraction <40% Smoking	Surgery type Type of anesthesia (general vs. local) Duration of surgery Manipulation of proximal aortic lesions Arrhythmias Hyperglycemia Hypotension Hypertension	Heart failure Low ejection fraction Myocardial infarction Arrhythmias Dehydration Blood loss Hyperglycemia

Preventive strategies for perioperative CVA are not well defined. Decreasing surgical time may reduce risk for CVA, but this may be difficult to modify. Patients with symptomatic carotid artery stenosis may benefit from carotid revascularization before undergoing major surgery. However, at least one study of 2000 high-risk patients undergoing noncardiac surgery suggested no association between carotid artery stenosis and perioperative stroke. Preliminary studies suggest a small reduction in perioperative stroke risk with perioperative β-blockers, statins, and glycemic control. Timing of elective noncardiac surgery in patients with a prior stroke is important. A large database study suggested that a recent stroke is associated with a 1.8-fold increase risk of death in patients undergoing noncardiac surgery less than 3 months after a stroke, which stabilizes at approximately 9 months. The perioperative care team might consider delaying elective noncardiac surgery when feasible.

Perioperative anticoagulation should be continued whenever the risk of bleeding is deemed low by the surgical team. Cessation of anticoagulation may result in an increased risk of perioperative CVA. Discontinuing aspirin is likely to exacerbate the already increased hypercoagulable state of surgery. Guidelines suggest continuing aspirin in all perioperative situations except for those with very low cardiac risk or in situations in which even minor bleeding may be catastrophic. Warfarin and clopidogrel are often stopped several days before surgery. Cessation of these medications should be based on each unique clinical situation. Bridging anticoagulation with heparin or low-molecular-weight heparin may be considered in patients at high perioperative risk of stroke and when hemorrhage is also a concern. If oral anticoagulants must be held before surgery, it is prudent for the managing service to restart these drugs as soon as appropriate in the postoperative period. Consultation with a specialist may be prudent.

Therapies for perioperative CVA are few. Recent guidelines suggest that early diagnosis and management in a stroke unit with general supportive care is paramount. Intravenous (IV) tPA is a proven therapy for ischemic CVA but is relatively contraindicated after major surgery because of bleeding risk. Each case should be evaluated by the perioperative team and, if possible, an expert in the field of CVA. Other modalities such as intraarterial thrombolysis and endovascular mechanical clot disruption may be appropriate for those who have undergone recent major noncardiac surgery, but the benefit remains unproven.

Pulmonary System

There are a broad spectrum of critical care issues involving the pulmonary system in the perioperative settings. These may arise from primary pulmonary disease, such as chronic obstructive pulmonary disease (COPD), or secondary manifestations such as cardiogenic pulmonary edema or neuromuscular weakness. This section focuses on key perioperative respiratory diseases, including pulmonary edema, COPD exacerbations, and acute lung injury or acute respiratory distress syndrome (ARDS) as well as management strategies for these syndromes in the perioperative setting.

Respiratory Failure

Respiratory failure can be categorized into two broad types, which are described next ( Table 21.3 ).

Table 21.3

Types of Respiratory Failure

Type	Definition	Mechanism	Common Diseases and Risk Factors
1	Hypoxemic	Low O ₂ admixture V/Q mismatch Shunting Diffusion impairment Alveolar hypoventilation	Cardiogenic pulmonary edema ARDS PE Pneumonia Shunts (right to left)
2	Hypercarbic	Central respiratory depression Respiratory system mechanical failure Respiratory muscle fatigue	Neuromuscular disorders (e.g., ALS, Guillain-Barré syndrome) COPD

ALS, Amyotrophic lateral sclerosis; ARDS, acute respiratory distress syndrome; COPD, chronic obstructive pulmonary disease; PE, pulmonary embolism; V/Q, ventilation/perfusion.

Type 1 Respiratory Failure: Hypoxemic

Hypoxemic respiratory failure is typically associated with parenchymal lung diseases that affect oxygen exchange at the alveolar level. It is defined as a PaO ₂ less than 50 mm Hg on room air. Five pathophysiologic mechanisms can explain hypoxemia—low oxygen admixture, ventilation/perfusion (V/Q) mismatch, shunting, diffusion impairment, and alveolar hypoventilation. Shunt physiology is unique because it is nonresponsive to supplemental oxygen. Pulmonary edema and ARDS are two examples of hypoxemic respiratory failure and are discussed later in this chapter.

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