29 Postoperative Care and Complications Management

• Major complication rates in skull base surgery have been reported in the range of 10 to 50%.1,2

Infratentorial meningioma and craniopharyngioma are associated with higher rates of complications (medical and neurologic) than convexity lesions.³

For management of diabetes insipidus (DI), syndrome of inappropriate antidiuretic hormone (SIADH), and postoperative endocrine management, see Chapter 9.

Predictors of Complications for All Neurosurgical Cases⁴

• Emergency case

• Requirement of blood transfusion before surgery

• Presence of preexisting neurologic symptoms (altered mental status, paraplegia/paraparesis or quadriplegia/quadriparesis, prior stroke)

• Complex surgical approach and prolonged anesthetic treatment

• Preexisting comorbidities, especially cardiovascular and pulmonary diseases

• Alcohol use

• Chronic steroid use

Admission Considerations and Monitoring Strategies

• The importance of patient handover (Table 29.1): Appropriate care and monitoring of the postoperative neurosurgical patient requires accurate knowledge of

preoperative clinical status and comorbidities

intraoperative procedure

problems that may have occurred during surgery

anesthesia.

• Admission considerations: Immediate postoperative care and monitoring of patients after skull base surgery is traditionally provided in an intensive care unit (ICU) or in a high-dependency unit with advanced monitoring capability. However, in selected patients, ICU admission may not be necessary.⁵ The required level and duration of monitoring after skull base surgery is determined by the following:

1. Preoperative clinical status and comorbidities

2. Characteristics of the surgical procedure

3. Intraoperative events

4. Specific needs in the immediate postoperative period

• Monitoring strategies: The goal of postoperative monitoring is to identify as soon as possible patients who are deteriorating after surgery. Any delay in identifying and treating these patients may severely affect the outcome.

• Systemic monitoring: Cardiovascular and respiratory monitoring is essential in patients undergoing skull base surgery (Table 29.1).

• Neuromonitoring (Table 29.1): Routine assessment of level of consciousness and pupillary reactivity, and a neurologic examination focused on detection and monitoring of focal deficits are the cornerstones of early detection of postoperative neurologic deterioration. Anything that interferes with the ability to perform this assessment should be avoided when possible. The assessment should be repeated at regular intervals (ideally every hour initially, if possible) and any time there are signs of change in clinical status (e.g., changes in respiratory pattern, blood pressure, increased intracranial pressure (ICP), if monitored).

Table 29.1 Postoperative Considerations

^aNoninvasive blood pressure measurement may be sufficient in minor neurosurgical procedures, but continuous intra-arterial blood pressure measurement is essential when tight blood pressure control is required.

^bThe use of central venous pressure monitoring to assess fluid status and fluid responsiveness, despite still being widely diffused, has been recently challenged. A recent meta-analysis looking at its utility to predict fluid responsiveness concluded that there are no data to support this practice and recommends to abandon this approach in fluid resuscitation.77

^cAdvanced hemodynamic monitors are not routinely used in postoperatively neurosurgical patients, but they may be indicated in selected patients with severe cardiovascular complications or comorbidities.

^dETCO₂ should not be considered a reliable substitute for PaCO₂, especially in the presence of significant pulmonary disease (acute or preexistent).

Level of consciousness

Glasgow Coma Scale (GCS)7: The best motor score response is considered the most important parameter.

The FOUR (Full Outline of UnResponsiveness) score incorporates assessment of brainstem reflexes and ventilation pattern, and overcomes the failure to assess the verbal score in intubated patients⁸ (Table 29.2). The FOUR score has been shown to have a better ability to predict outcome than the GCS, but is more difficult to administer than the GCS and has not gained wide implementation.

Table 29.2 Full Outline of UnResponsiveness (FOUR) Score

Pupillary reactivity: Changes in the pupillary size and reactivity can provide important information on neurologic deterioration, presence of increased ICP, or herniation syndromes.9 The automated pupillometer provides more accurate and sensitive measurements, although its clinical usefulness and reliability are still controversial.¹⁰

Neurologic examination: It is necessary to evaluate (1) persistence/worsening of previous deficits, (2) improvement of previous deficits after surgery, and (3) appearance of new neurologic findings.

Common “normal” findings: transient headache; upturned Babinski reflex up to 2 hours postsurgery; depressed pupillary response, unilateral pupillary dilatation in awake patients, or eccentric pupil; dysarthria; asterixis; mild exacerbation of previous hemiparesis (normally lasting no more than 2 hours); unsustained clonus; and shivering unrelated to body temperature.^11–13

Concerning findings suggestive of postoperative complications: rapidly increasing headache (especially with associated vomiting), progressive drowsiness, seizures, new evolving hemiparesis, new or worsening paresthesias, vertigo, facial paresis, and pupillary changes in a fully awake patient.¹²

Neurophysiology-based assessment, consisting of advanced intracranial monitoring (e.g., ICP, cerebral blood flow and brain oxygen delivery, bio-electrical activity, cerebral metabolism), is recommended in patients with poor baseline neurologic status or requiring continuous sedation for concurrent nonneurologic complications. This form of assessment is rarely indicated for the elective, uncomplicated, skull base patient.^14–16

Blood Pressure Monitoring

Postoperative hypertension is relatively common in neurosurgical patients, and it has been associated with a higher incidence of intracerebral hemorrhage, ischemic stroke, worsening edema, and myocardial infarction.^18,19 Acute elevation of blood pressure can cause intracranial complications. Alternatively, it can be a physiological response to maintain cerebral perfusion pressure in the presence of intracranial injury. Therefore, careful blood pressure monitoring and its tight control are among the most important strategies in preventing complications in postoperative neurosurgical patients. Postoperative acute hypertension can be attributed to different causes such as under-controlled pain, anxiety, and preexisting arterial hypertension, or it can be a sentinel of a cerebrovascular event (e.g., intracerebral bleeding at operative site, subdural hematoma, or epidural bleeding).

Management

• No absolute threshold can be recommended (the level to which elevated blood pressure should be lowered depends on several factors).

• The first step in the management of postoperative acute hypertension is the identification of the underlying problem (evaluate the patient for neurologic status changes, inadequate analgesia, bladder distention, shivering, etc.).

• If, after neurologic assessment, sufficient pain control, and exclusion of other reversible causes, the decision is made to control blood pressure with antihypertensive drugs, a short-acting, titratable, intravenous agent should be administered to achieve the target blood pressure quickly, while minimizing the risk of cerebral hypoperfusion. Intravenous β-adrenergic antagonists (labetalol, metoprolol, esmolol) are an acceptable choice for treatment if there are no contraindications. With refractory hypertension or marked bradycardia, angiotensin-converting enzyme (ACE) inhibitors (e.g., enalapril) and vasodilators (e.g., hydralazine or calcium channel blockers) can be used. Nicardipine is considered the safest calcium channel blocker. Concerns regarding elevated ICP accompany the use of calcium channel blockers. Sodium nitroprusside and nitroglycerin increase ICP and lower cerebral blood flow, and should therefore be avoided in patients with reduced intracerebral compliance (Table 29.3).^20,21 In patients with chronic hypertension, reinstitute the patient’s previous oral antihypertensive medications early.¹²

Postoperative Hypotension

Postoperative hypotension following elective neurosurgery is uncommon (2–5%), and it has been associated with poorer outcome. Immediate resuscitation with fluid and possibly vasoactive agents should be instituted to avoid cerebral hypoperfusion. Transfusion therapy should also be considered. Causes of shock should be rapidly investigated and treated (hypovolemic, neurogenic, distributive, cardiogenic, and obstructive shock).

Prevention of Venous Thromboembolism

Neurosurgical patients are at high risk of developing venous thromboembolism (VTE).

• Pulmonary embolism has been reported in up to 5% of neurosurgical patients (mortality between 9% and 50%).²²

• Estimated deep vein thrombosis (DVT) incidence ranges from 19 to 43% when standardized screening protocols are implemented.²³ In neurosurgical oncology, DVT has been shown to be the most common adverse event.² Meningiomas are associated with the highest postoperative rate of VTE events (the risk is three times higher than in patients with other brain tumors), especially skull base meningiomas.^24,25

Factors associated with increased risk of VTE in neurosurgical patients include cancer; advanced age; longer duration of surgery; prolonged immobilization (pre-, intra-, and postoperative); and the release of thromboplastin secondary to brain surgery.

Management

Postoperative management of VTE prophylaxis is a balancing act between the risk of thrombotic events and the risk of intracerebral bleeding. Based on current evidence and available strategies,^23,27 the 2012 American College of Chest Physicians (ACCP) Guidelines²⁸ suggest risk stratification, with an individualized approach based on the risk of VTE (Table 29.4). In selected patients with specific risk of ICH (e.g., tumor type, intraoperative findings, and course of neurosurgical procedure), an even more individualized approach should be considered. As a general measure applicable to every group of patients, early mobilization of patients, if appropriate, should be instituted.

High Risk for Venous Thromboembolism Patients (Elective Craniotomy for Nonmalignant Disease)

Mechanical Techniques

The ACCP guidelines²⁸ suggest the use of mechanical prophylaxis, preferably with sequential intermittent pneumatic compression (IPC) devices (rather than no prophylaxis, grade 2C, or pharmacological VTE prophylaxis, also grade 2C).

Table 29.4 Venous Thromboembolism (VTE) Risk Stratification

• Risk reductions with IPC devices (versus no prophylaxis): 59% for asymptomatic DVT, and 63% for pulmonary embolism.

• In high-risk patients, the ACCP guidelines28 consider pharmacological prophylaxis with LMWH more harmful than beneficial:

It is associated with a possible increase in the risk of death from any cause.

LMWH may prevent between eight and 36 VTE events/1,000 patients, but at a cost of four to 22 additional ICH events/1,000 patients.

• Low-dose UFH seems to have a more favorable trade-off, but the evidence is lacking.

• Therefore, the guidelines do not recommend UFH in high-risk neurosurgical patients.

Patients with Very High Risk for VTE (Elective Craniotomy for Malignant Disease)

• The use of IPC devices, low-dose UFH, or (possibly) LMWH seems to be associated with better outcome in very high-risk craniotomy patients as compared with no prophylaxis. However, when comparing LMWH with IPC devices, despite being associated with more nonfatal VTE events (6–26 more events/1,000 patients treated), IPC devices entail fewer episodes of nonfatal ICH (4–22 less events/1,000 patients treated)

• Adding pharmacological prophylaxis seems to prevent an additional 23 VTE events/1,000 patients treated, at the expense of 11 more ICH events/1,000 patients (considering 4.0% as the risk of symptomatic VTE in patients receiving IPC devices alone).

The current ACCP Guidelines²⁸ suggest a combination strategy in very high-risk patients, with the addition of pharmacological prophylaxis to mechanical prophylaxis once adequate hemostasis is established and the risk of bleeding decreases (grade 2C).

• When should pharmacological prophylaxis be started? No definitive answer exists and each case must be considered individually.

A study shows that early use of subcutaneous low-dose UFH at either 24 or 48 hours was associated with a 43% reduction of lower extremity DVT without an increased incidence of ICHs.29

Patients with Traumatic Brain Injury (Very High Risk for VTE)

• The current ACCP Guidelines²⁸ suggest the use, as soon as possible, of mechanical prophylaxis (preferably with IPC) rather than no prophylaxis when not contraindicated by lower-extremity injury (grade 2C).

• If the risk of bleeding diminishes, most authors suggest adding pharmacological prophylaxis, ideally at 24 hours (but definitively within 48 hours).

• Inferior vena cava filters are not suggested for primary VTE prevention (grade 2C).

Stress Ulcer Prophylaxis

Critically ill patients are at risk of stress-related gastrointestinal mucosal damage, which can progress to ulceration and overt gastrointestinal (GI) bleeding. In the absence of adequate pharmacological prophylaxis, GI bleeding has been reported in 5 to 25% of critically ill patients, with an estimated incidence of clinically important GI bleeding varying between 0.1% and 4% in the most recent studies.^30–33

Management

• Most neurosurgical postoperative patients, even if receiving corticosteroids, do not have high-risk profiles (Table 29.5) for GI bleeding and therefore should not receive stress ulcer prophylaxis.

• For patients at high-risk for GI complications, stress ulcer prophylaxis is currently considered the standard of care. The American Society of Health System Pharmacists34 recommends stress ulcer prophylaxis for patients with at least one major risk factor or at least two other risk factors (Table 29.5).

Table 29.5 Risk Factors for Overt Gastrointestinal (GI) Bleeding

*These factors are less strongly associated with significant GI bleeding.

• Suggested drugs are histamine-2 receptor antagonists (H2RAs) or proton pump inhibitors (PPIs). PPIs can significantly lower the risk of clinically important and overt gastrointestinal bleeding, without influencing ICU mortality or length of ICU stay (Table 29.6). Optimal resuscitation and early enteral nutrition seem to be key factors in further preventing stress ulcer development.

There are some possible harms from pharmacological stress ulcer prophyl-axis agents: H2RAs and PPIs have been associated with adverse drug events and increased medication costs, and they seem to enhance susceptibility to nosocomial pneumonia and Clostridium difficile infection.³³

Anemia

Bleeding and anemia are among the most common complications following neurosurgical procedures,³ and may require red blood cell (RBC) transfusion.

• Current evidence supports a restrictive RBC transfusion strategy (hemoglobin [Hb] threshold: ~ 70 g/L) in general critical care patients with normal brain function.^35,36 Moreover, in healthy subjects, brain hypoxia and dysfunction have been shown to manifest only when Hb is less than 60 to 70 g/L.

• Some physiological studies and observational data suggest that acute brain injury is exacerbated when Hb falls below 100 g/L.^37–39 In contrast, data on the effect of anemia in stable postoperative neurosurgical patients are very limited.⁴⁰

Table 29.6 Pharmacological and Nonpharmacological Stress Ulcer Prophylaxis Agents

• RBC transfusion has been shown to be an independent risk factor for adverse outcomes and complications in both general critical care35,41 and neurocritical care patients.^42,43

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