Anaesthetic management of neurosurgical patients

Sedation for Percutaneous Endoscopic Lumbar Discectomy

Although anesthetic requirements for minimally invasive neurosurgical techniques have been described in detail and applied successfully since the early 2000s, most of the literature on this subject has dealt with cranial cases that were operated on in the supine or sitting positions. However, spinal surgery has also used minimally invasive techniques that were performed in prone position for more than 30 years to date. Although procedures in both these neurosurgical techniques require the patient to be awake for a certain period of time, the main surgical difference with minimally invasive spinal surgery is that the patients are in the prone position, which may result in increased requirement of airway management because of deep sedation. In addition, although minimally invasive spinal surgery progresses slowly and different techniques are used with no agreement on the terminology used to describe these techniques thus far, the anesthetist needs to understand the surgical and anesthetic requirements for each type of intervention in order to take necessary precautions. This paper reviews the literature on this topic and discusses the anesthetic necessities for percutaneous endoscopic laser surgery.

Awake craniotomy: improving the patient's experience

PURPOSE OF REVIEW

Awake craniotomy patients are exposed to various stressful stimuli while their attention and vigilance is important for the success of the surgery. We describe several recent findings on the perception of awake craniotomy patients and address nonpharmacological perioperative factors that enhance the experience of awake craniotomy patients. These factors could also be applicable to other surgical patients.

RECENT FINDINGS

Proper preoperative counseling gives higher patient satisfaction and should be individually tailored to the patient. Furthermore, there is a substantial proportion of patients who have significant pain or fear during an awake craniotomy procedure. There is a possibility that this could induce post-traumatic stress disorder or related symptoms.

SUMMARY

Preoperative preparation is of utmost importance in awake craniotomy patients, and a solid doctor-patient relationship is an important condition. Nonpharmacological intraoperative management should focus on reduction of fear and pain by adaptation of the environment and careful and well considered communication.

Incidence, Risk Factors and Consequences of Emergence Agitation in Adult Patients after Elective Craniotomy for Brain Tumor: A Prospective Cohort Study

Emergence agitation is a frequent complication that can have serious consequences during recovery from general anesthesia. However, agitation has been poorly investigated in patients after craniotomy. In this prospective cohort study, adult patients were enrolled after elective craniotomy for brain tumor. The sedation-agitation scale was evaluated during the first 12 hours after surgery. Agitation developed in 35 of 123 patients (29%). Of the agitated patients, 28 (80%) were graded as very and dangerously agitated. By multivariate stepwise logistic regression analysis, independent predictors for agitation included male sex, history of long-term use of anti-depressant drugs or benzodiazepines, frontal approach of the operation, method and duration of anesthesia and presence of endotracheal intubation. Total intravenous anesthesia and balanced anesthesia with short duration were protective factors. Emergence agitation was associated with self-extubation (8.6% vs 0%, P = 0.005). Sedatives were administered more in agitated patients than non-agitated patients (85.7% vs 6.8%, P<0.001). In conclusion, emergence agitation was a frequent complication in patients after elective craniotomy for brain tumors. The clarification of risk factors could help to identify the high-risk patients, and then to facilitate the prevention and treatment of agitation. For patients undergoing craniotomy, greater attention should be paid to those receiving a frontal approach for craniotomy and those anesthetized under balanced anesthesia with long duration. More researches are warranted to elucidate whether total intravenous anesthesia could reduce the incidence of agitation after craniotomy.

Trial Registration

ClinicalTrials.gov NCT00590499.

Factors influencing delayed extubation after infratentorial craniotomy for tumour resection: a prospective cohort study of 800 patients in a Chinese neurosurgical centre

OBJECTIVES

To investigate prospectively the rate of, and factors influencing, delayed extubation following infratentorial craniotomy in a Chinese neurosurgical centre.

METHODS

Patients undergoing infratentorial craniotomy for tumour resection were prospectively enrolled and stratified according to whether extubation was attempted in the operating theatre (early extubation) or not (delayed extubation). Pre- and intraoperative variables were collected and analysed. Multiple logistic regression analysis was performed, to identify factors related to delayed extubation.

RESULTS

The study included 800 patients, 398 (49.8%) of whom underwent delayed extubation. The overall rate of extubation failure was 3.6%. Independent factors related to delayed extubation were: preoperative lower cranial nerve dysfunction; hydrocephalus; tumour location; duration of surgery ≥ 6 h; estimated blood loss ≥ 1000 ml. Compared with patients in the early extubation group, those in the delayed extubation group had a higher rate of pneumonia, longer intensive care unit and postoperative hospital stays, and higher hospitalization costs.

CONCLUSIONS

Brain stem and lower cranial nerve function were the main factors affecting extubation decision-making. Further research is required, to establish criteria for delayed extubation following infratentorial craniotomy.

Use of cerebral state index to predict long-term unconsciousness in patients after elective craniotomy with delay recovery

Background

The major difficulty in postoperative care in patients after craniotomy is to distinguish the intracranial deficits from the residual effect of general anesthesia. In present study, we used cerebral state index (CSI) monitoring in patients after craniotomy with delayed recovery, and evaluated the prediction probability of CSI for long-term postoperative unconsciousness.

Methods

We enrolled 57 consecutive adult patients admitted to neurosurgical intensive care unit (NICU) after elective craniotomy with delayed recovery. CSI was continuously monitored for 6 hours after admission. Patient's level of consciousness was followed up for 24 hours. According to whether obeyed verbal command, patients were divided into awaken group and non-awaken group. CSI values were compared between the two groups. Prediction probability (P_K) was calculated to determine the probability of CSI in predicting unconsciousness 24 hours after operation.

Results

In awaken group (n = 51), CSI increased significantly after the 2nd NICU admitted hour (P < 0.05). At each time point, CSI values in awaken group were significantly higher than those in non-awaken group (n = 6) (P < 0.05). The values of P_K (SE) for CSI in the first 6 admitted hours ranged from 0.94 (0.06) to 0.99 (0.02).

Conclusions

In patients after craniotomy with delayed recovery, CSI monitoring in early postoperative hours had high prediction probability for long-term unconsciousness. CSI monitoring may be a reliable objective method to predict level of consciousness after elective craniotomy.

Early postoperative complications after intracranial surgery: comparison between total intravenous and balanced anesthesia

This prospective study was performed to compare the incidence of complications occurring after neurosurgical procedures in patients anesthetized with either sevoflurane-fentanyl or propofol-remifentanil anesthesia. We enrolled 162 American Society of Anesthesiologists (ASA) I to III patients (82 females and 80 males, Glasgow 15) undergoing elective neurosurgical procedures. Anesthesia was conducted using either propofol-remifentanil (T group; n=80 patients) or sevoflurane-fentanyl (S group; n=82 patients). All patients were monitored in the postanesthesia care unit for 6 hours after extubation. We analyzed and compared in both groups the incidence of high severity complications such as respiratory events (PaO2 <90 mm Hg; PaCO2 >45 mm Hg) and neurologic events (seizures, new motor or sensory deficit, unexpected delay of awakening) and the incidence of low severity complications such as hypertension (mean arterial pressure increase above 30% of baseline), hypotension (mean arterial pressure decrease below 30% of baseline), pain, shivering, nausea, and vomiting. A total of 162 complications occurred in 92 patients (57%) with 50 patients (31%) having had 1, 26 patients (16%) having had 2, and 16 patients (10%) having had 3 or more events. The most frequent complication was respiratory impairment (28%) which was frequently reported only in the first postoperative hour. Out of the total number of complicating events, 77 (48 %) were found in group S, and 85 (52%) in group T (P=ns). Severe complications were rarely reported and evenly distributed in the 2 anesthetic groups. Similarly, no difference could be demonstrated in the composite incidence of less serious complications between the 2 anesthetic regimens tested in this study. This study confirms that the recovery period after neurosurgical procedures remains a time of great potential danger to patients given the high incidence of postoperative complicating events independently from the anesthetic strategy.

Awakening management after neurosurgery for intracranial tumours

PURPOSE OF REVIEW

Major complications after intracranial surgery occur in 13-27% of patients. These complications may have multiple causes, but a body of arguments suggests that the haemodynamic and metabolic changes of anaesthesia recovery may be responsible for intracranial complications. The aim of this review is to explain the rationale of this hypothesis and analyse the recent studies relevant to neuroanaesthesia recovery.

RECENT FINDINGS

Rapid recovery and extubation after intracranial tumour surgery is desirable in order to make an early diagnosis of intracranial complications. Since light pharmacological sedation may worsen a neurological deficit, short-acting anaesthetics are preferable intraoperatively. Extubation in the operating room, however, may be associated with agitation, increased oxygen consumption, catecholamine secretion, hypercapnia and systemic hypertension. This may exacerbate cerebral hyperaemia observed even during an uneventful recovery, leading to cerebral oedema or haemorrhage.

SUMMARY

Pain, hypothermia, hypercapnia, hypoxia, hypoosmolality, hypertension, and anaemia should be avoided during emergence. Early emergence is associated with minimal haemodynamic and metabolic changes. If there is any doubt as to whether the patient should be extubated in the operating room, a gradual emergence in the intensive care unit makes it possible to decide whether or not extubation can be performed safely.

Evaluation of an anaesthetic technique used in dogs undergoing craniectomy for tumour resection

OBJECTIVE

To evaluate a total intravenous anaesthetic technique in dogs undergoing craniectomy.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Ten dogs admitted for elective surgical resection of rostro-tentorial tumours.

METHODS

All dogs were premedicated with methadone, 0.2 mg kg(-1) intramuscularly 30 minutes prior to induction of anaesthesia. Anaesthesia was induced with propofol administered intravenously (IV) to effect, following administration of lidocaine 1 mg kg(-1) IV and maintained with a continuous infusion of propofol at < or =0.4 mg kg(-1) minute(-1) during instrumentation and preparation and during movement of the animals to recovery. During surgery, anaesthesia was maintained using a continuous infusion of propofol at <or =0.4 mg kg(-1) minute(-1) and alfentanil < or =1 microg kg(-1) minute(-1). Lidocaine was administered at 1 mg kg(-1) IV immediately prior to extubation. Arterial blood pressure and heart rate (HR) were recorded prior to induction and every 5 minutes throughout preparation and surgery. Central venous pressure was recorded every 5 minutes throughout surgery.

RESULTS

Administration of propofol and lidocaine prevented significant increases in mean arterial blood pressure (MAP) and HR during endotracheal intubation and extubation. Adequate MAP was maintained throughout anaesthesia. Recovery was smooth and excitement free. There was no association between duration of anaesthesia, total drugs administered, or severity of neurological disease and recovery times. Postoperatively there was no deterioration in neurological function in the immediate postoperative period with complete resolution of pre-existing neurological deficits within 7 days of surgery.

CONCLUSION

This technique provided minimal response to intubation and extubation, adequate arterial blood pressure and a smooth predictable recovery. All animals were neurologically improved by the time of discharge, suggesting that this technique had not caused significant neuronal damage.

CLINICAL RELEVANCE

Total intravenous anaesthesia with propofol and alfentanil appears to be a satisfactory anaesthetic technique for use in dogs undergoing surgery for debulking/removal of rostro-tentorial tumours.

Why we still use intravenous drugs as the basic regimen for neurosurgical anaesthesia

PURPOSE OF REVIEW

Evolution of neurosurgery mainly trends towards minimally invasive and functional procedures including endoscopies, small-size craniotomies, intraoperative imaging and stereotactic interventions. Consequently, new adjustments of anaesthesia should aim at providing brain relaxation, minimal interference with electrophysiological monitoring, rapid recovery, patients' cooperation during surgery and neuroprotection.

RECENT FINDINGS

In brain tumour patients undergoing craniotomy, propofol anaesthesia is associated with lower intracranial pressure and cerebral swelling than volatile anaesthesia. Hyperventilation used to improve brain relaxation may decrease jugular venous oxygen saturation below the critical threshold. It decreases the cerebral perfusion pressure in patients receiving sevoflurane, but not in those receiving propofol. The advantage of propofol over volatile agents has also been confirmed regarding interference with somatosensory, auditory and motor evoked potentials. Excellent and predictable recovery conditions as well as minimal postoperative side-effects make propofol particularly suitable in awake craniotomies. Finally, the potential neuroprotective effect of this drug could be mediated by its antioxidant properties which can play a role in apoptosis, ischaemia-reperfusion injury and inflammatory-induced neuronal damage.

SUMMARY

Although all the objectives of neurosurgical anaesthesia cannot be met by one single anaesthetic agent or technique, propofol-based intravenous anaesthesia appears as the first choice to challenge the evolution of neurosurgery in the third millennium.

Neurosurgery for the treatment of epilepsy

PURPOSE OF REVIEW

Epilepsy is a common condition that is estimated to afflict 0.5-1.0% of the world's population. Frequently commencing in childhood, it is often associated with life-long disability. Approximately one-third of patients with epilepsy are refractory to antiepileptic drug therapy and many of these patients are candidates for surgical treatment. A growing body of evidence supports the safety and efficacy of surgery for the treatment of selected patients with epilepsy. Little information is available in the anesthesia literature regarding the presurgical assessment of candidates for surgical treatment.

RECENT FINDINGS

The presurgical identification of suitable candidates involves a multidisciplinary approach to assessment. Recent advances, particularly in neuroimaging techniques, are dramatically enhancing the capacity to accurately identify patients who are most likely to benefit from surgery. Epilepsy surgery is underused worldwide and in developed countries. In view of current efforts to increase opportunities to provide surgical treatment to more patients and to offer surgery earlier in the course of the disorder, the number of patients requiring specialized perioperative anesthetic care is expected to increase.

SUMMARY

This article provides anesthesiologists with an overview of the assessment process, investigation techniques and current rationale that influence the selection of appropriate candidates for surgical treatment and the associated need for specialized anesthetic care.