Anaesthesia for awake craniotomy with non-invasive positive pressure ventilation

Non-Invasive Respiratory Support for Management of the Perioperative Patient: A Narrative Review

BACKGROUND

Non-invasive respiratory support including high-flow nasal oxygen (HFNO), continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) is routinely used in the perioperative period.

OBJECTIVES

The aim of this narrative review was to discuss some of the existing literature on perioperative non-invasive respiratory support outlining its potential roles in each of the three perioperative periods (pre-, intra- and postoperatively) and to propose the way forward.

RESULTS

During induction of anesthesia, non-invasive ventilation (NIV) was associated with improved ventilatory variables and reduced risk of postoperative respiratory complications. HFNO did not seem to confer an advantage in terms of peri-intubation hypoxemia. Intraoperative data on NIV are scarce. Upper airway obstruction and worsening hypoventilation are two risks associated with its use. Compared with conventional oxygenation, HFNO is associated with a reduced risk of hypoxemia. Postoperative NIV has been associated with improved arterial blood gases and a reduced reintubation rate, but no difference was reported for mortality, hospital length of stay, rate of anastomotic leakage, pneumonia-related complications and sepsis or infections. Head-to-head comparison of HFNO versus BiPAP showed no advantage to either mode of support.

CONCLUSION

In the preoperative setting, NIV seems to be associated with improved clinical outcomes in specific patient subgroups (obesity, pregnancy). In the postoperative setting, both NIV and HFNO were associated with lower reintubation rates. The literature has provided little evidence regarding the use of non-invasive ventilatory support in other patient subgroups or intraoperatively. There is also little literature regarding the appropriateness of combining different modes of support. In the next years, the combination of several modes of respiratory support should be assessed in targeted populations.

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.

Anaesthesia for awake craniotomy: A retrospective study of 54 cases

Background and Aims:

The anaesthetic challenge of awake craniotomy is to maintain adequate sedation, analgesia, respiratory and haemodynamic stability in an awake patient who should be able to co-operate during intraoperative neurological assessment. The current literature, sharing the experience on awake craniotomy, in Indian context, is minimal. Hence, we carried out a retrospective study with the aim to review and analyse the anaesthetic management and perioperative complications in patients undergoing awake craniotomy, at our centre.

Methods:

Medical records of 54 patients who underwent awake craniotomy for intracranial lesions over a period of 10 years were reviewed, retrospectively. Data regarding anaesthetic management, intraoperative complications and post-operative course were recorded.

Results:

Propofol (81.5%) and dexmedetomidine (18.5%) were the main agents used for providing conscious sedation to facilitate awake craniotomy. Hypertension (16.7%) was the most commonly encountered complication during intraoperative period, followed by seizures (9.3%), desaturation (7.4%), tight brain (7.4%), and shivering (5.6%). The procedure had to be converted to general anaesthesia in one of patients owing to refractory brain bulge. The incidence of respiratory and haemodynamic complications were comparable in the both groups (P > 0.05). There was less incidence of intraoperative seizures in patients who received propofol (P = 0.03). In post-operative period, 20% of patients developed new motor deficit. Mean intensive care unit stay was 2.8 ± 1.9 day (1–14 days) and mean hospital stay was 7.0 ± 5.0 day (3–30 days).

Conclusions:

‘Conscious sedation’ was the technique of choice for awake craniotomy, at our institute. Fentanyl, propofol, and dexmedetomidine were the main agents used for this purpose. Patients receiving propofol had less incidence of intraoperative seizure. Appropriate selection of patients, understanding the procedure of surgery, and judicious use of sedatives or anaesthetic agents are key to the success for awake craniotomy as a procedure.

The impact of sedation on brain mapping: a prospective, interdisciplinary, clinical trial

BACKGROUND

During awake craniotomies, patients may either be awake for the entire duration of the surgical intervention (awake-awake-awake craniotomy, AAA) or initially sedated (asleep-awake-asleep craniotomy, SAS).

OBJECTIVE

To examine whether prior sedation in SAS may restrict brain mapping, we conducted neuropsychological tests in patients by means of a standardized anesthetic regimen comparable to an SAS.

METHODS

We prospectively examined patients undergoing surgery either under total intravenous anesthesia (TIVA) or under regional anesthesia with slight sedation (RAS). The tests included the DO40 picture-naming test, the digit span, the Regensburg Word Fluency Test, and the finger-tapping test. Each test was conducted 3 times for every patient in the TIVA and RAS groups, once before surgery and twice within about 35 minutes after the end of sedation. Patients undergoing AAA were examined preoperatively and intraoperatively.

RESULTS

In the AAA group, no significant difference was found between preoperative and intraoperative test results. In the TIVA and RAS groups, postoperative tests showed worse results than preoperative tests. In most tests, patients improved from the first to the second postoperative test.

CONCLUSION

Cognitive and motor performance were significantly influenced by prior sedation in the TIVA and RAS groups, but not in the AAA group. Therefore, prior sedation may be assumed to cause a change in the baselines, which may compromise brain mapping and thus endanger a patient's neurological outcome in the case of an SAS.

Awake craniotomy: A qualitative review and future challenges

Neurosurgery in awake patients incorporates newer technologies that require the anesthesiologists to update their skills and evolve their methodologies. They need effective communication skills and knowledge of selecting the right anesthetic drugs to ensure adequate analgesia, akinesia, along with patient satisfaction with the anesthetic conduct throughout the procedure. The challenge of providing adequate anesthetic care to an awake patient for intracranial surgery requires more than routine vigilance about anesthetic management.

Awake Craniotomy with Intraoperative MRI: Description of a Sedation Technique Using Remifentanil and Dexmedetomidine

We describe the anaesthetic management of a patient requiring intra-operative MRI and awake neurological testing during neurosurgical resection of a frontal tumour. This tumour involved her motor and speech areas. The anaesthetic drugs administered during awake craniotomy should be safe and allow appropriate changes in the level of sedation, so that the patient is adequately sedated during periods of intense surgical stimulus, yet awake, comfortable and cooperative during functional testing and tumour resection. We report the novel and successful use of a sedative — dexmedetomidine in combination with a narcotic, remifentanil. There has not been much experience with this combination locally. Dexmedetomidine, a selective alpha-2 agonist with sedative, analgesic and anaesthetic-sparing effect does not suppress ventilation. Patients are sedated, but can be easily roused verbally. Remifentanil is a useful choice in this surgery as it can be rapidly titrated according to level of surgical intensity and has a reliable context sensitive half life. Potential problems associated with awake craniotomy such as impaired ventilation during sedation, nausea, vomiting and seizures are discussed. These anaesthetic challenges are compounded by the challenges posed by the iMRI environment. Emphasis is placed on patient selection and preparation peri-operatively. This is crucial to the success of the operation.

Asleep-awake-asleep craniotomy: a comparison with general anesthesia for resection of supratentorial tumors

The anesthetic plan for patients undergoing awake craniotomy, when compared to craniotomy under general anesthesia, is different, in that it requires changes in states of consciousness during the procedure. This retrospective review compares patients undergoing an asleep-awake-asleep technique for craniotomy (group AW: n = 101) to patients undergoing craniotomy under general anesthesia (group AS: n = 77). Episodes of desaturation (AW = 31% versus AS = 1%, p < 0.0001), although temporary, and hypercarbia (AW = 43.75 mmHg versus AS = 32.75 mmHg, p < 0.001) were more common in the AW group. The mean arterial pressure during application of head clamp pins and emergence was significantly lower in AW patients compared to AS patients (pinning 91.47 mmHg versus 102.9 mmHg, p < 0.05 and emergence 84.85 mmHg versus 105 mmHg, p < 0.05). Patients in the AW group required less vasopressors intraoperatively (AW = 43% versus AS = 69%, p < 0.01). Intraoperative fluids were comparable between the two groups. The post anesthesia care unit (PACU) administered significantly fewer intravenous opioids in the AW group. The length of stay in the PACU and hospital was comparable in both groups. Thus, asleep-awake-asleep craniotomies with propofol-dexmedetomidine infusion had less hemodynamic response to pinning and emergence, and less overall narcotic use compared to general anesthesia. Despite a higher incidence of temporary episodes of desaturation and hypoventilation, no adverse clinical consequences were seen.

[Anesthesia for craniotomy in the conscious patient]

Craniotomy in the conscious patient (CPC) enables the neurological changes to be assessed during the mapping in epilepsy surgery, the location of the electrodes during deep brain stimulation surgery, and tumor resection in eloquent areas of the brain. CPC is a useful technique for radical surgery in order to minimize the damage to the functional areas of the brain. The anesthesiologist must ensure, adequate patient comfort, analgesia and ensure optimal collaboration. The appropriate selection of potential candidates for CPC should be made jointly with all professionals involved in the case. Knowledge of the different phases of CPC, coordination and communication among specialists, the right management of the pharmacology, and anesthetic techniques specific to CPC, along with the ability of psycho-emotional communication with the patient, determine the success of the procedure to be performed in the culture of patient safety. The aim of this review was to describe the anesthetic management, comprehensive considerations, and intraoperative neurophysiological tests for CPC.

Epidural anesthesia and non-invasive ventilation for radical retropubic prostatectomy in two obese patients with chronic obstructive pulmonary disease

We report two cases of anesthesia for radical retropubic prostatectomy (RRP) in obese-chronic obstructive pulmonary disease (COPD) patients using the combination of epidural anesthesia and non-invasive ventilation (NIV). This technique avoided intubation, general anesthesia and perioperative pulmonary complications.

'Anesthesia' for awake neurosurgery

PURPOSE OF REVIEW

In this review we focus on recent findings in the anesthetic management of patients undergoing craniotomy while awake, and propose a structured approach to the clinical practice of 'anesthesia' for awake neurosurgery.

RECENT FINDINGS

The increasing use of functional neurosurgery and recent evidence favoring resection of tumor involving eloquent cortex has expanded the indications for awake craniotomy, a procedure needing a fully cooperative patient and expert intraoperative anesthetic management. Despite the shorter hospital stay, the more recently published studies have highlighted perioperative anesthetic complications and have proposed ways to improve anesthesia techniques for awake procedures in adults and children.

SUMMARY

Although anesthesia for awake craniotomy is usually a well tolerated procedure it requires an extensive knowledge of the principles underlying neuroanesthesia and of specific technical strategies including local anesthesia for scalp blockade, advanced airway management, dedicated sedation protocols, and skillful management of hemodynamics.

Awake craniotomy

Awake craniotomy has become an increasingly frequent procedure. In this paper, the principles of its anaesthetic management are reviewed. The means allowing achievement of anaesthetic objectives are described, with emphasis on points that determine success of the procedure. A careful and adequate selection and preparation of patients are mandatory, and the intervening team must be a skilled team. Choosing an awake technique or general anaesthesia depends on several factors, including the risk of obstructive apnoea, seizures, nausea and vomiting, patient's ability to cooperate, and localization of lesions. The main challenge of intraoperative anaesthetic management relies on the ability of rapidly adjusting the level of sedation and analgesia according to the sequence of surgical events, while ensuring haemodynamic stability, adequate ventilation, and minimal interference with eventual electrophysiological recordings. Throughout the procedure, complications must be anticipated and managed according to predefined guidelines. More prospective randomized clinical trials are still needed to improve safety and efficacy of awake craniotomies, as well as to validate this technique in comparison with more conventional anaesthetic management.

The asleep-awake technique using propofol-remifentanil anaesthesia for awake craniotomy for cerebral tumours

BACKGROUND AND OBJECTIVE

We retrospectively reviewed the first 25 planned cases of awake craniotomies using the 'asleep-awake' technique, an alternative to the often-used 'asleep-awake-asleep' technique.

METHODS

The patients were anaesthetized using propofol/remifentanil anaesthesia, a laryngeal mask and controlled ventilation according to a protocol defined before the start of this series of patients. The patients were awakened before the brain mapping and were kept awake throughout the rest of the procedure allowing for additional mapping and modification of the resection of the tumour if symptoms should develop. A small dose of remifentanil was infused during this period if necessary.

RESULTS

Twenty-three patients were mapped as planned. One patient was not awakened due to protrusion of the brain during the awakening phase. Another patient was intubated preoperatively as it was impossible to obtain a tight laryngeal mask. All of the 23 patients were awake as from when the mapping session began and throughout the rest of the operation. In five cases the resection of the tumour was modified as symptoms emerged. These symptoms all subsided in due course. No case of hypoxia was recorded. In no case the respiratory rate was below 10 breaths min-1 in the awake period. Complications were comparable to other studies. The patients in the present study were all satisfied with the method.

CONCLUSIONS

Different methods of anaesthesia have been described, but no method has been shown to be superior. The presented method seems to be a rational and useful technique allowing for modification of tumour resection, if symptoms should develop. The method was well tolerated by the patients.

Propofol and remifentanil effect-site concentrations estimated by pharmacokinetic simulation and bispectral index monitoring during craniotomy with intraoperative awakening for brain tumor resection

Different anesthetic techniques have been suggested for craniotomy with intraoperative awakening. We describe an asleep-awake-asleep technique with propofol and remifentanil infusions, with pharmacokinetic simulation to predict the effect-site concentrations and to modulate the infusion rates of both drugs, and bispectral index (BIS) monitoring. Five critical moments were defined: first loss of consciousness (LOC1), first recovery of consciousness (ROC1), final of neurologic testing (NT), second loss of consciousness (LOC2), and second recovery of consciousness (ROC2). At LOC1, predicted effect-site concentrations of propofol and remifentanil were, respectively, 3.6+/-1.2 microg/mL and 2.4+/-0.4 etag/mL. At ROC1, predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1+/-0.3 microg/mL and 1.8+/-0.3 etag/mL. At NT, predicted effect-site concentrations of propofol and remifentanil were, respectively, 0.9+/-0.3 microg/mL and 1.8+/-0.2 etag/mL. At LOC2, predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1+/-0.2 microg/mL and 2.5+/-0.2 etag/mL. At ROC2, predicted effect-site concentrations of propofol and remifentanil were, respectively, 1.2+/-0.5 microg/mL and 1.4+/-0.2 etag/mL (data are mean+/-SE). A significative correlation was found between BIS and predicted effect-site concentrations of propofol (r=0.547, P<0.001) and remifentanil (r=0.533, P<0.001). Multiple regression analysis between BIS and propofol and remifentanil predicted effect-site concentrations at the different critical steps of the procedure was done and found also significative (r=0.7341, P<0.001).

Anaesthesia for elective neurosurgery

Neuroanaesthesia continues to develop and expand. It is a speciality where the knowledge and expertise of the anaesthetist can directly influence patient outcome. Evolution of neurosurgical practice is accompanied by new challenges for the anaesthetist. Increasingly, we must think not only as an anaesthetist but also as a neurosurgeon and neurologist. With the focus on functional and minimally invasive procedures, there is an increased emphasis on the provision of optimal operative conditions, preservation of neurocognitive function, minimizing interference with electrophysiological monitoring, and a rapid, high-quality recovery. Small craniotomies, intraoperative imaging, stereotactic interventions, and endoscopic procedures increase surgical precision and minimize trauma to normal tissues. The result should be quicker recovery, minimal perioperative morbidity, and reduced hospital stay. One of the peculiarities of neuroanaesthesia has always been that as much importance is attached to wakening the patient as sending them to sleep. With the increasing popularity of awake craniotomies, there is even more emphasis on this skill. However, despite high-quality anaesthetic research and advances in drugs and monitoring modalities, many controversies remain regarding best clinical practice. This review will discuss some of the current controversies in elective neurosurgical practice, future perspectives, and the place of awake craniotomies in the armamentarium of the neuroanaesthetist.

Spinal anaesthesia and non-invasive positive pressure ventilation for hip surgery in an obese patient with advanced chronic obstructive pulmonary disease

We describe the use of non-invasive positive pressure ventilation combined with spinal anaesthesia to allow the insertion of a dynamic hip screw in an obese patient with advanced chronic obstructive pulmonary disease. The technique avoided the hazards of intubation and general anaesthesia in this high-risk patient.

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.

„Schlaf-Wach-Schlaf“-Technik zur CS Wachkraniotomie

Awake craniotomy in tumor and epilepsy surgery or for the implantation of electrodes for deep brain stimulation requires specific anesthesiological strategies. Propofol allows for quick emergence and has little effect on the respiratory function of the usually spontaneously breathing patient. Pain control may be instituted by hemiscalp block for trepanation or local infiltration for deep brain electrode implantation. In addition, low dose remifentanil is recommended for trepanation (i.e. tumor or epilepsy surgery). The airway may be secured by an ordinary Magill tube placed transnasally with its tip underneath the epiglottis. To protect the patient against vomiting an adequate antiemetic prophylaxis is required.

Anesthetic Complications of Awake Craniotomies for Epilepsy Surgery

Awake craniotomies are often performed for resection of epileptogenic foci close to vital areas of the brain. For awake craniotomies at our institution, propofol is infused during local anesthetic injection and craniotomy, spontaneous ventilation is preserved, and no endotracheal tube or laryngeal mask airway is used. Propofol is discontinued for language, motor, and/or sensory mapping and for electrocorticography. Patients are re-sedated with propofol for resection and closure. We performed a retrospective chart review of 332 propofol-based "asleep-awake-asleep" (AAA) techniques with unsecured airways and 129 general anesthesia with endotracheal intubation craniotomies for epilepsy surgery. We compared the incidence of intraoperative respiratory and hemodynamic complications and incidence of seizures, nausea, brain swelling, patient movement, bleeding, aspiration, air embolism, and death. Airway compromise was uncommon in AAA cases and although incidences of hypertension, hypotension, and tachycardia were statistically increased in AAA versus general anesthesia craniotomy, these were treated appropriately. In only one patient the use of our AAA technique may have contributed to a poor clinical outcome.

Prise en charge anesthésique des craniotomies en état vigile

This review article presents a detailed analysis of patients' management for awake craniotomy, at the light of the available data in the literature and the authors' experience. Indications of this type of surgery are discussed as well as anaesthetic management itself, from preoperative assessment of the patient to peroperative concerns. Anaesthetic strategy, choice of anaesthetic agents, anaesthetic technique, and management of the airway and possible complications are discussed. The authors emphasize the tricky aspect of the procedure, the necessity of rigorous patient selection and good preparation. They emphasize the need for controlled studies to validate the proposed techniques.