Innate immune function after breast, lung, and colorectal cancer surgery.

BACKGROUND: The cytotoxic activity and count of natural killer (NK) cells appear to be reduced after surgery; however, it is unknown whether the magnitude of this immune suppression is similar among different types of oncological surgery. In this study, we compared the innate immune function of patients undergoing three different oncological surgeries. METHODS: We compared the number and function of NK cells obtained from patients who had undergone mastectomies (n = 17), thoracotomies (n = 21), or liver resections for cancer (n = 22). Cytotoxicity assays were performed to measure the function of NK cells. We also determined the plasma concentrations of interleukins (IL) 2 and 4, interferon-γ, granzyme B, perforin, soluble major histocompatibility complex class I-related chain A, and epinephrine, both before and 24 h after surgery. Differences in immunologic parameters were compared preoperatively and postoperatively and by type of surgery. P values <0.05 were considered statistically significant. RESULTS: The preoperative NK cell count differed statistically (P < 0.006) among all three types of surgeries; however, within surgery postoperative counts and changes compared with baseline did not. The postoperative function of NK cells was similar among types of surgeries, but was significantly reduced compared with preoperative levels (mastectomy P < 0.0001, thoracotomy P = 0.001, and liver resections P = 0.002). We observed a significant increase in the postoperative plasma concentrations of epinephrine, whereas the concentrations of major histocompatibility class I polypeptide-related sequence A and the IL-2 and/or IL-4 ratio remained unchanged before and after surgery. CONCLUSIONS: The magnitude of innate immune suppression is similar among different oncological procedures. More studies are needed to better understand this complex phenomenon.

The effect of an anatomically classified procedure on antiemetic administration in the postanesthesia care unit.

BACKGROUND: The effect of the type of surgical procedure on postoperative nausea and vomiting (PONV) rate has been debated in the literature. Our goal in this retrospective database study was to investigate the effect the type of surgical procedure (categorized and compared anatomically) has on antiemetic therapy within 2 h of admission to the postanesthesia care unit (PACU). METHODS: We retrospectively analyzed data for oncology surgeries (n = 18,109), from our automated anesthesia information system database. We classified the types of surgical procedures anatomically into seven categories, with the integumentary musculoskeletal and the superficial surgeries chosen as the referent group. Our analysis included nine other risk factors for each patient, such as gender, smoking status, history of PONV or motion sickness, duration of anesthesia, number of prophylactic antiemetics administered, intraoperative opioids, ketorolac, epidural use, and postoperative opioids. Multivariate logistic regression was used to assess the effect of the type of surgery on antiemetic administration within the first 2 h of PACU admission, while adjusting for the other risk factors. RESULTS: Compared with integumentary musculoskeletal and superficial surgeries, patients undergoing neurological (P < 0.0001), head or neck (P < 0.0001), and abdominal (P < 0.0001) surgeries were administered PACU antiemetic significantly more often, whereas patients undergoing thoracic surgeries were administered PACU antiemetic significantly less often (P = 0.02). Breast or axilla (P = 0.74) and endoscopic (P = 0.28) procedures did not differ from the referent category. Female, nonsmoker, history of PONV or motion sickness, anesthesia duration, and intraoperative and postoperative opioid administration were significantly associated with antiemetic administration during early PACU admission. CONCLUSIONS: Using our automated anesthesia information system database, we found that the type of surgery, when categorized anatomically, was associated with an increased frequency of early PACU antiemetic administration in our population.

Ongoing provision of individual clinician performance data improves practice behavior.

BACKGROUND: Clinical practice guidelines summarize evidence from science and attempt to translate those findings into clinical practice. Pervasive and consistent adoption of these guidelines into daily provider practice has proven slow. METHODS: Using postoperative nausea and vomiting (PONV) prophylaxis guideline compliance as our metric, we compared the effects of continuing medical education (CME) alone (I), CME with a single snapshot of provider compliance (II), and ongoing reporting of provider compliance data without further CME (III). We retrospectively analyzed guideline compliance of 23,279 anesthetics at the University of Texas M.D. Anderson Cancer Center. Compliance was defined as a patient with 1 risk factor for PONV receiving at least 1 antiemetic, 2 risk factors receiving at least 2 antiemetics, and 3 risk factors receiving at least 3 antiemetics. Drugs of the same class were counted as single antiemetic administration. Propofol-based anesthetic techniques were counted as receiving 1 antiemetic. Patients with 0 risk factors for PONV were not included. We estimated the compliance rates for each of the 4 time periods of the study adjusting for multiple observations on the same clinician. Individual performance feedback was given once at 6 months after intervention I coincident with a refresher presentation on PONV (start of intervention II) and on an ongoing quarterly basis during intervention III. RESULTS: Compliance rates were not significantly influenced with CME (intervention I) compared with baseline behavior (54.5% vs 54.4%, P = 0.9140). Significant improvement occurred during the time period when CME was paired with performance data (intervention II) compared with intervention I (59.2% vs 54.4%, P = 0.0002). Further significant improvement occurred when data alone were presented (intervention III) compared with intervention II (65.1% vs 59.2%, P < 0.0001). For patients with 3 risk factors, we saw significant improvement in compliance rates during intervention III (P = 0.0002). In post hoc analysis of overtreatment, the percentage differences between the baseline and time period III decreased as the number of risk factors increased. CONCLUSIONS: We observed the greatest improvement in guideline compliance with ongoing personal performance feedback. Provider feedback can be an effective tool to modify clinical practice but can have unanticipated consequences.

Improved postoperative pain control using thoracic paravertebral block for breast operations.

Thoracic paravertebral block (PVB) in breast surgery can provide regional anesthesia during and after surgery with the potential advantage of decreasing postoperative pain. We report our institutional experience with PVB over the initial 8 months of use. All patients undergoing breast operations at the ambulatory care building from September 09, 2005 to June 28, 2005 were reviewed. Comparison was performed between patients receiving PVB and those who did not. Pain scores were assessed immediately, 4 hours, 8 hours and the morning after surgery. 178 patients received PVB and 135 patients did not. Patients were subdivided into three groups: Group A-segmental mastectomy only (n = 89), Group B-segmental mastectomy and sentinel node surgery (n = 111) and Group C-more extensive breast surgery (n = 113). Immediately after surgery there was a statistically significant difference in the number of patients reporting pain between PVB patients and those without PVB. At all time points up until the morning after surgery PVB patients were significantly less likely to report pain than controls. Patients in Group C who received PVB were significantly less likely to require overnight stay. The average immediate pain scores were significantly lower in PVB patients than controls in both Group B and Group C and approached significance in Group A. PVB in breast surgical patients provided improved postoperative pain control. Pain relief was improved immediately postoperatively and this effect continued to the next day after surgery. PVB significantly decreased the proportion of patients that required overnight hospitalization after major breast operations and therefore may decrease cost associated with breast surgery.

Continuous Quality Improvement Measured With Time-Driven Activity-Based Costing in an Outpatient Cancer Surgery Center.

PURPOSE: As health care costs rise, continuous quality improvement and increased efficiency are crucial to reduce costs while providing high-quality care. Time-driven activity-based costing (TDABC) can help identify inefficiencies in processes of cancer care delivery. This study measured the process performance of Port-a-Cath placement in an outpatient cancer surgery center by using TDABC to evaluate patient care process. METHODS: Data were collected from the Anesthesia Information Management System database and OneConnect electronic health record (EHR) for Port-a-Cath cases performed throughout four phases: preintervention (phase I), postintervention, stabilization, and pre-new EHR (phases II and III), and post-new EHR (phase IV). TDABC methods were used to map and calculate process times and costs. RESULTS: Comparing all phases, as measured with TDABC methodology, a decrease in post-anesthesia care unit (PACU) length of stay (LOS) was identified (83 minutes v 67 minutes; P < .05). The decrease in PACU LOS correlated with increased efficiency and decreasing process costs and PACU nurse resource use by fast tracking patients for Port-a-Cath placement. Port-a-Cath placement success and the functionality of ports remained the same as patient experience improved. CONCLUSION: TDABC can be used to evaluate processes of care delivery to patients with cancer and to quantify changes made to those processes. Patients' PACU LOS decreased on the basis of the 2013 Port-a-Cath process improvement initiative and after implementation of a new EHR, over the course of 3 years, as quantified by TDABC. TDABC use can lead to improved efficiencies in patient care delivery that are quantifiable and measurable.

Reduction of incorrect record accessing and charting patient electronic medical records in the perioperative environment.

Opening and charting in the incorrect patient electronic record presents a patient safety issue. The authors investigated the prevalence of reported errors and whether efforts utilizing the anesthesia time-out and barcoding have decreased the incidence of errors in opening and charting in the patient electronic medical record in the perioperative environment. The authors queried the database for all surgeries and procedures requiring anesthesia from January 2009 to September 2012. Of the 115,760 records of anesthesia procedures identified, there were 57 instances of incorrect record opening and charting during the study period. A decreasing trend was observed for all sites combined (p < 0.0001) and at the off-site locations (p = 0.0032). All locations and the off-site locations demonstrated a statistically significant decreasing pattern of errors over time. Barcoding and the anesthesia time-out may play an important role in decreasing errors in incorrect patient record opening in the perioperative environment.

A Prospective, Randomized, Controlled Trial of Paravertebral Block versus General Anesthesia Alone for Prosthetic Breast Reconstruction.

BACKGROUND: Paravertebral blocks have gained popularity because of ease of implementation and a shift toward ambulatory breast surgery procedures. Previous retrospective studies have reported potential benefits of paravertebral blocks, including decreased narcotic and antiemetic use. METHODS: The authors conducted a prospective controlled trial of patients undergoing breast reconstruction over a 3-year period. The patients were randomized to either a study group of paravertebral blocks with general anesthesia or a control group of general anesthesia alone. Demographic and procedural data, in addition to data regarding pain and nausea patient-reported numeric scores and consumption of opioid and antiemetic medications, were recorded. RESULTS: A total of 74 patients were enrolled to either the paravertebral block (n = 35) or the control group (n = 39). There were no significant differences in age, body mass index, procedure type, or cancer diagnosis between the two groups. Patients who received a paravertebral block required less opioid intraoperatively and postoperatively combined compared with patients who did not receive paravertebral blocks (109 versus 246 fentanyl equivalent units; p < 0.001), and reported significantly lower pain scores at 0 to 1 (3.0 versus 4.6; p = 0.02), 1 to 3 (2.0 versus 3.2; p = 0.01), and 3 to 6 (1.9 versus 2.7; p = 0.04) hours postoperatively. The study group also consumed less antiemetic medication (0.7 versus 2.1; p = 0.05). CONCLUSIONS: Incorporating paravertebral blocks carries considerable potential for improving pathways for breast cancer patients undergoing breast reconstruction--with minimal procedure-related morbidity. This is the first prospective study designed to assess paravertebral blocks in the setting of prosthetic breast reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Effect of adjunctive dexmedetomidine on postoperative intravenous opioid administration in patients undergoing thyroidectomy in an ambulatory setting.

STUDY OBJECTIVE: Two of the most feared complications for patients undergoing thyroid surgery are pain and postoperative nausea and vomiting. Thyroidectomy is considered high risk for postoperative nausea and vomiting, and recent studies have looked at adjuncts to treat pain, limit narcotic use, "fast-track" the surgical process, and enhance recovery without compromising the patient's safety. One such perioperative medication of interest is dexmedetomidine (Dex), a centrally acting α-2 agonist that has been associated with reducing pain and postoperative opioid consumption. Our aim was to examine the effectiveness of Dex as an adjunctive intraoperative medication to reduce postoperative narcotic requirements in patients undergoing outpatient thyroid surgery. DESIGN, SETTING, PATIENTS AND INTERVENTION: After obtaining approval from the Institutional Review Board at The University of Texas MD Anderson Cancer Center, we searched the electronic medical record for the period October 2013 to March 2015 to identify patients who had undergone thyroid surgery in the ambulatory setting under general anesthesia. MEASUREMENTS AND MAIN RESULTS: A total of 71 patients underwent thyroidectomy or thyroid lobectomy in the outpatient setting. Of the patients receiving adjunctive Dex, a lower proportion (50%, n=9) received postoperative intravenous opioids when compared with control patients (79%, n=42) (P=.017). One patient (5%) in the Dex group required rescue postoperative antiemetics as compared to 11 (21%) patients in the control group (P=.273). CONCLUSIONS: Our data suggest that intraoperative use of Dex reduced narcotic administration in the postoperative period among study population patients undergoing thyroidectomy.

Length of Stay in Ambulatory Surgical Oncology Patients at High Risk for Sleep Apnea as Predicted by STOP-BANG Questionnaire.

Background. The STOP-BANG questionnaire has been used to identify surgical patients at risk for undiagnosed obstructive sleep apnea (OSA) by classifying patients as low risk (LR) if STOP-BANG score < 3 or high risk (HR) if STOP-BANG score ≥ 3. Few studies have examined whether postoperative complications are increased in HR patients and none have been described in oncologic patients. Objective. This retrospective study examined if HR patients experience increased complications evidenced by an increased length of stay (LOS) in the postanesthesia care unit (PACU). Methods. We retrospectively measured LOS and the frequency of oxygen desaturation (<93%) in cancer patients who were given the STOP-BANG questionnaire prior to cystoscopy for urologic disease in an ambulatory surgery center. Results. The majority of patients in our study were men (77.7%), over the age of 50 (90.1%), and had BMI < 30 kg/m(2) (88.4%). STOP-BANG results were obtained on 404 patients. Cumulative incidence of the time to discharge between HR and the LR groups was plotted. By 8 hours, LR patients showed a higher cumulative probability of being discharged early (80% versus 74%, P = 0.008). Conclusions. Urologic oncology patients at HR for OSA based on the STOP-BANG questionnaire were less likely to be discharged early from the PACU compared to LR patients.

Presurgical caudal block attenuates stress response in children.

BACKGROUND: Our aim was to determine if the anesthesia technique for pain relief in children affects the stress response after minor surgery. A rise in blood glucose reflects stress-related effects in children who do not receive glucose perioperatively. METHODS: Twenty-eight children, ages 17-81 mos, undergoing elective urologic procedures, were enrolled. For pain relief, patients received presurgical caudal block (group 1), intravenous narcotics (group 2), or postsurgical caudal block (group 3). Blood samples were analyzed for glucose concentrations immediately after induction of anesthesia at baseline, 15 min after surgical incision (second sample), and 30 min after end of surgery (third sample). RESULTS: In group 1 there was no change in glucose concentration in the second or third samples compared to baseline, while in group 3 there were significant increases in those samples, and in group 2 there was a significant increase in the second sample compared to baseline. Children in group 1 required significantly fewer narcotics in the postanesthesia care unit (PACU), and those in group 2 had significantly longer PACU and hospital durations. CONCLUSIONS: Presurgical caudal analgesia attenuates the stress response of anesthesia and surgery and decreases postoperative narcotic use while narcotics prolong PACU and discharge times.

A case series of thoracic paravertebral blocks using a combination of ropivacaine, clonidine, epinephrine, and dexamethasone.

Five patients who underwent surgery for breast cancer were followed for 6 days after placement of a multiple-injection, one-time paravertebral block. Data were collected on patient satisfaction, analgesic consumption, side effects, and complications. Ropivacaine as a sole agent in paravertebral blocks has a clinical duration of up to 6 hours. The addition of epinephrine, clonidine, and dexamethasone prolonged the clinical duration considerably.

A novel nomenclature to classify parathyroid adenomas.

BACKGROUND: A uniform and reliable description of the exact locations of adenomatous parathyroid glands is necessary for accurate communications between surgeons and other specialists. We developed a nomenclature that provides a precise means of communicating the most frequently encountered parathyroid adenoma locations. METHODS: This classification scheme is based on the anatomic detail provided by imaging and can be used in radiology reports, operative records, and pathology reports. It is based on quadrants and anterior-posterior depth relative to the course of the recurrent laryngeal nerve and the thyroid parenchyma. The system uses the letters A-G to describe exact gland locations. RESULTS: A type A parathyroid gland is a gland that originates from a superior pedicle, lateral to the recurrent laryngeal nerve compressed within the capsule of the thyroid parenchyma. A type B gland is a superior gland that has fallen posteriorly into the tracheoesophageal groove and is in the same cross-sectional plane as the superior portion of the thyroid parenchyma. A type C gland is a gland that has fallen posteriorly into the tracheoesophageal groove and on a cross-sectional view lies at the level of or below the inferior pole of the thyroid gland. A type D gland lies in the midregion of the posterior surface of the thyroid parenchyma, near the junction of the recurrent laryngeal nerve and the inferior thyroid artery or middle thyroidal vein; because of this location, dissection is difficult. A type E gland is an inferior gland close to the inferior pole of the thyroid parenchyma, lying in the lateral plane with the thyroid parenchyma and anterior half of the trachea. A type F gland is an inferior gland that has descended (fallen) into the thyrothymic ligament or superior thymus; it may appear to be "ectopic" or within the superior mediastinum. An anterior-posterior view shows the type F gland to be anterior to the trachea. A type G gland is a rare, truly intrathyroidal parathyroid gland. CONCLUSIONS: A reproducible nomenclature can provide a means of consistent communication about parathyroid adenoma location. If uniformly adopted, it has the potential to reliably communicate exact gland location without lengthy descriptions. This system may be beneficial for surgical planning as well as operative and pathology reporting.

Outpatient minimally invasive parathyroidectomy is safe for elderly patients.

BACKGROUND: Elderly patients with primary hyperparathyroidism (PHPT) are often not referred for surgical intervention because of concern of comorbid conditions that may increase perioperative complications. Because PHPT is more common in the elderly, we sought to compare indications and complications of minimally invasive parathyroidectomy in patients 70 years of age and older (elderly) with their younger counterparts. STUDY DESIGN: A review was conducted of a prospectively collected database of all patients undergoing parathyroidectomy on our endocrine surgery service. Data collected included patient demographic, biochemical pathologic, and operative findings. Wilcoxon rank sum and chi-square tests were used for comparisons. RESULTS: Three hundred eighty-eight patients with PHPT recently underwent parathyroidectomy over a 3-year period (elderly, n=101; younger, n=287). The elderly cohort had significantly higher median preoperative creatinine (elderly, 2.0 mg/dL; younger,1.0 mg/dL; p=0.002) and parathyroid hormone (elderly, 145 pg/mL; younger, 123 pg/mL; p=0.026) levels. The elderly cohort also had more severe osteoporosis, with a significantly worse median bone mineral density T-score (elderly, -2.5; younger, -1.8; p<0.001). The rate of postoperative complications was similarly low in both groups (elderly, 5.9%; younger, 3.5%; p=0.38). CONCLUSIONS: Minimally invasive parathyroidectomy for PHPT can be performed as safely in elderly patients as in their younger counterparts. Elderly patients with PHPT are more likely to have osteoporosis and higher creatinine levels at the time of surgical referral. Additional study of the role of earlier intervention is warranted.

Prospective randomized trial of paravertebral block for patients undergoing breast cancer surgery.

BACKGROUND: The goal of the current study was to evaluate the effect of regional anesthesia using paravertebral block (PVB) on postoperative pain after breast surgery. METHODS: Patients undergoing unilateral breast surgery without reconstruction were randomized to general anesthesia (GA) only or PVB with GA and pain scores assessed. RESULTS: Eighty patients were randomized (41 to GA and 39 to PVB with GA). Operative times were not significantly different between groups. Pain scores were lower after PVB compared to GA at 1 hour (1 vs 3, P = .006) and 3 hours (0 vs 2, P = .001) but not at later time points. The overall worst pain experienced was lower with PVB (3 vs 5, P = .02). More patients were pain-free in the PVB group at 1 hour (44% vs 17%, P = .014) and 3 hours (54% vs 17%, P = .005) postoperatively. CONCLUSIONS: PVB significantly decreases postoperative pain up to 3 hours after breast cancer surgery.

Adaptation of the OODA Loop to reduce postoperative nausea and vomiting in a high-risk outpatient oncology population.

Postoperative nausea and vomiting (PONV) remains a ubiquitous concern for surgical outpatients with published rates ranging from 14% to 80%. An evidence-based approach was used to reduce PONV in a high-risk adult outpatient oncology population. The Observe, Orient, Decide, and Act (OODA) Loop, a rapid cycle management strategy, was adapted for use in an outpatient surgery center with six ORs. A PONV prophylaxis protocol was developed and adapted until a stable PONV rate was achieved. A combination of dexamethasone, promethazine, and ondansetron was used in patients with one to three PONV risk factors. Patients with four major risk factors received an additional intervention. The PONV rate for the final protocol stabilized below 4% by 46 weeks and remained stable through 79 weeks. The OODA paradigm provides an effective technique for interfacing health care research with clinical practice. In this case, an effective PONV prophylaxis plan was developed from within a collaborative nursing and medical setting.

Minimally invasive parathyroidectomy complicated by pneumothoraces: a report of 4 cases.

The traditional approach to primary hyperparathyroidism has been a bilateral neck exploration for evaluation of all four parathyroid glands. With the advent of minimally invasive surgery, minimally invasive parathyroidectomy has become a popular approach for the treatment of parathyroid adenomas. Though exceedingly rare, pneumothorax formation is a potential complication following this procedure. In this paper, we report four cases of pneumothorax following minimally invasive parathyroidectomies. The commonality in all these cases was positioning with extreme neck hyperextension. Additional risks in three patients were dissection in the superior mediastinum, traction on the thyrothymic ligament, and a low-lying inferior parathyroid gland. One patient developed a pneumothorax prior to dissection along the superior mediastinum. This suggests that further risk factors may be heat conduction from the electrocautery and total intravenous anesthesia with spontaneously breathing of the patient.

Critically ill cancer patients are not consistently hypercoagulable after craniotomy.

INTRODUCTION: Recent reports using thrombelastography have suggested that neurosurgical patients develop a hypercoagulable state in the postoperative period. Since venous thromboembolism is a potentially life threatening complication in these patients, we studied a similar population in our institution. METHODS: We conducted a prospective pilot study to evaluate postoperative coagulation changes in critically ill cancer patients after craniotomy. Data collected included demographics, diagnoses, severity of illness, all hematological information (coagulation tests included conventional and TEG), therapies, and complications. Analysis included descriptive statistics, and multivariate regression analysis. RESULTS: Eleven patients were included in the study. Mean age was 52 +/- 17 years, BMI 28 +/- 6.5, APACHE II and SOFA scores were 11.18 +/- 5.0 and 3.82 +/- 1.6 respectively. The Coagulation Index (CI), which is derived from the measured values of R, K, MA, and alpha angle was 1.22 +/- 3.5, R 4.2 +/- 1.6, K 2.0 +/- 2.1, MA 60.78 +/- 5.97, and alpha angle 66.88 +/- 14.9; while the Thrombodynamic Potential Index (TPI), which is derived from the measured values of K and MA only was 32.48 +/- 21. The CI correlated significantly with R, K, alpha angle, MA, TMA, TPI, PMA, E, A30 and A60 but not with the PTT, INR, or SOFA and APACHE II scores. One patient was hypocoagulable by CI and TPI values; in contrast, nine patients were hypercoagulable by TPI but only one by CI. There were no cases of VTE. CONCLUSIONS: Hypercoagulability as defined by the CI was not a common finding in this study. Although the TPI indicated hypercoagulability in a large number of patients, we do not believe it is a good tool to assess the patient's clotting status or predictor of thrombosis because in contrast to the CI, it does not take into account the enzymatic portions of the clotting cascade. A larger TEG study is warranted to determine the clinical significance of these changes in this and other populations.

Anaesthesia for magnetoencephalography in children with intractable seizures.

BACKGROUND: Magnetoencephalography (MEG), a noninvasive technique for evaluation of epileptic patients, records magnetic fields during neuronal electrical activity within the brain. Anaesthesia experience for MEG has not yet been reported. METHODS: We retrospectively reviewed records of 48 paediatric patients undergoing MEG under anaesthesia. Thirty-one patients (nonprotocol group) were managed according to the anaesthesiologist's discretion. Premedication included oral midazolam, chloral hydrate or fentanyl oralet, intravenous midazolam or inhalational anaesthesia with sevoflurane. Anaesthesia was maintained with propofol, midazolam, fentanyl, alone or in combination. A subsequent protocol group (17 patients) received chloral hydrate as premedication and propofol for maintenance of anaesthesia. RESULTS: There was an overall 25% failure of interictal activity and localization on the MEG scan. In the nonprotocol group, 11 scans failed (35.5%). Of these, eight (72.7%) received midazolam orally. Only one failure (5.8%) was recorded in the protocol group in a patient who received chloral hydrate as sedation supplemented by sevoflurane. CONCLUSIONS: In our experience, midazolam premedication resulted in a high MEG failure rate (73%). Chloral hydrate premedication and propofol maintenance resulted in a lower incidence of MEG failure (5.8%). General anaesthesia with a continuous infusion of propofol or sevoflurane appears acceptable, although, lighter levels of anaesthesia might be required to avoid interference with interictal activity of the brain.