Volatile induction/maintenance of anaesthesia with sevoflurane increases jugular venous oxygen saturation and lumbar cerebrospinal fluid pressure in patients undergoing craniotomy:

Continuous cardiac output estimation using a new modified Fick method during off-pump coronary artery bypass graft surgery: a retrospective observational study

PURPOSE

Several technical aspects of the Fick method limit its use intraoperatively. A data-driven modification of the Fick method may enable its use in intraoperative settings.

METHODS

This two-center retrospective observational study included 57 (28 and 29 in each center) patients who underwent off-pump coronary artery bypass graft (OPCAB) surgery. Intraoperative recordings of physiological data were obtained and divided into training and test datasets. The Fick equation was used to calculate cardiac output (CO-Fick) using ventilator-determined variables, intraoperative hemoglobin level, and SvO2, with continuous thermodilution cardiac output (CCO) used as a reference. A modification CO-Fick was derived and validated: CO-Fick-AD, which adjusts the denominator of the original equation.

RESULTS

Increased deviation between CO-Fick and CCO was observed when oxygen extraction was low. The root mean square error of CO-Fick was decreased from 6.07 L/min to 0.70 L/min after the modification. CO-Fick-AD showed a mean bias of 0.17 (95% CI 0.00-0.34) L/min, with a 36.4% (95% CI 30.6-44.4%) error. The concordance rates of CO-Fick-AD ranged from 73.3 to 87.1% depending on the time interval and exclusion zone.

CONCLUSIONS

The original Fick method is not reliable when oxygen extraction is low, but a modification using data-driven approach could enable continuous estimation of cardiac output during the dynamic intraoperative period with minimal bias. However, further improvements in precision and trending ability are needed.

The choice of the hypnotic drug (volatile or propofol) for maintenance of anesthesia does not influence surgical conditions during cranioplasty

Background and Aims:

In contrast to propofol, volatile agents are often considered harmful to maintain anesthesia due to increasing brain volume and potential deleterious effects. Patients for cranioplasty, including patients with large bone defects, could be susceptible for intraoperative complications but have not properly been investigated so far. The aim of the present study was to evaluate brain swelling, intraoperative conditions, surgical course, and postoperative complication rates of propofol-based vs. volatile-based anesthesia.

Material and Methods:

In this monocentric, retrospective, and observational study, we collected demographic, clinical, and outcome data of patients undergoing cranioplasty between December 2010 and September 2014. According to the hypnotic drug used, patients were assigned to either a propofol or a volatile group. The primary outcome parameter was brain swelling. For comparison of the groups, univariate analysis was performed using Chi-square and Mann–Whitney-U test.

Results:

One hundred and one patients were identified in the period. Twenty-three patients were excluded due to cerebrospinal fluid diversion. Baseline characteristics and preoperative conditions did not vary between the groups except a higher body mass index and positive end-expiratory pressure (PEEP) in the propofol group. The choice of anesthesia (volatile or intravenous) influence neither the intraoperative local conditions nor postoperative complication rate. No significant risk factor for impaired bone flap placement was identified.

Conclusions:

In a well-defined cohort, the choice of the anesthetic agent does not influence the degree of intraoperative brain swelling, bone flap fit, and postoperative course.

Comparison of propofol and desflurane for postanaesthetic morbidity in patients undergoing surgery for aneurysmal SAH: a randomized clinical trial

PURPOSE

Surgery for aneurysmal clipping after subarachnoid haemorrhage (SAH) poses a unique anaesthetic challenge. However, data on the influence of anaesthetic agents in these patients are lacking. The study aims to evaluate the superiority of propofol over desflurane for postanaesthetic morbidity in patients undergoing surgery following aneurysmal SAH.

METHODS

Seventy World Federation of Neurosurgeons Grade I and II patients were randomized into propofol (n = 35) and desflurane groups (n = 35). Anaesthesia was maintained with propofol/fentanyl in propofol group and desflurane/fentanyl in the desflurane group. Jugular venous oxygen saturation (SjVO2) and brain relaxation were assessed intraoperatively. Time to eye opening, response to verbal commands, and extubation were noted from the time of discontinuing the anaesthetic agent. Duration of postoperative hospital stay and modified Rankin score (MRS) at discharge were subsequently compared.

RESULTS

Median postoperative hospital stay was 9 (6, 14) days with use of propofol and 9 (7, 12) days in desflurane group (P = 0.671). 18 patients in the propofol group and 14 patients in the desflurane group had good outcome (modified Rankin score 0-1; P = 0.453). Both the anaesthetics were similar in terms of intraoperative haemodynamics, brain relaxation, time to eye opening, response to verbal commands, and extubation time (P > 0.05). Emergence hypertension was more in the desflurane group (P = 0.007). The intraoperative SjVO2 values were significantly higher in the desflurane group (P < 0.05).

CONCLUSION

Propofol and desflurane are comparable in terms of postoperative morbidity in patients undergoing aneurysm neck clipping following SAH.

Target-controlled Infusion Propofol Versus Sevoflurane Anaesthesia for Emergency Traumatic Brain Surgery: Comparison of the Outcomes

Background

The choice of anaesthetic techniques is important for the outcome of traumatic brain injury (TBI) emergency surgery. The objective of this study was to compare patient outcomes for target-controlled infusion (TCI) of propofol and sevoflurane anaesthesia.

Methods

A total of 110 severe TBI patients, aged 18-60, who underwent emergency brain surgery were randomised into Group T (TCI) (n = 55) and Group S (sevoflurane) (n = 55). Anaesthesia was maintained in Group T with propofol target plasma concentration of 3-6 μg/mL and in Group S with minimum alveolar concentration (MAC) of sevoflurane 1.0-1.5. Both groups received TCI remifentanil 2-8 ng/mL for analgesia. After the surgery, patients were managed in the intensive care unit and were followed up until discharge for the outcome parameters.

Results

Demographic characteristics were comparable in both groups. Differences in Glasgow Outcome Scale (GOS) score at discharge were not significant between Group T and Group S (P = 0.25): the percentages of mortality (GOS 1) [27.3% versus 16.4%], vegetative and severe disability (GOS 2-3) [29.1% versus 41.8%] and good outcome (GOS 4-5) [43.6% versus 41.8%] were comparable in both groups. There were no significant differences in other outcome parameters.

Conclusion

TCI propofol and sevoflurane anaesthesia were comparable in the outcomes of TBI patients after emergency surgery.

Sevoflurane preserves regional cerebral oxygen saturation better than propofol: Randomized controlled trial

STUDY OBJECTIVE

To investigate possible effects of volatile induction and maintenance anesthesia with sevoflurane (VIMA) and total intravenous anesthesia with propofol (TIVA) on regional cerebral oxygen saturation (rcSo₂) during laparoscopic cholecystectomy.

DESIGN

Randomized, prospective and single-blinded study.

SETTING

Academic hospital.

PATIENTS

ASA physical status of I and II surgical patients, scheduled for elective laparoscopic cholecystectomy from March 2013 to October 2014.

MEASUREMENTS

Changes of regional cerebral oxygen saturation were measured by near-infrared spectroscopy on the left and right sides of forehead at different time points: before anesthesia induction (Tbas), immediately after induction (Tind), after applaying a pneumoperitoneum (TCo₂), 10 minutes after positioning the patient into reverse Trendelenburg's position (TrtCo₂), immediately after desufflation of gas (Tpost) and 30 (Trec30) and 60 (Trec60) minutes after emergence from anesthesia.

MAIN RESULTS

Study population included 124 patients, 62 in each group. There was no significant difference between these groups according to demographic characteristics, surgery and anesthesia times as well as in the basal rcSo₂ values. Statistically higher rSco₂ values were noted in the VIMA group when compared to the TIVA group in all time points Tind, TCo₂, TrtCo₂, Tpost, Trec30 and Trec60 and incidence of critical rcSo₂ decreases was statistically lower in VIMA group (P<.05). There were no serious perioperative complications.

CONCLUSIONS

VIMA technique provides significantly (4%-11%) higher rcSO₂ values during general anesthesia for laparoscopic cholecystectomy, when compared with TIVA and also provides significantly less number of critical rcSO₂ decreases.

Effects of propofol versus sevoflurane on cerebral oxygenation and cognitive outcome in patients with impaired cerebral oxygenation

Background

Postoperative neurocognitive dysfunction induced by anesthetics, particularly in elderly patients with impaired oxygenation, is a common complication of surgery and is eliciting increased interest in clinical practice. To investigate the effects of anesthetics on neurocognition, we compared the effects of propofol versus sevoflurane on cerebral oxygenation and cognitive outcome in patients with impaired cerebral oxygenation undergoing general anesthesia.

Methods

Sixty-three patients with impaired cerebral oxygenation (jugular venous bulb oxygen saturation [SjvO₂] <50%) or cerebral blood flow/cerebral metabolic rate of oxygen ([CBF/CMRO₂] ≤15%) undergoing elective abdominal surgery were randomly allocated into propofol group (group P) or sevoflurane group (group S). The clinical parameters and jugular venous bulb blood gas analysis were monitored throughout the surgical procedure. Cognitive function was assessed with the mini-mental state examination and Montreal Cognitive Assessment at day 1 and day 7 following surgery. S100β protein in plasma was measured using enzyme-linked immunosorbent assay.

Results

The SjvO₂ increased during anesthesia induction and surgery when compared to baseline but had no significant difference between group P and group S. When compared to baseline, the CBF/CMRO₂ was increased only at the end of surgery and extubation in group P; however, the CBF/CMRO₂ in group S was increased during anesthesia induction at 1 hour, 2 hours, end of surgery, and extubation. Furthermore, the CBF/CMRO₂ in group S was significantly higher than that in group P during anesthesia induction at 1 hour, 2 hours, and end of surgery. S100β protein did not significantly change at extubation and 1 day after surgery in both groups when compared to baseline. There was no significant difference in mini-mental state examination and Montreal Cognitive Assessment scores between group P and group S at all time points.

Conclusion

Sevoflurane showed similar effects in postoperative neurocognitive function as propofol but could improve cerebral oxygenation in patients with impaired cerebral oxygenation.

Sedation agents differentially modulate cortical and subcortical blood oxygenation: evidence from ultra-high field MRI at 17.2 T

BACKGROUND

Sedation agents affect brain hemodynamic and metabolism leading to specific modifications of the cerebral blood oxygenation level. We previously demonstrated that ultra-high field (UHF) MRI detects changes in cortical blood oxygenation following the administration of sedation drugs commonly used in animal research. Here we applied the UHF-MRI method to study clinically relevant sedation drugs for their effects on cortical and subcortical (thalamus, striatum) oxygenation levels.

METHODS

We acquired T2*-weighted images of Sprague-Dawley rat brains at 17.2T in vivo. During each MRI session, rats were first anesthetized with isoflurane, then with a second sedative agent (sevoflurane, propofol, midazolam, medetomidine or ketamine-xylazine) after stopping isoflurane. We computed a T2*-oxygenation-ratio that aimed at estimating cerebral blood oxygenation level for each sedative agent in each region of interest: cortex, hippocampus, thalamus and striatum.

RESULTS

The T2*-oxygenation-ratio was consistent across scan sessions. This ratio was higher with inhalational agents than with intravenous agents. Under sevoflurane and medetomidine, T2*-oxygenation-ratio was homogenous across the brain regions. Intravenous agents (except medetomidine) induced a T2*-oxygenation-ratio imbalance between cortex and subcortical regions: T2*-oxygenation-ratio was higher in the cortex than the subcortical areas under ketamine-xylazine; T2*-oxygenation-ratio was higher in subcortical regions than in the cortex under propofol or midazolam.

CONCLUSION

Preclinical UHF MRI is a powerful method to monitor the changes in cerebral blood oxygenation level induced by sedative agents across brain structures. This approach also allows for a classification of sedative agents based on their differential effects on cerebral blood oxygenation level.

Impact of sevoflurane anesthesia on brain oxygenation in children younger than 2 years

OBJECTIVE/AIM

To assess the impact of sevoflurane and anesthesia-induced hypotension on brain oxygenation in children younger than 2 years.

BACKGROUND

Inhalational induction with sevoflurane is the most commonly used technique in young children. However, the effect of sevoflurane on cerebral perfusion has been only studied in adults and children older than 1 year. The purpose of this study was to assess the impact of sevoflurane anesthesia on brain oxygenation in neonates and infants, using near-infrared spectroscopy.

METHODS

Children younger than 2 years, ASA I or II, scheduled for abdominal or orthopedic surgery were included. Induction of anesthesia was started by sevoflurane 6% and maintained with an expired fraction of sevoflurane 3%. Mechanical ventilation was adjusted to maintain an endtidal CO2 around 39 mmHg. Brain oxygenation was assessed measuring regional cerebral saturation of oxygen (rSO2 c), measured by NIRS while awake and 15 min after induction, under anesthesia. Mean arterial pressure (MAP) variation was recorded.

RESULTS

Hundred and ninety-five children were included. Anesthesia induced a significant decrease in MAP (-27%). rSO2 c increased significantly after induction (+18%). Using children age for subgroup analysis, we found that despite MAP reduction, rSO2 c increase was significant but smaller in children ≤ 6 months than in children >6 months (≤ 6 months: rSO2 c = +13%, >6 months: rSO2 c = +22%; P < 0.0001). Interindividual comparison showed that, during anesthesia at steady-state with comparable CMRO2, rSO2 c values were significantly higher when MAP was above 36 mmHg. And the higher the absolute MAP value during anesthesia was, the higher the rSO2 c was. We observed a rSO2 c variation ≤ 0 in 21 patients among the 195 studied, and the majority of these patients were younger than 6 months (n = 19). No increase or decrease of rSO2 c during anesthesia despite reduction of CMRO2 can be explained by a reduction of oxygen supply. Using the ROC curves, we determined that the threshold value of MAP under anesthesia, associated with rSO2 c variation ≤ 0%, was 39 mmHg in all the studied population (AUC: 0.90 ± 0.02; P < 0.001). In children younger than 6 months, this value of MAP was 33 mmHg, and 43 mmHg in children older than 6 months.

CONCLUSION

Despite a significant decrease of MAP, 1 MAC of sevoflurane induced a significant increase in regional brain oxygenation. But subgroup analysis showed that MAP decrease had a greater impact on brain oxygenation, in children younger than 6 months. According to our results, MAP value during anesthesia should not go under 33 mmHg in children ≤6 months and 43 mmHg in children >6 months, as further changes in MAP, PaCO2 or hemoglobin during anesthesia may be poorly tolerated by the brain.