Spectral edge frequency during general anaesthesia: A narrative literature review

Previous studies have attempted to determine the depth of anaesthesia with different anaesthetic agents using electroencephalogram (EEG) measurements with variable success. Measuring depth of anaesthesia is confounded by the complexity of the EEG and the fact that different agents create different pattens. A narrative review was undertaken to examine the available research evidence on the effect and reliability of spectral edge frequency (SEF) for assessing the depth of anaesthesia in adult patients under general anaesthesia. A systematic search of the PubMed®, Scopus®, CINAHL and Cochrane databases identified six randomized controlled trials and five observational studies. The findings of these studies suggest that SEF varies according to the anaesthetic drugs used. Remifentanil and age are two factors that can affect SEF, while other opioids and benzodiazepine (administered separately) seem to have no effect. No patients experienced intraoperative awareness. However, this does not indicate that SEF can provide full protection against it and the number of articles in which intraoperative awareness was studied was too small to afford any certainty. None of the studies demonstrated a reliable SEF interval associated with adequate general anaesthesia. SEF must be adapted to the anaesthetic drug used, the patient’s age and state while under general anaesthesia.

Total opioid-free general anaesthesia can improve postoperative outcomes after surgery, without evidence of adverse effects on patient safety and pain management: A systematic review and meta-analysis

BACKGROUND

Opioid-based treatment is used to manage stress responses during surgery and postoperative pain. However, opioids have both acute and long-term side effects, calling for opioid-free anaesthetic strategies. This meta-analysis compares adverse events, postoperative recovery, discharge time from post-anaesthesia care unit, and postoperative pain, nausea, vomiting, and opioid consumption between strict opioid-free and opioid-based general anaesthesia.

METHODS

We conducted a systematic review and meta-analysis. We searched PubMed, Embase, Cinahl, Cochrane Library, selected reference lists, and Google Scholar. We included randomised controlled trials (RCTs) published between January 2000 and February 2021 with at least one opioid-free study arm, i.e. no opioids administered preoperatively, during anaesthesia induction, before skin closure, or before emergence from anaesthesia.

RESULTS

The study comprised 1934 patients from 26 RCTs. Common interventions included laparoscopic gynaecological surgery, upper gastrointestinal surgery, and breast surgery. There is firm evidence that opioid-free anaesthesia significantly reduced adverse postoperative events (OR 0.32, 95% CI 0.22 to 0.46, I²  = 56%, p < 0.00001), mainly driven by decreased nausea (OR 0.27, (0.17 to 0.42), p < 0.00001) and vomiting (OR 0.22 (0.11 to 0.41), p < 0.00001). Postoperative opioid consumption was significantly lower in the opioid-free group (-6.00 mg (-8.52 to -3.48), p < 0.00001). There was no significant difference in length of post-anaesthesia care unit stay and overall postoperative pain between groups.

CONCLUSIONS

Opioid-free anaesthesia can improve postoperative outcomes in several surgical settings without evidence of adverse effects on patient safety and pain management. There is a need for more evidence-based non-opioid anaesthetic protocols for different types of surgery as well as postoperative phases.

Cerebral autoregulation in infants during sevoflurane anesthesia for craniofacial surgery

BACKGROUND

Data on cerebral pressure-flow autoregulation in the youngest children are scarce. We studied the correlation between mean arterial pressure and cerebral tissue oxygen saturation (rSO₂ ) by near-infrared spectroscopy (NIRS) in patients undergoing nose, lip, and palate surgery.

AIM

We tested the hypothesis that cerebral pressure-flow autoregulation is impaired in children less than 1 year undergoing surgery and general anesthesia with sevoflurane under controlled mechanical ventilation.

METHOD

After approval from the Ethical board, 15 children aged <1 year were included. Before anesthesia induction, a NIRS sensor (INVOS^TM , Medtronic, Minneapolis, USA) was placed over the cerebral frontal lobe. Frontal rSO₂ , a surrogate for cerebral perfusion, mean arterial pressure, end-tidal CO₂ - and sevoflurane concentration, and arterial oxygen saturation were sampled every minute after the induction. A repeated measures correlation analysis was performed to study correlation between mean arterial pressure and cerebral rSO₂ , and the repeated measures correlation coefficient (r_rm ) was calculated.

RESULTS

Fifteen patients, aged 7.7 ± 1.9 months, were studied. rSO₂ showed a positive correlation with mean arterial pressure ([95% CI: 9.0-12.1], P < 0.001) with a moderate to large effect size (r_rm  = 0.462), indicating an impaired cerebral pressure-flow autoregulation. The slopes of the rSO₂ -mean arterial pressure correlations were steeper in patients who were hypotensive (mean arterial pressure <50 mm Hg) compared to patients having a mean arterial pressure ≥50 mm Hg, indicating that at lower mean arterial pressure, the cerebral pressure dependence of cerebral oxygenation is even more pronounced.

CONCLUSION

During sevoflurane anesthesia in the youngest pediatric patients, cerebral perfusion is pressure-dependent, suggesting that the efficiency of the cerebral blood flow autoregulation is limited.

Nurse anesthetists' experiences using smart glasses to monitor patients' vital signs during anesthesia care: A qualitative study

PURPOSE

To describe nurse anesthetists' experiences using smart glasses to monitor patients' vital signs during anesthesia care.

METHODS

Data was collected through individual semi-structured interviews with seven nurse anesthetists who had used smart glasses, with a customized application for monitoring vital signs, during clinical anesthesia care. Data was analyzed using thematic content analysis.

RESULTS

An overarching theme became evident during analysis; Facing and embracing responsibility. Being a nurse anesthetist entails a great responsibility, and the participants demonstrated that they shouldered this responsibility with pride. The theme was divided in two sub-themes. The first of these, A new way of working, comprised the categories Adoption and Utility. This involved incorporating smart glasses into existing routines in order to provide safe anesthesia care. The second sub-theme, Encountering side effects, consisted of the categories Obstacles and Personal affect. This sub-theme concerned the possibility to use smart glasses as intended, as well as the affect on nurse anesthetists as users.

CONCLUSION

Smart glasses improved access to vital signs and enabled continuous monitoring regardless of location. Continued development and improvement, both in terms of the application software and the hardware, are necessary for smart glasses to meet nurse anesthetists' needs in clinical practice.

Smart Glasses for Anesthesia Care: Initial Focus Group Interviews with Specialized Health Care Professionals

PURPOSE

Smart glasses are a kind of wearable technology that gives users sustained, hands-free access to data and can transmit and receive information wirelessly. Earlier studies have suggested that smart glasses have the potential to improve patient safety in anesthesia care. Research regarding health care professionals' views of the potential use of smart glasses in anesthesia care is limited. The purpose of this study was to describe anesthesia health care professionals' views of smart glasses before clinical use.

DESIGN

A qualitative descriptive study.

METHODS

Data were collected from focus group interviews and analyzed using thematic content analysis.

FINDINGS

Three categories of participants' views of smart glasses were created during the analysis: views of integrating smart glasses in clinical setting; views of customized functionality of smart glasses; and views of being a user of smart glasses. One theme, striving for situational control, was identified in the analysis.

CONCLUSIONS

Smart glasses were seen as a tool that can impact and improve access to patient-related information, and aid health care professionals in their struggle to gain situational control during anesthesia care. These are factors related to increased patient safety.

Agreement between frontal and occipital regional cerebral oxygen saturation in infants during surgery and general anesthesia an observational study

BACKGROUND

Advances in perioperative pediatric care have resulted in an increased number of procedures requiring anesthesia. During anesthesia and surgery, the patient is subjected to factors that affect the circulatory homeostasis, which can influence oxygenation of the brain. Near-infrared spectroscopy (NIRS) is an easy applicable noninvasive method for monitoring of regional tissue oxygenation (rScO₂%). Alternate placements for NIRS have been investigated; however, no alternative cranial placements have been explored.

AIM

To evaluate the agreement between frontal and occipital recordings of rScO₂% in infants using INVOS^TM during surgery and general anesthesia.

METHOD

A standard frontal monitoring of rScO₂% with NIRS was compared with occipital rScO₂% measurements in fifteen children at an age <1 year, ASA 1-2, undergoing cleft lip and/or palate surgery during general anesthesia with sevoflurane. An agreement analysis was performed according to Bland and Altman.

RESULTS

Mean values of frontal and occipital rScO₂% at baseline were largely similar (70.7 ± 4.77% and 69.40 ± 5.04%, respectively). In the majority of the patients, the frontal and occipital recordings of rScO₂ changed in parallel. There was a moderate positive correlation between frontal and occipital rScO₂% INVOS™ readings (rho[ρ]: 0.513, P < .01). The difference between frontal and occipital rScO₂ ranged from -31 to 28 with a mean difference (bias) of -0.15%. The 95% limit of agreement was -18.04%-17.74%. The error between frontal and occipital rScO₂ recordings was 23%.

CONCLUSION

The agreement between frontal and occipital recordings of brain rScO₂% in infants using INVOS^TM during surgery and general anesthesia was acceptable. In surgical procedures where the frontal region of the head is not available for monitoring, occipital recordings of rScO₂% could be an option for monitoring.

What can a mobile App add to improve quality of care, with focus on ambulatory surgery?

Rationale, aims and objectives: Many surgical procedures are nowadays performed as ambulatory or short stay procedures, reducing hospital length of stay. Patient safety and quality of care remain imperative especially when adopting enhanced recovery pathways. Patients should be adequately informed and prepared prior to admission. Recovery is to a major extent dependent after discharge on self-care and thus techniques to follow the post-operative course after leaving hospital are warranted. Telemedicine has grown tremendously over recent years and the incorporation of mobile telephone app technology for the pre- and post-operative coaching of the ambulatory surgical patient may represent an effective means of assisting patients. The present paper presents a feasibility study of a mobile telephone app providing pre-operative information and following the post-operative recovery following day surgery.Method: Patients scheduled for elective day surgery were asked to participate, testing the app and to assess its usefulness on visual analogue scales.Results: Sixty-nine patients aged 18 to 73 years tested the app. Patients aged 30 to 50 where the most frequent users and patients < 30 less frequent. The app was in general assessed as useful and most users expressed an interest in the option of having an app as a source of information before undergoing a scheduled procedure. General pre-operative information was assessed as the most important. A willingness to submit follow-up information decreased rapidly, only 26 and 16 responded at day 10 and 30, respectively.Conclusion: A mobile telephone app is a feasible and appreciated tool for pre-operative information and coaching as part of person-centered healthcare, but its use for follow-up after discharge is challenging and requires further investigation.

Isocapnic hyperventilation provides early extubation after head and neck surgery: A prospective randomized trial

BACKGROUND

Isocapnic hyperventilation (IHV) shortens recovery time after inhalation anaesthesia by increasing ventilation while maintaining a normal airway carbon dioxide (CO2 )-level. One way of performing IHV is to infuse CO2 to the inspiratory limb of a breathing circuit during mechanical hyperventilation (HV). In a prospective randomized study, we compared this IHV technique to a standard emergence procedure (control).

METHODS

Thirty-one adult ASA I-III patients undergoing long-duration (>3 hours) sevoflurane anaesthesia for major head and neck surgery were included and randomized to IHV-treatment (n = 16) or control (n = 15). IHV was performed at minute ventilation 13.6 ± 4.3 L/min and CO2 delivery, dosed according to a nomogram tested in a pilot study. Time to extubation and eye-opening was recorded. Inspired (FICO2 ) and expired (FETCO2 ) CO2 and arterial CO2 levels (PaCO2 ) were monitored. Cognition was tested preoperatively and at 20, 40 and 60 minutes after surgery.

RESULTS

Time from turning off the vapourizer to extubation was 13.7 ± 2.5 minutes in the IHV group and 27.4 ± 6.5 minutes in controls (P < .001). Two minutes after extubation, PaCO2 was 6.2 ± 0.5 and 6.2 ± 0.6 kPa in the IHV and control group respectively. In 69% (IHV) vs 53% (controls), post-operative cognition returned to pre-operative values within 40 minutes after surgery (NS). Incidences of pain and nausea/vomiting did not differ between groups.

CONCLUSIONS

In this randomized trial comparing an IHV method with a standard weaning procedure, time to extubation was reduced with 50% in the IHV group. The described IHV method can be used to decrease emergence time from inhalation anaesthesia.

Evaluation of a method for isocapnic hyperventilation: a clinical pilot trial

BACKGROUND

Isocapnic hyperventilation (IHV) is a method that shortens time to extubation after inhalation anaesthesia using hyperventilation (HV) without lowering airway CO₂ . In a clinical trial on patients undergoing long-duration sevoflurane anaesthesia for major ear-nose-throat (ENT) surgery, we evaluated the utility of a technique for CO₂ delivery (DCO₂ ) to the inspiratory limb of a closed breathing circuit, during HV, to achieve isocapnia.

METHODS

Fifteen adult ASA 1-3 patients were included. After end of surgery, mechanical HV was started by doubling baseline minute ventilation. Simultaneously, CO₂ was delivered and dosed using a nomogram developed in a previous experimental study. Time to extubation and eye opening was recorded. Inspired (FICO₂ ) and expired (FETCO₂ ) CO₂ and arterial CO₂ levels were monitored during IHV. Cognition was tested pre-operatively and at 20, 40 and 60 min after surgery.

RESULTS

A DCO₂ of 285 ± 45 ml/min provided stable isocapnia during HV (13.5 ± 4.1 l/min). The corresponding FICO₂ level was 3.0 ± 0.3%. Time from turning off the vaporizer (1.3 ± 0.1 MACage) to extubation (0.2 ± 0.1 MACage) was 11.3 ± 1.8 min after 342 ± 131 min of anaesthesia. PaCO₂ and FETCO₂ remained at normal levels during and after IHV. In 85% of the patients, post-operative cognition returned to pre-operative values within 60 min.

CONCLUSIONS

In this cohort of patients, a DCO₂ nomogram for IHV was validated. The patients were safely extubated shortly after discontinuing long-term sevoflurane anaesthesia. Perioperatively, there were no adverse effects on arterial blood gases or post-operative cognition. This technique for IHV can potentially be used to decrease emergence time from inhalation anaesthesia.

Anaesthesia for open wrist fracture surgery in adults/elderly

Anaesthetic technique for open surgery of acute distal for arm fracture in adults/elderly is not well defined. Regional anaesthesia, general anaesthesia or a combined general and regional block may be considered. General anaesthetic technique, the timing and drug/drug combination for the regional block must also be considered. This is a study around published studies assessing anaesthtic technique for wrist surgery. A systematic database search was performed and papers describing the effect of anaesthetic techniques were included.

We found sparse evidence for what anaesthetic technique is optimal for open wrist fracture repair. In total only six studies were found using our inclusion criteria, which all supported the short term, early recovery benefits of regional anaesthesia as part of multi-modal analgesia. More protracted outcomes and putting the type of block into context of quality of recovery and patients’ satisfaction is lacking in the literature. The risk for a pain rebound when the block vanishes should also be acknowledged. Therefore, further high quality studies are warranted concerning the anaesthetic technique for this type of surgery.

The choice between surgical scrubbing and sterile covering before or after induction of anaesthesia: A prospective study

Background : Day surgery is increasing, and safe and effective logistics are sought. One part of the in-theatre logistics commonly discussed is whether surgical scrub and sterile covering should be done before or after induction of anaesthesia. The aim of the present study was to compare the impact of surgical scrub and sterile covering before vs. after the induction of anaesthesia in male patients scheduled for open hernia repair.    Methods : This is a prospective randomised study. Sixty ASA 1-3 patients scheduled for open hernia repair were randomised to surgical scrub and sterile covering before or after induction of anaesthesia; group "awake" and "anaesthetised". Need for vasoactive medication during anaesthesia was primary study objective. Duration of anaesthesia and surgery, theatre time, recovery room stay and time to discharge, patients and theatre nurses experiences and willingness to have the same logistics on further potential surgeries, by a questionnaire provided before discharge was also assessed.  Results : The duration of anaesthesia was shorter and doses of propofol and remifentanil were reduced by 10 and 13%, respectively, in the awake group. We found still no difference in the need for vasoactive medication during anaesthesia Time in recovery area was significantly reduced in the awake group 39 (SD 15) vs. 48 SD 16) (p<0.05), but time to discharge was not different. There was further no difference in the patients' assessment of quality of care, and only one patient in the awake group would prefer to be anaesthetised on a future procedure. All nurses found pre-anaesthesia scrubbing acceptable as routine.  Conclusion : Surgical scrub and sterile covering before the induction of anaesthesia can be done safely and without jeopardising patients' quality of care and possibly improve perioperative logistics. Further studies are warranted assessing impact of awake scrubbing and sterile covering on quality and efficacy of perioperative care.

At-home monitoring after surgery/anaesthesia - a challenge

RATIONALE, AIMS AND OBJECTIVES

Day surgery is evolving, with a majority of recoveries occurring at home. There is, in parallel, an evolution in telemedical technology. The aim of the present project was to identify patients' willingness to use predefined follow-up techniques and to clinically test preferred techniques at home using a two-step study.┅ METHODS: In Part I, a paper-based questionnaire study of identified patients' attitudes with three follow-up techniques was used. In Part II, a feasibility test of a mobile (smart-phone) application for follow-up at home was used.

RESULTS

Part I showed overall positive attitudes to telemedical follow-ups. Part II showed the preference for a follow-up technique with a mobile application was not fully consistent with the clinical study of the smart-phone app, where there was a large non-response. The application provided safe transfer of data to the hospital and helped make it easy to retrieve and analyse patient self-assessment of recovery. This application is one-way directed, and no feedback to the patient was given, which may have influenced the non-response.

CONCLUSION

Bringing telemedicine into follow-up after surgery/anaesthesia is requested, and furthermore, the feasibility study on day surgery presented here shows that it is technically easy to perform and will provide robust information. It should be noted that further studies are needed in order to find better patient cooperation.

Evaluation of the Postoperative Quality of Recovery Scale test and re-test in Swedish among healthy volunteers

Introduction Patient outcome measures are required to assess the quality of healthcare. Tools for a patients' self-assessment of quality of recovery, during perioperative care, have been developed during the last decade. The Postoperative Quality of Recovery Scale (PostopQRS) questionnaire is one of the most well-accepted and validated tools available. Here we assess the PostopORS questionnaire in Swedish. Methods Sixty-one students from the Bachelor Program in Nursing, (50 female and 11 male; mean age, 25; range, 21-46) filled in the Swedish translation of the PostopQRS questionnaire twice. They also evaluated whether they found the queries easy to understand and respond to .Results The participants found the Swedish translation of the PostopQRS questionnaire easy to read and understand. There were minor differences in test responses between the initial test and the re-test 48 hours later. We found that the PostopQRS questionnaire has some background noise; 12 out of 61 participants (20%) reported mild pain, 25 (41%) scored some depression and 33 scored mild anxiety (54%). The cognitive domain showed a learning effect between tests in "word recall" and "word generation", while "digit recall forward" and "digit recall backward" showed no change. We found a difference in cognitive test performance with age; younger participants had higher mean cognitive test scores compared to participants >30 years. Overall, nine participants showed a decrease in re-test scores; two experienced a mild increase in pain; one experienced a mild increase in anxiety; and six performed more poorly on cognitive tests. Conclusion The Swedish translation of the PostopQRS was found to be adequate for use in the assessment of quality of recovery, and the questions were well understood by participants. Our study shows the importance of baseline testing for assessment of recovery, since recovery is assessed as a return to or improvement in each individual's baseline score.

Upper extremity nerve block: how can benefit, duration, and safety be improved? An update

Upper extremity blocks are useful as both sole anaesthesia and/or a supplement to general anaesthesia and they further provide effective postoperative analgesia, reducing the need for opioid analgesics. There is without doubt a renewed interest among anaesthesiologists in the interscalene, supraclavicular, infraclavicular, and axillary plexus blocks with the increasing use of ultrasound guidance. The ultrasound-guided technique visualising the needle tip and solution injected reduces the risk of side effects, accidental intravascular injection, and possibly also trauma to surrounding tissues. The ultrasound technique has also reduced the volume needed in order to gain effective block. Still, single-shot plexus block, although it produces effective anaesthesia, has a limited duration of postoperative analgesia and a number of adjuncts have been tested in order to prolong analgesia duration. The addition of steroids, midazolam, clonidine, dexmedetomidine, and buprenorphine has been studied, all being off-label when administered by perineural injection, and the potential neurotoxicity needs further study. The use of perineural catheters is an effective option to improve and prolong the postoperative analgesic effect.

Upper extremity plexus blocks have an obvious place as a sole anaesthetic technique or as a powerful complement to general anaesthesia, reducing the need for analgesics and hypnotics intraoperatively, and provide effective early postoperative pain relief. Continuous perineural infusion is an effective option to prolong the effects and improve postoperative quality.