Calculation of volatile anaesthetics consumption from agent concentration and fresh gas flow

Effect of real-time oxygen consumption versus fixed flow-based low flow anesthesia on oxygenation and perfusion: a randomized, single-blind study

Although low-flow anesthesia is widely used due to its various advantages, there are concerns about potential and relative hypoxia. Furthermore, oxygen is also a drug with benefits and adverse effects. We aimed to evaluate and compare the effect of real-time oxygen consumption versus fixed flow-based low flow anesthesia on oxygenation and perfusion and to compare the economic benefits. With ethical approvals and informed consent, participants were randomly assigned to a dynamic group (13 males, and 27 females) receiving fresh gas flows depending on real-time oxygen consumption (dynamic O2: N2O), and a fixed group (20 males, and 13 females) receiving fixed fresh gas flows of 600 mL/min (with O2: N2O of 1:1). Oxygen partial pressure and serum lactate were comparable between groups. However, isoflurane consumed and costs incurred were significantly different. Total oxygen consumption per minute was also significantly lower in the dynamic group than the fixed group. No episodes of hypoxia were observed in either group. Real-time oxygen consumption-based low flow anesthesia is feasible and cost-effective without affecting the patient's global perfusion and outcome.

Inhalational anaesthetic agent consumption within a multidisciplinary veterinary teaching hospital: an environmental audit

Inhalational anaesthetic agents are routinely used in veterinary anaesthesia practices, yet their consumption contributes significantly to greenhouse gas emissions and environmental impact. We conducted a 55-day observational study at a veterinary teaching hospital in Switzerland, monitoring isoflurane and sevoflurane consumption across small, equine and farm animal clinics and analysed the resulting environmental impact. Results revealed that in total, 9.36 L of isoflurane and 1.27 L of sevoflurane were used to anaesthetise 409 animals across 1,489 h. Consumption rates varied among species, with small and farm animals ranging between 8.7 and 13 mL/h, while equine anaesthesia exhibited a higher rate, 41.2 mL/h. Corresponding to 7.36 tonnes of carbon dioxide equivalent in total environmental emissions or between 2.4 and 31.3 kg of carbon dioxide equivalent per hour. Comparison to human anaesthesia settings showed comparable consumption rates to small animals, suggesting shared environmental implications, albeit on a smaller scale. This research highlights the importance of continued evaluation of veterinary anaesthesia practices to balance patient safety with environmental stewardship; potential mitigation strategies are explored and discussed.

Efficiency of passive activated carbon anaesthetic gas capturing systems during simulated ventilation

BACKGROUND

Interest in passive flow filter systems to remove sevoflurane from anaesthetic machine exhaust have increased recently to mitigate the environmental impact of volatile anaesthetics. These filter systems consist of chemically activated carbon, with limited evidence on their performance characteristics. We hypothesised that their efficiency depends on filter material.

METHODS

Binding capacity was tested for three carbon filter materials (CONTRAfluran®, FlurAbsorb®, and Anaesthetic Agent Filter AAF633). Adsorption efficiency and resistive pressure were determined during simulated ventilation at different stages of filter saturation and fresh gas flow. In addition, sevoflurane concentration in filtered gas was measured at randomly selected anaesthesia workstations.

RESULTS

Sevoflurane concentration in filtered gas exceeded 10 ppm when saturated with 184 ml sevoflurane each for CONTRAfluran and FlurAbsorb and 276 ml for AAF633. During simulated ventilation, sevoflurane concentration >10 ppm passed through CONTRAfluran and AAF633 at fresh gas flow 10 L min-1 only at maximum saturation, but through FlurAbsorb at all stages of saturation. The resistance pressure of all filters was negligible during simulated ventilation, but increased up to 5.2 (0.2) cm H2O during simulated coughing. At two of seven anaesthesia workstations, sevoflurane concentration in filtered exhaust gas was >10 ppm.

CONCLUSIONS

Depending on the filter material and saturation, the likelihood of sevoflurane passing through passive flow carbon filters depends on the filter material and fresh gas flow. Combining the filter systems with anaesthetic gas scavenging systems could protect from pollution of ambient air with sevoflurane.

Pharmacokinetics of desflurane uptake and disposition in piglets

Introduction

Many respiratory but few arterial blood pharmacokinetics of desflurane uptake and disposition have been investigated. We explored the pharmacokinetic parameters in piglets by comparing inspiratory, end-tidal, arterial blood, and mixed venous blood concentrations of desflurane.

Methods

Seven piglets were administered inspiratory 6% desflurane by inhalation over 2 h, followed by a 2-h disposition phase. Inspiratory and end-tidal concentrations were detected using an infrared analyzer. Femoral arterial blood and pulmonary artery mixed venous blood were sampled to determine desflurane concentrations by gas chromatography at 1, 3, 5, 10, 20, 30, 40, 50, 60, 80, 100, and 120 min during each uptake and disposition phase. Respiratory and hemodynamic parameters were measured simultaneously. Body uptake and disposition rates were calculated by multiplying the difference between the arterial and pulmonary artery blood concentrations by the cardiac output.

Results

The rates of desflurane body uptake increased considerably in the initial 5 min (79.8 ml.min-1) and then declined slowly until 120 min (27.0 ml.min-1). Similar characteristics of washout were noted during the subsequent disposition phase. Concentration-time curves of end-tidal, arterial, and pulmonary artery blood concentrations fitted well to zero-order input and first-order disposition kinetics. Arterial and pulmonary artery blood concentrations were best fitted using a two-compartment model. After 2 h, only 21.9% of the desflurane administered had been eliminated from the body.

Conclusion

Under a fixed inspiratory concentration, desflurane body uptake in piglets corresponded to constant zero-order infusion, and the 2-h disposition pattern followed first-order kinetics and best fitted to a two-compartment model.

Inhaled volatile anesthetics in the intensive care unit

The discovery and utilization of volatile anesthetics has significantly transformed surgical practices since their inception in the mid-19th century. Recently, a paradigm shift is observed as volatile anesthetics extend beyond traditional confines of the operating theatres, finding diverse applications in intensive care settings. In the dynamic landscape of intensive care, volatile anesthetics emerge as a promising avenue for addressing complex sedation requirements, managing refractory lung pathologies including acute respiratory distress syndrome and status asthmaticus, conditions of high sedative requirements including burns, high opioid or alcohol use and neurological conditions such as status epilepticus. Volatile anesthetics can be administered through either inhaled route via anesthetic machines/devices or through extracorporeal membrane oxygenation circuitry, providing intensivists with multiple options to tailor therapy. Furthermore, their unique pharmacokinetic profiles render them titratable and empower clinicians to individualize management with heightened accuracy, mitigating risks associated with conventional sedation modalities. Despite the amounting enthusiasm for the use of these therapies, barriers to widespread utilization include expanding equipment availability, staff familiarity and training of safe use. This article delves into the realm of applying inhaled volatile anesthetics in the intensive care unit through discussing their pharmacology, administration considerations in intensive care settings, complication considerations, and listing indications and evidence of the use of volatile anesthetics in the critically ill patient population.

Investigation of euthanasia techniques in four species of cockroaches

While cockroaches are commonly exhibited in zoos and museums, studied in research laboratories, and even kept as pets, scientifically based guidelines for their euthanasia are lacking. This study assessed euthanasia techniques in four species of cockroaches (Dubia (Blaptica dubia), red runner (Shelfordella lateralis), Madagascar hissing (Gromphadorhina portentosa), and giant cave (Blaberus giganteus)). In an initial pilot study, two hundred fifty adult Dubia cockroaches were exposed in groups of ten to a cotton ball soaked with 2 mL of isoflurane in a 1 L air-tight chamber. Thirty minutes beyond loss of any individual movement, groups were exposed to one of the following secondary treatments: freezing at -18 °C or -80 °C from 0.25 to 24 hours; immersion in 10% neutral buffered formalin, 70% isopropyl alcohol, or reverse osmosis water for 0.25 or 0.5 hours; or intracoelomic injection of potassium chloride (456 mEq/kg) or pentobarbital-based euthanasia solution (3.9 g/kg). A control group remained in the air-tight isoflurane chamber for 24 hours. Following all treatments, cockroaches were monitored for an additional 24 hours for spontaneous movement. Irreversible loss of movement was considered synonymous with irreversible loss of consciousness (death). Across all species, isoflurane anesthesia followed by either 70% isopropyl alcohol immersion for 0.25 or 0.5 hours or isoflurane exposure for 24 hours resulted in euthanasia in 100% of cockroaches. This study is the first evaluation of American Veterinary Medical Association-recommended euthanasia protocols in cockroaches.

The effect of erector spinae plane block on fentanyl consumption during open abdominal hysterectomy: a randomised controlled study

BACKGROUND

Perioperative analgesia is very important during an abdominal hysterectomy. Determining the impact of the erector spinae plane block (ESPB) on patients undergoing an open abdominal hysterectomy while under general anesthesia was our aim.

METHODS

In order to create equal groups, 100 patients who underwent elective open abdominal hysterectomies under general anesthesia were enlisted. The preoperative bilateral ESPB with 20 ml of bupivacaine 0.25% was administered to the ESPB group (n = 50). The same procedure was performed on the control group (n = 50), but they received a 20-ml saline injection instead. The primary outcome is the total amount of fentanyl consumed during surgery.

RESULTS

We found that the mean (SD) intraoperative fentanyl consumption was significantly lower in the ESPB group than in the control group (82.9 (27.4) g vs. 148.5 (44.8) g, with a 95% CI = -80.3 to -50.8; p 0.001). Likewise, mean (SD) postoperative fentanyl consumption was significantly lower in the ESPB group than in the control group (442.4 (17.8) g vs. 477.9 (10.4) g, with a 95% CI = -41.3 to -29.7; p 0.001). On the other hand, there is no statistically significant difference between the two study groups regarding sevoflurane consumption (89.2 (19.5) ml vs. 92.4 (15.3) ml, with a 95% CI = -10.1 to 3.8; p 0.4). We documented that during the post-operative period (0-24 h), VAS scores at rest were, on average, 1.03 units lower in the ESPB group (estimate = -1.03, 95% CI = -1.16-(-0.86), t = -14.9, p-value 0.001), and VAS scores during cough were, on average, 1.07 units lower in the ESPB group (estimate = -1.07, 95% CI = -1.21-(-0.93), t = -14.8, p-value 0.001).

CONCLUSION

Bilateral ESPB can be utilized as an adjuvant method to reduce intraoperative fentanyl consumption and enhance postoperative pain control in patients undergoing open total abdominal hysterectomy under general anesthesia. It is effective, secure, and little obtrusive.

TRIAL REGISTRATION

No protocol revisions or study amendments have been made since the trial's inception, according to the information on ClinicalTrials.gov (NCT05072184; principal investigator: Mohamed Ahmed Hamed; date of registration: October 28, 2021).

Evaluation of Targeted Injections of Ivermectin or Potassium Chloride for Euthanasia of Anesthetized Thorny Devil Stick Insects (Eurycantha calcarata)

Insects are commonly utilized in biomedical research and have become increasingly popular in museum collections and as pets. Despite this, objective evaluation of insect euthanasia is scarce. This study investigated the effectiveness of targeted injections of ivermectin or potassium chloride (KCl) for the euthanasia of anesthetized thorny devil stick insects (Eurycantha calcarata). Ten clinically healthy mature insects (six males, four females) were enrolled. Insects were weighed and anesthetized via exposure to a cotton ball soaked with 1.6 mL of liquid isoflurane in a 1 L sealed chamber until loss of righting reflex and response to stimulation (induction). Insects then received one of three treatments: ivermectin 100 mg/kg (n = 4), KCl 200 mEq/kg (n = 4), or 0.9% sodium chloride 100 mL/kg (n = 2) injected along the ventral thoracic midline between the first leg plate and the caudal adjacent plate. Following injection, insects were serially monitored for return of spontaneous movement and righting reflex. Death was defined as the absence of spontaneous movement for 48 h. Median (range) induction time and isoflurane concentration at induction was 36 (22–39) min (n = 9) and 22 (19–22)%, respectively. Euthanasia was successful in 4/4, 3/4, and 0/2 isoflurane-anesthetized insects receiving ivermectin, KCl, or 0.9% sodium chloride, respectively. Recovery was prolonged at 10.5 (sodium chloride female), 11.0 (KCl male), and 18.0 (sodium chloride male) hours. This is the first prospective investigation of euthanasia in adult E. calcarata. In this preliminary study, ivermectin 100 mg/kg via ventral midline injection was effective for euthanasia of thorny devil stick insects.

The financial and environmental impact of purchased anaesthetic agents in an Australian tertiary hospital

Anaesthetic agents have various financial and environmental impacts. Climate change is one of the biggest threats to human health, and anaesthetic gases contribute to global heating by acting as greenhouse gases. The primary aim of this study was to quantify the financial and environmental impacts of anaesthesia maintenance agents used during surgery in an Australian university teaching hospital. The volume of desflurane, sevoflurane, isoflurane and propofol purchased by a university teaching hospital between 2010 and 2020 was analysed and described in terms of financial and environmental impact. Estimated carbon emissions and financial costs of each agent per annum were calculated using the volumes purchased for each agent. A model of ideal anaesthetic agent usage was used to hypothesise the financial and environmental impact of replacing desflurane (the most environmentally damaging and expensive agent) with alternative agents. Using 2019 as an example year at our health service, replacing desflurane with low flow sevoflurane would save greenhouse gas emissions equivalent to driving over 1.4 million kilometres in an average petrol car. Removing desflurane from machines at our institution could save an estimated A$14,630 per annum through reduced machine testing alone. Our findings and calculations indicate that reducing the use of desflurane would have both financial and environmental benefits for healthcare.

An Accessible Clinical Decision Support System to Curtail Anesthetic Greenhouse Gases in a Large Health Network: Implementation Study

BACKGROUND

Inhaled anesthetics in the operating room are potent greenhouse gases and are a key contributor to carbon emissions from health care facilities. Real-time clinical decision support (CDS) systems lower anesthetic gas waste by prompting anesthesia professionals to reduce fresh gas flow (FGF) when a set threshold is exceeded. However, previous CDS systems have relied on proprietary or highly customized anesthesia information management systems, significantly reducing other institutions' accessibility to the technology and thus limiting overall environmental benefit.

OBJECTIVE

In 2018, a CDS system that lowers anesthetic gas waste using methods that can be easily adopted by other institutions was developed at the University of California San Francisco (UCSF). This study aims to facilitate wider uptake of our CDS system and further reduce gas waste by describing the implementation of the FGF CDS toolkit at UCSF and the subsequent implementation at other medical campuses within the University of California Health network.

METHODS

We developed a noninterruptive active CDS system to alert anesthesia professionals when FGF rates exceeded 0.7 L per minute for common volatile anesthetics. The implementation process at UCSF was documented and assembled into an informational toolkit to aid in the integration of the CDS system at other health care institutions. Before implementation, presentation-based education initiatives were used to disseminate information regarding the safety of low FGF use and its relationship to environmental sustainability. Our FGF CDS toolkit consisted of 4 main components for implementation: sustainability-focused education of anesthesia professionals, hardware integration of the CDS technology, software build of the CDS system, and data reporting of measured outcomes.

RESULTS

The FGF CDS system was successfully deployed at 5 University of California Health network campuses. Four of the institutions are independent from the institution that created the CDS system. The CDS system was deployed at each facility using the FGF CDS toolkit, which describes the main components of the technology and implementation. Each campus made modifications to the CDS tool to best suit their institution, emphasizing the versatility and adoptability of the technology and implementation framework.

CONCLUSIONS

It has previously been shown that the FGF CDS system reduces anesthetic gas waste, leading to environmental and fiscal benefits. Here, we demonstrate that the CDS system can be transferred to other medical facilities using our toolkit for implementation, making the technology and associated benefits globally accessible to advance mitigation of health care-related emissions.

Sevoflurane administration from extracorporeal membrane oxygenation via the AnaConDa device for a patient with COVID-19: a breakthrough solution for the shortage of intravenous anesthetics

One of the major issues encountered during the coronavirus disease 2019 (COVID-19) pandemic has been the shortage of intravenous anesthetics. Moreover, patients undergoing extracorporeal membrane oxygenation (ECMO) need large quantities of intravenous anesthetics for sedation. We report the case of a 52-year-old man who was admitted to our hospital due to acute respiratory distress syndrome by COVID-19 and treated with ECMO. As controlling sedation with intravenous anesthetics was challenging, we attempted to administer inhaled anesthetics via the gas flow of ECMO. We decreased the quantity of intravenous anesthetics and opioids. This method might help overcome the shortage of intravenous anesthetics.

Clinical and histological safety assessment of repeated intra-articular sevoflurane injections into knee joints of Sprague-Dawley rats

Objectives

We investigated the effects of repeated intra-articular injections of liquid sevoflurane to articular structures, as this inhalational anesthetic is being repurposed as an antimicrobial agent, which would make sevoflurane a novel alternative for the treatment of septic arthritis.

Methods

The left knees of nine Sprague-Dawley rats were injected with 150 μL of liquid sevoflurane for five consecutive days, whereas the right knees were injected with the same volume of saline to serve as controls. Animals were examined daily for clinical signs of local and systemic toxic effects attributable to sevoflurane. Rats were euthanized in groups of three at days 7, 14, and 35 after the first injection, and left and right knees were sent for histological assessment.

Results

Local signs on knees consisted of transient bilateral scabs, and an unexpected subcutaneous emphysema affecting only left knees, which was attributed to sevoflurane. No rat presented with limp, and animal welfare was good during the study period. Two out of the three left knees from rats sacrificed at day 7 showed mild histological changes, specifically a mild infiltration of lymphocytes. All other seven left knees as well as all nine right knees were completely normal at histological examination.

Conclusion

We concluded that repeated intra-articular injections of sevoflurane seemed safe for articular structures in noninfected knees. Further studies focused on the safety of intra-articular sevoflurane in infected knees, as well as on its effectiveness for the treatment of septic arthritis are warranted.

Comparison of direct costs associated with the use of balanced general anesthesia and total intravenous anesthesia (TIVA) techniques

Introduction: Healthcare costs are increasing against the backdrop of scarce resources. Surgical procedures are an important part of healthcare spending, and the cost of anesthetic techniques is relevant as part of the total cost of care and it is a potential target for expenditure optimization. Although important economic differences have been reported internationally for general anesthesia options, there are no publications in Colombia that compare current costs and allow for informed and financially responsible decision-making. Objective: To quantify and compare direct costs associated with the various general anesthesia options most frequently used at the present time. Methods: Cost minimization analysis based on a theoretical model of balanced general anesthesia using isoflurane, sevoflurane, desflurane in combination with remifentanil, and TIVA (propofol and remifentanil). Initial results were obtained using a deterministic simulation method and a sensitivity analysis was performed using a Monte Carlo simulation. Results: The average total cost per case for the different anesthetic techniques was COP 126381 for sevoflurane, COP 97706 for isoflurane, COP 288605 for desflurane and COP 222 960 for TIVA. Conclusions: Balanced general anesthesia with desflurane is the most costly alternative, 1.2 times more expensive than TIVA, and 2 and 3 times more costly than balanced anesthesia with sevoflurane and isoflurane, respectively. TIVA ranks second with a cost 1.8 times higher than balanced anesthesia with sevoflurane and 2.5 times higher than balanced anesthesia with isoflurane.

Dexamethasone as a ropivacaine adjuvant to pre-emptive incision-site infiltration analgesia in pediatric craniotomy patients: A prospective, multicenter, randomized, double-blind, controlled trial

BACKGROUND

Dexamethasone added to incision-site infiltration has been routinely used to reduce pain after tonsillectomy in children. However, this has not been studied in pediatric craniotomy patients yet. We hypothesized that incision-site infiltration with a combination of ropivacaine and dexamethasone might provide superior analgesia to ropivacaine alone in pediatric craniotomy patients.

METHODS

In this multicenter, double-blind, randomized, controlled trial, children aged 2-12 years, scheduled for craniotomy, were prospectively enrolled at two study centers, from September 2, 2019, to July 5, 2020. Eighty children were randomly assigned (1:1) to either ropivacaine plus dexamethasone group who received pre-emptive incision-site infiltration with 0.2% ropivacaine plus 0.025% dexamethasone, or ropivacaine group who received 0.2% ropivacaine alone. Primary outcome was the modified Children's Hospital of Eastern Ontario Pain Scale (mCHEOPS) at 24 h postoperatively. Primary analysis was performed using the modified intention-to-treat principle.

RESULTS

Pre-emptive incision-site infiltration with ropivacaine plus dexamethasone had a reduced pain score of 2.0, compared with the pain score of 2.9 in the ropivacaine group, at 24 h postoperatively (mean difference -0.9, 95% confidence interval [CI], -1.7 to -0.2; p = .019). Estimated median of the time of first rescue analgesic demand was 24 h in the ropivacaine plus dexamethasone group and 8.5 h in the ropivacaine group [hazard ratio 0.43, 95% CI 0.24 to 0.08; Log-rank p = .0025]. No adverse events related to incision-site infiltration with dexamethasone were observed in this study.

DISCUSSION

Dexamethsone reduces the local production of pro-inflammatory factors after tissue damage and as a ropivacaine adjuvant for incision-site infiltration reduced the pain scores by 31% at 24 h postoperatively. The results were similar to several prior studies on to tonsillectomy patients. However, this changes on pain scores might has limited clinical significance.

CONCLUSIONS

The addition of dexamethasone to ropivacaine for preoperative incision-site infiltration has better postoperative analgesic effect than ropivacaine alone in pediatric craniotomy patients.

Analgesic Effectiveness and Improvement in Quality of Life after Using Topical Sevoflurane for an Extremely Painful Anal Fissure

Painful anal fissures could be distressing conditions that severely impair the patients' quality of life. The analgesic effectiveness of topical drugs, such as calcium-antagonists and nitrates is quite variable. The inhalational anesthetic sevoflurane is being repurposed as a topical analgesic for painful chronic wounds. We report a pioneer experience treating a painful chronic anal fissure with topical sevoflurane. A young adult male was suffering from an extremely painful chronic anal fissure, which severely affected his quality of life. The topical treatment with nitroglycerine and diltiazem gels failed. The patient agreed to the treatement with topical sevoflurane as an off-label medication, and it produced an immediate, intense, and long-lasting analgesic effect. An intense but rapidly transient burning sensation, as well as persistent but well-tolerated flatulence were the only adverse effects. The quality of life was greatly improved, and the cost of the treatment was affordable. Therefore, the off-label use of topical sevoflurane appears to be an effective alternative for the symptomatic treatment of painful anal fissures.

Sustainable veterinary anaesthesia: single centre audit of oxygen and inhaled anaesthetic consumption and comparisons to a hypothetical model

OBJECTIVES

Single centre carbon footprint audit of oxygen and inhaled anaesthetic agent consumption.

STUDY DESIGN

Retrospective audit with hypothetical intervention.

MATERIALS AND METHODS

Records of 100 consecutive anaesthetics were examined. Consumption of oxygen and inhaled anaesthetic agent were estimated from oxygen flowmeter and vaporiser settings. Carbon dioxide equivalents (kg CO₂ e) were calculated. Records were reassessed to identify potential reductions in oxygen flow. Animals >5 kg were assigned to use circle systems set at a maintenance flow of 1 L/min following a short transitional period of higher flow. Animals <5 kg were assigned to Mapleson-A breathing systems at a flow of 1 L/min. Potential reductions in oxygen and inhaled anaesthetic agent consumption and CO₂ e were calculated.

RESULTS

A total of 14,370 minutes of anaesthesia were audited. Median bodyweight of the animals was 12.1 (interquartile range 5 to 25.8) kg. Median anaesthetic time was 110 (interquartile range 73.8 to 205) minutes. It was estimated 43,132 L of oxygen were used to vaporise 2605 mL of liquid sevoflurane and 1654 mL of liquid isoflurane. Potential oxygen consumption was 16,798 L, lowering sevoflurane consumption to 1123 mL and isoflurane to 589 mL. Using the suggested technique, oxygen and inhaled anaesthetic agent could have been reduced in 97% of anaesthetics with a median inhaled anaesthetic agent reduction of 59% (interquartile range 43 to 71%). Carbon footprint of the inhaled anaesthetic agent used was calculated as 1.82 metric tonnes of CO₂ e. This could have been lowered to 0.67 metric tonnes (63% reduction).

CLINICAL SIGNIFICANCE

Large reductions in oxygen and inhaled anaesthetic agent consumption and therefore greenhouse gas emission and financial expenditure can be made if we audit and adapt our practices.

Efficacy of dexmedetomidine versus propofol in patients undergoing endoscopic transnasal transsphenoidal pituitary tumor resection

Background:

Dexmedetomidine is associated with good perioperative hemodynamics together with decreased opioid requirements. Furthermore, propofol has been used to achieve hypotensive anesthesia as a part of total intravenous anesthesia.

Aims:

This study was performed to compare dexmedetomidine and propofol on the adequacy of hypotensive anesthesia during transsphenoidal resection of pituitary tumors.

Patients and Methods:

A total of 110 cases were included in this prospective randomized study. They were randomized into two equal groups; Group D commenced on Dexmedetomidine, and Group P, which received propofol. Comparing intraoperative hemodynamic parameters and the Boezaart Bleeding Scale was our primary outcome. The secondary outcomes included isoflurane and propranolol consumption, recovery, postoperative analgesic profile.

Statistical Analysis:

IBM's SPSS Statistics (Statistical Package for the Social Sciences) for Windows (version 25, 2017) was used for the statistical analysis of the collected data. Shapiro–Wilk test was used to check the normality of the data distribution. The quantitative variables were expressed as mean and standard deviation, whereas the categorical variables were expressed as frequency and percentage. Independent sample t and Mann − Whitney tests were used for the comparison of parametric and nonparametric continuous data, respectively. For pair-wise comparison of data (within-subjects), the follow-up values were compared to their corresponding basal value using the paired samples t-test or Wilcoxon matched-pairs signed-ranks test. Fisher exact and Chi-square tests were used for inter-group comparison of nominal data using the crosstabs function.

Results:

Age, gender, body mass index, and systemic comorbidities did not significantly differ between the two groups. Furthermore, heart rate and blood pressure were comparable at baseline, during operation, and after extubation. Boezaart score, blood loss, isoflurane, and propranolol consumption were also comparable between the two groups. Group D expressed significantly longer emergence and extubation times than Group P. Nevertheless, cases in the same group expressed lower Visual Analog Scale values and postoperative analgesic requirements.

Conclusion:

Although Dexmedetomidine and propofol are associated with comparable intraoperative hemodynamic changes, the former drug appears to be superior regarding pain control, postoperative analgesic requirement.

Comparison of bispectral index-guided and fixed-gas concentration techniques in desflurane and remifentanil anesthesia: A randomized controlled trial

Anesthesia with desflurane and remifentanil can be maintained with either fixed or titrated desflurane concentration. We hypothesized that the fixed-gas concentration (FG) method would reduce the number of anesthetic titrations without hypnotic and hemodynamic instability compared to the bispectral index (BIS)-guided (BG) method. Forty-eight patients were randomly allocated to the FG or BG groups. In the FG group, desflurane vaporizer setting was fixed at 1 age-corrected minimum alveolar concentration (MAC). In the BG group, desflurane was titrated to target a BIS level at 50. Remifentanil was titrated to maintain a systolic arterial pressure (SAP) of 120 mmHg in both groups. Our primary endpoint was the hypnotic stability measured by the wobble of BIS in performance analysis, and the secondary endpoints included the wobble of SAP, mean BIS value during surgery, and the number of anesthetic titrations. The BIS in the FG group showed significantly less wobble (3.9 ± 1.1% vs 5.5 ± 1.5%, P <0.001) but lower value (33 ± 6 vs 46 ± 7, P <0.001) than BG group. The wobble of SAP showed no difference between groups [median (inter-quartile range), 5.0 (4.1-7.5)% vs 5.2 (4.2-8.3)%, P = 0.557]. The numbers of anesthetic titrations in the FG group were significantly lower than the BG group (0 ± 0 vs 8 ± 5, P<0.001 for desflurane, 13 ± 13 vs 22 ± 17, P = 0.047 for remifentanil). Less wobble in BIS and reduced anesthetic titration without hemodynamic instability during the FG technique may be practical in balanced anesthesia using desflurane and remifentanil anesthesia. Clinical trial: This study was registered at ClinicalTrials.gov (NCT02283866).

Effects of Minimal Flow Sevoflurane or Desflurane Anaesthesia on Hemodynamic Parameters, Body Temperature and Anaesthetic Consumption

Objective

We aimed to compare minimal flow sevoflurane and desflurane anaesthesia in terms of hemodynamic parameters, body temperature, anaesthetic gas consumption and cost.

Methods

120 patients with ASA I–II (>18yo) who underwent elective surgery for longer than 60 min after general anaesthesia were randomized into two groups. The Dräger Perseus^® A500 workstation was used. Pre-oxygenation was performed for 3 min with 6 L min⁻¹ to 100% oxygen. Fractional inspirium oxygen concentration (FiO₂) was reduced to 40%, fresh gas flow was 4 L min⁻¹ after intubation. Sevoflurane or desflurane was started at 1.5 minimal alveolar concentration (MAC). When the MAC value reached 0.9, fresh gas flow was reduced to 0.5 L min⁻¹, FiO₂ was increased to 68%. At the end of the surgery, the vaporizer was switched off, the fresh gas flow was increased (4 L min⁻¹, FiO₂ 100%). When the train-of-four (TOF) ratio was 100%, extubation was carried out.

Results

There were no differences in patient characteristics and initial hemodynamic parameters of the groups. There were statistically significant differences between the times to reach 0.9 MAC, extubation and eye opening; anaesthetic, O₂ and air consumption in both groups.

Conclusion

With minimal flow, the time to reach target MAC, time to extubation and eye opening were significantly faster for desflurane and anaesthetic, oxygen and air consumption in desflurane anaesthesia were less than sevoflurane. Thus, we can say that desflurane has faster anaesthetic induction and recovery time with lower anaesthetic consumption than sevoflurane.

The impact of implementation of a hysterectomy enhanced recovery pathway on anesthetic medication costs

Aim: To evaluate the effect of implementation of a hysterectomy Enhanced Recovery After Surgery (ERAS) protocol on perioperative anesthetic medication costs. Patients & methods: Historical cohort study of 84 adult patients who underwent a hysterectomy. Forty-two patients who underwent surgery before protocol implementation comprised the pre-ERAS group. Forty-two patients who underwent surgery after protocol implementation comprised the post-ERAS group. Data on anesthetic medication costs and outcomes were analyzed. Results: Compared with the pre-ERAS group, the post-ERAS group's total medication cost was significantly lower (median: 325.20 USD; interquartile range [IQR]: 256.12-430.65 USD vs median: 273.10 USD; IQR: 220.63-370.59 USD, median difference: -40.76, 95% CI: -130.39, 16.99, p = 0.047). Length of stay was significantly longer in pre-ERAS when compared with post-ERAS groups (median: 5.0 days; IQR: 4.0-7.0 days vs median: 3.0 days; IQR: 3.0-4.0 days, median difference: -2.0 days, 95% CI: -2.5581, -1.4419, p < 0.0001). Conclusion: ERAS protocols may reduce perioperative medication costs.

Comparison of Percentage Prolonged Times to Tracheal Extubation Between a Japanese Teaching Hospital and One in the United States, Without and With a Phase I Postanesthesia Care Unit

BACKGROUND

Prolonged times to tracheal extubation are those from end of surgery (dressing on the patient) to extubation 15 minutes or longer. They are so long that others in the operating room (OR) generally have exhausted whatever activities can be done. They cause delays in the starts of surgeons' to-follow cases and are associated with longer duration workdays. Anesthesiologists rate them as being inferior quality. We compare prolonged times to extubation between a teaching hospital in the United States with a phase I postanesthesia care unit (PACU) and a teaching hospital in Japan without a PACU. Our report is especially important during the coronavirus disease 2019 (COVID-19) pandemic. Anesthesiologists with some patients undergoing general anesthetics and having initial PACU recovery in the ORs where they had surgery can learn from the Japanese anesthesiologists with all patients recovering in ORs.

METHODS

The historical cohort study included all patients undergoing gynecological surgery at a US hospital (N = 785) or Japanese hospital (N = 699), with the time from OR entrance to end of surgery of at least 4 hours.

RESULTS

The mean times from end of surgery to OR exit were slightly longer at the US hospital than at the Japanese hospital (mean difference 1.9 minutes, P < .0001). The mean from end of surgery to discharge to surgical ward at the US hospital also was longer (P < .0001), mean difference 2.2 hours. The sample standard deviations of times from end of surgery until tracheal extubation was 40 minutes for the US hospital versus 4 minutes at the Japanese hospital (P < .0001). Prolonged times to tracheal extubation were 39% of cases at the US hospital versus 6% at the Japanese hospital; relative risk 6.40, 99% confidence interval (CI), 4.28-9.56. Neither patient demographics, case characteristics, surgeon, anesthesiologist, nor anesthesia provider significantly revised the risk ratio. There were 39% of times to extubation that were prolonged among the patients receiving neither remifentanil nor desflurane (all such patients at the US hospital) versus 6% among the patients receiving both remifentanil and desflurane (all at the Japanese hospital). The relative risk 7.12 (99% CI, 4.59-11.05) was similar to that for the hospital groups.

CONCLUSIONS

Differences in anesthetic practice can facilitate major differences in patient recovery soon after anesthesia, useful when the patient will recover initially in the OR or if the phase I PACU is expected to be unable to admit the patient.

A prospective randomized controlled study of combined spinal-general anesthesia vs. general anesthesia for laparoscopic gynecological surgery: Opioid sparing properties

STUDY OBJECTIVE

We aimed to determine the magnitude of peri-operative opioid sparing effect when general anesthesia is combined with spinal analgesia for laparoscopic gynecological surgery.

DESIGN

A prospective randomized controlled study; a three-group trial with two comparisons (each intervention group to control).

SETTING

Operating room and postoperative recovery area.

PATIENTS

Patients aged between 18 and 65 years with American Society of Anesthesiologists physical status 1 or 2 who were scheduled for inpatient elective laparoscopic gynecological surgery with expected pneumoperitoneum duration of at least 20 min. Of 102 randomized patients, 99 completed the study.

INTERVENTIONS

Patients were randomized to general anesthesia alone (control group) or combined with very-low-dose (levobupivacaine 3.75 mg; sufentanil 2.5 μg) or low-dose (levobupivacaine 7.5 mg; sufentanil 2.5 μg) spinal analgesia.

MEASUREMENTS

Primary endpoints were perioperative opioid consumption and pain scores (11-point numeric rating scale) at 30 min, 1 h, 2 h, 4 h and 24 h post-surgery. Secondary endpoints were patient satisfaction with anesthetic care and participation in research, sevoflurane consumption and adverse effects.

MAIN RESULTS

Intra-operative sufentanil (median [95% CI]) consumption was 16.1 (10.5-22.6) μg/h in the control group versus 4.7 (3.2-9.2) μg/h in the very-low-dose and versus 2.9 (0.0-4.0) μg/h in the low-dose spinal analgesia groups (p < 0.001, for both comparisons). Median (95% CI) piritramide consumption at 24 h post-surgery was 7.5 (3-8) mg in the control group versus 5 (0-7.5) mg in the very-low dose spinal analgesia group (p = 0.182) and versus 2 (0-2.5) mg in the low-dose spinal analgesia group (p = 0.001). Postoperative pain scores were consistently <3 only in the low dose spinal analgesia group. Patient satisfaction with anesthetic care and participation in research was very high in all groups.

CONCLUSIONS

Low-dose spinal analgesia in combination with general anesthesia reduces peri-operative opioid consumption in laparoscopic gynecological surgery in immediate postoperative period.

Cost identification analysis of general anesthesia

BACKGROUND AND AIMS

Rising health costs are challenging anesthesiologists to search for cost-effective anesthetic techniques. We conducted a study to estimate variable cost per case and cost of drug wastage as percentage of total drug cost associated with different modalities of general anesthesia (GA).

MATERIAL AND METHODS

This prospective study was carried out after approval by institutional ethical committee in 258 adult patients aged 18-60 years of either sex, American Society of Anesthesiologists physical status I or II, with a surgical duration of 1-4 hours, posted for elective surgery under GA with endotracheal intubation. At the end of surgery, total utilization of each drug, anesthetic gases, and consumables were noted and remaining drug was regarded as wastage. Cost was recorded as per maximum retail price for that particular brand in the market at start of study and total cost was calculated. For purpose of analysis, cases were divided into low flow sevoflurane, high flow sevoflurane, high flow isoflurane, low flow isoflurane, and total intravenous anesthesia (TIVA).

RESULTS

The mean variable cost was highest with TIVA (₹2713.82 ± 509.57) and lowest with low flow isoflurane (₹1981.62 ± 335.03; P < 0.001). Drug wastage was 13.1% overall, with highest in low sevoflurane group and lowest in TIVA.

CONCLUSION

Low flow anesthesia with isoflurane is more cost-effective as compared to high flow techniques and TIVA even for short duration surgeries. Rational use of drugs and consumables and minimizing wastage can further reduce anesthesia costs.

Observational audit of sevoflurane consumption during paediatric anaesthesia

There is a recognition of the contribution to global warming from emissions of anaesthetic gases into the atmosphere. We audited sevoflurane use to help guide future initiatives to reduce consumption. We observed sevoflurane use during paediatric anaesthesia in a single operating theatre over eight weeks. We recorded demographics, timing of induction and maintenance of anaesthesia, type of circuit used and amount of liquid sevoflurane used (in mL). Ninety-four cases were available for analysis. Of these, 65 had gas inductions and 29 had intravenous (IV) inductions. The median sevoflurane use was 19 mL (interquartile range, IQR 13–24 mL). The median duration of cases was 50.5 min (IQR 35–78 min). The median sevoflurane consumption for cases with a gas induction was 22 mL (IQR 16–26 mL) and for those with an IV induction was 11 mL (IQR 7–17 mL; P < 0.00001). The duration of cases for the gas and IV induction cohorts were similar. During maintenance of anaesthesia, there was no difference between the IV and gas induction cohorts. There was little difference in sevoflurane use between the T-piece and circle system groups. Cases performed with gas inductions consumed twice the sevoflurane as those with IV inductions. Future interventions to reduce sevoflurane consumption should focus on this period.

Perioperative interdisciplinary approach for reduction of opioid use in pediatric tonsillectomy: Protocol using dexmedetomidine and bupivicaine as adjunct agents

IMPORTANCE

Pediatric tonsillectomy is a common procedure now being performed most often for patients with obstructive sleep apnea, which has been associated with increased sensitivity to the respiratory side effects of opioid medications. This study investigates a strategy to decrease the use of opiate medications in a particularly vulnerable population.

OBJECTIVE

Describe an interdisciplinary approach between Otolaryngologists and Anesthesiologists to decrease opiate use in tonsillectomy patients. Demonstrate safety of this protocol. Evaluate the effect of the protocol on intraoperative need for opiate medications and inhaled anesthetic use. Perform cost analysis of the protocol.

DESIGN

Retrospective case-control study with cost analysis.

SETTING

Tertiary Care Hospital.

PARTICIPANTS

Pediatric patients undergoing tonsillectomy at a tertiary care hospital.

INTERVENTIONS

Preoperative and intraoperative dexmedetomidine with local bupivacaine injection into the tonsillar fossa.

MEASURES

Intraoperative need for sevoflurane, opiate, and propofol. Post-operative pain scores, and utilization of post-operative opiate, acetaminophen, and ibuprofen pain medications. Post-operative adverse events. Cost analysis of protocol.

RESULTS

This protocol led to a decrease in intraoperative opiate use by 49.6%, a decrease in intraoperative sevofluorane use by 18%, and a lower reported maximum post-operative pain score without any increase in adverse events. The protocol added a small increase in medication cost of $4.07 to each procedure.

CONCLUSION

The use of dexmedetomidine and local anesthetic in pediatric tonsillectomy is a safe and effective protocol that allows for the reduction of opiate use and improved post-operative pain control.

KEY POINTS

Question: Can the combination of dexmedetomidine and infiltration of local anesthetic reduce overall opioid use for peediatric patients undergoing tonsillectomy?

FINDINGS

In this case-control study, use of dexmedetomidine and local anesthetic injected into the tonsillar fossa led to a decrease in intraoperative opiate use by 49.6%, a decrease in intraoperative sevofluorane use by 18%, and a lower reported maximum pain score without an increase in adverse events. Meaning: Use of dexmedetomidine and local anesthetic as anesthetic adjuncts may help reduce need for intraoperative opiates and decrease the use of volatile anesthetic agents in pediatric tonsillectomy patients, which are undesirable medications in the pediatric population for their respective respiratory depression and potentially neurotoxic side effects.

The effects of transversus abdominis plane block on analgesic and anesthetic consumption during total abdominal hysterectomy: a randomized controlled study

Background and objectives

A transversus abdominis plane block is a peripheral block method that has been used successfully for pain relief after total abdominal hysterectomy. However, the effects of the combination of the transversus abdominis plane block and general anesthesia on analgesic and anesthetic requirements remain unclear. This randomized placebo-controlled study is aimed to evaluate the effects of transversus abdominis plane block on analgesic and anesthetic consumption during total abdominal hysterectomy under general anesthesia.

Methods

Sixty-six women undergoing total abdominal hysterectomy were randomized into two groups to receive general anesthesia alone (control group) or with transversus abdominis plane block using 20 mL of 0.25% bupivacaine (transversus abdominis plane group). Intraoperative remifentanil and sevoflurane consumption were recorded. We also evaluated the postoperative pain, nausea, quality of recovery scores and rescue analgesic requirement during postoperative 24 hours.

Results

The total remifentanil and sevoflurane consumption is significantly lower in transversus abdominis plane group; respectively mean (SD) 0.130 (0.25) vs. 0.094 (0.02) mcg.kg⁻¹.min⁻¹; p < 0.01 and 0.295 (0.05) vs. 0.243 (0.06) mL.min⁻¹; p < 0.01. In the postoperative period, pain scores were significantly reduced in transversus abdominis plane group soon after surgery; median (range) 6 (2–10) vs. 3 (0–5); p < 0.001, at 2 h (5 [3–9] vs. 2.5 [0–6]; p < 0.001), at 6 h (4 [2–7] vs. 3[0–6], p < 0.001), at 12 h (3.5 [1–6] vs. 2 [1–5]; p = 0.003). The patients in the transversus abdominis plane group had significantly higher QoR-40 scores 190.5 (175–197) vs. 176.5 (141–187); p < 0.001).

Conclusion

Combining transversus abdominis plane block with general anesthesia can provide reduced opioid and anesthetic consumption and can improve postoperative pain and quality of recovery scores in patients undergoing total abdominal hysterectomy.

[The effects of transversus abdominis plane block on analgesic and anesthetic consumption during total abdominal hysterectomy: a randomized controlled study]

BACKGROUND AND OBJECTIVES

A transversus abdominis plane block is a peripheral block method that has been used successfully for pain relief after total abdominal hysterectomy. However, the effects of the combination of the transversus abdominis plane block and general anesthesia on analgesic and anesthetic requirements remain unclear. This randomized placebo-controlled study is aimed to evaluate the effects of transversus abdominis plane block on analgesic and anesthetic consumption during total abdominal hysterectomy under general anesthesia.

METHODS

Sixty-six women undergoing total abdominal hysterectomy were randomized into two groups to receive general anesthesia alone (control group) or with transversus abdominis plane block using 20mL of 0.25% bupivacaine (transversus abdominis plane group). Intraoperative remifentanil and sevoflurane consumption were recorded. We also evaluated the postoperative pain, nausea, quality of recovery scores and rescue analgesic requirement during postoperative 24hours.

RESULTS

The total remifentanil and sevoflurane consumption is significantly lower in transversus abdominis plane group; respectively mean (SD) 0.130 (0.25) vs. 0.094 (0.02) mcg.kg^-1.min^-1; p<0.01 and 0.295 (0.05) vs. 0.243 (0.06) mL.min^-1; p<0.01. In the postoperative period, pain scores were significantly reduced in transversus abdominis plane group soon after surgery; median (range) 6 (2-10) vs. 3 (0-5); p<0.001, at 2h (5 [3-9] vs. 2.5 [0-6]; p<0.001), at 6h (4 [2-7] vs. 3[0-6], p<0.001), at 12h (3.5 [1-6] vs. 2 [1-5]; p=0.003). The patients in the transversus abdominis plane group had significantly higher QoR-40 scores 190.5 (175-197) vs. 176.5 (141-187); p<0.001).

CONCLUSION

Combining transversus abdominis plane block with general anesthesia can provide reduced opioid and anesthetic consumption and can improve postoperative pain and quality of recovery scores in patients undergoing total abdominal hysterectomy.

The impact of fresh gas flow on wash-in, wash-out time and gas consumption for sevoflurane and desflurane, comparing two anaesthesia machines, a test-lung study

Low-flow anaesthesia is considered beneficial for the patient and the environment, and it is cost reducing due to reduced anaesthetic gas consumption. An initial high-flow to saturate the circle system ( wash-in) is desirable from a clinical point of view. We measured the wash-in and wash-out times (time to saturate and to eliminate the anaesthetic agent, AA), for sevoflurane and desflurane, in a test-lung with fixed 3 MAC vaporizer setting at different fresh gas flow (FGF) and calculated the consumption of AA. We tried to find an optimal flow rate for speed and gas consumption, comparing two anaesthesia machines (AMs): Aisys and Flow-i. Time to reach 1 minimal alveolar concentration (MAC) (wash-in) decreased (p<0.05) at higher flow rates (1 – 2 – 4) but plateaued at 4-4.8 l/min. The consumption of AA was at its lowest around 4-4.8 l/min (optimal flow) for all but the Aisys /desflurane group. Wash-out times decreased as FGF increased, until reaching plateau at FGF of 4-6 l/min. Aisys had generally shorter wash-in times at flow rates < 4 l/min as well as lower consumption of AA. At higher flow rates there were little difference between the AMs. The “optimal FGF” for wash-out, elimination of gas from the test-lung and circle system, plateaued with no increase in speed beyond 6 l/min. A fresh gas flow of 4 l/min. seems “optimal” taking speed to reach a 1 MAC ET and gas consumption into account during wash-in with a fixed 3 MAC vaporizer setting, and increasing fresh gas flow beyond 6 l/min does not seem to confirm major benefit during wash-out.

A critical test of Drosophila anaesthetics: Isoflurane and sevoflurane are benign alternatives to cold and CO2

Anaesthesia is often a necessary step when studying insects like the model organism Drosophila melanogaster. Most studies of Drosophila and other insects that require anaesthesia use either cold exposure or carbon dioxide exposure to induce a narcotic state. These anaesthetic methods are known to disrupt physiology and behavior with increasing exposure, and thus ample recovery time is required prior to experimentation. Here, we examine whether two halogenated ethers commonly used in vertebrate anaesthesia, isoflurane and sevoflurane, may serve as alternative means of insect anaesthesia. Using D. melanogaster, we generated dose-response curves to identify exposure times for each anaesthetic (cold, CO₂, isoflurane and sevoflurane) that allow for five-minutes of experimental manipulation of the animals after the anaesthetic was removed (i.e. 5min recovery doses). We then compared the effects of this practical dose on high temperature, low temperature, starvation, and desiccation tolerance, as well as locomotor activity and fecundity of female flies following recovery from anaesthesia. Cold, CO₂ and isoflurane each had significant or near significant effects on the traits measured, but the specific effects of each anaesthetic differed, and effects on stress tolerance generally did not persist if the flies were given 48h to recover from anaesthesia. Sevoflurane had no measureable effect on any of the traits examined. Care must be taken when choosing an anaesthetic in Drosophila research, as the impacts of specific anaesthetics on stress tolerance, behavior and reproduction can widely differ. Sevoflurane may be a practical alternative to cold and CO₂ anaesthesia in insects - particularly if flies are to be used for experiments shortly after anesthesia.

Accuracy of calculated volatile agent consumption from fresh gas content

BACKGROUND

Case-by-case assessment of volatile anesthetic (VA) consumption is necessary to perform agent sparing dosing measures and for billing purposes. The gold standard technique for this purpose is to measure the weight difference of the vaporizer that occurs during VA delivery. Because suitable equipment is rarely available and weighing the vaporizer is only possible in prospectively planned fashion, a calculation method from recorded fresh gas flow (FGF) and VA courses is a viable alternative. The objective was to evaluate the accuracy of VA calculation from fresh gas composition vs. the gold standard of weighing the vaporizer before and after anesthesia.

METHODS

In this prospective laboratory investigation, we compared the formula-based calculations of VA consumption to the measured vaporizer weight differences before and after 10 sevoflurane and 10 desflurane anesthesia. We assessed the average difference and spread of values between the calculated and the measured values.

RESULTS

The calculated sevoflurane consumption overestimated the measured values by 3.0 ± 2.9 ml (6.2%). The calculated desflurane consumption overestimated the measured values by 3.5 ± 6.7 ml (5.0%). All pairs of values from both agents were within ± 1.96 standard deviations.

CONCLUSION

The calculated VA consumption for sevoflurane and desflurane are sufficiently accurate to estimate the economic impact of VA delivery during inhalational anesthesia. This method enables the assessment of VA consumption both ways: (1) retrospectively from sufficiently detailed and accurate anesthesia recordings, as well as (2) by using this method in a prospective setting.