Renal Integrity in Sevoflurane Sedation in the Intensive Care Unit with the Anesthetic-Conserving Device: A Comparison with Intravenous Propofol Sedation

Volatile Anesthetic Sedation for Critically Ill Patients

Volatile anesthetics have multiple properties that make them useful for sedation in the intensive care unit. The team-based approach to volatile anesthetic sedation leverages these properties to provide a safe and effective alternative to intravenous sedatives.

Early sevoflurane sedation in severe COVID-19-related lung injury patients. A pilot randomized controlled trial

BACKGROUND

This study aimed to assess a potential organ protective effect of volatile sedation in a scenario of severe inflammation with an early cytokine storm (in particular IL-6 elevation) in patients suffering from COVID-19-related lung injury with invasive mechanical ventilation and sedation.

METHODS

This is a small-scale pilot multicenter randomized controlled trial from four tertiary hospitals in Switzerland, conducted between April 2020 and May 2021. 60 patients requiring mechanical ventilation due to severe COVID-19-related lung injury were included and randomized to 48-hour sedation with sevoflurane vs. continuous intravenous sedation (= control) within 24 h after intubation. The primary composite outcome was determined as mortality or persistent organ dysfunction (POD), defined as the need for mechanical ventilation, vasopressors, or renal replacement therapy at day 28. Secondary outcomes were the length of ICU and hospital stay, adverse events, routine laboratory parameters (creatinine, urea), and plasma inflammatory mediators.

RESULTS

28 patients were randomized to sevoflurane, 32 to the control arm. The intention-to-treat analysis revealed no difference in the primary endpoint with 11 (39%) sevoflurane and 13 (41%) control patients (p = 0.916) reaching the primary outcome. Five patients died within 28 days in each group (16% vs. 18%, p = 0.817). Of the 28-day survivors, 6 (26%) and 8 (30%) presented with POD (p = 0.781). There was a significant difference regarding the need for vasopressors (1 (4%) patient in the sevoflurane arm, 7 (26%) in the control one (p = 0.028)). Length of ICU stay, hospital stay, and registered adverse events within 28 days were comparable, except for acute kidney injury (AKI), with 11 (39%) sevoflurane vs. 2 (6%) control patients (p = 0.001). The blood levels of IL-6 in the first few days after the onset of the lung injury were less distinctly elevated than expected.

CONCLUSIONS

No evident benefits were observed with short sevoflurane sedation on mortality and POD. Unexpectedly low blood levels of IL-6 might indicate a moderate injury with therefore limited improvement options of sevoflurane. Acute renal issues suggest caution in using sevoflurane for sedation in COVID-19.

TRIAL REGISTRATION

The trial was registered on ClinicalTrials.gov (NCT04355962) on 2020/04/21.

Guidelines for inhaled sedation in the ICU

INTRODUCTION AND OBJECTIVES

Sedation is used in intensive care units (ICU) to improve comfort and tolerance during mechanical ventilation, invasive interventions, and nursing care. In recent years, the use of inhalation anaesthetics for this purpose has increased. Our objective was to obtain and summarise the best evidence on inhaled sedation in adult patients in the ICU, and use this to help physicians choose the most appropriate approach in terms of the impact of sedation on clinical outcomes and the risk-benefit of the chosen strategy.

METHODOLOGY

Given the overall lack of literature and scientific evidence on various aspects of inhaled sedation in the ICU, we decided to use a Delphi method to achieve consensus among a group of 17 expert panellists. The processes was conducted over a 12-month period between 2022 and 2023, and followed the recommendations of the CREDES guidelines.

RESULTS

The results of the Delphi survey form the basis of these 39 recommendations - 23 with a strong consensus and 15 with a weak consensus.

CONCLUSION

The use of inhaled sedation in the ICU is a reliable and appropriate option in a wide variety of clinical scenarios. However, there are numerous aspects of the technique that require further study.

Inhaled Volatiles for Status Asthmaticus, Epilepsy, and Difficult Sedation in Adult ICU and PICU: A Systematic Review

OBJECTIVES

Inhaled volatile anesthetics support management of status asthmaticus (SA), status epilepticus (SE), and difficult sedation (DS). This study aimed to evaluate the effectiveness, safety, and feasibility of using inhaled anesthetics for SA, SE, and DS in adult ICU and PICU patients.

DATA SOURCES

MEDLINE, Cochrane Central Register of Controlled Trials, and Embase.

STUDY SELECTION

Primary literature search that reported the use of inhaled anesthetics in ventilated patients with SA, SE, and DS from 1970 to 2021.

DATA EXTRACTION

Study data points were extracted by two authors independently. Quality assessment was performed using the Joanna Briggs Institute appraisal tool for case studies/series, Newcastle criteria for cohort/case-control studies, and risk-of-bias framework for clinical trials.

DATA SYNTHESIS

Primary outcome was volatile efficacy in improving predefined clinical or physiologic endpoints. Secondary outcomes were adverse events and delivery logistics. From 4281 screened studies, the number of included studies/patients across diagnoses and patient groups were: SA (adult: 38/121, pediatric: 28/142), SE (adult: 18/37, pediatric: 5/10), and DS (adult: 21/355, pediatric: 10/90). Quality of evidence was low, consisting mainly of case reports and series. Clinical and physiologic improvement was seen within 1-2 hours of initiating volatiles, with variable efficacy across diagnoses and patient groups: SA (adult: 89-95%, pediatric: 80-97%), SE (adults: 54-100%, pediatric: 60-100%), and DS (adults: 60-90%, pediatric: 62-90%). Most common adverse events were cardiovascular, that is, hypotension and arrhythmias. Inhaled sedatives were commonly delivered using anesthesia machines for SA/SE and miniature vaporizers for DS. Few (10%) of studies reported required non-ICU personnel, and only 16% had ICU volatile delivery protocol.

CONCLUSIONS

Volatile anesthetics may provide effective treatment in patients with SA, SE, and DS scenarios but the quality of evidence is low. Higher-quality powered prospective studies of the efficacy and safety of using volatile anesthetics to manage SA, SE, and DS patients are required. Education regarding inhaled anesthetics and the protocolization of their use is needed.

Sedation for Patients with Sepsis: Towards a Personalised Approach

This article looks at the challenges of sedoanalgesia for sepsis patients, and argues for a personalised approach. Sedation is a necessary part of treatment for patients in intensive care to reduce stress and anxiety and improve long-term prognoses. Sepsis patients present particular difficulties as they are at increased risk of a wide range of complications, such as multiple organ failure, neurological dysfunction, septic shock, ARDS, abdominal compartment syndrome, vasoplegic syndrome, and myocardial dysfunction. The development of any one of these complications can cause the patient's rapid deterioration, and each has distinct implications in terms of appropriate and safe forms of sedation. In this way, the present article reviews the sedative and analgesic drugs commonly used in the ICU and, placing special emphasis on their strategic administration in sepsis patients, develops a set of proposals for sedoanalgesia aimed at improving outcomes for this group of patients. These proposals represent a move away from simplistic approaches like avoiding benzodiazepines to more "objective-guided sedation" that accounts for a patient's principal pathology, as well as any comorbidities, and takes full advantage of the therapeutic arsenal currently available to achieve personalised, patient-centred treatment goals.

Renal safety of critical care sedation with sevoflurane: a systematic review and meta-analysis

Volatile anesthetic agents are increasingly widely used for critical care sedation. There are concerns that sevoflurane presents a risk of renal injury when used in this role. RCTs comparing the use of critical care sevoflurane sedation with any control in humans were systematically identified using MEDLINE, Cochrane CENTRAL, web of Science, and CINAHL (until May 2022), if they presented comparative data on renal function or serum inorganic fluoride levels. Pooled SMDs (95% CI) were calculated where possible after assessment of quality with GRADE and risk of bias with ROB-2. Eight studies analyzing 793 patients were included. The median duration of use of critical care sevoflurane sedation was 4.8 [IQR 3.5-9.2] hours; however, most trials also included a period of prior intraoperative use. No significant difference was found in serum creatinine at 1 day (SMD 0.05, 95% CI - 0.12 to 0.21), 48 h (SMD = - 0.04; 95% Cl - 0.25 to 0.17), 72 h (SMD = - 0.15; 95% CI - 0.45 to 0.15), and at discharge (SMD = - 0.1; 95% CI - 0.3 to 0.13) between the sevoflurane group and the control groups. Creatinine clearance was measured in two studies at 48 h with no significant difference (SMD = - 0.13; 95% Cl - 0.38 to 0.11). Levels of serum inorganic fluoride were significantly elevated in patients where sevoflurane was used. Sevoflurane was not associated with renal failure when used for critical care sedation of fewer than 72-h duration, despite the elevation of serum fluoride. Longer-term studies are currently inadequate, including in patients with compromised renal function, to further evaluate the role of sevoflurane in this setting.Trial registration PROSPERO (CRD42022333099).

Effect of inhaled anaesthetics on cognitive and psychiatric outcomes in critically ill adults: a systematic review and meta-analysis

BACKGROUND

Sedation of critically ill patients with inhaled anaesthetics may reduce lung inflammation, time to extubation, and ICU length of stay compared with intravenous (i.v.) sedatives. However, the impact of inhaled anaesthetics on cognitive and psychiatric outcomes in this population is unclear. In this systematic review, we aimed to summarise the effect of inhaled anaesthetics on cognitive and psychiatric outcomes in critically ill adults.

METHODS

We searched MEDLINE, EMBASE, and PsycINFO for case series, retrospective, and prospective studies in critically ill adults sedated with inhaled anaesthetics. Outcomes included delirium, psychomotor and neurological recovery, long-term cognitive dysfunction, ICU memories, anxiety, depression, post-traumatic stress disorder (PTSD), and instruments used for assessment.

RESULTS

Thirteen studies were included in distinct populations of post-cardiac arrest survivors (n=4), postoperative noncardiac patients (n=3), postoperative cardiac patients (n=2), and mixed medical-surgical patients (n=4). Eight studies reported delirium incidence, two neurological recovery, and two ICU memories. One study reported on psychomotor recovery, long-term cognitive dysfunction, anxiety, depression, and PTSD. A meta-analysis of five trials found no difference in delirium incidence between inhaled and i.v. sedatives (relative risk 0.95 [95% confidence interval: 0.59-1.54]). Compared with i.v. sedatives, inhaled anaesthetics were associated with fewer hallucinations and faster psychomotor recovery but no differences in other outcomes. There was heterogeneity in the instruments used and timing of these assessments.

CONCLUSIONS

Based on the limited evidence available, there is no difference in cognitive and psychiatric outcomes between adults exposed to volatile sedation or intravenous sedation in the ICU. Future studies should incorporate outcome assessment with validated tools during and after hospital stay.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42021236455.

Inhaled Sedation with Volatile Anesthetics for Mechanically Ventilated Patients in Intensive Care Units: A Narrative Review

Inhaled sedation was recently approved in Europe as an alternative to intravenous sedative drugs for intensive care unit (ICU) sedation. The aim of this narrative review was to summarize the available data from the literature published between 2005 and 2023 in terms of the efficacy, safety, and potential clinical benefits of inhaled sedation for ICU mechanically ventilated patients. The results indicated that inhaled sedation reduces the time to extubation and weaning from mechanical ventilation and reduces opioid and muscle relaxant consumption, thereby possibly enhancing recovery. Several researchers have reported its potential cardio-protective, anti-inflammatory or bronchodilator properties, alongside its minimal metabolism by the liver and kidney. The reflection devices used with inhaled sedation may increase the instrumental dead space volume and could lead to hypercapnia if the ventilator settings are not optimal and the end tidal carbon dioxide is not monitored. The risk of air pollution can be prevented by the adequate scavenging of the expired gases. Minimizing atmospheric pollution can be achieved through the judicious use of the inhalation sedation for selected groups of ICU patients, where the benefits are maximized compared to intravenous sedation. Very rarely, inhaled sedation can induce malignant hyperthermia, which prompts urgent diagnosis and treatment by the ICU staff. Overall, there is growing evidence to support the benefits of inhaled sedation as an alternative for intravenous sedation in ICU mechanically ventilated patients. The indication and management of any side effects should be clearly set and protocolized by each ICU. More randomized controlled trials (RCTs) are still required to investigate whether inhaled sedation should be prioritized over the current practice of intravenous sedation.

Safety and Feasibility of AnaConDa™ to Deliver Inhaled Isoflurane for Sedation in Patients Undergoing Elective Postoperative Mechanical Ventilation: A Prospective, Open-label, Interventional Trial (INSTINCT I Study)

Aim

Sedation is essential during invasive mechanical ventilation, and conventionally intravenous analgesic and sedative drugs are used. Sedation with inhaled anesthetics using anesthesia conserving device (ACD) is an alternative. There is no data on the safety and ease of use of AnaConDa™ from India.

Materials and methods

After IEC approval and informed consent, we used AnaConDa™-S for Isoflurane sedation in 50 hemodynamically stable (need for <0.5 µg/kg/min of Noradrenaline infusion), ASA I and II patients aged 18-80 years, undergoing elective mechanical ventilation for up to 24 hours after elective oncosurgeries. Patients with mental obtundation (GCS <14), or if pregnant, were excluded. The primary outcome was time spent between RASS scores of -3 and -4, while secondary outcomes were incidence of delirium, technical problems with AnaConDa™, and adverse systemic effects of isoflurane. Bolus doses of isoflurane 0.2-0.5 mL were given if the Richmond agitation sedation scale (RASS) score was not achieved.

Results

Fifty patients received isoflurane infusion for a median of 720 (IQR 630-900) minutes, and all remained in the target sedation range. Median time to awakening [19 (IQR, 5-85) minutes], to follow simple verbal commands [20 (IQR 5-180) minutes], and extubation after stopping the infusion of isoflurane was quick [100 (10-470) minutes]. All patients remained hemodynamically stable. None of the patients had delirium.

Conclusion

Target sedation levels were achieved with initial boluses of isoflurane using AnaConDa™-S. Isoflurane sedation delivery using AnaConDa™-S is safe and feasible.

How to cite this article

Kulkarni AP, Bhosale SJ, Kalvit KR, Sahu TK, Mohanty R, Dhas MM, et al. Safety and Feasibility of AnaConDa™ to Deliver Inhaled Isoflurane for Sedation in Patients Undergoing Elective Postoperative Mechanical Ventilation: A Prospective, Open-label, Interventional Trial (INSTINCT I Study). Indian J Crit Care Med 2022;26(8):906-912.

Inhaled Anesthetics for Sedation in ICU: Widening Horizons!

How to cite this article: Krishna B. Inhaled Anesthetics for Sedation in ICU: Widening Horizons! Indian J Crit Care Med 2022;26(8):889–891.

Nephrogenic Diabetes Insipidus following an Off-Label Administration of Sevoflurane for Prolonged Sedation in a COVID-19 Patient and Possible Influence on Aquaporin-2 Renal Expression

During the recent COVID-19 pandemic, the rapidly progressive shortage of intravenous sedative drugs led numerous intensive care units to look for potential alternatives in patients requiring mechanical ventilation for severe acute respiratory distress syndrome (ARDS). Inhalational sedation using the AnaConDa® device for sevoflurane administration is a possible option. In a 54-year-old COVID-19 patient with severe ARDS requiring extracorporeal membranous oxygenation (ECMO), sevoflurane on AnaConDa® device was administered for 8 days but was complicated by the development of nephrogenic diabetes insipidus (NDI). Other causes of NDI or central diabetes insipidus were reasonably excluded, as in other previously published cases of NDI in ICU patients receiving prolonged sevoflurane-based sedation. In addition, the postmortem examination suggested a lower expression of aquaporin-2 in renal tubules. This observation should prompt further investigations to elucidate the role of aquaporin-2 in sevoflurane-related NDI. Inhaled isoflurane sedation is a possible alternative.

Perioperative Clinical Trials in AKI

To characterize current evidence and current foci of perioperative clinical trials, we systematically reviewed Medline and identified perioperative trials involving 100 or more adult patients undergoing surgery and reporting renal end points that were published in high-impact journals since 2004. We categorized the 101 trials identified based on the nature of the intervention and summarized major trial findings from the five categories most applicable to perioperative management of patients. Trials that targeted ischemia suggested that increasing perioperative renal oxygen delivery with inotropes or blood transfusion does not reliably mitigate acute kidney injury (AKI), although goal-directed therapy with hemodynamic monitors appeared beneficial in some trials. Trials that have targeted inflammation or oxidative stress, including studies of nonsteroidal anti-inflammatory drugs, steroids, N-acetylcysteine, and sodium bicarbonate, have not shown renal benefits, and high-dose perioperative statin treatment increased AKI in some patient groups in two large trials. Balanced crystalloid intravenous fluids appear safer than saline, and crystalloids appear safer than colloids. Liberal compared with restrictive fluid administration reduced AKI in a recent large trial in open abdominal surgery. Remote ischemic preconditioning, although effective in several smaller trials, failed to reduce AKI in two larger trials. The translation of promising preclinical therapies to patients undergoing surgery remains poor, and most interventions that reduced perioperative AKI compared novel surgical management techniques or existing processes of care rather than novel pharmacologic interventions.

Sedation, Analgesia, and Paralysis in COVID-19 Patients in the Setting of Drug Shortages

The rapid spread of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to a global pandemic. The 2019 coronavirus disease (COVID-19) presents with a spectrum of symptoms ranging from mild to critical illness requiring intensive care unit (ICU) admission. Acute respiratory distress syndrome is a major complication in patients with severe COVID-19 disease. Currently, there are no recognized pharmacological therapies for COVID-19. However, a large number of COVID-19 patients require respiratory support, with a high percentage requiring invasive ventilation. The rapid spread of the infection has led to a surge in the rate of hospitalizations and ICU admissions, which created a challenge to public health, research, and medical communities. The high demand for several therapies, including sedatives, analgesics, and paralytics, that are often utilized in the care of COVID-19 patients requiring mechanical ventilation, has created pressure on the supply chain resulting in shortages in these critical medications. This has led clinicians to develop conservation strategies and explore alternative therapies for sedation, analgesia, and paralysis in COVID-19 patients. Several of these alternative approaches have demonstrated acceptable levels of sedation, analgesia, and paralysis in different settings but they are not commonly used in the ICU. Additionally, they have unique pharmaceutical properties, limitations, and adverse effects. This narrative review summarizes the literature on alternative drug therapies for the management of sedation, analgesia, and paralysis in COVID-19 patients. Also, this document serves as a resource for clinicians in current and future respiratory illness pandemics in the setting of drug shortages.

Minimal alveolar concentration for deep sedation (MAC-DS) in intensive care unit patients sedated with sevoflurane: A physiological study

BACKGROUND

Volatile anaesthetic agents, especially sevoflurane, could be an alternative for sedating ICU patients. In the operating theatre, volatile anaesthetic agents are monitored using minimal alveolar concentration (MAC). In ICU, MAC may be used to assess sedation level and may replace clinical scale especially when they are unusable. Therefore, we sought to investigate the minimal sevoflurane end-tidal concentration to achieved deep sedation in critical ill patients: MAC-deep sedation (MAC-DS).

METHODS

In a prospective interventional study, we included patients with a Richmond Assessment Sedation Score (RASS) of 0 without any sedation. We stepwise increased sevoflurane concentration level before assessing for deep sedation (RASS≤-3). MAC-DS was defined as the minimal sevoflurane MAC fraction or sevoflurane expiratory fraction (FeSevo) to get 90% and 95% of patients in deep sedation (MAC-DS 90 and MAC-DS 95, respectively).

RESULTS

Between June and November 2014, 30 patients were included (median age=60 years [interquartile range: 47-69]). Increasing sevoflurane MAC was correlated with a decrease in RASS values (r=-0.83, P<0.001). MAC-DS 90 and MAC-DS 95 were achieved at 0.42 MAC (CI 95 [0.38-0.46]) and 0.46 MAC (CI 95 [0.42-0.51]), respectively. FeSevo to achieve MAC-DS 90 and MAC-DS 95 was 0.72 (CI 95 [0.65-0.79]) and 0.80 (CI 95 [0.72-0.89]), respectively.

CONCLUSION

In this physiological study involving 30 ICU patients, MAC-DS, end-tidal sevoflurane concentration to get 95% of patients in deep sedation determined over more than 500 observations, is achieved at 0.8% of expired fraction of sevoflurane or at 0.5 age-adjusted MAC.

Volatile sedation in the intensive care unit: A systematic review and meta-analysis

BACKGROUND

Volatile sedation in the intensive care unit (ICU) may reduce the number of adverse events and improve patient outcomes compared with intravenous (IV) sedation. We performed a systematic review and meta-analysis comparing the effects of volatile and IV sedation in adult ICU patients.

METHODS

We searched the PubMed, Embase, Cochrane Central Register, and Web of Science databases for all randomized trials comparing volatile sedation using an anesthetic-conserving device (ACD) with IV sedation in terms of awakening and extubation times, lengths of ICU and hospital stay, and pharmacologic end-organ effects.

RESULTS

Thirteen trials with a total of 1027 patients were included. Volatile sedation (sevoflurane or isoflurane) administered through an ACD shortened the awakening time [mean difference (MD), -80.0 minutes; 95% confidence intervals (95% CIs), -134.5 to -25.6; P = .004] and extubation time (MD, -196.0 minutes; 95% CIs, -305.2 to -86.8; P < .001) compared with IV sedation (midazolam or propofol). No differences in the lengths of ICU and hospital stay were noted between the 2 groups. In the analysis of cardiac effects of sedation from 5 studies, patients who received volatile sedation showed lower serum troponin levels 6 hours after ICU admission than patients who received IV sedation (P < .05). The effect size of troponin was largest between 12 and 24 hours after ICU admission (MD, -0.27 μg/L; 95% CIs, -0.44 to -0.09; P = .003).

CONCLUSION

Compared with IV sedation, volatile sedation administered through an ACD in the ICU shortened the awakening and extubation times. Considering the difference in serum troponin levels between both arms, volatile anesthetics might have a myocardial protective effect after cardiac surgery even at a subanesthetic dose. Because the included studies used small sample sizes with high heterogeneity, further large, high-quality prospective clinical trials are needed to confirm our findings.

Volatile Anesthetics. Is a New Player Emerging in Critical Care Sedation?

Volatile anesthetic agent use in the intensive care unit, aided by technological advances, has become more accessible to critical care physicians. With increasing concern over adverse patient consequences associated with our current sedation practice, there is growing interest to find non-benzodiazepine-based alternative sedatives. Research has demonstrated that volatile-based sedation may provide superior awakening and extubation times in comparison with current intravenous sedation agents (propofol and benzodiazepines). Volatile agents may possess important end-organ protective properties mediated via cytoprotective and antiinflammatory mechanisms. However, like all sedatives, volatile agents are capable of deeply sedating patients, which can have respiratory depressant effects and reduce patient mobility. This review seeks to critically appraise current volatile use in critical care medicine including current research, technical consideration of their use, contraindications, areas of controversy, and proposed future research topics.

Does sevoflurane add to outpatient procedural sedation in children? A randomised clinical trial

BACKGROUND

There is little evidence concerning the effect of sevoflurane in outpatient procedural sedation, especially in children. We hypothesised that the addition of sevoflurane to a sedation regimen improves children's behaviour with minimal adverse events.

METHODS

This is a randomised, triple-blind clinical trial conducted on an outpatient basis. Participants were 27 healthy children aged 4 to 6 years, who previously refused dental treatment with non-pharmacologic methods. All participants received oral midazolam (0.5 mg/kg, maximum 20 mg) and oral ketamine (3 mg/kg, maximum 50 mg) and, in addition: Group MK - 100% oxygen; Group MKS - inhalational sevoflurane at a sedative dose (final expired concentration between 0.3 and 0.4%). Dental appointments were video recorded for assessment of the children's sleep patterns, crying, movements, and overall behaviour during the procedure with the Houpt scale. Intra- and post-operative adverse events were systematically reported. Data were analysed by bivariate analyses in the IBM SPSS v. 19, at a significance level of 5%.

RESULTS

MK (n = 13) and MKS (n = 14) did not differ regarding the Houpt scores (P > 0.05), but 53.8% of children in the MK group showed hysterical and continuous crying at the time of the local anaesthesia injection, compared to 7.1% of children in the MKS group (P = 0.01; phi = 0.5). There was a trend toward less crying and movement over time during the dental appointment in the MKS group (P = 0.48). Minor adverse events were observed in 10 MK children and 4 MKS children (P = 0.01).

CONCLUSIONS

The addition of sevoflurane to oral midazolam-ketamine improved the children's crying behaviour during local anaesthetic administration, and did not increase the occurrence of adverse events.

TRIAL REGISTRATION

Clinical Trials NCT02284204 . Registered 5 October 2014.

Evaluating the efficiency of desflurane reflection in two commercially available reflectors

With the AnaConDa™ and the MIRUS™ system, volatile anesthetics can be administered for inhalation sedation in intensive care units. Instead of a circle system, both devices use anesthetic reflectors to save on the anesthetic agent. We studied the efficiency of desflurane reflection with both devices using different tidal volumes (V_T), respiratory rates (RR), and 'patient' concentrations (C_Pat) in a bench study. A test lung was ventilated with four settings (volume control, RR × V_T: 10 × 300 mL, 10 × 500 mL, 20 × 500 mL, 10 × 1000 mL). Two different methods for determination of reflection efficiency were established: First (steady state), a bypass flow carried desflurane into the test lung (flow_in), the input concentration (C_in) was varied (1-17 vol%), and the same flow (flow_ex, C_ex) was suctioned from the test lung. After equilibration, C_Pat was stored online and averaged; efficiency [%] was calculated [Formula: see text]. Second (washout), flow_in and flow_ex were stopped, the decline of C_Pat was measured; efficiency was calculated from the decay constant of the exponential regression equation. Both measurement methods yielded similar results (Bland-Altman: bias: -0.9 %, accuracy: ±5.55 %). Efficiencies higher than 80 % (>80 % of molecules exhaled are reflected) could be demonstrated in the clinical range of C_Pat and V_T. Efficiency inversely correlates with the product of C_Pat and V_T which can be imagined as the volume of anesthetic vapor exhaled by the patient in one breath, but not with the respiratory frequency. Efficiency of the AnaConDa™ was higher for each setting compared with the MIRUS™. Desflurane is reflected by both reflectors with efficiencies high enough for clinical use.

AnaConDa™ and Mirus™ for intensive care sedation, 24 h desflurane versus isoflurane in one patient

Introduction

With the AnaConDa™ system, inhalational sedation in the intensive care unit has become popular. The device can be used with common intensive care unit ventilators and is inserted between the Y-piece and the patient. Liquid isoflurane or sevoflurane are delivered by a syringe pump. 90 % of anesthetic exhaled by the patient is absorbed by a reflector and resupplied during the next inspiration. The new Mirus™ system also uses a reflector. Its control unit identifies end-tidal concentrations from the flow, injects anesthetics during early inspiration, controls anesthetic concentrations automatically, and can also apply desflurane. The AnaConDa™ and Mirus™ system are certified ‘conformité établi’, however, little is known about the Mirus™ and case reports are still lacking.

Case description

We used the Mirus™ with desflurane for 24 h in a patient suffering from acute respiratory distress syndrome. The patient was treated with kinetic lateral rotational therapy. While deeply sedated, our patient breathed 9.0–12.0 l min⁻¹ spontaneously. Thereafter, awakening and wash-out were considerably shorter than after isoflurane in the same patient with AnaConDa™. There were no major problems during the sedation. However, consumption of desflurane was high.

Conclusion

Desflurane sedation with the Mirus™ seems promising, but the reflector should be improved to absorb and resupply more of the anesthetic agent.

Renal and hepatic integrity in long-term sevoflurane sedation using the anesthetic conserving device: a comparison with intravenous propofol sedation in an animal model

INTRODUCTION

Critically ill patients are sedated with intravenous agents because the use of inhaled agents is limited by their potential risk of toxicity. Increasing levels of inorganic fluorides after the metabolism of these agents have been considered potentially nephrotoxic. However, hepatic involvement after prolonged administration of sevoflurane has not yet been studied. The present study evaluated the potential renal and hepatic toxicity caused by prolonged administration (72h) of sevoflurane.

METHODS

For this experimental, prospective, randomized, controlled trial, 22 Landrace x Large-White female pigs were randomly assigned to two groups: intravenous propofol (P) or inhaled sevoflurane via the AnaConDa™ device (S, end-tidal 2.5 vol%). The P group remained sedated for 108h with propofol. In the S group, sevoflurane was administered for 72h and then changed to propofol for the remaining 36h in order to observe the kinetics of fluoride after discontinuation of sevoflurane. Serum creatinine was the primary outcome variable, but inorganic fluoride concentrations and other renal, hepatic, and cardiorespiratory variables were also measured.

RESULTS

Both groups of animals were comparable at baseline. No differences were found between the two groups for plasma creatinine and urea or creatinine clearance throughout the study. Fluoride levels were significantly higher in the sevoflurane group. No correlation was found between inorganic fluoride and serum creatinine values. No significant differences were observed for hepatic function. Hemodynamic, respiratory, and blood gas variables were comparable between the groups.

CONCLUSIONS

Long-term sedation with sevoflurane using AnaConDa™ or propofol does not negatively affect renal or hepatic function.

The volatile anesthetic sevoflurane attenuates ventilator-induced lung injury through inhibition of ERK1/2 and Akt signal transduction

Background

Ventilator-induced lung injury (VILI) sustained during mechanical ventilator support is still a cause of a high rate of morbidity and mortality in intensive care units and in operating rooms. VILI is characterized by pulmonary inflammation that appears to be mediated by proinflammatory cytokines. This study investigates whether the volatile anesthetic sevoflurane has an anti-inflammatory effect that attenuates VILI.

Methods

Twenty one male rabbits were anesthetized and were mechanically ventilated with 50% oxygen at a peak inspiratory pressure (PIP) of 10 cmH₂O, I : E ratio of 1 : 4, and positive end expiratory pressure of 5 cmH₂O. All animals were randomly assigned to one of three groups that were ventilated for 5 h with 10 cmH₂O of PIP (Sham group, n = 7); 30 cmH₂O of PIP (Control group, n = 7); or 30 cmH₂O of PIP and 0.8 vol% sevoflurane (Sevoflurane group, n = 7). The wet/dry weight (W/D) ratio and histopathology of the lung; concentration of interleukin-8 (IL-8) in the bronchoalveolar lavage fluid; and activation of extracellular signal-regulated kinases (ERK) 1/2, p38 mitogen-activated protein kinase, and Akt were measured in the lung tissue after completing the protocol.

Results

Histopathology indicated that the sevoflurane group showed fewer inflammatory cells and architectural changes than the control group did. The W/D ratio [(5.36 ± 0.13) versus (6.61 ± 0.20)], expression of IL-8 [(144.08 ± 14.61) versus (228.56 ± 15.13) pg/ml] and phosphorylation of ERK1/2 and Akt decreased significantly in the sevoflurane group relative to the control group.

Conclusions

Sevoflurane attenuates VILI in rabbits mainly by inhibiting expression of IL-8, and Sevoflurane-induced inhibition of phosphorylated ERK1/2 and Akt might be a possible pathway for protection.

Sevoflurane therapy for life-threatening acute severe asthma: a case report

INTRODUCTION

Acute severe asthma is a life-threatening form of bronchial constriction in which the progressively worsening airway obstruction is unresponsive to the usual appropriate bronchodilator therapy. Pathophysiological changes restrict airflow, which leads to premature closure of the airway on expiration, impaired gas exchange, and dynamic hyperinflation ("air-trapping"). Additionally, patients suffering from asthma for a prolonged period of time usually have serious comorbidities. These conditions constitute a challenge during the treatment of this disease. Therapeutic interventions are designed to reduce airway resistance and improve respiratory status. To achieve therapeutic goals, appropriate bronchodilator treatment is indispensable, and mechanical ventilation under adequate sedation may also be required. The volatile anesthetic agent, sevoflurane, meets both criteria; therefore, its use can be beneficial and should be considered.

CASE PRESENTATION

A 67-yr-old Caucasian male presented with acute life-threatening asthma provoked by an assumed upper airway infection and non-steroidal anti-inflammatory drug antipyretics, complicated by chronic atrial fibrillation and hemodynamic instability. Due to frequent premature ventricular contractions, conventional treatment was considered unsafe and discontinued, and sevoflurane inhalation was initiated via the AnaConDa (Anaesthetic Conserving Device). Symptoms of life-threatening bronchospasm resolved, and the patient's respiratory status improved within hours. Adequate sedation was also achieved without any hemodynamic adverse effects.

CONCLUSION

The volatile anesthetic agent, sevoflurane, is used widely in anesthesia practice. Its utility for treatment of refractory bronchospasm has been appreciated for years; however, its administration was difficult within the environment of the intensive care unit due to the need for an anesthesia machine and a scavenging system. The introduction of the AnaConDa eliminates these obstacles and makes the use of sevoflurane safe and simple. Our case report reveals the potential of sevoflurane as a "two-in-one" (bronchodilator and sedative) drug to treat a severe acute asthma attack.

A novel device for target controlled administration and reflection of desflurane--the Mirus™

The Anaconda™ system is used to deliver inhalational sedation in the intensive care unit in mainland Europe. The new Mirus™ system also uses a reflector like the Anaconda; however, it also identifies end-tidal concentrations from the gas flow, injects anaesthetics during early inspiration, controls anaesthetic concentrations automatically, and can be used with desflurane, which is not possible using the Anaconda. We tested the Mirus with desflurane in the laboratory. Compared with an external gas monitor, the bias (two standard deviations) of the end-tidal concentration was 0.11 (0.29)% volume. In addition, automatic control was reasonable and maximum concentration delivered was 10.2%, which was deemed to be sufficient for clinical use. Efficiency was > 80% and was also deemed to be acceptable, but only when delivering a low concentration of desflurane (≤ 1.8%). By modifying the reflector, we improved efficiency up to a concentration of 3.6%. The Mirus appears to be a promising new device for long-term sedation with desflurane on the intensive care unit, but efficiency must be improved before routine clinical use becomes affordable.

Health worker exposure risk during inhalation sedation with sevoflurane using the (AnaConDa®) anaesthetic conserving device

INTRODUCTION AND OBJECTIVE

Occupational exposure to sevoflurane should not exceed 2 ppm. During inhalation sedation with sevoflurane using the anaesthetic conserving device (AnaConDa(®)) in the post-anaesthesia care unit, waste gases can be reduced by gas extraction systems or scavenging devices such as CONTRAfluran™. However, the efficacy of these methods has not been clearly established. To determine the safest scenario for healthcare workers during inhalation sedation with sevoflurane in the post-surgical intensive care unit.

MATERIALS AND METHODS

An experimental study on occupational exposure was conducted in a post-cardiothoracic care unit during March-August 2009. The measurements were performed in four post-cardiac surgery sedated adults in post-surgical intensive care unit and four nurses at the bedside, and at four points: scenario A, inhalation sedation without gas extraction system or contrafluran as a reference scenario; scenario B, applying a gas extraction system to the ventilator; scenario C, using contrafluran; and scenario 0, performing intravenous isolation sedation. Sevoflurane concentrations were measured in the nurses' breathing area during patient care, and at 1.5 and 8 m from the ventilator using diffusive passive monitor badges.

RESULTS

All badges corresponding to the nurses' breathing area were below 2 ppm. Levels of sevoflurane detected using prevention systems were lower than that in the control situation. Only one determination over 2 ppm was found, corresponding to the monitor placed nearest the gas outlet of the ventilator in scenario A. Trace concentrations of sevoflurane were found in scenario 0 during intravenous sedation.

CONCLUSIONS

Administration of sevoflurane through the AnaConDa(®) system during inhalation sedation in post-surgical intensive care units is safe for healthcare workers, but gas extraction systems or scavenging systems, such as CONTRAfluran™ should be used to reduce occupational exposure as much as possible.

Sevoflurane has no adverse effects on renal function in cirrhotic patients: a comparison with propofol

BACKGROUND

Cirrhotic patients are prone to developing renal dysfunction after anaesthesia and surgery. However, no consensus has been reached whether sevoflurane could have adverse effects on renal function in cirrhotic patients. We hypothesised that the use of sevoflurane for general anaesthesia would lead to post-operative renal dysfunction in cirrhotic patients undergoing liver resection.

METHODS

A total of 200 patients undergoing liver resection were randomly assigned to a propofol or sevoflurane group. The influence of sevoflurane or propofol on renal function was evaluated by the maximal change, the difference between the pre-operative baseline and the highest values of serum creatinine and blood urea nitrogen measured at day 1, 3 and 6 post-operatively.

RESULTS

The maximal change in serum creatinine after liver resection was -4.52 (5.78) μmol/l and -3.37 (7.34) μmol/l with P = 0.398, and that in blood urea nitrogen was 0.41 (1.49) mmol/l and 0.93 (1.54) mmol/l with P = 0.098 between the sevoflurane group (n = 52) and the propofol group (n = 50), respectively.

CONCLUSIONS

Sevoflurane does not seem to impair post-operative renal function in cirrhotic patients undergoing liver resection.

A review of the practice of sedation with inhalational anaesthetics in the intensive care unit with the AnaConDa(®) device

The intensive care unit (ICU) environment is often perceived to be hostile and frightening by patients due to unfamiliar surroundings coupled with presence of numerous personnel, monitors and other equipments as well as a loss of perception of time. Mechanical ventilation and multiple painful procedures that often need to be carried out in these critically ill patients add to their overall anxiety. Sedation is therefore required not only to allay the stress and anxiety, but also to allow for mechanical ventilation and other invasive therapeutic and diagnostic procedures to be performed. The conventional intravenous sedative agents used in ICUs suffer from problems of over sedation, tachyphylaxis, drug accumulation, organ specific elimination and often lead to patient agitation on withdrawal. All this tend to prolong the ventilatory as well as ICU and hospital discharge time, which increase the risk for infection and add to the overall increase in morbidity, mortality and hospital costs. In 2005, the anaesthetic conserving device (AnaConDa(®)) was marketed for ICU sedation with volatile anaesthetic agents. A number of trials have shown the effectiveness of using volatile anaesthetic agents for ICU sedation with the AnaConDa device. Compared with intravenous sedatives, use of volatile anaesthetic agents have resulted in shorter wake up and extubation time, lesser duration of mechanical ventilation and faster discharge from hospitals. This review shall focus on the benefits, technical pre-requisites and status of sedation with volatile anaesthetic agents in ICUs with the AnaConDa(®) device.

Post-conditioning: promising answers and more questions

Volatile anesthetic agents have been used for decades in the peri-operative setting. Data from the past 15 years have shown that pre-injury administration of volatile anesthetic can decrease the impact of ischemia-reperfusion injury on the heart, brain, and kidney. Recent data demonstrated that volatile agents administered shortly after injury can decrease the ischemia-reperfusion injury. Several questions need to be answered to optimize this therapeutic target, but this is a promising era of secondary injury mitigation.

Volatile isoflurane sedation in cerebrovascular intensive care patients using AnaConDa(®): effects on cerebral oxygenation, circulation, and pressure

PURPOSE

The anesthetic-conserving device AnaConDa(®), a miniature vaporizer, allows volatile sedation in the intensive care unit (ICU). We investigated the effects of isoflurane sedation on cerebral and systemic physiology parameters in neuromonitored ICU stroke patients.

METHODS

Included in the study were 19 consecutive ventilated patients with intracerebral hemorrhage (12), subarachnoid hemorrhage (4), and ischemic stroke (3) who were switched from intravenous propofol or midazolam to inhalative isoflurane sedation for an average of 3.5 days. During the sedation transition, the following parameters were assessed: mean arterial pressure (MAP), intracranial pressure (ICP), cerebral perfusion pressure (CPP), middle cerebral artery mean flow velocity (MFV) and cerebral fractional tissue oxygen extraction (FTOE), as well as systemic cardiopulmonary parameters and administered drugs.

RESULTS

After the first hour, mean ICP showed an increase of 2.1 mmHg that was not clinically relevant. Likewise, MFV did not change. MAP and CPP, however, decreased by 6.5 and 6.3 mmHg, respectively. FTOE was reduced slightly from 0.24 to 0.21 (p = 0.03). Over an observation period of 12 h, ICP remained stable, while MAP and thus CPP showed distinct decreases (CPP: -10 mmHg at 6 h, p < 0.001; -7.5 mmHg at 12 h, p = 0.005, when compared to preswitch levels) despite a 1.5-fold increase in vasopressor administration.

CONCLUSIONS

We suggest that that it is possible to reach sufficient sedation levels in cerebrovascular ICU patients by applying volatile isoflurane long-term without a relevant increase in ICP, if baseline ICP values are low or only moderately elevated. However, caution should be exercised in view of isoflurane's decreasing effect on MAP and CPP. Multimodal neuromonitoring is strongly recommended when applying this off-label sedation method.

Efficiency and safety of inhalative sedation with sevoflurane in comparison to an intravenous sedation concept with propofol in intensive care patients: study protocol for a randomized controlled trial

Background

State of the art sedation concepts on intensive care units (ICU) favor propofol for a time period of up to 72 h and midazolam for long-term sedation. However, intravenous sedation is associated with complications such as development of tolerance, insufficient sedation quality, gastrointestinal paralysis, and withdrawal symptoms including cognitive deficits. Therefore, we aimed to investigate whether sevoflurane as a volatile anesthetic technically implemented by the anesthetic-conserving device (ACD) may provide advantages regarding ‘weaning time’, efficiency, and patient’s safety when compared to standard intravenous sedation employing propofol.

Method/Design

This currently ongoing trial is designed as a two-armed, monocentric, randomized prospective phase II study including intubated intensive care patients with an expected necessity for sedation exceeding 48 h. Patients are randomly assigned to either receive intravenous sedation with propofol or sevoflurane employing the ACD. Primary endpoint is the comparison of the ‘weaning time’ defined as the time required from discontinuation of the sedating agent until sufficient spontaneous breathing occurs. Moreover, sedation depth evaluated by Richmond Agitation Sedation Scale and parameters of patient’s safety (that is, vital signs, laboratory monitoring of organ function) as well as the duration of mechanical ventilation and overall stay on the ICU are analyzed and compared. An intention-to-treat analysis will be carried out with all patients for whom it will be possible to define a wake-up time. In addition, a per-protocol analysis is envisaged. Completion of patient recruitment is expected by the end of 2012.

Discussion

This clinical study is designed to evaluate the impact of sevoflurane during long-term sedation of critically ill patients on ‘weaning time’, efficiency, and patient’s safety compared to the standard intravenous sedation concept employing propofol.

Trial registration

EudraCT2007-006087-30; ISCRTN90609144

Sedation and analgesia in the mechanically ventilated patient

Sedation and analgesia are important components of care for the mechanically ventilated patient in the intensive care unit (ICU). An understanding of commonly used medications is essential to formulate a sedation plan for individual patients. The specific physiological changes that a critically ill patient undergoes can have direct effects on the pharmacology of drugs, potentially leading to interpatient differences in response. Objective assessments of pain, sedation, and agitation have been validated for use in the ICU for assessment and titration of medications. An evidence-based strategy for administering these drugs can lead to improvements in short- and long-term outcomes for patients. In this article, we review advances in the field of ICU sedation to provide an up-to-date perspective on management of the mechanically ventilated ICU patient.

Organ protection by volatile anesthetics in non-coronary artery bypass grafting surgery

The cardioprotective properties of volatile anesthetics have been widely demonstrated by numerous randomized studies and meta-analyses in the setting of cardiac surgery, above of all during coronary artery bypass grafting procedures. Recently, conflicting results have been presented in cardiac non-coronary artery bypass grafting surgery. Unfortunately, despite the existence of a great number of studies comparing a total intravenous anesthetic regimen with an inhalational regimen, at present there are no randomized studies presenting data regarding mortality and important outcomes, such as myocardial infarction, in non-cardiac surgery. In this review we analyze and present the results of the most recent and important studies regarding anesthetic preconditioning in cardiac and in noncardiac surgery. Furthermore, we focus on the emerging data from animal experiments, discussing in particular the molecular mechanisms underlying anesthetic preconditioning.