Desflurane compared with propofol for postoperative sedation in the intensive care unit

Weaning-associated interventions for ventilated intensive care patients: A scoping review

BACKGROUND

Mechanical ventilation is a core intervention in critical care, but may also lead to negative consequences. Therefore, ventilator weaning is crucial for patient recovery. Numerous weaning interventions have been investigated, but an overview of interventions to evaluate different foci on weaning research is still missing.

AIM

To provide an overview of interventions associated with ventilator weaning.

STUDY DESIGN

We conducted a scoping review. A systematic search of the Medline, CINAHL and Cochrane Library databases was carried out in May 2023. Interventions from studies or reviews that aimed to extubate or decannulate mechanically ventilated patients in intensive care units were included. Studies concerning children, outpatients or non-invasive ventilation were excluded. Screening and data extraction were conducted independently by three reviewers. Identified interventions were thematically analysed and clustered.

RESULTS

Of the 7175 records identified, 193 studies were included. A total of six clusters were formed: entitled enteral nutrition (three studies), tracheostomy (17 studies), physical treatment (13 studies), ventilation modes and settings (47 studies), intervention bundles (42 studies), and pharmacological interventions including analgesic agents (8 studies), sedative agents (53 studies) and other agents (15 studies).

CONCLUSIONS

Ventilator weaning is widely researched with a special focus on ventilation modes and pharmacological agents. Some aspects remain poorly researched or unaddressed (e.g. nutrition, delirium treatment, sleep promotion).

RELEVANCE TO CLINICAL PRACTICE

This review compiles studies on ventilator weaning interventions in thematic clusters, highlighting the need for multidisciplinary care and consideration of various interventions. Future research should combine different interventions and investigate their interconnection.

Sedaconda ACD-S for Sedation with Volatile Anaesthetics in Intensive Care: A NICE Medical Technologies Guidance

Intensive care unit (ICU) patients receive highly complex care and often require sedation as part of their management. ICU sedation has traditionally been delivered using intravenous (IV) agents due to the impractical use of anaesthetic machines in this setting, which are used to deliver volatile sedation. Sedaconda anaesthetic conserving device (ACD)-S (previously known as AnaConDa-S) is a device which allows for the delivery of volatile sedation via the majority of mechanical ventilators by being inserted in the breathing circuit where the heat and moisture exchanger is normally placed. The National Institute of Health and Care Excellence (NICE), as part of the Medical Technologies Evaluation Programme, considered the potential benefits of using Sedaconda ACD-S compared to standard IV sedation in ICU patients. Here we describe the evidence evaluation undertaken by NICE on this technology, supported by CEDAR. CEDAR considered the evidence present in 21 publications that compared the clinical outcomes of patients receiving Sedaconda ACD-S-delivered sedation and IV sedation, and critiqued the economic model provided by the manufacturer. Clinical expert input during the evaluation process was used extensively to ensure that the relevant clinical evidence was captured and that the economic model was suitable for the UK setting. Due to the uncertainty of the evidence, sensitivity analysis was carried out on the key economic inputs to ensure the reliability of the results. Economic modelling has shown that Sedaconda ACD-S-delivered isoflurane sedation is cost saving on a 30-day horizon compared to IV sedation by £3833.76 per adult patient and by £2837.41 per paediatric patient. Clinical evidence indicated that Sedaconda ACD-S-delivered isoflurane sedation is associated with faster patient wake-up times than standard of care. Consequently, NICE recommended Sedaconda ACD-S as an option for delivering sedation in the ICU setting, but noted that further research should inform whether Sedaconda ACD-S-delivered sedation is of benefit to any particular subgroup of patients.

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.

The advantages of inhalational sedation using an anesthetic-conserving device versus intravenous sedatives in an intensive care unit setting: A systematic review

BACKGROUND

Sedation is fundamental to the management of patients in the intensive care unit (ICU). Its indications in the ICU are vast, including the facilitating of mechanical ventilation, permitting invasive procedures, and managing anxiety and agitation. Inhaled sedation with halogenated agents, such as isoflurane or sevoflurane, is now feasible in ICU patients using dedicated devices/systems. Its use may reduce adverse events and improve ICU outcomes compared to conventional intravenous (IV) sedation in the ICU. This review examined the effectiveness of inhalational sedation using the anesthetic conserving device (ACD) compared to standard IV sedation for adult patients in ICU and highlights the technical aspects of its functioning.

METHODS

We searched the PubMed, Cochrane Central Register of Controlled Trials, The Cochrane Library, MEDLINE, Web of Science, and Sage Journals databases using the terms "anesthetic conserving device," "Anaconda," "sedation" and "intensive care unit" in randomized clinical studies that were performed between 2012 and 2022 and compared volatile sedation using an ACD with IV sedation in terms of time to extubation, duration of mechanical ventilation, and lengths of ICU and hospital stay.

RESULTS

Nine trials were included. Volatile sedation (sevoflurane or isoflurane) administered through an ACD shortened the awakening time compared to IV sedation (midazolam or propofol).

CONCLUSION

Compared to IV sedation, volatile sedation administered through an ACD in the ICU shortened the awakening and extubation times, ICU length of stay, and duration of mechanical ventilation. More clinical trials that assess additional clinical outcomes on a large scale are needed.

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.

Sedation with Sevoflurane versus Propofol in COVID-19 Patients with Acute Respiratory Distress Syndrome: Results from a Randomized Clinical Trial

BACKGROUND

Acute respiratory distress syndrome (ARDS) related to COVID-19 (coronavirus disease 2019) led to intensive care units (ICUs) collapse. Amalgams of sedative agents (including volatile anesthetics) were used due to the clinical shortage of intravenous drugs (mainly propofol and midazolam).

METHODS

A multicenter, randomized 1:1, controlled clinical trial was designed to compare sedation using propofol and sevoflurane in patients with ARDS associated with COVID-19 infection in terms of oxygenation and mortality.

RESULTS

Data from a total of 17 patients (10 in the propofol arm and 7 in the sevoflurane arm) showed a trend toward PaO₂/FiO₂ improvement and the sevoflurane arm's superiority in decreasing the likelihood of death (no statistical significance was found).

CONCLUSIONS

Intravenous agents are the most-used sedative agents in Spain, even though volatile anesthetics, such as sevoflurane and isoflurane, have shown beneficial effects in many clinical conditions. Growing evidence demonstrates the safety and potential benefits of using volatile anesthetics in critical situations.

Prolonged sedation with sevoflurane in comparison to intravenous sedation in critically ill patients - A randomized controlled trial

BACKGROUND

Volatile anesthetics are used more commonly for sedation in the intensive-care-unit (ICU). However, evidence for long-term use remains low. We therefore conducted a randomized-controlled trial comparing sevoflurane with intravenous sedation with particular focus on efficacy and safety.

METHODS

In this prospective, randomized-controlled phase-IIb monocentric clinical-trial ICU patients requiring at least 48 h of sedation were randomized to receive sevoflurane (S) or propofol/midazolam (P). Sedation quality was monitored using the Richmond-Agitation-Sedation-Scale. Following termination of sedation, the time to spontaneous breathing and extubation, opioid consumption, hemodynamics, ICU and hospital length of stay (LOS) and adverse events were recorded.

RESULTS

79 patients were eligible to randomization. Sedation quality was comparable between sevoflurane (n = 39) and propofol (n = 40). However, the use of sevoflurane lead to a reduction in time to spontaneous breathing (26 min vs. 375 min, P < 0.001). Patients sedated with propofol had lower opioid requirements (remifentanil:400 μg/h vs. 500 μg/h, P = 0.007; sufentanil:40 μg/h vs. 30 μg/h, P = 0.007) while hemodynamics, LOS or the occurrence of adverse events did not differ.

CONCLUSION

ICU patients sedated with sevoflurane >48 h may return to spontaneous breathing faster, while the quality of sedation is comparable to a propofol-based sedation regime. Sevoflurane might be considered to be safe for long-term sedation in this patient population, while being non-inferior compared to propofol.

Laryngeal mask general anaesthesia versus spinal anaesthesia for promoting early recovery of cervical conisation: A randomised, controlled clinical study

Background

Although both spinal and general anaesthesia provides good anaesthesia for cervical conization, spinal anaesthesia delays the return of lower limb movements and urinary function, whereas general anaesthesia requires the patient to be unconscious. It is unclear which anaesthetic technique is more conducive to early postoperative recovery in patients undergoing cervical conization.

Patients and methods

140 patients undergoing cervical conization underwent either laryngeal mask general anaesthesia (LMA, n = 70) or spinal anaesthesia (SA, n = 70). In the LMA group, an i-gel mask was used for airway management. In the SA group, spinal anaesthesia was received with 0.75% ropivacaine (15 mg) in the L3-4 interval. The quality of recovery score (QoR-15) was the primary endpoint of the study. Secondary endpoints included incidence of adverse 24-h analgesia (NRS>3); return of lower limb activity; first bed activity and feeding; and the number of catheters removed at 6, 12 and 24 h postoperatively.

Result

The LMA group significantly improved QoR-15 scores (136.62 ± 11.02 vs 119.97 ± 12.75; P < 0.001); and reduced the incidence of poor analgesia (NRS >3) within 24 h postoperatively (20% vs 42.8%, P = 0.006); reduced time in bed (15.62 ± 3.83 h vs 18.27 ± 5.57 vs, P = 0.001); improved patient satisfaction (86% vs 27%; P < 0.001); and catheters removal within 24 h (70/70 vs 42/70, P < 0.001).

Conclusion

LMA general anaesthesia can facilitate early postoperative recovery in patients undergoing cervical conization compared with conventional spinal anaesthesia.

Trial registration

Chinese Clinical Trial Registry (ID: ChiCTR1800019384), http://www.chictr.org.cn/listbycreater.aspx (08/11/2018).

Inhaled sedation in the intensive care unit

Inhaled sedation with halogenated agents, such as isoflurane or sevoflurane, is now feasible in intensive care unit (ICU) patients through dedicated vaporisers and scavenging systems. Such a sedation strategy requires specific equipment and adequate training of ICU teams. Isoflurane and sevoflurane have ideal pharmacological properties that allow efficient, well-tolerated, and titratable light-to-deep sedation. In addition to their function as sedative agents, these molecules may have clinical benefits that could be especially relevant to ICU patients. Our goal was to summarise the pharmacological basis and practical aspects of inhaled ICU sedation, review the available evidence supporting inhaled sedation as a viable alternative to intravenous sedation, and discuss the remaining areas of uncertainty and future perspectives of development.

TIVA versus Inhalational Agents for Pediatric Cardiac Intensive Care

The field of pediatric intensive care has come a long way, especially with the recognition that adequate sedation and analgesia form an imperative cornerstone of patient management. With various drugs available for the same, the debate continues as to which is the better: total intravenous anesthesia (TIVA) or inhalational agents. While each have their own advantages and disadvantages, in the present era of balance toward the IV agents, we should not forget the edge our volatile agents (VAs) might have in special scenarios. And ultimately as anesthesiologists, let us not forget that be it knob and dial, or syringe and plunger, our aim is to put pain to sleep and awaken a new faith to breathe.

Negative drift of sedation depth in critically ill patients receiving constant minimum alveolar concentration of isoflurane, sevoflurane, or desflurane: a randomized controlled trial

Background

Intensive care unit (ICU) physicians have extended the minimum alveolar concentration (MAC) to deliver and monitor long-term volatile sedation in critically ill patients. There is limited evidence of MAC’s reliability in controlling sedation depth in this setting. We hypothesized that sedation depth, measured by the electroencephalography (EEG)-derived Narcotrend-Index (burst-suppression N_Index 0—awake N_Index 100), might drift downward over time despite constant MAC values.

Methods

This prospective single-centre randomized clinical study was conducted at a University Hospital Surgical Intensive Care Unit and included consecutive, postoperative ICU patients fulfilling the inclusion criteria. Patients were randomly assigned to receive uninterrupted inhalational sedation with isoflurane, sevoflurane, or desflurane. The end-expiratory concentration of the anaesthetics and the EEG-derived index were measured continuously in time-stamped pairs. Sedation depth was also monitored using Richmond-Agitation-Sedation-Scale (RASS). The paired t-test and linear models (bootstrapped or multilevel) have been employed to analyze MAC, N_Index and RASS across the three groups.

Results

Thirty patients were recruited (female/male: 10/20, age 64 ± 11, Simplified Acute Physiology Score II 30 ± 10). In the first 24 h, 21.208 pairs of data points (N_Index and MAC) were recorded. The median MAC of 0.58 ± 0.06 remained stable over the sedation time in all three groups. The t-test indicated in the isoflurane and sevoflurane groups a significant drop in RASS and EEG-derived N_Index in the first versus last two sedation hours. We applied a multilevel linear model on the entire longitudinal data, nested per patient, which produced the formula N_Index = 43 − 0.7·h (R² = 0.76), showing a strong negative correlation between sedation’s duration and the N_Index. Bootstrapped linear models applied for each sedation group produced: N_Index of 43–0.9, 45–0.8, and 43–0.4·h for isoflurane, sevoflurane, and desflurane, respectively. The regression coefficient for desflurane was almost half of those for isoflurane and sevoflurane, indicating a less pronounced time-effect in this group.

Conclusions

Maintaining constant MAC does not guarantee stable sedation depth. Thus, the patients necessitate frequent clinical assessments or, when unfeasible, continuous EEG monitoring. The differences across different volatile anaesthetics regarding their time-dependent negative drift requires further exploration.

Trial registration: NCT03860129.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03556-y.

Washout and Awakening Times after Inhaled Sedation of Critically Ill Patients: Desflurane Versus Isoflurane

In recent years, inhaled sedation has been increasingly used in the intensive care unit (ICU). The aim of this prospective, controlled trial was to compare washout and awakening times after long term sedation with desflurane and isoflurane both administered with the Mirus™ system (TIM GmbH, Koblenz, Germany). Twenty-one consecutive critically ill patients were alternately allocated to the two study groups, obtaining inhaled sedation with either desflurane or isoflurane. After 24 h study sedation, anesthetic washout curves were recorded, and a standardized wake-up test was performed. The primary outcome measure was the time required to decrease the endtidal concentration to 50% (T50%). Secondary outcome measures were T80% and awakening times (all extremities moved, RASS -2). Decrement times (min) (desflurane versus isoflurane, median (1st quartile-3rd quartile)) (T50%: 0.3 (0.3-0.4) vs. 1.3 (0.4-2.3), log-rank test P = 0.002; P80%: 2.5 (2-5.9) vs. 12.1 (5.1-20.2), P = 0.022) and awakening times (to RASS -2: 7.5 (5.5-8.8) vs. 41.0 (24.5-43.0), P = 0.007; all extremities moved: 5.0 (4.0-8.5) vs. 13.0 (8.0-41.25), P = 0.037) were significantly shorter after desflurane compared to isoflurane. The use of desflurane with the Mirus™ system significantly shortens the washout times and leads to faster awakening after sedation of critically ill patients.

Reflection efficiencies of AnaConDa-S and AnaConDa-100 for isoflurane under dry laboratory and simulated clinical conditions: a bench study using a test lung

Background: Adequate sedation is important for the treatment of ICU patients. AnaConDa (Anesthetic-Conserving-Device; ACD; Sedana Medical, Sweden), connected between ventilator and the patient, retains isoflurane during expiration, and releases it back during inspiration. The reflection efficiency (Ref_Eff) corresponds to the percentage of expired anesthetic molecules that are re-inspired. We compared Ref_Eff of AnaConDa-S (ACD-50) and AnaConDa-100 (ACD-100) under laboratory (DRY) and simulated clinical conditions (CLIN) using a test lung.Methods: Measurements were made under DRY and CLIN, with different tidal volumes (TV: 300 mL & 500 mL) and infusion rates (0.5-10 mL·h^-1). Ref_Eff was calculated from the isoflurane concentration in the test-lung (C_ISO) and plotted against the anesthetic vapor volume exhaled in one breath (V-exh = C_ISO·TV).Results: DRY: Ref_Eff of both devices was ≈90% over a wide range of V-exh, but decreased when V-exh exceeded 5-7 mL (ACD-50) or 10-15 mL (ACD-100).CLIN: Ref_Eff of ACD-50 was 70-80% (ACD-100: 80-90%), decreasing gradually with increasing V-exh. For 1 Vol.% isoflurane at TV500, the infusion rate with ACD-50 was twofold higher compared to ACD-100 (4 versus 2 mL·h^-1).Conclusion: Under DRY and concentrations <1.5 Vol.%, Ref_Eff of both devices is around 90%. Under CLIN, ACD-100 performs better with Ref_Eff between 80% and 90% (ACD-50:70-80%), decreasing with increased vapor volume exhaled in one breath.

Use of MIRUS™ for MAC-driven application of isoflurane, sevoflurane, and desflurane in postoperative ICU patients: a randomized controlled trial

Background

The MIRUS™ (TIM, Koblenz, Germany) is an electronical gas delivery system, which offers an automated MAC (minimal alveolar concentration)-driven application of isoflurane, sevoflurane, or desflurane, and can be used for sedation in the intensive care unit. We investigated its consumption of volatile anesthetics at 0.5 MAC (primary endpoint) and the corresponding costs. Secondary endpoints were the technical feasibility to reach and control the MAC automatically, the depth of sedation at 0.5 MAC, and awakening times. Mechanically ventilated and sedated patients after major surgery were enrolled. Upon arrival in the intensive care unit, patients obtained intravenous propofol sedation for at least 1 h to collect ventilation and blood gas parameters, before they were switched to inhalational sedation using MIRUS™ with isoflurane, sevoflurane, or desflurane. After a minimum of 2 h, inhalational sedation was stopped, and awakening times were recorded. A multivariate electroencephalogram and the Richmond Agitation Sedation Scale (RASS) were used to assess the depth of sedation. Vital signs, ventilation parameters, gas consumption, MAC, and expiratory gas concentrations were continuously recorded.

Results

Thirty patients obtained inhalational sedation for 18:08 [14:46–21:34] [median 1st–3rd quartiles] hours. The MAC was 0.58 [0.50–0.64], resulting in a Narcotrend Index of 37.1 [30.9–42.4] and a RASS of − 3.0 [− 4.0 to (− 3.0)]. The median gas consumption was significantly lowest for isoflurane ([ml h⁻¹]: isoflurane: 3.97 [3.61–5.70]; sevoflurane: 8.91 [6.32–13.76]; and desflurane: 25.88 [20.38–30.82]; p < 0.001). This corresponds to average costs of 0.39 € h⁻¹ for isoflurane, 2.14 € h⁻¹ for sevoflurane, and 7.54 € h⁻¹ for desflurane. Awakening times (eye opening [min]: isoflurane: 9:48 [4:15–20:18]; sevoflurane: 3:45 [0:30–6:30]; desflurane: 2:00 [1:00–6:30]; p = 0.043) and time to extubation ([min]: isoflurane: 10:10 [8:00–20:30]; sevoflurane: 7:30 [4:37–14:22]; desflurane: 3:00 [3:00–6:00]; p = 0.007) were significantly shortest for desflurane.

Conclusions

A target-controlled, MAC-driven automated application of volatile anesthetics is technically feasible and enables an adequate depth of sedation. Gas consumption was highest for desflurane, which is also the most expensive volatile anesthetic. Although awakening times were shortest, the actual time saving of a few minutes might be negligible for most patients in the intensive care unit. Thus, using desflurane seems not rational from an economic perspective.

Trial registration Clinical Trials Registry (ref.: NCT03860129). Registered 24 September 2018—Retrospectively registered.

Sedative drugs used for mechanically ventilated patients in intensive care units: a systematic review and network meta-analysis

BACKGROUND

The effects of different sedative drugs on all-cause mortality rate, duration of ICU stay, and risk of delirium in mechanically ventilated ICU patients are unclear. This meta-analysis aimed to compare the effectiveness and safety of individual sedative drugs and drug combinations in mechanically ventilated ICU patients.

MATERIALS AND METHODS

Medline, Embase, Cochrane, EBSCOhost, and ISI Web of Science databases were searched for studies that assessed sedation in ICU mechanically ventilated patients. A Bayesian random-effects model was used to combine the direct comparisons and indirect evidence.

RESULTS

Thirty-one randomized, controlled trials were included, which consisted of 4491 patients who received one of seven sedative drugs or a combination of drugs. There were no significant differences regarding the all-cause mortality rate. Compared to propofol, inhalation anesthetics (hazard ratio [HR] 0.121; 95% credible interval [CrI] -7.58 to 7.62), alpha agonists (HR 2.2; 95% CrI 0.776 to 5.22), propofol with benzodiazepines (HR 0.306; 95% CrI -6.97 to 7.65), ketamine with benzodiazepines (HR 6.57; 95% CrI -6.05 to 19.1) and placebo (HR 2.4; 95% CrI -5.37 to 10.3), benzodiazepines (HR 3.62; 95% CrI 0.834 to 6.2) may increase the duration of ICU stay. Compared to alpha agonists, propofol (HR 2.4; 95% CrI 0.304 to 21.1) and placebo (HR 6.12; 95% CrI 0.745 to 54.6), benzodiazepines (HR 2.59; 95% CrI 1.08 to 7.4) were associated with incremental risks of delirium.

CONCLUSION

Compared to propofol, benzodiazepines may increase the duration of ICU stay. Compared to alpha agonists, benzodiazepines were associated with an increased risk of delirium.

Effect of dexmedetomidine infusion for intravenous patient-controlled analgesia on the quality of recovery after laparotomy surgery

Background

The Quality of Recovery-15 (QoR-15) is a patient-centered questionnaire to evaluate the recovery after surgery and anesthesia. Dexmedetomidine has sedative, analgesic, antiinflammatory and inhibitory sympathetic effects, which may contribute to early recovery. We hypothesized dexmedetomidine added to intravenous patient-controlled analgesia (PCA) could enhance the quality of recovery (QoR) in patients undergoing laparotomy surgery.

Methods

In this randomized, double-blind, controlled study, 100 patients undergoing laparotomy surgery were randomly allocated into two groups: Dexmedetomidine (group D) and control (group S). Patients in the group D (n = 46) received dexmedetomidine 0.04 ug/(kg·h) plus sufentanil 0.02 ug/(kg·h) for 48 h after laparotomy surgery, and in the group S (n = 47) received sufentanil 0.04 ug/(kg·h) only. The QoR-15 scores, postoperative pain, rescue analgesia, recovery of gastrointestinal function, patient satisfaction and adverse effects were recorded.

Results

The QoR-15 scores were significantly higher in the group D than in the group S on postoperative day (POD) 1, 2, 3 and 5 (P < 0.05). The visual analog scale (VAS) scores were significantly lower in the group D compared with group S within 48 h after surgery (P < 0.05). The pressing times of analgesic pump and rescue tramadol were not significantly different between the two groups (P > 0.05). The incidence of nausea was significantly lower in the Group D. No hypotension, bradycardia, or respiratory depression was observed.

Conclusions

The addition of dexmedetomidine to PCA enhanced patient-centered recovery, reduced pain and adverse effect, and improved patient satisfaction after laparotomy surgery.

[New technical developments for inhaled sedation]

The circle system has been in use for more than 100 years, whereas the first clinical application of an anaesthetic reflector was reported just 15 years ago. In the circle system, all breathing gas is rebreathed after carbon dioxide absorption. A reflector, on the other hand, with the breathing gas flowing to and fro, specifically retains the anaesthetic during expiration and resupplies it during the next inspiration. A high reflection efficiency (number of molecules resupplied/number of molecules exhaled, RE 80-90%) decreases consumption. In analogy to the fresh gas flow of a circle system, pulmonary clearance ((1-RE) × minute ventilation) defines the opposition between consumption and control of the concentration.It was not until reflection systems became available that volatile anaesthetics were used routinely in some intensive care units. Their advantages, such as easy handling, and better ventilatory capabilities of intensive care versus anaesthesia ventilators, were basic preconditions for this. Apart from AnaConDa™ (Sedana Medical, Uppsala, Sweden), the new MIRUS™ system (Pall Medical, Dreieich, Germany) represents a second, more sophisticated commercially available system.Organ protective effects, excellent control of sedation, and dose-dependent deep sedation while preserving spontaneous breathing with hardly any accumulation or induction of tolerance, make volatile anaesthetics an interesting alternative, especially for patients needing deep sedation or when intravenous drugs are no longer efficacious.But obviously, the outcome is most important. We know that deep intravenous sedation increases mortality, whereas inhalational sedation could prove beneficial. We now need prospective clinical trials examining mortality, but also the psychological outcome of those most critically ill patients sedated by inhalation or intravenously.

Inhaled anesthetic agent sedation in the ICU and trace gas concentrations: a review

There is a growing interest in the use of volatile anesthetics for inhalational sedation of adult critically ill patients in the ICU. Its safety and efficacy has been demonstrated in various studies and technical equipment such as the anaesthetic conserving device (AnaConDa™; Sedana Medical, Uppsala, Sweden) or the MIRUS™ system (Pall Medical, Dreieich, Germany) have significantly simplified the application of volatile anesthetics in the ICU. However, the personnel's exposure to waste anesthetic gas during daily work is possibly disadvantageous, because there is still uncertainty about potential health risks. The fact that average threshold limit concentrations for isoflurane, sevoflurane and desflurane either differ significantly between countries or are not even defined at all, leads to raising concerns among ICU staff. In this review, benefits, risks, and technical aspects of inhalational sedation in the ICU are discussed. Further, the potential health effects of occupational long-term low-concentration agent exposure, the staffs' exposure levels in clinical practice, and strategies to minimize the individual gas exposure are reviewed.

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.

Survival after long-term isoflurane sedation as opposed to intravenous sedation in critically ill surgical patients: Retrospective analysis

BACKGROUND

Isoflurane has shown better control of intensive care sedation than propofol or midazolam and seems to be a useful alternative. However, its effect on survival remains unclear.

OBJECTIVE

The objective of this study is to compare mortality after sedation with either isoflurane or propofol/midazolam.

DESIGN

A retrospective analysis of data in a hospital database for a cohort of consecutive patients.

SETTING

Sixteen-bed interdisciplinary surgical ICU of a German university hospital.

PATIENTS

Consecutive cohort of 369 critically ill surgical patients defined within the database of the hospital information system. All patients were continuously ventilated and sedated for more than 96 h between 1 January 2005 and 31 December 2010. After excluding 169 patients (93 >79 years old, 10 <40 years old, 46 mixed sedation, 20 lost to follow-up), 200 patients were studied, 72 after isoflurane and 128 after propofol/midazolam.

INTERVENTIONS

Sedation with isoflurane using the AnaConDa system compared with intravenous sedation with propofol or midazolam.

MAIN OUTCOME MEASURES

Hospital mortality (primary) and 365-day mortality (secondary) were compared with the Kaplan-Meier analysis and a log-rank test. Adjusted odds ratios (ORs) [with 95% confidence interval (95% CI)] were calculated by logistic regression analyses to determine the risk of death after isoflurane sedation.

RESULTS

After sedation with isoflurane, the in-hospital mortality and 365-day mortality were significantly lower than after propofol/midazolam sedation: 40 versus 63% (P = 0.005) and 50 versus 70% (P = 0.013), respectively. After adjustment for potential confounders (coronary heart disease, chronic obstructive pulmonary disease, acute renal failure, creatinine, age and Simplified Acute Physiology Score II), patients after isoflurane were at a lower risk of death during their hospital stay (OR 0.35; 95% CI 0.18 to 0.68, P = 0.002) and within the first 365 days (OR 0.41; 95% CI 0.21 to 0.81, P = 0.010).

CONCLUSION

Compared with propofol/midazolam sedation, long-term sedation with isoflurane seems to be well tolerated in this group of critically ill patients after surgery.

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.

Volatile Agents in Medical and Surgical Intensive Care Units: A Meta-Analysis of Randomized Clinical Trials

OBJECTIVE

To comprehensively assess published randomized peer-reviewed studies related to volatile agents used for sedation in intensive care unit (ICU) settings, with the hypothesis that volatile agents could reduce time to extubation in adult patients.

DESIGN

Systematic review and meta-analysis of randomized trials.

SETTING

Intensive care units.

PARTICIPANTS

Critically ill patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The BioMedCentral, PubMed, Embase, and Cochrane Central Register databases of clinical trials were searched systematically for studies on volatile agents used in the ICU setting. Articles were assessed by trained investigators, and divergences were resolved by consensus. Inclusion criteria included random allocation to treatment (volatile agents versus any intravenous comparator, with no restriction on dose or time of administration) in patients requiring mechanical ventilation in the ICU. Twelve studies with 934 patients were included in the meta-analysis. The use of halogenated agents reduced the time to extubation (standardized mean difference = -0.78 [-1.01 to -0.55] hours; p for effect<0.00001; p for heterogeneity = 0.18; I(2) = 32% in 7 studies with 503 patients). Results for time to extubation were confirmed in all subanalyses (eg, medical and surgical patients) and sensitivity analyses. No differences in length of hospital stay, ICU stay, and mortality were recorded.

CONCLUSIONS

In this meta-analysis of randomized trials, volatile anesthetics reduced time to extubation in medical and surgical ICU patients. The results of this study should be confirmed by large and high-quality randomized controlled studies.

The use of volatile anesthetic agents for long-term critical care sedation (VALTS): study protocol for a pilot randomized controlled trial

Background

Sedatives are administered to 85 % of intensive care unit (ICU) patients. The most commonly used sedatives are intravenous benzodiazepines and propofol. These agents are associated with over-sedation in 40 to 60 % of patients, which can lead to prolonged intubation, delirium and drug-induced hypotension. Evidence is increasing that volatile anesthetic agents are associated with faster extubation times, improved cardiovascular stability with no end-organ toxicity in comparison to our standard intravenous agents for short-term critical care sedation. Use of volatile agents within the ICU is a novel technique using a specialized delivery and scavenging system, which requires staff training and cultural acceptance. This pilot randomized controlled trial aims to assess the safety and feasibility of delivering volatile agents for long-term patient sedation in the ICU with limited or no experience of this technique.

Methods/Design

This is a prospective multicenter pragmatic pilot RCT that is blinded to the data analyst. This study aims to recruit 60 adult ICU patients requiring mechanical ventilation and sedation for more than 48 h. Patients will be randomized 2:1 to receive inhaled isoflurane (40 patients) or intravenous midazolam and/or propofol (20 patients) sedation. Sedation is titrated to a targeted Sedation Analgesia Score (SAS) using an explicit sedation-analgesia algorithm until extubation or tracheostomy. Primary safety and feasibility outcomes will assess atmospheric volatile concentration levels and adherence to our sedation-analgesia protocol. Secondary outcomes include time to extubation, duration of ventilation, quality of sedation, delirium, vasoactive drug support, length of stay, serum fluoride levels and mortality.

Discussion

This pilot project will serve as the basis for a larger RCT that will be powered for important clinical outcomes.

Trial Registration

ClinicalTrials.gov, NCT01983800 (registration date 2 July 2013).

Late Post-Conditioning with Sevoflurane after Cardiac Surgery--Are Surrogate Markers Associated with Clinical Outcome?

Introduction

In a recent randomized controlled trial our group has demonstrated in 102 patients that late post-conditioning with sevoflurane performed in the intensive care unit after surgery involving extracorporeal circulation reduced damage to cardiomyocytes exposed to ischemia reperfusion injury. On the first post-operative day the sevoflurane patients presented with lower troponin T values when compared with those undergoing propofol sedation. In order to assess possible clinical relevant long-term implications in patients enrolled in this study, we performed the current retrospective analysis focusing on cardiac and non-cardiac events during the first 6 months after surgery.

Methods

All patients who had successfully completed the late post-conditioning trial were included into this follow-up. Our primary and secondary endpoints were the proportion of patients experiencing cardiac and non-cardiac events, respectively. Additionally, we were interested in assessing therapeutic interventions such as initiation or change of drug therapy, interventional treatment or surgery.

Results

Of 102 patients analyzed in the primary study 94 could be included in this follow-up. In the sevoflurane group (with 41 patients) 16 (39%) experienced one or several cardiac events within 6 months after cardiac surgery, in the propofol group (with 53 patients) 19 (36%, p=0.75). Four patients (9%) with sevoflurane vs. 7 (13%) with propofol sedation had non-cardiac events (p=0.61). While a similar percentage of patients suffered from cardiac and/or non-cardiac events, only 12 patients in the sevoflurane group compared to 20 propofol patients needed a therapeutic intervention (OR: 0.24, 95% CI: 0.04-1.43, p=0.12). A similar result was found for hospital admissions: 2 patients in the sevoflurane group had to be re-admitted to the hospital compared to 8 in the propofol group (OR 0.23, 95% CI: 0.04-1.29, p=0.10).

Conclusions

Sevoflurane does not seem to provide protection with regard to the occurrence of cardiac and non-cardiac events in the 6-month period following cardiac surgery with the use of extracorporeal circulation. However, there was a clear trend towards fewer interventions (less need for treatment, fewer hospital admissions) associated with sevoflurane post-conditioning in patients experiencing any event. Such results might encourage launching large multicenter post-conditioning trials with clinical outcome defined as primary endpoint.

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.

Propofol increases morbidity and mortality in a rat model of sepsis

INTRODUCTION

Severe sepsis is associated with approximately 50% mortality and accounts for tremendous healthcare costs. Most patients require ventilatory support and propofol is commonly used to sedate mechanically ventilated patients. Volatile anesthetics have been shown to attenuate inflammation in a variety of different settings. We therefore hypothesized that volatile anesthetic agents may offer beneficial immunomodulatory effects during the course of long-term intra-abdominal sepsis in rats under continuous sedation and ventilation for up to 24 hours.

METHODS

Sham operation or cecal ligation and puncture (CLP) was performed in adult male Wistar rats followed by mechanical ventilation. Animals were sedated for 24 hours with propofol (7 to 20 mg/kg/h), sevoflurane, desflurane or isoflurane (0.7 minimal alveolar concentration each).

RESULTS

Septic animals sedated with propofol showed a mean survival time of 12 hours, whereas >56% of all animals in the volatile groups survived 24 hours (P <0.001). After 18 hours, base excess in propofol + CLP animals (-20.6 ± 2.0) was lower than in the volatile groups (isoflurane + CLP: -11.7 ± 4.2, sevoflurane + CLP: -11.8 ± 3.5, desflurane + CLP -14.2 ± 3.7; all P <0.03). Plasma endotoxin levels reached 2-fold higher levels in propofol + CLP compared to isoflurane + CLP animals at 12 hours (P <0.001). Also blood levels of inflammatory mediators (tumor necrosis factor-α, interleukin-1β, interleukin-10, CXCL-2, interferon-γ and high mobility group protein-1) were accentuated in propofol + CLP rats compared to the isoflurane + CLP group at the same time point (P <0.04).

CONCLUSIONS

This is the first study to assess prolonged effects of sepsis and long-term application of volatile sedatives compared to propofol on survival, cardiovascular, inflammatory and end organ parameters. Results indicate that volatile anesthetics dramatically improved survival and attenuate systemic inflammation as compared to propofol. The main mechanism responsible for adverse propofol effects could be an enhanced plasma endotoxin concentration, leading to profound hypotension, which was unresponsive to fluid resuscitation.

Anaesthetic conserving device AnaConDa: dead space effect and significance for lung protective ventilation

BACKGROUND

The anaesthetic conserving device AnaConDa (ACD) reflects exhaled anaesthetic agents thereby facilitating the use of inhaled anaesthetic agents outside operating theatres. Expired CO₂ is, however, also reflected causing a dead space effect in excess of the ACD internal volume. CO₂ reflection from the ACD is attenuated by humidity. This study tests the hypothesis that sevoflurane further attenuates reflection of CO₂. An analysis of clinical implications of our findings was performed.

METHODS

Twelve postoperative patients received mechanical ventilation using a conventional heat and moisture exchanger (HME, internal volume 50 ml) and an ACD (100 ml), the latter with or without administration of sevoflurane. The ACD was also studied with a test lung at high sevoflurane concentrations. Reflection of CO₂ and dead space effects were evaluated with the single-breath test for CO2.

RESULTS

Sevoflurane reduced but did not abolish CO₂ reflection. In patients, the mean dead space effect with 0.8% sevoflurane was 88 ml larger using the ACD compared with the HME (P<0.001), of which 38 ml was due to CO₂ reflection. Our calculations show that with the use of the ACD, normocapnia cannot be achieved with tidal volume <6 ml kg(-1) even when respiratory rate is increased.

CONCLUSIONS

An ACD causes a dead space effect larger than its internal volume due to reflection of CO₂, which is attenuated but not abolished by sevoflurane administration. CO₂ reflection from the ACD limits its use with low tidal volume ventilation, such as with lung protection ventilation strategies.

CLINICAL TRIAL REGISTRATION

Clinical Trials NCT01699802.

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.

ABCDEs of ICU: Choice of sedative

When the clinical picture of a patient in the intensive care unit necessitates placement of an artificial airway supported by mechanical ventilation, a regimen of sedation and analgesia is initiated with the goal of providing anxiolysis and pain control to facilitate ventilation and therapeutic and diagnostic intervention. However, some of the most commonly used sedative agents, such as benzodiazepines, may have profound long-term effects on patients' health, including neuropsychological functioning. With more patients now surviving intensive care, more patients are suffering from these negative health consequences. A review of recent research on the subject suggests that more novel, non-benzodiazepine agents such as dexmedetomidine, fluorinated ether gases, and remifentanil function effectively as sedative agents in intubated patients in the intensive care unit, and are less likely to lead to delirium, agitation, aggression, psychosis, and other complications; in addition, use of these alternatives is associated with shorter times to awakening, extubation, and ICU discharge, as well as shorter overall length of stay and decreased cost of care.

The scavenging of volatile anesthetic agents in the cardiovascular intensive care unit environment: a technical report

PURPOSE

The use of volatile-based sedation within critical care environments has been limited by difficulties of drug administration and safety concerns over environment pollution and staff exposure in an intensive care unit (ICU) with no scavenging. The aim of this study was to develop a simple scavenging system to be used with the Anesthesia Conserving Device (AnaConDa(®)) and to determine whether or not ambient concentrations of residual anesthetic are within current acceptable limits.

TECHNICAL FEATURES

The scavenging system consists of two Deltasorb(®) canisters attached to the ICU ventilator in series. AnaConDa is a miniature vaporizer designed to provide volatile-based sedation within an ICU. The first ten patients recruited into a larger randomized trial assessing outcomes after elective coronary graft bypass surgery were sedated within the cardiac ICU using either isoflurane or sevoflurane. Sedation was guided by the Sedation Agitation Scale, resulting in an end-tidal minimum anesthetic concentration of volatile agent ranging from 0.1-0.3. At one hour post ICU admission, infrared photometric analysis was used to assess environmental contamination at four points along the ventilator circuit and scavenging system and around the patient's head. All measurements taken within the patient's room were below 1 part per million, which satisfies criteria for occupational exposure.

CONCLUSIONS

This study shows that volatile agents can be administered safely within critical care settings using a simple scavenging system. Our scavenging system used in conjunction with the AnaConDa device reduced the concentration of environmental contamination to a level that is acceptable to Canadian standards and standards in most Western countries and thus conforms to international safety standards. The related clinical trial was registered at www.clinicaltrials.gov (NCT01151254).

Late pharmacologic conditioning with volatile anesthetics after cardiac surgery

INTRODUCTION

The aim of this randomized controlled trial was to investigate whether volatile anesthetics used for postoperative sedation have any beneficial effects on myocardial injury in cardiac surgery patients after on-pump valve replacement.

METHODS

Anesthesia was performed with propofol. After arrival in the intensive care unit (ICU), 117 patients were randomized to be sedated for at least 4 hours with either propofol or sevoflurane. Sevoflurane was administered by using the anesthetic-conserving device. Troponin T, creatine kinase, creatine kinase from heart muscle tissue, myoglobin, and oxygenation index were determined on arrival at the ICU, 4 hours after sedation, and in the morning of the first postoperative day (POD1). Primary end points were cardiac injury markers on POD1. As secondary end points oxygenation, postoperative pulmonary complications, and ICU and hospital stay were documented.

RESULTS

Fifty-six patients were analyzed in the propofol arm, and 46 patients in the sevoflurane arm. Treatment groups were comparable with regard to patient demographics and intraoperative characteristics. Concentration of troponin T as the most sensitive marker for myocardial injury at POD1 was significantly lower in the sevoflurane group compared with the propofol group (unadjusted difference, -0.4; 95% CI, -0.7 to -0.1; P < 0.01; adjusted difference, -0.2; 95% CI, -0.4 to -0.02; P = 0.03, respectively).

CONCLUSIONS

The data presented in this investigation indicate that late postconditioning with the volatile anesthetic sevoflurane might mediate cardiac protection, even with a late, brief, and low-dose application.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00924222.

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

Wake-up times following sedation with sevoflurane versus propofol after cardiac surgery

OBJECTIVES

Intravenous sedation in the intensive care unit (ICU) may contribute to altered consciousness and prolonged mechanical ventilation. We tested the hypothesis that replacing intravenous propofol with inhaled sevoflurane for sedation after cardiac surgery would lead to shorter wake-up times, quicker patient cooperation, and less delusional memories.

DESIGN

Following coronary artery bypass surgery with cardiopulmonary bypass, 100 patients were randomized to sedation with sevoflurane via the anesthetic conserving device or propofol. Study drugs were administered for a minimum of 2 hours until criteria for extubation were met. Primary endpoints were time from drug stop to extubation and to adequate verbal response. Secondary endpoints were adverse recovery events, memories reported in the ICU Memory Tool test, and ICU/hospital stay.

RESULTS

Median time from drug stop to extubation (interquartile range/total range) was shorter after sevoflurane compared to propofol sedation; 10 (10/100) minutes versus 25 (21/240) minutes (p <0.001). Time from extubation to adequate verbal response was shorter (p =0.036). No differences were found in secondary endpoints.

CONCLUSIONS

Sevoflurane sedation after cardiac surgery leads to shorter wake-up times and quicker cooperation compared to propofol. No differences were seen in ICU-stay, adverse memories or recovery events in our short-term sedation.

[Anesthetic conserving device (AnaConDa) used after cardiac surgery: experience in a postoperative recovery unit]

OBJECTIVE

To assess the safety and efficacy of using the Anesthetic Conserving Device (AnaConDa) when maintaining sedation after cardiac surgery.

MATERIAL AND METHODS

Descriptive study of 46 consecutive patients in the postoperative recovery unit after cardiac surgery between January and April 2009. The patients were under sevoflurane sedation administered with the AnaConDa placed in the inhalation tube. No exclusion criteria were established before enrollment. The sevoflurane dose was set using the manufacturer's normogram and was later adjusted to give an end-tidal concentration of sevoflurane between 0.5% and 0.7% on the basis of data from a gas analyzer. Remifentanil was administered to all patients; a fast-track extubation protocol was used. The only criterion for excluding a patient's data from analysis was prolonged sedation (> 5 hours).

RESULTS

The mean (SD) time patients were under sedation with the AnaConDa in place was 2588 (12.32) minutes. The end-tidal concentration of sevoflurane never exceeded 1%. Scores on the Richmond agitation-sedation scale were -5 at 60 minutes in all cases; there was some score variability at 120 minutes. Deeper sedation was desired for the first 60 minutes to avoid awakening related to rewarming. The mean time until awakening was 6.17 minutes (range, 1-30 minutes). The mean time until extubation was 43 (6.69) minutes. The most common adverse effect was arterial hypotension (12 cases). Hypotension was related to bleeding in 3 patients and to low cardiac output in 4 patients.

CONCLUSION

Administering sevoflurane through the AnaConDa can be a safe, valid, and reliable method for sedating patients after cardiac surgery. With this device, it is possible to monitor the concentration administered.

Pharmacology of sedative-analgesic agents: dexmedetomidine, remifentanil, ketamine, volatile anesthetics, and the role of peripheral Mu antagonists

In this article, the authors discuss the pharmacology of sedative-analgesic agents like dexmedetomidine, remifentanil, ketamine, and volatile anesthetics. Dexmedetomidine is a highly selective alpha-2 agonist that provides anxiolysis and cooperative sedation without respiratory depression. It has organ protective effects against ischemic and hypoxic injury, including cardioprotection, neuroprotection, and renoprotection. Remifentanil is an ultra-short-acting opioid that acts as a mu-receptor agonist. Ketamine is a nonbarbiturate phencyclidine derivative and provides analgesia and apparent anesthesia with relative hemodynamic stability. Volatile anesthetics such as isoflurane, sevoflurane, and desflurane are in daily use in the operating room in the delivery of general anesthesia. A major advantage of these halogenated ethers is their quick onset, quick offset, and ease of titration in rendering the patient unconscious, immobile, and amnestic.

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.

Analgesia and sedation after pediatric cardiac surgery

In recent years, the importance of appropriate intra-operative anesthesia and analgesia during cardiac surgery has become recognized as a factor in postoperative recovery. This includes the early perioperative management of the neonate undergoing radical surgery and more recently the care surrounding fast-track and ultra fast-track surgery. However, outside these areas, relatively little attention has focused on postoperative sedation and analgesia within the pediatric intensive care unit (PICU). This reflects perceived priorities of the primary disease process over the supporting structure of PICU, with a generic approach to sedation and analgesia that can result in additional morbidities and delayed recovery. Management of the marginal patient requires optimisation of not only cardiac and other attendant pathophysiology, but also every aspect of supportive care. Individualized sedation and analgesia strategies, starting in the operating theater and continuing through to hospital discharge, need to be regarded as an important aspect of perioperative care, to speed the process of recovery.

[Functioning of the anaesthetic conserving device: aspects to consider for use in inhalational sedation]

The new anaesthetic conserving device (ACD) allows the use of isoflurane and sevoflurane without classical anaesthesia workstations. Volatile anaesthetic exhaled by the patient is absorbed by a reflector and released to the patient during the next inspiration. Liquid anaesthetic is delivered via a syringe pump. Currently the use of the ACD is spreading among European intensive care units (ICU). This article focuses on the functioning of the device and on particularities which are important to consider. The ACD constantly reflects 90% of the exhaled anaesthetic back to the patient, but if one exhaled breath contains more than 10 ml of anaesthetic vapour (e.g. >1 vol% in 1,000 ml), the capacity of the reflector will be exceeded and relatively more anaesthetic will be lost to the patient. This spill over decreases efficiency but it also contributes to safety as very high concentrations are averted. Compared to classical anaesthesia systems the ACD used in conjunction with ICU ventilators offers advantages in the ICU setting: investment costs are low, carbon dioxide absorbent is not needed, breathing comfort is higher, anaesthetic consumption is low (equal to an anaesthesia circuit with a fresh gas flow of approximately 1 l/min) and anaesthetic concentrations can be controlled very quickly (increased by small boluses and decreased by removal of the ACD). On the other hand, case costs are higher (single patient use) and a dead space of 100 ml is added. There are pitfalls: by a process called auto-pumping, expansion of bubbles inside the syringe may lead to uncontrolled anaesthetic delivery. Auto-pumping is provoked by high positioning of the syringe pump, heat and prior cooling of the liquid anaesthetic. Inherent to the device is an early inspiratory concentration peak and an end-inspiratory dip which may mislead commonly used gas monitors. Workplace concentrations can be minimized by proper handling, a sufficient turnover of room air is important and gas from the expiration port of the ventilator should be scavenged. Inhalational compared to intravenous ICU sedation offers the advantages of better control of the sedation level, online drug monitoring, no accumulation in patients with renal or hepatic insufficiency and bronchodilation. With a lowered opioid dose spontaneous breathing and intestinal motility are well preserved. A clinical algorithm for the care of patients with respiratory insufficiency including inhalational sedation is proposed. Inhalational sedation with isoflurane has been widely used for more than 20 years in many countries and even for periods of up to several weeks. In the German S3 guidelines for the management of analgesia, sedation and delirium in intensive care (Martin et al. 2010), inhalational sedation is mentioned as an alternative sedation method for patients ventilated via an endotracheal tube or a tracheal cannula. Nevertheless, isoflurane is not officially licensed for ICU sedation and its use is under the responsibility of the prescribing physician.

The effect of sevoflurane and desflurane on markers of oxidative status in erythrocyte

The aim of our study was to evaluate the markers of oxidative status of erythrocyte during general anesthesia and compare the markers of oxidative status of erythrocyte in both sevoflurane and desflurane. Venous blood samples of patients were collected the following time intervals; initial time (IT) and first hour (1st h), first (1st day) and third days (3rd day) after anesthesia (sevoflurane and Desflurane). The levels of magnesium (Mg), zinc (Zn) as a cofactor of these enzymes, malondialdehyde (MDA) and the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) enzymes were also determined. No significant changes were observed in these measurements when the patients were exposed to desflurane anesthesia. On the other hand, the levels of Zn on erythrocytes were significantly increased at 1st hour and 1st and 3rd days compared to initial time in sevoflurane group (p < 0.01, p < 0.01, and p < 0.05, respectively). The activity of GSH-Px was significantly increased (p = 0.05) while the activity of SOD was significantly decreased (p < 0.01) at 1st hour after administration of sevoflurane compared to the initial time. There were no changes on the levels of Mg and MDA. Our results showed that sevoflurane has more impacts on the antioxidant status of erythrocytes than desflurane.