Sorptive loss of volatile and gaseous anesthetics from in vitro drug application systems

Feasibility of sedation with sevoflurane inhalation via AnaConDa for Covid-19 patients under venovenous extracorporeal membrane oxygenation

Critical care centers around the world have faced a shortage of intravenous sedatives caused by the coronavirus pandemic. Many patients infected with SARS-CoV-2 virus develop severe Acute Respiratory Distress syndrome (ARDS) for which some of them are supported by extra corporeal membrane oxygenation. Under these circumstances, the pharmacokinetics of the sedatives is modified. We observed that many of our COVID-19 infected patients receiving Extracorporeal Membrane Oxygenator (ECMO) require high doses of intravenous drugs. Continuous sedation with halogenated gases in the intensive care unit has shown many benefits on systemic inflammation and offers the possibility of a rapid recovery of consciousness. In this article we describe 3 cases that show the feasibility of sedation with sevoflurane via AnaConDa (Sedana Medical AB, Danderyd, Sweden) for Covid-19 patients under ECMO. Halogenated drugs could be considered as an interesting alternative to intravenous sedatives especially in the context of drug shortage.

Volatile Isoflurane in Critically Ill Coronavirus Disease 2019 Patients-A Case Series and Systematic Review

OBJECTIVES

The ongoing coronavirus pandemic is challenging, especially in severely affected patients who require intubation and sedation. Although the potential benefits of sedation with volatile anesthetics in coronavirus disease 2019 patients are currently being discussed, the use of isoflurane in patients with coronavirus disease 2019-induced acute respiratory distress syndrome has not yet been reported.

DESIGN

We performed a retrospective analysis of critically ill patients with hypoxemic respiratory failure requiring mechanical ventilation.

SETTING

The study was conducted with patients admitted between April 4 and May 15, 2020 to our ICU.

PATIENTS

We included five patients who were previously diagnosed with severe acute respiratory syndrome coronavirus 2 infection.

INTERVENTION

Even with high doses of several IV sedatives, the targeted level of sedation could not be achieved. Therefore, the sedation regimen was switched to inhalational isoflurane. Clinical data were recorded using a patient data management system. We recorded demographical data, laboratory results, ventilation variables, sedative dosages, sedation level, prone positioning, duration of volatile sedation and outcomes.

MEASUREMENTS & MAIN RESULTS

Mean age (four men, one women) was 53.0 (± 12.7) years. The mean duration of isoflurane sedation was 103.2 (± 66.2) hours. Our data demonstrate a substantial improvement in the oxygenation ratio when using isoflurane sedation. Deep sedation as assessed by the Richmond Agitation and Sedation Scale was rapidly and closely controlled in all patients, and the subsequent discontinuation of IV sedation was possible within the first 30 minutes. No adverse events were detected.

CONCLUSIONS

Our findings demonstrate the feasibility of isoflurane sedation in five patients suffering from severe coronavirus disease 2019 infection. Volatile isoflurane was able to achieve the required deep sedation and reduced the need for IV sedation.

In vitro clearance of dexmedetomidine in extracorporeal membrane oxygenation

Dexmedetomidine (DMET) is a useful agent for sedation, both alone and in combination with other agents, in critically ill patients, including those on extracorporeal membrane oxygenation (ECMO) therapy. The drug is a clonidine-like derivative with an 8-fold greater specificity for the alpha 2-receptor while maintaining respiratory and cardiovascular stability. An in vitro ECMO circuit was used to study the effects of both “new” and “old” membrane oxygenators on the clearance of dexmedetomidine over the course of 24 hours. Once primed, the circuit was dosed with 840 μg of dexmedetomidine for a final concentration of 0.9 μg/ml. Serial samples, both pre- and post-oxygenator, were taken at 5, 60, 360, and 1440 minutes. Concentrations of the drug were expressed as a percentage of the original concentration remaining at each time point, both for new and old circuits. The new circuits were run at a standard flow for 24 hours, after which time the circuit was considered old and re-dosed with dexmedetomidine and the trial repeated. Results show that dexmedetomidine losses occur early in the circuits and then continue to decline. Initial losses in the first hour were 11+-65% and 59-73% pre- and post-oxygenator in the new circuit and 36-50% and 42-72% in the old circuit. The clearance of the drug through the membrane oxygenator exhibits no statistical difference between pre and post or new and old circuits. Dexmedetomidine can be expected to exhibit concentration changes during ECMO therapy. This effect appears to be more related to adsorption to the polyvinyl chloride (PVC) tubing rather than the membrane oxygenator. Dosage adjustments during dexmedetomidine administration during ECMO therapy may be warranted in order to maintain adequate serum concentrations and, hence, the desired degree of sedation.*(Lack of equilibrium)

Washout of sevoflurane from the GE Avance and Amingo Carestation anesthetic machines

BACKGROUND

Inhalational anesthetics must be removed from anesthetic machines to prevent malignant hyperthermia (MH) in susceptible patients or to treat MH occurring during inhalational general anesthesia. This study examines the sevoflurane washout from the GE Avance and Amingo Carestations™.

METHODS

The care stations were contaminated with sevoflurane during general anesthesia. Then, the vaporizer was removed, the CO₂ absorber was exchanged against an empty one and the breathing tubes were substituted by clean ones. In the first part, the fresh gas flow was 10 l/min. In the second part, the Advanced Breathing System™ (ABS™), the internal breathing circuit, was replaced by a laundered component. The fresh gas flow was set to 10 l/min for 10 min and to 5 l/min for the following 20 min.

RESULTS

In the 25 measurements of the first part, the sevoflurane concentration decreased from a median of 31.60 ppm [interquartile range (IQR) 130.12 ppm] within 22 min in every case to values below 5 ppm and stayed there for the last 8 min of the measuring (P < 0.0001). In the 15 measurements of the second part, the sevoflurane concentration fell from the median of 8.56 ppm (IQR 8.99 ppm) within 5 min to values being significantly below 5 ppm and stayed there for the following 25 min (P < 0.0001).

CONCLUSIONS

In case of sudden onset of MH, the Avance or Amingo Carestation™ can stay in place, if the fresh gas flow is increased to 10 l/min or more. To prepare these machines for MH-susceptible patients, the ABS™ should be substituted by a laundered component.