Reduced sevoflurane loss during cardiopulmonary bypass when using a polymethylpentane versus a polypropylene oxygenator

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.

Polymeric Biomaterials for Medical Implants and Devices

In this review article, we focus on the various types of materials used in biomedical implantable devices, including the polymeric materials used as substrates and for the packaging of such devices. Polymeric materials are used because of the ease of fabrication, flexibility, and their biocompatible nature as well as their wide range of mechanical, electrical, chemical, and thermal behaviors when combined with different materials as composites. Biocompatible and biostable polymers are extensively used to package implanted devices, with the main criteria that include gas permeability and water permeability of the packaging polymer to protect the electronic circuit of the device from moisture and ions inside the human body. Polymeric materials must also have considerable tensile strength and should be able to contain the device over the envisioned lifetime of the implant. For substrates, structural properties and, at times, electrical properties would be of greater concern. Section 1 gives an introduction of some medical devices and implants along with the material requirements and properties needed. Different synthetic polymeric materials such as polyvinylidene fluoride, polyethylene, polypropylene, polydimethylsiloxane, parylene, polyamide, polytetrafluoroethylene, poly(methyl methacrylate), polyimide, and polyurethane have been examined, and liquid crystalline polymers and nanocomposites have been evaluated as biomaterials that are suitable for biomedical packaging (section 2). A summary and glimpse of the future trend in this area has also been given (section 3). Materials and information used in this manuscript are adapted from papers published between 2010 and 2015 representing the most updated information available on each material.

Medication adsorption into contemporary extracorporeal membrane oxygenator circuits

OBJECTIVE

This study was conducted to evaluate the amount of medication adsorbed into extracorporeal membrane oxygenation (ECMO) circuits with a polymethylpentane membrane oxygenator and heparin-coated polyvinyl chloride tubing.

METHODS

An ECMO circuit with the aforementioned components was set up ex vivo and primed with expired blood. Midazolam, lorazepam, morphine, and fentanyl were administered to the circuit. Fifteen minutes after medication administration, 60 mL of blood were removed and stored in a 60-mL syringe to serve as a control. Medication levels were drawn from the ECMO circuit (test) and control syringe (control) 15 minutes, 24 hours, and 48 hours after the medications were administered. ECMO circuit medication levels were compared to their corresponding syringe control medication levels. Descriptive statistics were used to determine the percentage of medication remaining in the blood and compare it to the control value.

RESULTS

Except for morphine, there was a large decline in medication levels over the 48-hour period. Compared to control values, 17.2% of midazolam, 41.3% of lorazepam, 32.6% of fentanyl, and 102% of morphine remained in the ECMO circuit.

CONCLUSION

Despite the use of newer components in ECMO circuits, a large quantity of medication is adsorbed into the ECMO circuit. Midazolam, lorazepam, and fentanyl all showed reductions in medication levels greater than 50%. Morphine may have advantages for patients on ECMO, as its concentration does not appear to be affected.