Preparation of Dräger Atlan A350 and General Electric Healthcare Carestation 650 anesthesia workstations for malignant hyperthermia susceptible patients

Background Patients at risk of malignant hyperthermia need trigger-free anesthesia. Therefore, anesthesia machines prepared for safe use in predisposed patients should be free of volatile anesthetics. The washout time depends on the composition of rubber and plastic in the anesthesia machine. Therefore, new anesthesia machines should be evaluated regarding the safe preparation for trigger-free anesthesia. This study investigates wash out procedures of volatile anesthetics for two new anesthetic workstations: Dräger Atlan A350 and General Electric Healthcare (GE) Carestation 650 and compare it with preparation using activated charcoal filters (ACF). Methods A Dräger Atlan and a Carestation 650 were contaminated with 4% sevoflurane for 90 min. The machines were decontaminated with method (M1): using ACF, method 2 (M2): a wash out method that included exchange of internal parts, breathing circuits and soda lime canister followed by ventilating a test lung using a preliminary protocol provided by Dräger or method 3 (M3): a universal wash out instruction of GE, method 4 (M4): M3 plus exchange of breathing system and bellows. Decontamination was followed by a simulated trigger-free ventilation. All experiments were repeated with 8% desflurane contaminated machines. Volatile anesthetics were detected with a closed gas loop high-resolution ion mobility spectrometer with gas chromatographic pre-separation attached to the bacterial filter of the breathing circuits. Primary outcome was time until < 5 ppm of volatile anesthetics and total preparation time. Results Time to < 5 ppm for the Atlan was 17 min (desflurane) and 50 min (sevoflurane), wash out continued for a total of 60 min according to protocol resulting in a total preparation time of 96-122 min. The Carestation needed 66 min (desflurane) and 24 min (sevoflurane) which could be abbreviated to 24 min (desflurane) if breathing system and bellows were changed. Total preparation time was 30-73 min. When using active charcoal filters time to < 5 ppm was 0 min for both machines, and total preparation time < 5 min. Conclusion Both wash out protocols resulted in a significant reduction of trace gas concentrations. However, due to the complexity of the protocols and prolonged total preparation time, feasibility in clinical practice remains questionable. Especially when time is limited preparation of the anesthetic machines using ACF remain superior.

PERKEMBANGAN JUMLAH EKTOPARASIT Pseudorhabdosynochus spp. PADA INSANG KERAPU HIBRIDA CANTIK (Epinephelus fuscoguttatus x E. polyphekadion) MELALUI METODE KOHABITASI

Genus Pseudorhabdosynocus merupakan Monogenea yang sering menginfeksi ikan kerapu. Pengaruh perbedaan jarak antara ikan sakit dengan ikan sehat terhadap perkembangan jumlah Pseudorhabdosynochus spp. pada ikan kerapu hibrida “cantik” dipelajari dalam penelitian ini melalui metode kohabitasi. Kohabitasi dilakukan dengan dua metode yaitu (a) menempatkan lima ekor ikan sakit ke dalam keranjang dengan jarak 25 cm dari dasar bak, dan (b) menempatkan lima ekor ikan sakit ke dalam keranjang dengan jarak 10 cm dari dasar bak. Kedua keranjang tersebut diapungkan ke dalam bak plastik berbeda dengan volume 100 L air laut (33 ppt) yang masing-masing telah berisi 30 ekor ikan kerapu hibrida “cantik” sehat. Masing-masing lima ekor ikan dari kedua metode kohabitasi diambil pada hari ke-2, 4, 6, 8, 10, dan 15 pemeliharaan. Hasil penelitian menunjukkan bahwa infeksi buatan menggunakan metode kohabitasi (b) lebih cepat menyebarkan Pseudorhabdosynochus spp. dari ikan sakit ke ikan sehat dibandingkan dengan metode kohabitasi (a). Perkembangan populasi Pseudorhabdosynochus spp. dan telurnya pada metode kohabitasi (b) lebih tinggi yaitu 1.495 ± 206,3 ekor/ikan dan 18,6 ± 3,8 telur/ikan dibandingkan dengan metode kohabitasi (a) yaitu 163,2 ± 16,3 ekor/ikan dan 3,8 ± 0,7 telur/ikan pasca 15 hari kohabitasi. Secara histopatologi, lamela insang yang terinfeksi Pseudorhabdosynochus spp. menunjukkan adanya hyperplasia epitel sel filamen insang yang menimbulkan fusi filamen. Kerusakan filamen di hampir semua lamela insang menyebabkan terganggunya sistem pernapasan ikan kerapu. Hasil tersebut dapat disimpulkan bahwa penyebaran Pseudorhabdosynochus spp. semakin cepat dengan semakin dekat jarak kontak antara ikan sakit dengan ikan sehat.Pseudorhabdosynocus is a genus of Monogenea that frequently infect grouper fish. This study aimed to observe the changes of density patterns of Pseudorhabdosynochus spp. in hybrid grouper gill through cohabitation. Two cohabitation methods were applied to understand the effects of distance between sick and healthy fish in terms of parasite infection. The cohabitation methos were arranged as follows: (a) five fish infected with Pseudorhabdosynochus spp. were placed into a basket at a distance of 25 cm from the bottom of the tank, and (b) five fish infected with Pseudorhabdosynochus spp. were placed into a basket at a distance of 10 cm from the bottom of the tank. The two baskets were floated into different plastic tanks of 100 L of seawater (33 ppt), each of which contained 30 healthy hybrid groupers. Each of the five fish from the two cohabitation methods was sampled on day 2, 4, 6, 8, 10, and 15 after cohabitation. The results showed that the spread of Pseudorhabdosynochus spp. from sick fish to healthy fish with the cohabitation method b was faster than the cohabitation method a. The development number of Pseudorhabdosynochus spp. and its eggs in the cohabitation method b were higher, reaching 1,495 ± 206.3 parasite/fish and 18.6 ± 3.8 eggs/fish than the cohabitation method a, 163.2 ± 16.3 parasite/fish and 3.8 ± 0.7 eggs/fish after 15 days of cohabitation. Histopathologically, gill lamella infected with Pseudorhabdosynochus spp. showed the presence of epithelial hyperplasia of gill filament cells causing fusion. Damage of the gill filament in all of gill lamella has caused disruption of the grouper breathing system. From these findings, it can be concluded that the spread of Pseudorhabdosynochus spp. was faster if the distance of direct contact between sick and healthy fish was closer.

Correlation of exhaled propofol with Narcotrend index and calculated propofol plasma levels in children undergoing surgery under total intravenous anesthesia - an observational study

Background Exhaled propofol concentrations correlate with propofol concentrations in adult human blood and the brain tissue of rats, as well as with electroencephalography (EEG) based indices of anesthetic depth. The pharmacokinetics of propofol are however different in children compared to adults. The value of exhaled propofol measurements in pediatric anesthesia has not yet been investigated. Breathing system filters and breathing circuits can also interfere with the measurements. In this study, we investigated correlations between exhaled propofol (exP) concentrations and the Narkotrend Index (NI) as well as calculated propofol plasma concentrations. Methods A multi-capillary-column (MCC) combined with ion mobility spectrometry (IMS) was used to determine exP. Optimal positioning of breathing system filters (near-patient or patient-distant) and sample line (proximal or distal to filter) were investigated. Measurements were taken during induction (I), maintenance (M) and emergence (E) of children under total intravenous anesthesia (TIVA). Correlations between ExP concentrations and NI and predicted plasma propofol concentrations (using pediatric pharmacokinetic models Kataria and Paedfusor) were assessed using Pearson correlation and regression analysis. Results Near-patient positioning of breathing system filters led to continuously rising exP values when exP was measured proximal to the filters, and lower concentrations when exP was measured distal to the filters. The breathing system filters were therefore subsequently attached between the breathing system tubes and the inspiratory and expiratory limbs of the anesthetic machine. ExP concentrations significantly correlated with NI and propofol concentrations predicted by pharmacokinetic models during induction and maintenance of anesthesia. During emergence, exP significantly correlated with predicted propofol concentrations, but not with NI. Conclusion In this study, we demonstrated that exP correlates with calculated propofol concentrations and NI during induction and maintenance in pediatric patients. However, the correlations are highly variable and there are substantial obstacles: Without patient proximal placement of filters, the breathing circuit tubing must be changed after each patient, and furthermore, during ventilation, a considerable additional loss of heat and moisture can occur. Adhesion of propofol to plastic parts (endotracheal tube, breathing circle) may especially be problematic during emergence. Trial Registration The study was registered in the German registry of clinical studies (DRKS-ID: DRKS00015795).

In vitro performance evaluation of AnaConDaTM-100 and AnaConDaTM-50 compared to a circle breathing system for control and consumption of volatile anaesthetics

To identify the better volatile anaesthetic delivery system in an intensive care setting, we compared the circle breathing system and two models of reflection systems (AnaConDa™ with a dead space of 100 ml (ACD-100) or 50 ml (ACD-50)). These systems were analysed for the parameters like wash-in, consumption, and wash-out of isoflurane and sevoflurane utilising a test lung model. The test lung was connected to a respirator (circle breathing system: Aisys CS™; ACD-100/50: Puriton Bennett 840). Set parameters were volume-controlled mode, tidal volume-500 ml, respiratory rate-10/min, inspiration time-2 sec, PEEP-5 mbar, and oxygen-21%. Wash-in, consumption, and wash-out were investigated at fresh gas flows of 0.5, 1.0, 2.5, and 5.0 l/min. Anaesthetic target concentrations were 0.5, 1.0, 1.5, 2.0, and 2.5%. Wash-in was slower in ACD-100/-50 compared to the circle breathing system, except for fresh gas flows of 0.5 and 1.0 l/min. The consumption of isoflurane and sevoflurane in ACD-100 and ACD-50 corresponded to the fresh gas flow of 0.5-1.0 l/min in the circle breathing system. Consumption with ACD-50 was higher in comparison to ACD-100, especially at gas concentrations > 1.5%. Wash-out was quicker in ACD-100/-50 than in the circle breathing system at a fresh gas flow of 0.5 l/min, however, it was longer at all the other flow rates. Wash-out was comparable in ACD-100 and ACD-50. Wash-in and wash-out were generally quicker with the circle breathing system than in ACD-100/-50. However, consumption at 0.5 minimum alveolar concentration was comparable at flows of 0.5 and 1.0 l/min.