The impact of FFP3 respirators on the blood saturation.

This study aims to investigate whether wearing a filtering facepiece class 3 respirators with personal protective equipment (FPP3/PPE) during work in the intensive care unit (ICU) affects the blood saturation (SpO2), the heart rate (HR), and the well-being of health care workers (HCWs). This preliminary study included a group of 21 volunteers (including 16 females (76%), with a median age of 23 years). Each worker served as his own control and performed the test two times: they wore the FFP3/PPE and did not wear it for a three-hour shift in the ICU. The working with an FFP3/PPE compared to not working with an FFP3/PPE caused a significant, but within normal ranges, influence on the level of SpO2 with a mean decrease of - 1.43%. The highest reduction in the SpO2 was - 2.29% and occurred after 150 min of work. All of the score scales of the well-being markers increased consecutively but moderately during the shift while wearing the FFP3/PPE. We assume that a 3-h shift rhythm is a safe and reliable solution, i.e., three hours of working in the FFP3/PPE in the ICU, followed by rest or working without an FFP3/PPE.

The effect of volatile anesthetics on cellular responses in the microcirculation of free tissue transfers.

The purpose of this review was to summarize the anti-inflammatory and immunosuppressive properties of volatile anesthetics and present their potential impact on the outcomes of major surgical procedures as well as microsurgical cases of free tissue transfer. Inhaled anesthetics are commonly used as a component of general anesthesia in interventional procedures, reconstructive surgery, free tissue transfers and transplantation. Experimental and clinical studies have shown that volatile anesthetics such as halothane, sevoflurane, isoflurane or desflurane can affect the immune system of patients exposed to general anesthesia. In patients with no serious systemic diseases, this effect is transient and mostly clinically irrelevant. However, in patients subjected to the inflammatory response due to the active disease, cardiac or pulmonary failure or advanced age, the prognosis may improve or worsen following inhalation anesthesia depending on the type of systemic pathology. The available data from reported clinical trials, as well as the in vitro and in vivo experimental studies, have often reported conflicting statements regarding the impact of inhalation anesthetics on outcomes of surgical procedures. These differences may be due to the heterogeneity of the evaluated patients, the extent and duration of surgical procedures, and different experimental design and methodologies applied for assessment of the reported clinical and research studies. In this review, based on the available literature reports we have summarized the anti-inflammatory and immunosuppressive effects as well as cellular responses of inhalation anesthetics at the microcirculatory level and discussed their potential clinical implications for the outcomes of surgical procedures of free tissue transfers.

The influence of cardiac output on propofol and fentanyl pharmacokinetics and pharmacodynamics in patients undergoing abdominal aortic surgery.

Cardiac output (CO) is expected to affect elimination and distribution of highly extracted and perfusion rate-limited drugs. This work was undertaken to quantify the effect of CO measured by the pulse pressure method on pharmacokinetics and pharmacodynamics of propofol and fentanyl administrated during total intravenous anesthesia (TIVA). The data were obtained from 22 ASA III patients undergoing abdominal aortic surgery. Propofol was administered via target-controlled infusion system (Diprifusor) and fentanyl was administered at a dose of 2-3 µg/kg each time analgesia appeared to be inadequate. Hemodynamic measurements as well as bispectral index were monitored and recorded throughout the surgery. Data analysis was performed by using a non-linear mixed-effect population modeling (NONMEM 7.4 software). Three compartment models that incorporated blood flows as parameters were used to describe propofol and fentanyl pharmacokinetics. The delay of the anesthetic effect, with respect to plasma concentrations, was described using a biophase (effect) compartment. The bispectral index was linked to the propofol and fentanyl effect site concentrations through a synergistic Emax model. An empirical linear model was used to describe CO changes observed during the surgery. Cardiac output was identified as an important predictor of propofol and fentanyl pharmacokinetics. Consequently, it affected the depth of anesthesia and the recovery time after propofol-fentanyl TIVA infusion cessation. The model predicted (not observed) CO values correlated best with measured responses. Patients' age was identified as a covariate affecting the rate of CO changes during the anesthesia leading to age-related difference in individual patient's responses to both drugs.

Population Pharmacokinetic Model of Dexmedetomidine in a Heterogeneous Group of Patients.

Dexmedetomidine is a hepatically eliminated drug with sedative, anxiolytic, sympatholytic, and analgesic properties that has been increasingly used for various indications in the form of a short or continuous intravenous infusion. This study aimed to propose a population pharmacokinetic (PK) model of dexmedetomidine in a heterogeneous group of intensive care unit patients, incorporating 29 covariates potentially linked with dexmedetomidine PK. Data were collected from 70 patients aged between 0.25 and 88 years and treated with dexmedetomidine infusion for various durations at 1 of 4 medical centers. Statistical analysis was performed using a nonlinear mixed-effect model. Categorical and continuous covariates including demographic data, hemodynamic parameters, biochemical markers, and 11 single-nucleotide polymorphisms were tested. A 2-compartment model was used to describe dexmedetomidine PK. An allometric/isometric scaling was used to account for body weight difference in PK parameters, and the Hill equation was used to describe the maturation of clearance. Typical values of the central and peripheral volume of distribution and the systemic and distribution clearance for a theoretical adult patient were central volume of distribution = 22.50 L, peripheral volume of distribution = 86.1 L, systemic clearance = 34.7 L/h, and distribution clearance = 40.8 L/h. The CYP1A2 genetic polymorphism and noradrenaline administration were identified as significant covariates for clearance. A population PK model of dexmedetomidine was successfully developed. The proposed model is well calibrated to the observed data. The identified covariates account for <5% of interindividual variability and consequently are of low clinical significance for the purpose of dose adjustment.

BEST Life-"Bringing ECMO Simulation To Life"-How Medical Simulation Improved a Regional ECMO Program.

The implemented "ECMO for Greater Poland" program takes full advantage of the ECMO (extracorporeal membrane oxygenation) perfusion therapy to promote health for 3.5 million inhabitants in the region. The predominant subjects of implementation are patients with hypothermia, with severe reversible respiratory failure (RRF), and treatment of other critical states leading to heart failure such as sudden cardiac arrest, cardiogenic shock or acute intoxication. Finally, it promotes donation after circulatory death (DCD) strategy in selected organ donor cases. ECMO enables recovery of organs' function after unsuccessful lifesaving treatment. Because this organizational model is complex and expensive, we use advanced high-fidelity medical simulation to prepare for real-life implementation. During the first four months, we performed scenarios mimicking "ECMO for DCD," "ECMO for ECPR (extended cardiopulmonary resuscitation)," "ECMO for RRF" and "ECMO in hypothermia." It helped to create algorithms for aforementioned program arms. In the following months, three ECMO courses for five departments in Poznan (capitol city of Greater Poland) were organized and standardized operating procedures for road ECMO transportation within Medical Emergency System were created. Soon after simulation program, 38 procedures with ECMO perfusion therapy including five road transportations on ECMO were performed. The Maastricht category II DCD procedures were done four times on real patients and in two cases double successful kidney transplantations were carried out for the first time in Poland. ECMO was applied in two patients with hypothermia, nine adult patients with heart failure, and five with RRF, for the first time in the region. In the pediatric group, ECMO was applied in four patients with RRF and 14 with heart failure after cardiac surgery procedures. Additionally, one child was treated successfully following 200 km-long road transport on ECMO. We achieved good and promising results especially in VV ECMO therapy. Simulation-based training enabled us to build a successful procedural chain, and to eliminate errors at the stage of identification, notification, transportation, and providing ECMO perfusion therapy. We discovered the important role of medical simulation, not only to test the medical professional's skills, but also to promote ECMO therapy in patients with critical/life-threatening states. Moreover, it also resulted in increase of the potential organ pool from DCD in the Greater Poland region.

Pharmacokinetics and pharmacodynamics of propofol and fentanyl in patients undergoing abdominal aortic surgery - a study of pharmacodynamic drug-drug interactions.

Propofol is routinely combined with opioid analgesics to ensure adequate anesthesia during surgery. The aim of the study was to assess the effect of fentanyl on the hypnotic effect of propofol and the possible clinical implications of this interaction. The pharmacokinetic/pharmacodynamic (PK/PD) data were obtained from 11 patients undergoing abdominal aortic surgery, classified as ASA III. Propofol was administered by a target-controlled infusion system. Fentanyl 2-3 µg/kg was given whenever insufficient analgesia occurred. The bispectral index (BIS) was used to monitor the depth of anesthesia. A population PK/PD analysis with a non-linear mixed-effect model (NONMEM 7.2 software) was conducted. Two-compartment models satisfactorily described the PK of propofol and fentanyl. The delay of the anesthetic effect in relation to PK was described by the effect compartment. The BIS was linked to propofol and fentanyl effect-site concentrations through an additive Emax model. Context-sensitive decrement times (CSDT) determined from the final model were used to assess the influence of fentanyl on the recovery after anesthesia. The population PK/PD model was successfully developed to describe simultaneously the time course and variability of propofol and fentanyl concentrations and BIS. Additive propofol-fentanyl interactions were observed and quantitated. The duration of the fentanyl infusion had minimal effect on CSDT when it was shorter than the duration of the propofol infusion. If the fentanyl infusion was longer than the propofol infusion, an almost two-fold increase in CSDT occurred. Additional doses of fentanyl administered after the cessation of the propofol infusion result in lower BIS values, and can prolong the time of recovery from anesthesia. Copyright © 2016 John Wiley & Sons, Ltd.

Exposure to volatile anaesthetics is not followed by a massive induction of single-strand DNA breaks in operation theatre personnel.

Volatile anaesthetics such as halothane, isoflurane and others were expected to produce a health challenge for operation room personnel because of prolonged occupational exposure to anaesthetic gases. To estimate a molecular background of adverse health effects, a cohort of 100 exposed individuals was studied by the single-cell gene electrophoresis (comet assay) test. DNA lesions in lymphocytes of the exposed group did not differ significantly compared with non-exposed blood donors. Then, the exposed group was further divided according to job position. A highest level of DNA lesions was established in nurses but without significant difference compared with other groups. When a time period of exposure was taken into account, a tendency to cumulate DNA lesions was found only in the group of anaesthesiologists. A very weak genotoxic effect established in this study is discussed in relation to DNA repair, adaptative response and potential self-elimination of sensitive individuals.

Pharmacokinetics and pharmacodynamics of propofol in patients undergoing abdominal aortic surgery.

Available propofol pharmacokinetic protocols for target-controlled infusion (TCI) were obtained from healthy individuals. However, the disposition as well as the response to a given drug may be altered in clinical conditions. The aim of the study was to examine population pharmacokinetics (PK) and pharmacodynamics (PD) of propofol during total intravenous anesthesia (propofol/fentanyl) monitored by bispectral index (BIS) in patients scheduled for abdominal aortic surgery. Population nonlinear mixed-effect modeling was done with Nonmem. Data were obtained from ten male patients. The TCI system (Diprifusor) was used to administer propofol. The BIS index served to monitor the depth of anesthesia. The propofol dosing was adjusted to keep BIS level between 40 and 60. A two-compartment model was used to describe propofol PK. The typical values of the central and peripheral volume of distribution, and the metabolic and inter-compartmental clearance were V(C) = 24.7 l, V(T) = 112 l, Cl = 2.64 l/min and Q = 0.989 l/min. Delay of the anesthetic effect, with respect to plasma concentrations, was described by the effect compartment with the rate constant for the distribution to the effector compartment equal to 0.240 min(-1). The BIS index was linked to the effect site concentrations through a sigmoidal E(max) model with EC(50) = 2.19 mg/l. The body weight, age, blood pressure and gender were not identified as statistically significant covariates for all PK/PD parameters. The population PK/PD model was successfully developed to describe the time course and variability of propofol concentration and BIS index in patients undergoing surgery.

Utility of measurements of abdominal perfusion pressure as a measure of isovolemic status and intestinal perfusion in patients with ruptured aortic aneurysm.

UNLABELLED: Ruptured abdominal aorta aneurysm of ten results in intraabdominal hypertension (IAH). When IAH exceeds 20 mm Hg, intestinal ischemia can result that is a common cause of severe postoperative complications, including death. THE AIM OF THE STUDY: was to evaluate utility of measurement of abdominal perfusion pressure (APP) to estimate intestinal perfusion and isovolemic status in patients undergoing surgical treatment for ruptured abdominal aorta aneurysm. MATERIAL AND METHODS: A group of 40 patients of either sex, aged 47-93 years (average age 70 ± 10) was treated at an Intensive Care Unit after surgical reconstruction of abdominal aorta due to ruptured aortic aneurysm. The study was prospective. The following were measured: parameters of intraabdominal pressure (intraabdominal pressure - IAP, abdominal perfusion pressure - APP); parameters of intestinal perfusion - tonometric (intramucosal gastric carbon dioxide partial pressure PgCO(2), intramucosal-arterial difference in carbon dioxide partial pressure - Pg-aCO(2)); hemodynamic parameters (mean arterial pressure - MAP, central venous pressure - CVP). RESULTS: A statistically significant correlation was demonstrated between parameters of visceral perfusion and abdominal perfusion pressure. Pearson correlation coefficient for APP/PgCO(2) and APP/Pg-aCO(2) was negative and was -0.4664 and -0.3498, respectively. CONCLUSIONS: Abdominal perfusion pressure is an useful parameter in the evaluation of intestinal perfusion in IAH patients after surgical treatment of ruptured aortic aneurysm. MAP reflects current physiological body reserves at a critical stage of the disease, informing about possibility to provide visceral perfusion and indirectly, about adequacy of fluid replacement therapy. In intraabdominal hypertension, CVP is falsely elevated, making it of low utility in the evaluation of volemic status and intestinal perfusion.

Air-blood barrier injury during cardiac operations with the use of cardiopulmonary bypass (CPB). An old story? A morphological study.

OBJECTIVE: In spite of the advances in technology and surgical techniques, cardiac surgical operations with the use of cardiopulmonary bypass (CPB) are still associated with pulmonary morbidity and mortality. The purpose of this study is to morphologically analyze the structure of air-blood barriers in patients who underwent coronary artery bypass grafting (CABG) with use of CPB. DESIGN: The investigation involved 50 patients aged 48-75 who underwent CABG with the use of extracorporeal circulation (ECC). Lung tissue specimens, which were taken before and after CPB, were observed with light and electron microscopy. RESULTS: Both light and electron microscopic observations of pre-pump specimens did not show any pathological changes within the terminal part of the respiratory system. Morphological observations of tissue samples obtained after CPB revealed features of air-blood barrier injury and presence of surfactant within the alveolar capillaries. CONCLUSION: Whatever the mechanism of the aforementioned changes one should be aware that the presented results indicate that air-blood barriers become leaky after CABG is performed with the aid of ECC.