Mechanical ventilation is controlled by volume or pressure during neurosurgery. Is there an advantage?

Background. One of the main technologies of modern anesthesiology is mechanical ventilation (MV). At present, the protective technology of MV is widely recognized. The feasibi-lity of using this technology in the operating room, especially in patients with intact lungs, is not so obvious. Most of the scientific sources that cover this problem relate to patients with abdominal pathology, and less coverage remains in patients with neurosurgical pathology. However, patients who are operated on for neurosurgical pathology belong to the group of patients of high surgical risk, which forced us to conduct this study. The study was aimed to examine the feasibility of using protective MV during surgery in neurosurgical patients. Materials and methods. We examined 46 patients who were hospitalized in KNP 8 MKL in Lviv for spinal pathology and who underwent surgery for vertebroplasty with spondylodesis. Patients were divided into two groups: in the first group (34 patients), MV was performed by S-IPPV technology — synchronized intermittent positive pressure ventilation with volume control; and in the second group (12 patients), MV was performed by PCV technology — controlled ventilation pressure. Results. We retrospectively determined the incidence of post-operative pulmonary complications (POPC) in patients of the first and second groups. Of the 34 patients of the first group, the signs of POPC were detected in 17 patients (50 %), and of 12 patients of the second group, POPC were detected in 4 patients (33.3 %). It should be noted that MV in patients of both groups did not differ in such parameters as respiratory rate, end-alveolar pressure, and the fraction of oxygen in the respiratory mixture. Conclusions. A relatively small number of patients clearly do not allow the conclusions to be drawn, but it should be noted that MV (especially volume-controlled) contributes to postoperative pulmonary complications in patients with intact lungs in the preoperative period. And pressure-controlled MV tends to reduce the incidence of postoperative pulmonary complications in the postoperative period. Given that respiration rate, end-alveolar expiratory pressure and oxygen fraction in the respiratory mixture were comparable in patients of both groups, it can be assumed that the factor influencing the incidence of POPC is the mechanics of pulmonary ventilation.

Optimal Positive End-Expiratory Pressure Obtained with Titration of Fraction of Inspiratory Oxygen: A Randomized Controlled Clinical Trial

Background Optimal intraoperative positive end expiratory pressure (PEEP) improves patient outcomes. The pulse-oximetry has been used to determine the lung opening and closing pressures. Therefore, we hypothesized that intraoperative optimal PEEP obtained by titrating inspiratory oxygen fraction (FiO2) guided with pulse-oximetry could improve perioperative oxygenation. Methods Forty-six males undergoing elective robotic assisted laparoscopic prostatectomy were randomly assigned to either optimal PEEP (Group O, n=23) or control with fixed PEEP of 5 cmH2O (Group C, n=23). Optimal PEEP, defined as the PEEP with lowest FiO2 or 0.21 to maintain SpO2≥ 95%, was obtained in both groups after placing the patients in Trendelenburg position and peritoneal insufflation. Patients in Group O maintained the optimal PEEP and in Group C maintained PEEP of 5cmH2O intraoperatively. Both groups were extubated in a sitting position once the extubation criteria met. The primary outcome was the partial arterial oxygen pressure (PaO2)/inspiratory oxygen fraction (FiO2) prior to extubation. Secondary outcome was the incidence of postoperative hypoxemia (SpO2༜92% on room-air after extubation) in post-operative care unit. Results The median optimal PEEP was 16 cm H2O [inter-quartile range, 12-18]. The PaO2/FiO2prior to extubation was significantly higher in Group O than that in Group C (77.0±4.9kPa vs.60.6±5.9kPa, p=0.04); PaO2/FiO2 was also significantly higher in Group O 30minutes after extubation (57.6±1.9 vs. 46.6±1.8kPa, p=0.01). The incidence of hypoxemia on room air in the post-operative care unit was significantly lower in the Group O than in the Group C (1/23, or 4.3% vs. 7/23 or 30.4%, p =0.02). Conclusions Intraoperative optimal PEEP can be achieved by titration of FiO2 guided with SpO2. Maintaining intraoperative optimal PEEP improves intraoperative oxygenation and reduces the incidence of post-operative hypoxemia. Trial registration : Chinese Clinical Trial Registry identifier: ChiCTR2100051010. Prospectively registered on 10 September, 2021

Influence of oxygen fraction on the characteristics of titanium oxide coatings obtained by the magnetron method

Titanium oxide coatings were obtained by magnetron sputtering on a glass substrate with different oxygen fraction in the plasma. Studies were carried out by scanning electron microscopy of the obtained coating samples establishing the role of oxygen in the process of crystallization of TiOx-coatings. It was found that with increasing the oxygen fraction in the vacuum arc discharge plasma the crystal grain size increases, the time of coating on the substrate increases, and the crystal layer has a columnar structure. The presence of amorphous and crystalline phase for all coating samples was revealed, with the predominance of the former. On the surface microphotographs of the coatings microcraters were found, on the surface of the samples obtained at the concentration of O2 in the plasma 14% of their concentration is maximum, this can be explained by changes in the state of the plasma, starting to occur at this concentration of reaction gas. Vacuum photonic annealing of the obtained coatings was performed. Vacuum radiation annealing in the furnace led to modification of coatings: sintering of coatings, increase of their crystallinity. An increase in crystallite size in a sample with an oxygen fraction of 12% was detected.

Efficiency of different flows for apneic oxygenation when using high flow nasal oxygen application – a technical simulation

Background Preoxygenation and application of apneic oxygenation are standard to prevent patients from desaturation e.g. during emergency intubation. The time before desaturation occurs can be prolonged by applying high flow oxygen into the airway. Aim of this study was to scientifically assess the flow that is necessary to avoid nitrogen entering the airway of a manikin model during application of pure oxygen via high flow nasal oxygen. Methods We measured oxygen content over a 20-min observation period for each method in a preoxygenated test lung applied to a human manikin, allowing either room air entering the airway in control group, or applying pure oxygen via high flow nasal oxygen at flows of 10, 20, 40, 60 and 80 L/min via nasal cannula in the other groups. Our formal hypothesis was that there would be no difference in oxygen fraction decrease between the groups. Results Oxygen content in the test lung dropped from 97 ± 1% at baseline in all groups to 43 ± 1% in the control group (p < 0.001 compared to all other groups), to 92 ± 1% in the 10 L/min group, 92 ± 1% in the 20 L/min group, 90 ± 1% in the 40 L/min group, 89 ± 0% in the 60 L/min group and 87 ± 0% in the 80 L/min group. Apart from comparisons 10 l/ min vs. 20 L/min group (p = .715) and 10/L/min vs. 40 L/min group (p = .018), p was < 0.009 for all other comparisons. Conclusions Simulating apneic oxygenation in a preoxygenated manikin connected to a test lung over 20 min by applying high flow nasal oxygen resulted in the highest oxygen content at a flow of 10 L/min; higher flows resulted in slightly decreased oxygen percentages in the test lung.

Physiological and Clinical Impact of Repeated Inhaled Oxygen Variation on Erythropoietin Levels in Patients After Surgery

The “Normobaric Oxygen Paradox” (NOP) is a physiologic mechanism that induces an increase of endogenous erythropoietin (EPO) production by creating a state of relative hypoxia in subjects previously exposed to hyperoxia, followed by a rapid return to normoxia. Oxygen exposure duration and inspired oxygen fraction required to observe a significant increase in EPO or hemoglobin are not clearly defined. Consequently, we here study the effect of one model of relative hypoxia on EPO, reticulocytes and hemoglobin stimulation in patients after surgery. Patients were prospectively randomized in two groups. The O2 group (n = 10) received 100% oxygen for 1 h per day for eight consecutive days, via a non-rebreathing mask. The control group (n = 12) received no oxygen variation. Serum EPO, hemoglobin and reticulocyte count were measured on admission and postoperatively on days seven and nine. Percentage EPO at day nine with respect to the baseline value was significantly elevated within the groups [O2 group: 323.7 (SD ± 139.0); control group: 365.6 (SD± 162.0)] but not between them. No significant difference was found between the groups in terms of reticulocytes count and hemoglobin. Our NOP model showed no difference on EPO increase between the two groups. However, both groups expressed separately significant EPO elevation.

Clinical outcome of patients with COVID-19 Pneumonia treated with corticosteroids and colchicine in Colombia

Background To date, there is no specific antiviral therapy for severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) that causes Coronavirus disease 2019 (Covid-19). Since there is no specific therapy against SARS-CoV2, current efforts aim to prevent contagion through public health measures and develop a protective vaccine. While waiting for the latter, it is necessary to evaluate the drugs that at least, in initial studies, suggested some degree of utility in the management of Covid-19 or its complications. The main objective of the study was to describe the clinical manifestations and outcomes of patients with severe Covid-19 Pneumonia treated with corticosteroids and colchicine. Materials and methods A cross sectional study of 301 adult patients with Covid-19 Pneumonia confirmed by Real-Time Polymerase Chain Reaction for SARS-CoV2 (RT-PCR SARS-CoV2), Berlin protocol, who required hospitalization in three hospitals in Antioquia, Colombia. Patients were treated according to the institutional protocol (from March 20, 2020 to June 30, 2020) with corticosteroid if the patient required supplemental oxygen. From July 1, 2020, the management protocol changed with the addition of colchicine to all patients admitted to the institutions. The treatment was supervised and monitored by the same specialist in Infectology of the institutions. We describe the clinical manifestations and outcomes of the patients who received these treatments. The information of the patients was analyzed according to the outcome of interest (alive/dead) with univariate, bivariate, and multivariate measures to adjust the variables that presented statistical association. Results All patients had pneumonia documented by chest computed tomography with ground glass images and presented an alveolar pressure/inspired oxygen fraction (PaFi) less than 300. Three hundred one patients were included, 240 (79.7%) received corticosteroids, within these 145 (48.2%) received colchicine also, and the remaining 61 (20.3%) patients did not receive corticosterioids or colchicine. Mortality in the group that received colchicine was lower compared to the group that did not receive it (9.6 vs 14.6%, p-value = 0.179). Conclusions Treatment with corticosteroids and colchicine for managing patients with severe Covid-19 Pneumonia was associated with low mortality at the hospital level. Randomized, placebo-controlled studies are required to evaluate the effect of corticosteroids and colchicine on complications or death from Covid-19.