Acute Gravitational Stress Selectively Impairs Dynamic Cerebrovascular Reactivity in the Anterior Circulation Independent of Changes to the Central Respiratory Chemoreflex

Cerebrovascular reactivity (CVR) to changes in the partial pressure of arterial carbon dioxide (PaCO2) is an important mechanism that maintains CO2 or pH homeostasis in the brain. To what extent this is influenced by gravitational stress and corresponding implications for the regulation of cerebral blood flow (CBF) remain unclear. The present study examined the onset responses of pulmonary ventilation (V̇E) and anterior middle (MCA) and posterior (PCA) cerebral artery mean blood velocity (Vmean) responses to acute hypercapnia (5% CO2) to infer dynamic changes in the central respiratory chemoreflex and cerebrovascular reactivity (CVR), in supine and 50° head-up tilt (HUT) positions. Each onset response was evaluated using a single-exponential regression model consisting of the response time latency [CO2-response delay (t0)] and time constant (τ). Onset response of V̇E and PCA Vmean to changes in CO2 was unchanged during 50° HUT compared with supine (τ: V̇E, p = 0.707; PCA Vmean, p = 0.071 vs. supine) but the MCA Vmean onset response was faster during supine than during 50° HUT (τ: p = 0.003 vs. supine). These data indicate that gravitational stress selectively impaired dynamic CVR in the anterior cerebral circulation, whereas the posterior circulation was preserved, independent of any changes to the central respiratory chemoreflex. Collectively, our findings highlight the regional heterogeneity underlying CBF regulation that may have translational implications for the microgravity (and hypercapnia) associated with deep-space flight notwithstanding terrestrial orthostatic diseases that have been linked to accelerated cognitive decline and neurodegeneration.

Hemorrhagic Risks of Percutaneous Dilated Tracheotomy in Thrombocytopenia

The objective: to assess the incidence and influence of platelets level on the hemorrhagic complications during percutaneous dilated tracheotomy (PDT) in patients with thrombocytopenia.Subjects and Methods. The study included 85 consecutive patients with varying degrees of thrombocytopenia at the stages of hematopoietic stem cell transplantation. The control group included 56 patients who underwent classical tracheotomy. The study group included 29 patients who underwent PDT (Griggs method). The operations were performed for prolonged artificial pulmonary ventilation. When the platelets level was below 20 × 109/L, platelet concentrate transfusion was performed before the operation.Results. The incidence of hemorrhagic complications in patients with thrombocytopenia during PDT was 13.8% (95% CI 9.13–18.45%). In open tracheotomy, the bleeding rate was 3.8% (95% CI 2.65–4.49%). These results are comparable to the incidence of hemorrhagic complications in patients with normal platelet counts. The influence of the platelet level on the presence of hemorrhagic complications in both groups was not established.Conclusion. Thrombocytopenia is not a contraindication to performing PDT. However, platelet concentrate transfusion should be performed in patients with platelet counts less than 20 × 109/L. An experienced team of anesthesiologists and endoscopists can reduce the incidence of other complications.

Monitoring Expired CO2 Kinetics to Individualize Lung-Protective Ventilation in Patients With the Acute Respiratory Distress Syndrome

Mechanical ventilation (MV) is a lifesaving supportive intervention in the management of acute respiratory distress syndrome (ARDS), buying time while the primary precipitating cause is being corrected. However, MV can contribute to a worsening of the primary lung injury, known as ventilation-induced lung injury (VILI), which could have an important impact on outcome. The ARDS lung is characterized by diffuse and heterogeneous lung damage and is particularly prone to suffer the consequences of an excessive mechanical stress imposed by higher airway pressures and volumes during MV. Of major concern is cyclic overdistension, affecting those lung segments receiving a proportionally higher tidal volume in an overall reduced lung volume. Theoretically, healthier lung regions are submitted to a larger stress and cyclic deformation and thus at high risk for developing VILI. Clinicians have difficulties in detecting VILI, particularly cyclic overdistension at the bedside, since routine monitoring of gas exchange and lung mechanics are relatively insensitive to this mechanism of VILI. Expired CO2 kinetics integrates relevant pathophysiological information of high interest for monitoring. CO2 is produced by cell metabolism in large daily quantities. After diffusing to tissue capillaries, CO2 is transported first by the venous and then by pulmonary circulation to the lung. Thereafter diffusing from capillaries to lung alveoli, it is finally convectively transported by lung ventilation for its elimination to the atmosphere. Modern readily clinically available sensor technology integrates information related to pulmonary ventilation, perfusion, and gas exchange from the single analysis of expired CO2 kinetics measured at the airway opening. Current volumetric capnography (VCap), the representation of the volume of expired CO2 in one single breath, informs about pulmonary perfusion, end-expiratory lung volume, dead space, and pulmonary ventilation inhomogeneities, all intimately related to cyclic overdistension during MV. Additionally, the recently described capnodynamic method provides the possibility to continuously measure the end-expiratory lung volume and effective pulmonary blood flow. All this information is accessed non-invasively and breath-by-breath helping clinicians to personalize ventilatory settings at the bedside and minimize overdistension and cyclic deformation of lung tissue.

RELATIONSHIPS BETWEEN AEROBIC AND ANAEROBIC CARDIOPULMONARY INDICES OF YOUNG MALE SOCCER PLAYERS WHEN PERFORMING LABORATORY FUNCTIONAL TESTS

Soccer is a high-intensity intermittent team sport where both the aerobic and anaerobic energy systems contribute to the physiological demands of the game. The study aims to search and determine relationships between the values of cardiopulmonary and gas exchange indices during frequently used laboratory tests - the CardioPulmonary Exercise Test (CPET) and the Wingate Anaerobic Test (WAnT), exploring the capacity of the energy systems. Forty-seven soccer players (15.06 ± 0.84 years of age) performed both tests as Oxygen uptake (VO2), Oxygen pulse (O2HR), Pulmonary ventilation (VE), Volume of expired air (VTex), and Breath frequency (BF) were measured online using a breathby-breath cardiopulmonary exercise testing system. Ergometric achievements during WAnT: PP (Peak Power) 662.4 ± 121.2 W; AP (Average Power) 494.67 ± 98.5 W; FI (Fatigue Index) 61.2 ± 28.7%. There was no correlation between WAnT PP and AP and maximum power output in CPET. WAnT VE and VTex correlate significantly with CPET VO2max (r = .676 and r = .772, respectively). The main finding was a presence of approximately identical maximal values of cardiopulmonary parameters achieved in the very different in duration and intensity CPET and WАnT: insignificant differences between CPET versus WAnT: VO2max (55.97 ± 2.02 versus 56.02 ± 17.3 ml.kg.min-1); VEmax (133.96 ± 21.77 versus 126.77 ± 24.77 l.min-1); VTex max (2.19 ± 0.37 l versus 2.06 ± 0.43 l); BFmax (62.20 versus 75.43.min-1). We assume that when conducting WAnT with simultaneous registration of respiration, together with the indices of athletes’ power output, reliable information about the magnitude of VO2max and other cardiopulmonary parameters of players could be obtained. This will greatly facilitate the ongoing control of the exercise conditioning status of athletes.

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.

Atypical bilateral ventilation/perfusion mismatches in an asymptomatic patient suffering from metastatic thyroid cancer

Background Pulmonary embolism is indicated by ventilation/perfusion (V/P) mismatches in ventilation/perfusion scintigraphy. However, other pathologies may also evoke segmental or lobar mismatches. Thus, diagnosis can be difficult in asymptomatic patients with equivocal clinical presentation. Case presentation We present a case of multiple bilateral pulmonary ventilation/perfusion mismatches in a poorly differentiated thyroid cancer patient. Exact diagnosis was difficult, as the patient was asymptomatic and pulmonary embolism is commonly unilateral in tumour patients and not typical for thyroid cancer. External pulmonary artery compression by aortic aneurysm, multiple metastases or additional bronchopulmonary malignancies were considered as differential diagnosis. After unilateral pulmonary and hilar metastasectomy, perfusion normalised on the operated side. Pulmonary perfusion defects due to pulmonary artery compression by hilar metastases were finally diagnosed. Pulmonary embolism was deemed unlikely due to the left-sided post-operative normalisation, persistence of right-sided V/P mismatches, and the lack of clinical symptoms. Conclusion Pulmonary artery compression may mimic pulmonary artery embolism in lung perfusion scintigraphy and should be considered in bronchopulmonary tumour patients with hilar metastases and unilateral ventilation/perfusion mismatches affecting a complete lobe or even lung. Following the presented case, also bilateral segmental and subsegmental mismatches in patients with hilar metastases from non-bronchopulmonary cancer entities should be carefully evaluated.

TO CHARACTERISTICS OF THE ETIOLOGICAL STRUCTURE AND ANTIBIOTIC SENSITIVITY PATHOGENSOF INFECTIOUS RESPIRATORY ORGANS IN NEWBORN AFTER ARTIFICIAL PULMONARY VENTILATION

Objective. The study of the etiological structure, properties of pathogens of the Vinnytsia National Medical University named after E. Pirogova, respiratory process in newborns who have underwent artificial mechanical lung ventilation (MLV) and their resistance to antibacterial agents is especially relevant in modern conditions, expands the search for new approaches to pathogens, improves treatment and reduces mortality from this pathology. The purpose of the study - to determine the etiological structure, sensitivity to antibiotics of the leading pathogens of the infectious process of the respiratory system in newborns who were on mechanical ventilation. Materials and methods. In total, the species composition of the leading microorganisms that colonized the airways of 180 newborns treated in the Neonatal Intensive Care Unit (VAITN) of Vinnytsia Regional Children’s Clinical Hospital (VRCCH) was studied in 2020. A total of 285 isolates of microorganisms were isolated. 62 patients who underwent mechanical ventilation were involved in a prospective microbiological study, 86 clinical strains of microorganisms were isolated. The susceptibility of microorganisms to 30 antibacterial agents was determined according to the generally accepted method (order of the Ministry of Health of Ukraine №167; recommendations). Research results. The etiological significance of opportunistic pathogens (Enterobacter cloacae - 29%, Staphylococcus aureus - 24.4%, Pseudomonas aeruginosa - 18.6%, Candida albicans) was proved in patients who were on mechanical ventilation in VAITN VRCCH in 2020 for pneumonia. Clinical strains of S. aureus are sensitive to vancomycin, oxacillin and clindamycin. Conclusions. Pathogens of the respiratory process in newborns who have been on mechanical ventilation, are resistant to a number of antibiotic drugs (cefepime, gentamicin amikacin, piperacillin).

Fully Automated 68Ga-Labeling and Purification of Macroaggregated Albumin Particles for Lung Perfusion PET Imaging

Lung PET/CT is a promising imaging modality for regional lung function assessment. Our aim was to develop and validate a fast, simple, and fully automated GMP compliant [68Ga]Ga-MAA labeling procedure, using a commercially available [99mTc]Tc-MAA kit, a direct gallium-68 eluate and including a purification of the [68Ga]Ga-MAA.Method: The synthesis parameters (pH, heating temperature) were manually determined. Automated 68Ga-labeling of MAA was then developed on a miniAIO (Trasis®, Ans, Belgium) module. An innovative automated process was developed for the purification. The process was then optimized and adapted to automate both the [68Ga]Ga-MAA synthesis and the isolation of gallium-68 eluate required for the pulmonary ventilation PET/CT.Results: The 15-min process demonstrated high reliability and reproducibility, with high synthesis yield (>95 %). Mean [68Ga]Ga-MAA radiochemical purity was 99 % ± 0.6 %. The 68Ga-labeled MAA particles size and morphology remained unchanged.Conclusion: A fast, user friendly, and fully automated process to produce GMP [68Ga]Ga-MAA for clinical use was developed. This automated process combining the advantages of using a non-modified MAA commercial kit, a gallium-68 eluate without pre-purification and an efficient final purification of the [68Ga]Ga-MAA may facilitate the implementation of lung PET/CT imaging in nuclear medicine departments.

Identification of The Intersegmental Plane By Arterial-Ligation Method During Thoracoscopic Segmentectomy

Purpose The purpose of this study is to explore the feasibility of identifying the intersegmental plane by arterial ligation alone during thoracoscopic anatomical segmentectomy. Methods We selected 35 patients with peripheral small lung nodules who underwent thoracoscopic anatomical segmentectomy between May and December 2020. First, the targeted segmental arteries were distinguished and ligated during the operation. Then, bilateral pulmonary ventilation was performed with pure oxygen to fully inflate the entirety pulmonary lobes. After waiting for a while, the intersegmental plane appeared. Finally, the intersegmental plane was observed using thoracoscopy after indocyanine green was injected into the peripheral vein. The intersegmental planes determined by these two methods were compared. Results Thirty-four patients underwent segmental resection and one patient finally underwent lobectomy. The intersegmental planes were successfully observed in all patients using the arterial ligation method. The time from contralateral pulmonary ventilation to the appearance of the intersegmental plane was 13.7±3.2 min (6-19 min). The intersegmental planes determined by the arterial ligation method and the fluorescence method were comparable. After the operation, CT examinations showed that the remaining lung segments of all patients were well inflated. The mean duration of closed thoracic drainage was 3.1±0.9 days. Conclusion The arterial ligation method can be used to determine the intersegmental plane in anatomical segmentectomy. The method is feasible, reliable, and safe.

Pathophysiological bases of maladjustment formation in high mountains and polar zones

The pathophysiological features of the development of maladjustment under mountain-cold conditions as a manifestation of the syndrome of mutual burdening are considered. In this study, contents of various literary sources, characterizing a persons resistance to the effects of a complex of factors under high mountains and polar zones conditions, were analyzed. With the simultaneous exposure to hypoxia and hypothermia from a pathophysiological point of view, intersecting links of terminological paths, often having diametrically opposite dynamics of changes in the characterized concepts, will be significant. Thus, in the terminological mitochondrial pathway of energy metabolism, uncoupling proteins are present, which, to increase the resistance to hypothermia, should be activated to switch the energy metabolism to predominantly use fatty acids. However, hypoxic conditions should be suppressed to maintain the level of adenosine triphosphate acid available for cells. In the terminological tract of compensatory reactions in response to hypoxemia, the volume of pulmonary ventilation is released, which must increase to improve tolerance to hypoxia, which, under mountain-cold conditions, increased heat loss and promote the deterioration of the condition, i.e., tolerance to low temperatures. Under hypoxic and hypothermic conditions, a synergistic interaction can form, which can be manifested by the development of a syndrome of mutual burdening, which will result in a significant decrease in the functional capabilities of the body, result, and productivity. Maladjustment to mountain cold, with maximum probability, will manifest as disorders of the central nervous system, decreased physical performance, depletion of the functional and regulatory reserves of the body, functional immunodeficiency, decreased regenerative potential, and development of endogenous intoxication. With a high degree of probability, a significant synergistic interaction of hypoxia and hypothermia can be found in relation to the indicators of pulmonary ventilation, blood gases (hypercapnia), acidbase balance (gas alkalosis and lactic acidosis), heart rate (tachycardia), blood pressure (hypotension), central venous pressure (increase), blood viscosity (increase) and its coagulability (hypercoagulation), peroxide and free radical oxidation (activation), and protein catabolism (increase). These changes will negatively affect the functional state of specialists performing complex professional tasks in polar latitudes.