Low-volume lung injury encompasses local concentration of stresses in the vicinity of collapsed regions in heterogeneously ventilated lungs. We aimed to study the effects on ventilation and perfusion distributions of a sequential lateral positioning (30°) strategy using electrical impedance tomography imaging in a porcine experimental model of early acute respiratory distress syndrome (ARDS). We hypothesized that such strategy, including a real-time individualization of positive end-expiratory pressure (PEEP) whenever in lateral positioning, would provide attenuation of collapse in the dependent lung regions. A two-hit injury acute respiratory distress syndrome experimental model was established by lung lavages followed by injurious mechanical ventilation. Then, all animals were studied in five body positions in a sequential order, 15 min each: Supine 1; Lateral Left; Supine 2; Lateral Right; Supine 3. The following functional images were analyzed by electrical impedance tomography: ventilation distributions and regional lung volumes, and perfusion distributions. The induction of the acute respiratory distress syndrome model resulted in a marked fall in oxygenation along with low regional ventilation and compliance of the dorsal half of the lung (gravitational-dependent in supine position). Both the regional ventilation and compliance of the dorsal half of the lung greatly increased along of the sequential lateral positioning strategy, and maximally at its end. In addition, a corresponding improvement of oxygenation occurred. In conclusion, our sequential lateral positioning strategy, with sufficient positive end-expiratory pressure to prevent collapse of the dependent lung units during lateral positioning, provided a relevant diminution of collapse in the dorsal lung in a porcine experimental model of early acute respiratory distress syndrome.
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: The aim of this study was to quantify and understand the unloading effect of percutaneous balloon atrial septostomy (BAS) in acute cardiogenic shock (CS) treated with venoarterial (VA) extracorporeal membranous oxygenation (ECMO). BACKGROUND: In CS treated with VA ECMO, increased left ventricular (LV) afterload is observed that commonly interferes with myocardial recovery or even promotes further LV deterioration. Several techniques for LV unloading exist, but the optimal strategy and the actual extent of such procedures have not been fully disclosed. METHODS: In a porcine model (n = 11; weight 56 kg [53-58 kg]), CS was induced by coronary artery balloon occlusion (57 minutes [53-64 minutes]). Then, a step-up VA ECMO protocol (40-80 mL/kg/min) was run before and after percutaneous BAS was performed. LV pressure-volume loops and multiple hemoglobin saturation data were evaluated. The Wilcoxon rank sum test was used to assess individual variable differences. RESULTS: Immediately after BAS while on VA ECMO support, LV work decreased significantly: pressure-volume area, end-diastolic pressure, and stroke volume to ∼78% and end-systolic pressure to ∼86%, while superior vena cava and tissue oximetry did not change. During elevating VA ECMO support (40-80 mL/kg/min) with BAS vs without BAS, we observed 1) significantly less mechanical work increase (122% vs 172%); 2) no end-diastolic volume increase (100% vs 111%); and 3) a considerable increase in end-systolic pressure (134% vs 144%). CONCLUSIONS: In acute CS supported by VA ECMO, atrial septostomy is an effective LV unloading tool. LV pressure is a key component of LV work load, so whenever LV work reduction is a priority, arterial pressure should carefully be titrated low while maintaining organ perfusion.
- MeSH
- kardiogenní šok * diagnóza terapie MeSH
- lidé MeSH
- mimotělní membránová oxygenace * metody MeSH
- modely nemocí na zvířatech MeSH
- prasata MeSH
- vena cava superior MeSH
- výsledek terapie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Among the challenges for personalizing the management of mechanically ventilated patients with coronavirus disease (COVID-19)-associated acute respiratory distress syndrome (ARDS) are the effects of different positive end-expiratory pressure (PEEP) levels and body positions in regional lung mechanics. Right-left lung aeration asymmetry and poorly recruitable lungs with increased recruitability with alternating body position between supine and prone have been reported. However, real-time effects of changing body position and PEEP on regional overdistension and collapse, in individual patients, remain largely unknown and not timely monitored. The aim of this study was to individualize PEEP and body positioning in order to reduce the mechanisms of ventilator-induced lung injury: collapse and overdistension. METHODS: We here report a series of five consecutive mechanically ventilated patients with COVID-19-associated ARDS in which sixteen decremental PEEP titrations were performed in the first days of mechanical ventilation (8 titration pairs: supine position immediately followed by 30° targeted lateral position). The choice of lateral tilt was based on X-Ray. This targeted lateral position strategy was defined by selecting the less aerated lung to be positioned up and the more aerated lung to be positioned down. For each PEEP level, global and regional collapse and overdistension maps and percentages were measured by electrical impedance tomography. Additionally, we present the incidence of lateral asymmetry in a cohort of forty-four patients. RESULTS: The targeted lateral position strategy resulted in significantly smaller amounts of overdistension and collapse when compared with the supine one: less collapse along the PEEP titration was found within the left lung in targeted lateral (P = 0.014); and less overdistension along the PEEP titration was found within the right lung in targeted lateral (P = 0.005). Regarding collapse within the right lung and overdistension within the left lung: no differences were found for position. In the cohort of forty-four patients, ventilation inequality of > 65/35% was observed in 15% of cases. CONCLUSIONS: Targeted lateral positioning with bedside personalized PEEP provided a selective attenuation of overdistension and collapse in mechanically ventilated patients with COVID-19-associated ARDS and right-left lung aeration/ventilation asymmetry. TRIAL REGISTRATION: Trial registration number: NCT04460859.
- MeSH
- atelektáza prevence a kontrola terapie MeSH
- COVID-19 terapie MeSH
- dospělí MeSH
- elektrická impedance MeSH
- lidé středního věku MeSH
- lidé MeSH
- polohování pacienta metody MeSH
- poškození plic mechanickou ventilací prevence a kontrola MeSH
- prospektivní studie MeSH
- SARS-CoV-2 MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- syndrom dechové tísně terapie MeSH
- umělé dýchání metody MeSH
- ventilace umělá s výdechovým přetlakem metody MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- pozorovací studie MeSH
The aims were to explore the effect of head-up tilt (HUT) to 30 and 60 degrees on hemodynamics and tissue oxygenation in anesthetized healthy swine. The data serve as a reference for a study of resuscitation efficacy at HUT such as during transport. Nine healthy swine (49+/-4 kg) were anesthetized and multiple sensors including myocardial pressure-volume loops catheter, carotid flow probe, blood pressure catheters, near infrared spectroscopy (NIRS) tissue oximetry and mixed venous oximetry (SVO2) catheter were introduced and parameters continuously recorded. Experimental protocol consisted of baseline in supine position (15 min), 30 degrees HUT (15 min), recovery at supine position (15 min) and 60 degrees HUT (5 min). Vacuum mattress was used for body fixation during tilts. We found that 30 and 60 degrees inclination led to significant immediate reduction in hemodynamic and oximetry parameters. Mean arterial pressure (mm Hg) decreased from 98 at baseline to 53 and 39, respectively. Carotid blood flow dropped to 47 % and 22 % of baseline values, end diastolic volume to 49 % and 53 % and stroke volume to 47 % and 45 % of baseline. SVO2 and tissue oximetry decreased by 17 and 21 percentage points. The values are means. In conclusions, within minutes, both 30 and 60 degrees head-up tilting is poorly tolerated in anesthetized swine. Significant differences among individual animals exist.
- MeSH
- arteriae carotides patofyziologie MeSH
- arteriální tlak MeSH
- blízká infračervená spektroskopie MeSH
- časové faktory MeSH
- celková anestezie * MeSH
- hemodynamika * MeSH
- kyslík krev MeSH
- modely u zvířat MeSH
- ortostatická intolerance krev patofyziologie MeSH
- oxymetrie metody MeSH
- postura těla * MeSH
- prasata MeSH
- regionální krevní průtok MeSH
- spotřeba kyslíku MeSH
- supinační poloha MeSH
- test na nakloněné rovině MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Extracorporeal membranous oxygenation (ECMO) is increasingly used in the management of refractory cardiac arrest. Our aim was to investigate early effects of ECMO after prolonged cardiac arrest. In fully anesthetized swine (48 kg, N=18) ventricular fibrillation (VF) was induced and untreated period (20 min) of cardiac arrest commenced, followed by 60 min extracorporeal reperfusion (ECMO flow 100 ml/kg.min). Hemodynamics, arterial blood gasses, plasma potassium, tissue oximetry (StO2) and cardiac (EGM) and cerebral (BIS) electrophysiological parameters were continuously recorded and analyzed. Within 3 minutes of VF hemodynamic and oximetry parameters fall abruptly while metabolic parameters destabilize gradually over 20 minutes peaking at pH 7.04±0.05, pCO2 89±14 mmHg, K+ 8.5±1.6 mmol/l. During reperfusion most parameters restore rapidly: within 3-5 minutes mean arterial pressure reaches >40 mmHg, StO2>50 %, paO2>100 mmHg, pCO2<50 mmHg, K+<5 mmol/l. EGMs mean amplitude peaks at 4.5±2.4 min. Cerebral activity (BIS>60) reappeared in 5 animals after 87±21 min. In 12/18 animals return of spontaneous circulation was achieved. In conclusions, ECMO provides rapid restitution of internal milieu even after prolonged arrest. However, despite normalization of global parameters full recovery was not guaranteed since cardiac and cerebral electrical activities were sufficiently restored only in some animals. More sensitive and organ specific indicators need to be identified in order to estimate adequacy of cardiac support devices.
- MeSH
- analýza krevních plynů MeSH
- arteriální tlak fyziologie MeSH
- fibrilace komor patofyziologie MeSH
- kardiopulmonální resuscitace veterinární MeSH
- mimotělní oběh * metody rehabilitace veterinární MeSH
- modely nemocí na zvířatech MeSH
- prasata MeSH
- reperfuze myokardu * metody MeSH
- srdeční zástava * patofyziologie rehabilitace veterinární MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
Východisko. V návaznosti na výsledky našich recentních studií, které zjistily zvýšení QT disperze (QTd) u skupiny těhotných, bylymatematickými postupy hledánymožné geometrické příčiny tohoto nálezu, zejména, zda pozorované změny mohou být důsledkem rotace případně posunu srdce. Metody a výsledky. Byl vytvořen model elektrického pole srdečního, které bylo studováno jako pole časově proměnného dipólu v homogenním prostorovém vodiči. Z experimentálně získaných vektorkardiografických záznamů, reprezentujících časový průběh srdečního dipólu, byly pomocí modelu vypočteny povrchové elektrokardiogramy. Ověření adekvátnosti modelu bylo provedeno srovnáním takto rekonstruovaných elekrokardiogramů s empirickými daty. Pro zjištění vlivu rotace byla originální empirická VKG data kontrolní skupiny transformována ve shodě s předpokládanými či zjištěnými změnami v důsledku těhotenství, proveden výpočet povrchových elektrokardiogramů a ty porovnány s empiricky získanými kardiogramy skupiny těhotných. Závěry. Na základě uvedených výsledků lze odvodit několik závěrů: 1) Na QT disperzi se nutně podílí složka způsobená čistě geometrickými vztahy mezi orientací srdečního vektoru terminální fáze repolarizace a směrem os konkrétního svodového systému. Takto vzniklá disperze má typický výskyt na povrchu hrudníku – minima trvání QT se nacházejí v rovině kolmé na osu svodu terminálního vektoru. 2) Při stanovení trvání repolarizace z klasických hrudních svodů existují v rámci fyziologické variability sklonu elektrické osy orientace terminálního vektoru, z nichž u některých zmíněné minimum trvání QT bude a u jiných nebude zachyceno. Hodnota zjištěné QT disperze mezi těmito dvěma extrémy pak bude významně různá. 3) U horizontálního sklonu srdce bude mít EKG signál ve velké většině svodů systému povrchového mapování vyšší voltáž oproti svodům s vertikálnějším sklonem srdeční osy v důsledku menšího úhlu mezi osami terminálního vektoru a většinou svodů. Tato skutečnost bude přispívat k přesnějšímu odečtu konce vlny T a stanovení trvání QT intervalu, obvykle s menší hodnotou QTd. 4) Změna srdečního pole odpovídající změněné poloze srdce (rotace) sama o sobě nevede ke změně QTd, pokud je tato hodnocena z EKG záznamů z celého hrudníku. Naopak, horizontalizace srdce spíše přispívá ke stanovení nižších hodnot QTd, jak je uvedeno výše. 5) QT disperze zjištěná u souboru těhotných ve vysokém stupni těhotenství je spíše než důsledkem geometrických změn zapříčiněná změnou morfologie T smyčky, která byla u souboru těhotných pozorována. Dalším možným vysvětlením pozorované disperze je nedipolární charakter změn elektrického pole během těhotenství. Naše výsledky svědčí pro hypotézu, že nález QT disperze je v podstatné míře důsledkem rozdílných geometrických poměrů (srdce, hrudníku a detekčního systému) a takto nutně subjektem možných chyb díky ne zcela standardizovanému způsobu měření. Vyvinuté prostředí umožňuje další, podrobnější studium problematiky elektrického pole srdečního.
Background. In concurrence of our recent findings of the elevation of QT dispersion (QTd) in the group of pregnant women, mathematical approaches were developed aimed to give possible geometrical explanation whether the observed changes result from the rotation or from the changed position of the heart. Methods and Results. Mathematical model of the cardiac electrical field approximated as a time variable dipole in a homogenous spatial conductor was developed. From the experimental vectocardiographic records, representing time course of the cardiac dipole, body surface potential maps were calculated on the basis of the model. To validate the adequacy of the model, the reconstructed electrocardiograms were compared with the empiric data. To determine the effects of rotation, original empiric VCG data of the control group were transformed accordingly the hypothetic pregnancy related changes. Calculated surface electrocardiograms were then compared with empiric cardiograms of the pregnant women. Conclusions. Based on the results, several conclusions can be drawn: 1) QT dispersion is associated also with the geometrical relations between the direction of cardiac vector during the terminal phase of repolarization and the direction of axes in the given system of leads. The dispersion then has its typical occurrence at the thoracic surface – minimums of the QT duration are found in the plane perpendicular to the axis of the terminal vector lead. 2) When the duration of repolarization is estimated from the classic thoracic leads within the phisiological variations of terminal–depolarization vector orientations, can exist that in some cases the minimum of QT interval is and in others it is not recorded by the lead system. Value of QT dispersion between these two extremes will be significantly different. 3) In case of the horizontal declination of the heart, the ECG signal in most of the leads of the body surface mapping has a higher voltage than in case of vertical declination due to a smaller angle between axes of the terminal vector and most of the leads. Such factwill contribute tomore accurate reading of the T wave end and to the estimation of QT interval, usually with smaller value of QTd. 4) The change of the cardiac electrical field corresponding to the changed position of the heart (rotation) does not result by itself in QTd changes, if it is evaluated from the records from the whole thorax. Obversely, horizontalization of the heart contributes more to the evaluation of lower QTd values, as it is given above. 5) More then the result of geometrical changes, QT dispersion found in the group women in high level of pregnancy is an effect of changes in the T loop morphology, which was observed in this group. Another possible explanation of the observed dispersion is the non-dipolar character of the electrical field changes during pregnancy.
