The effects of a large arteriovenous fistula (AVF) on pulmonary perfusion remains to be elucidated. We aimed to study, for the first time, the real-time acute effects of a large AVF on regional distribution of pulmonary perfusion in a novel porcine model. Ten healthy swine under general anesthesia were studied. AVF was created by the connection of femoral artery and femoral vein using high-diameter perfusion cannulas. The AVF was closed and after 30 min of stabilization the first values were recorded. The fistula was then opened, and new data were collected after reaching stable state. Continuous hemodynamic monitoring was performed throughout the protocol. The following functional images were analyzed by electrical impedance tomography (EIT): perfusion and ventilation distributions. We found an increased cardiac output and right ventricular work, which was strongly correlated to an increased pulmonary artery mean pressure (r=0.878, P=0.001). The ventral/dorsal ratio of pulmonary perfusion decreased from 1.9+/-1.0 to 1.5+/-0.7 (P=0.025). The percentage of total pulmonary blood flow through the dorsal lung region increased from 38.6+/-11.7 to 42.2+/-10.4 (P=0.016). In conclusion, we have used EIT for the first time for studying the acute effects of a large AVF on regional distribution of pulmonary perfusion in a novel porcine model. In this new experimental model of hyperkinetic circulation caused by AVF, we documented an increased percentage of total pulmonary blood flow through the dorsal lung region and a more homogeneous perfusion distribution. Key words Arteriovenous fistula, Hyperkinetic circulation, Tissue perfusion, Animal model, Pulmonary blood flow.
- MeSH
- arteria pulmonalis diagnostické zobrazování patofyziologie MeSH
- arteriovenózní píštěl patofyziologie diagnostické zobrazování MeSH
- arteriovenózní zkrat MeSH
- plíce krevní zásobení diagnostické zobrazování MeSH
- plicní oběh * fyziologie MeSH
- prasata MeSH
- vena femoralis diagnostické zobrazování MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Adrenaline (ADR) is a cornerstone of advanced life support (ALS) in cardiac arrest (CA), although its neurologically favourable survival outcomes remain unclear. ADR increases coronary perfusion pressure (CPP), with levels >15 mmHg associated with successful defibrillation. This study aimed to elucidate the relationship between ADR, myocardial microvascular blood flow, and resuscitation outcomes using a porcine CA model simulating refractory ventricular fibrillation (VF). METHODS: This study involved 24 domestic pigs. After instrumentation, intubation, and baseline measurements, the animals were randomised into the ADR or control (saline) groups. VF was induced, and cardiopulmonary resuscitation was initiated using continuous mechanical chest compressions and ventilation. ADR or saline was administered following ALS guidelines. After 21 min of ALS, defibrillation was performed. Continuous measurements of arterial and venous blood pressures using an electrocardiogram and index of myocardial resistance (IMR) and transit mean time (Tmn) 1 min before and after each injection or peak blood pressure were recorded and compared between the groups. CPP-IMR, amplitude spectrum area (AMSA)-IMR, CPP-Tmn, and AMSA-Tmn correlations were assessed. RESULTS: Compared with six animals in the control group, three in the ADR group achieved a return of spontaneous circulation. No difference was observed in IMR or AMSA; however, significant increases in CPP and arterial end-diastolic blood pressure were observed at several time points. Tmn differed between groups only at two time points. CONCLUSION: Repeated ADR doses during prolonged ALS simulating refractory VF did not improve myocardial microvascular blood flow, as measured using IMR, despite leading to an increase in CPP.
- Publikační typ
- časopisecké články MeSH
- MeSH
- acidobazická rovnováha fyziologie MeSH
- enterální výživa metody MeSH
- lidé MeSH
- parenterální výživa metody MeSH
- pooperační komplikace * metabolismus patofyziologie terapie MeSH
- poruchy acidobazické rovnováhy klasifikace patofyziologie terapie MeSH
- roztoky pro parenterální výživu klasifikace MeSH
- šok patofyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
Since its implementation into the clinical medicine by Willem Einthoven electrocardiography had become one of crucial diagnostic method in cardiology. In spite of this fact effects of gender differences on parameters of electrocardiographic recordings started to be studied only recently. Sex related differences in physiological ECG are only minimal in childhood but there are developing during adolescence reflecting rapidly evolving differences particularly in hormonal secretion and activity of an autonomic nervous system. The heart rate is approximately 7 % higher in women than in men, PQ and QRS intervals are longer in men while QT interval is longer in women. The ST segment in females is flatter but generally the sex-related differences in ST-T waveform patterns are relatively very small with higher level of ST segment and taller T wave in men. The effects of sex-related differences, including sex hormones, on cardiac cell injury and death and their influence in determining rhythmogenesis and action potential configuration and conduction play an important role in clinics. Women have a higher prevalence of sick sinus syndrome, inappropriate sinus tachycardia, atrioventricular nodal reentry tachycardia, idiopathic right ventricular tachycardia, and arrhythmic events in the long QT syndrome. In contrast, men have a higher prevalence of atrioventricular block, carotid sinus syndrome, atrial fibrillation, supraventricular tachycardia due to accessory pathways, Wolff-Parkinson-White syndrome, reentrant ventricular tachycardia, ventricular fibrillation and sudden death, and the Brugada syndrome.
- Publikační typ
- časopisecké články MeSH
[This corrects the article DOI: 10.3389/fphys.2023.1113568.].
- Publikační typ
- tisková chyba MeSH
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
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
There are substantial differences in autonomic nervous system activation among heart (cardiac) failure (CF) patients. The effect of acute CF on autonomic function has not been well explored. The aim of our study was to assess the effect of experimental acute CF on heart rate variability (HRV). Twenty-four female pigs with a mean body weight of 45 kg were used. Acute severe CF was induced by global myocardial hypoxia. In each subject, two 5-min electrocardiogram segments were analyzed and compared: before the induction of myocardial hypoxia and >60 min after the development of severe CF. HRV was assessed by time-domain, frequency-domain and nonlinear analytic methods. The induction of acute CF led to a significant decrease in cardiac output, left ventricular ejection fraction and an increase in heart rate. The development of acute CF was associated with a significant reduction in the standard deviation of intervals between normal beats (50.8 [20.5−88.1] ms versus 5.9 [2.4−11.7] ms, p < 0.001). Uniform HRV reduction was also observed in other time-domain and major nonlinear analytic methods. Similarly, frequency-domain HRV parameters were significantly changed. Acute severe CF induced by global myocardial hypoxia is associated with a significant reduction in HRV.
