Biomedical subjects

M Javorka

Publications and source records attributed to M Javorka.

6 recordsLinked to original sources

PubMed2003

Lung lavage using high-frequency jet ventilation in rabbits with meconium aspiration.

AIM: To determine the efficacy of the expulsion effect of high-frequency jet ventilation (HFJV) on meconium clearance from the airways in comparison with conventional suctioning in adult rabbits with meconium aspiration. METHODS: Experiments were carried out on tracheotomized, anaesthetized and paralysed adult rabbits. A suspension of human meconium in saline (25 mg ml(-1), 4 ml kg(-1)) was instilled into the tracheal cannula. When respiratory failure developed, saline lavage (10 ml kg(-1) in 3 portions) was performed during conventional ventilation or by means of the inpulsion and expulsion regime of HFJV. Animals were further ventilated for 2 h with either conventional ventilation or HFJV. RESULTS: There was no significant difference between groups in the amount of meconium recovered by lavage. Compared to conventional ventilation, the application of HFJV enhanced the elimination of carbon dioxide, increased lung compliance and diminished right-to-left shunts after 30 min of ventilatory treatment. Oxygenation also improved during HFJV, although this was not a consistent finding during the ventilation period. CONCLUSION: HFJV improved gas exchange, lung compliance and reduced right-to-left pulmonary shunts, but saline lung lavage by HFJV was not found to be more efficient than lavage during conventional ventilation in rabbits with meconium aspiration.

Animals↗

PubMed2003

[Analysis of variability in physiologic parameters using sequence plots].

The assessment of cardiovascular (and respiratory) parameters changes provides an information about the control systems involved and about their complex regulation. Methods based on nonlinear dynamics are able to quantify characteristics of the biosignal, that cannot be detected by conventional analysis methods. The sequence plot analysis is one of them. The aim of this paper is to provide basic information about this simple method and its application in the physiological research and in the clinical practice.

Analysis of Variance↗

PubMed2002

Heart rate recovery after exercise: relations to heart rate variability and complexity.

Physical exercise is associated with parasympathetic withdrawal and increased sympathetic activity resulting in heart rate increase. The rate of post-exercise cardiodeceleration is used as an index of cardiac vagal reactivation. Analysis of heart rate variability (HRV) and complexity can provide useful information about autonomic control of the cardiovascular system. The aim of the present study was to ascertain the association between heart rate decrease after exercise and HRV parameters. Heart rate was monitored in 17 healthy male subjects (mean age: 20 years) during the pre-exercise phase (25 min supine, 5 min standing), during exercise (8 min of the step test with an ascending frequency corresponding to 70% of individual maximal power output) and during the recovery phase (30 min supine). HRV analysis in the time and frequency domains and evaluation of a newly developed complexity measure - sample entropy - were performed on selected segments of heart rate time series. During recovery, heart rate decreased gradually but did not attain pre-exercise values within 30 min after exercise. On the other hand, HRV gradually increased, but did not regain rest values during the study period. Heart rate complexity was slightly reduced after exercise and attained rest values after 30-min recovery. The rate of cardiodeceleration did not correlate with pre-exercise HRV parameters, but positively correlated with HRV measures and sample entropy obtained from the early phases of recovery. In conclusion, the cardiodeceleration rate is independent of HRV measures during the rest period but it is related to early post-exercise recovery HRV measures, confirming a parasympathetic contribution to this phase.

Adult↗

PubMed2002

[Analysis of variability of physiologic parameters using the Poincare plot].

The noninvasive assessment of spontaneous temporal physiological parameters variations can provide valuable information about control systems involved in their complex regulations. Recently, in addition to conventional measures describing variability in time and frequency domains, methods based on nonlinear dynamics are increasingly used in physiology. The graphical analysis using Poincaré plot analysis with subsequent qualitative and quantitative analysis is one of them. The aim of this paper is to provide basic information about this method and its application in physiological research and clinical praxis.

Electrocardiography, Ambulatory↗

PubMed2002

Do the oscillations of cardiovascular parameters persist during voluntary apnea in humans?

The aim of this study was to ascertain the persistence of heart rate and blood pressure oscillations at the onset of voluntary apnea in humans and to assess the dependence of the fluctuations parameters on the chemoreceptor activity. In 24 young subjects (10 males, 14 females, mean age 20.4 years) heart rate (represented by its reciprocal value--RR-intervals), systolic blood pressure (SBP) and diastolic blood pressure (DBP) during controlled breathing (CB) of atmospheric air and oxygen followed by apnea were recorded continuously. The cosine functions were then fitted by nonlinear regression analysis to the heart rate, SBP and DBP oscillations during CB and at the onset of apnea. The parameters of oscillations were different during atmospheric air breathing compared to oxygen breathing. During oxygen breathing there was an increase of the RR-interval oscillations--relative bradycardia and enhanced magnitude of respiratory sinus arythmia. During apnea, the base level of the blood pressure oscillations was higher after breathing of atmospheric air compared to oxygen breathing. At least one cosine-like wave oscillation was present at the onset of apnea in the heart rate, SBP and DBP and the second wave was present in all assessed parameters in at least 70% of recordings. The oscillations in RR-intervals are, to some extent, independent of blood pressure oscillations. No significant gender differences were found either in the duration of breath holding or in the RR and SBP oscillations parameters.

Adolescent↗

PubMed2001

'Respiratory' oscillations of cardiovascular parameters during voluntary apnea.

The aim of this study was to ascertain the persistence of heart rate and blood pressure oscillations at the onset of voluntary apnea in humans. In 24 young subjects (10 males, 14 females, mean age 20.4 years) RR intervals, systolic blood pressure (SBP) and diastolic blood pressure (DBP) during controlled breathing (CB) of atmospheric air followed by voluntary apnea on FRC level were recorded continuously. The cosine functions were then fitted by nonlinear regression analysis to heart rate, SBP and DBP oscillations during CB and at the onset of apnea. During apnea, the changes of base of RR intervals indicate primary tachycardic reaction followed by a decrease in heart rate. The base of the blood pressure oscillations was higher (hypertensive reaction) in apnea. At least one cosine-like wave oscillation was present at the onset of apnea in heart rate, SBP and DBP and the second wave was present in all assessed parameters at least in 70% of recordings. There were no significant gender differences neither in the duration of breath holding nor in the RR and SBP oscillations parameters.

Adult↗