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Biomedical subjects

K Javorka

Publications and source records attributed to K Javorka.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Does short-term high-frequency jet ventilation damage the tracheobronchial mucosa?].

In anesthetized rabbits, the occurrence of histopathological changes was studied above below and the level of the endotracheal tube opening after one-hour high-frequency jet ventilation (f = 150.min-1,Pin = 70-90 kPa, Ti = 0.5) with nonhumidified air and oxygen mixture (FiO2 = 0.6). The findings were compared with those obtained in intact rabbits and in rabbits which were inhaling nonhumidified air from the environment spontaneously via the endotracheal tube. Mechanical obstruction of the airways by mucus or necrosis of the mucous membrane was not observed. The major histopathological changes characteristic of inflammation and mechanical damage of the mucosa were recorded above the opening of the endotracheal tube. Towards the main bronchi the degree of the injury was decreasing. (Tab. 2, Fig. 2, Ref. 11.)

Animals↗
PubMed1993

[Use of high-frequency modulated continuous positive airway pressure in experimental respiratory distress syndrome and pulmonary edema].

The effect of high frequency (f = 300.min-1) modulated continuous positive airway pressure (CPAP) (0.49 kPa) was compared with that of CPAP without modulation (0.49 kPa) in 24 anesthetized rabbits in experimental respiratory distress syndrome (RDS) and pulmonary edema. RDS was induced by single excessive lavage of the lung on using the impulse and expulse effect of high frequency jet ventilation. Pulmonary edema was elicited by i.v. administration of a mixture of fatty acids. Decreased dynamic compliance of the lung and increased respiration work and rate were recorded both in experimental RDS and pulmonary edema. In RDS paO2 was reduced and paCO2 increased. In pulmonary edema, despite diminished respiration volume, ventilation was enhanced by the higher respiration rate and both paO2 and paCO2 were reduced. Application of CPAP resulted in normalization of blood gases. Modulated CPAP, compared to CPAP without modulation, further decreased paCO2 and increased paO2. The results obtained in experimental models of RDS and pulmonary edema in rabbits show the beneficial effect of high frequency modulated CPAP by pressure oscillation on values of blood gas tension.

Animals↗
PubMed1992

[Changes in the parameters of respiratory mechanics after the aspiration reflex and asphyxia].

Parameters of respiration mechanics (dynamic compliance--Cdyn and total lung resistance--RL), ventilation, blood gases, and right-to-left pulmonary shunts were studied after aspiration reflex in experiments on 29 anesthetized cats. Attacks of aspiration reflex were induced without asphyxia (8 cats) and during two-minute asphyxia (9 cats). The control group consisted of 12 animals. A series of aspiration reflex attacks resulted in short-term improvement of the parameters of respiration mechanics with an increase in Cdyn and reduction of RL. A simultaneous elevation of PaO2 and a decrease of PaCO2 were recorded. In combination with asphyxia (hypoxemia and hyperkapnia), the aspiration reflex induced a reversed reaction, i.e. decreased Cdyn lasting till the end of experiment (3 hours) and an increase of functional alveolar right-to-left shunts. The results indicate that in cats impairment of respiration mechanics parameters is brought on only when deep inspiration is combined with asphyxia.

Airway Resistance↗
PubMed1992

[The effect of postural changes on respiration and blood pressure in premature neonates].

Changes in respiratory rate, heart rate, and blood pressure in supine, orthostatic (45 degrees), and prone position were studied in 23 premature neonates of mean gestational age 34.5 weeks (30-36), mean birth weight 2100 g (1540-2480) and mean postnatal age 52 hours (12-72). The individual positions of the newborn were changed in 5-minute intervals. In the orthostatic position, the respiratory rate decreased, yet heart rate and blood pressure did not change. In pronation, respiration became more regular. In the preceding supine position, the coefficient of variation of the duration of respiratory cycles was 28.2 +/- 3.5%, while in the 1st minute of pronation it was 15.9 +/- 2.4% and in the 5th minute 14.3 +/- 1.9% (p < 0.001). In the 5th minute of pronation systemic blood pressure was increased. (Tab. 1, Fig. 4, Ref. 20).

Blood Pressure↗
PubMed1990

[Reversible cardiorespiratory failure induced by CO2 inhalation in cats].

Experiments on anesthetized cats showed that short-term inhalation of concentrated CO2 induced reversible asphyxia resulting in acute cardiorespiratory failure. The stage of hyperventilation was followed by apnea initially interrupted by primary gasps and by bradycardia and drop in systemic blood pressure. After termination of CO2 supply in the state of apnea or after onset of resuscitation the blood pressure started to increase, secondary gasps appeared and regular respiration was gradually restored. The rate and duration of gasps decreased but the inspiratory force and the achieved tidal volume and airflow were greater than at normal respiration. During reversible asphyxia induced by CO2 inhalation the ECG exhibited invariably severe arrhythmias, most frequently atrioventricular block of different degrees. Bilateral cervical vagotomy failed to prevent the occurrence of ECG changes. After administration of Indral, however, arrhythmias were recorded only exceptionally.

Animals↗
PubMed1990

[New methods of artificial respiratory ventilation].

High frequency ventilation, a new nonconventional method, has been introduced into clinical practice also in Czechoslovakia, where mainly high frequency jet ventilation (HFJV) is being developed. The HFJ ventilator Best-2 (Konstrukta, Trencín) and Chirajet (Chirana, Stará Turá) which enable HFJV with a multijet generator are used. These equipments reduce inadvertent positive end expiratory pressure by means of an expiration jet and are so designed that Brychta's impulse and expulse regimen can be used to advantage at programmed lavage of the lungs and at selective ventilation of individual parts of the lungs. The paper presents the basic principles of HFJV as well as the author's experience in using this method of ventilation in experimental animals.

High-Frequency Jet Ventilation↗
PubMed1989

[The effect of trigeminal zone irritation on parameters of forced vital capacity in humans].

In 44 healthy males aged 18-21 years, the authors studied the effect of irritation of the trigeminal zone by ammonia vapors and by immersion of the face into water on parameters of forced vital capacity. Inhalation of ammonia immediately induced impairment of all the studied parameters of forced expiration. In the later time intervals (up to the 10th minute after inhalation) the air flow remained reduced over the whole forced expiration (FVC/FET), mainly at the expense of decreased air flow at the end of forced expiration (FEF75-85%). Inhalation of ammonia also resulted in abolition of the psychically induced higher heart rate and in its normalization. Immersion of the face into cold water caused reduction in the values of FVC, FEV1, FVC/FET, and FEF0-25%. After voluntary apnea in the air there was only a small reduction of FEF0-25%. In the light of these findings, the authors consider irritation of cold receptors of the face to be the main cause of the changes in functional parameters of the lungs during immersion reflex.

Adolescent↗
PubMed1988

Heart rate and its variability in juvenile hypertonics during respiratory maneuvers.

In 27 children (14 juvenile hypertonics and 13 healthy control children, with the mean age 14.7 +/- 0.4 y. or 15.2 +/- 0.5 y., respectively, P greater than 0.05) the changes of heart rate (HR), its variability (HRV) during deep inspiration and subsequent expiration, Valsalva's maneuver, doubled breathing frequency and the deepening of breathing were studied. The resting supine mean HR was significantly higher (P less than 0.001) in hypertonics than in controls. Deep inspiration was in both groups accompanied with the HR increase. However, the percentage increase in hypertonics was significantly lower than in normals (P less than 0.02). With subsequent expiration, the HR fell in both groups. There was no significant difference between the percentage decreases in both groups (P greater than 0.05). During the Valsalva's maneuver, in the first phase the tachycardic response occurred, which was in hypertonics significantly less pronounced. After the recovery of breathing a bradycardic reaction occurred which was equal in both groups (P greater than 0.05). Both, in juvenile hypertonics and in controls the doubled frequency of breathing increased the mean HR and decreased the HRV. During the deepened breathing there was an increase in mean HR in both groups, and only in the controls there was an increase in HRV. Heart rate variability in hypertonics was lower than in the controls under all the conditions.

Adolescent↗