Measurement of Total Respiratory Impedance in Calves by the Forced Oscillation Technique

in Journal of Applied Physiology (Bethesda, Md. : 1985) (1988), 64(5), 1786-91

We have determined the resistance (Rrs) and the reactance (Xrs) of the total respiratory system in unsedated spontaneously breathing calves at various frequencies. A pseudorandom noise pressure wave was ... [more ▼]

We have determined the resistance (Rrs) and the reactance (Xrs) of the total respiratory system in unsedated spontaneously breathing calves at various frequencies. A pseudorandom noise pressure wave was produced at the nostrils of the animals by means of a loudspeaker adapted to the nose by a tightly fitting mask. A Fourier analysis of the pressure in the nostrils and flow signals yielded mean Rrs and Xrs, over 16 s, at frequencies of 2-26 Hz. A good correlation was found between values of pulmonary resistances measured by the isovolume method at the respiratory frequency of animals and values obtained at a frequency of 6 Hz by use of our technique. The linearity of the respiratory system, the reproducibility of the technique, and the effects of upper airways on results have been studied. In healthy calves, Rrs increases with frequency. Mean resonant frequency is 7.5 Hz. Bronchospasm was induced in six calves by administration of intravenous organophosphates. Rrs tended to decrease with increasing frequency. Resonant frequency exceeded 26 Hz. All parameters returned to initial values after administration of atropine. In healthy calves, atropine produces a decrease in Rrs, especially at low frequencies. Values of resonant frequency are not modified. [less ▲]

Influence of the intrapleural pressure on the variability of the pulmonary arterial pressures measurements in calves

in Proceedings of 7th comparative Respiratory Society Meeting, Chicago (USA) (1988)

The topographical distribution of the inhalation-to-perfusion ratio in double-muscled and Friesian calves.

in Veterinary Research Communications (1988), 12(4-5), 401-5

Five healthy Friesian calves and five double-muscled Belgian White and Blue calves were studied, using a 99m Technetium (99mTc) aerosol inhalation combined with a 99mTc macroaggregate injection and ... [more ▼]

Five healthy Friesian calves and five double-muscled Belgian White and Blue calves were studied, using a 99m Technetium (99mTc) aerosol inhalation combined with a 99mTc macroaggregate injection and collimated scintillation counters. The inhalation-to-perfusion ratio (I/P) was calculated for both left and right sides of the thorax at four sites situated at three different levels in the auscultatory area on the same vertical axis and at a more anterior site just behind the scapulohumeral joint. I/P was higher in the left than in the right hemithorax. In both breeds, a vertical and a horizontal gradient were observed. I/P was higher in the lower and in the more cranial zones of the lungs. However the vertical gradient was more pronounced in Friesian calves while the horizontal one was greater in Belgian White and Blue animals. It was concluded that the factors affecting the topographical distribution of pulmonary ventilation and perfusion seem to be different in calves as compared to other species. [less ▲]

A Comparison of Po2, Pco2, Ph and Bicarbonate in Blood from the Carotid and Coccygeal Arteries of Calves

in Veterinary Research Communications (1988), 12(4-5), 343-346

A technique is described for the subcutaneous deviation of the carotid artery into the jugular groove of calves weighing between 90 and 200 kg. This makes sampling arterial blood or chronic cannulation ... [more ▼]

A technique is described for the subcutaneous deviation of the carotid artery into the jugular groove of calves weighing between 90 and 200 kg. This makes sampling arterial blood or chronic cannulation for further experimentation very easy. Values of oxygen tension, carbon dioxide tension, pH and bicarbonate concentration in blood sampled from the ventral coccygeal artery were compared with the values obtained in blood from carotid artery puncture. The high correlations observed indicate that blood samples from the ventral coccygeal artery can be used for measurement of blood gases and pH in calves. [less ▲]

Cardio-Pulmonary Function Values in Double-Muscled Cattle During Muscular Exercise

in Veterinary Research Communications (1988), 12(4-5), 407-16

Eleven double-muscled calves of the Belgian White and Blue breed and eleven Friesian calves have been investigated at rest, during exercise on a treadmill (11% incline; speed 1.3 m.sec-1) and 10 and 30 ... [more ▼]

Eleven double-muscled calves of the Belgian White and Blue breed and eleven Friesian calves have been investigated at rest, during exercise on a treadmill (11% incline; speed 1.3 m.sec-1) and 10 and 30 minutes after the end of this exercise. Blood gases and acid-base status were determined in mixed venous and arterial blood sampled from the pulmonary and the carotid artery respectively. Expired gases were collected in a balloon. The time of collection, volume of expired gases and fractional O2 and CO2 concentrations in expired gases were measured. In double-muscled calves, inadequate oxygen intake and carbon dioxide elimination were demonstrated by the increase in the carbon dioxide tension (PaCO2) and in the hydrogen ion concentration [H+]a and the decrease in the oxygen tension (PaO2) in arterial blood during exercise. In Friesian calves, an adequate increase in oxygen intake occurred and no acidosis was recorded. A metabolic acidosis explained by only a 1.5-fold increase in the cardiac output and by the small increase in haemoglobin concentration was recorded in double-muscled calves. It was concluded that some aspects of the cardio-pulmonary and metabolic responses to exercise in double-muscled calves can be related to their inability to greatly increase their O2 consumption. [less ▲]

Mechanical properties of excised calf lungs: effects of airway obstruction with beads

in Research in Veterinary Science (1987), 42(3), 277-279

Isolated lungs of five calves were suspended in an airtight box used as a ventilator. Lungs were ventilated from the outside at different levels of transpulmonary pressure. Dynamic compliance (Cdyn) and ... [more ▼]

Isolated lungs of five calves were suspended in an airtight box used as a ventilator. Lungs were ventilated from the outside at different levels of transpulmonary pressure. Dynamic compliance (Cdyn) and total pulmonary resistance (RL) were measured. These pulmonary function values were also measured during central and peripheral airway obstructions. It was demonstrated that both central and peripheral obstructions induced significant variations of Cdyn and RL. However, decrease of Cdyn was greater and increase of RL was smaller during a peripheral obstruction than during a central one [less ▲]

Partitioning of pulmonary resistance in calves

in Journal of Applied Physiology (Bethesda, Md. : 1985) (1987), 62(5), 1826-1831

Nine right apical lobes of healthy Friesian calves and 10 right apical lobes of double-muscled calves of Belgian White and Blue (BWB) breed were suspended in an airtight box, inflated at a constant ... [more ▼]

Nine right apical lobes of healthy Friesian calves and 10 right apical lobes of double-muscled calves of Belgian White and Blue (BWB) breed were suspended in an airtight box, inflated at a constant transpulmonary pressure (Ptp), and subjected to quasi-sinusoidal pressure changes (amplitude: 0.5 kPa) at a frequency of 30 cycles/min. Lobar resistance (RL) was partitioned at six different lung volumes into three components: central airway resistance (Rc), small airway resistance (Rp), and tissue resistance (Rt). Pressure in small airways (2-3 mm ID) was measured with a retrograde catheter. Alveolar pressure was sampled in capsules glued onto the punctured pleural surface. RL was minimal at values of Ptp comprised between 0.5 and 0.7 kPa and increased at higher and lower values of Ptp. At a Ptp of 0.5 kPa, Rc, Rp, and Rt represented 30, 15, and 55% of RL, respectively, in Friesian calves and 25, 25, and 50% in BWB calves. Rp increased markedly at low lung volumes. Rt was responsible for the increase of RL at high Ptp. Rc tended to decrease at high Ptp. The significantly higher values of Rp in BWB calves (P less than 0.05) might explain the sensitivity of this breed to severe bronchopneumonia [less ▲]

Partitioning of pulmonary resistance in Friesian calves

in Research in Veterinary Science (1987), 42(3), 313-317

Eight right cranial lobes of healthy Friesian calves were suspended in an airtight box. They were inflated at a constant transpulmonary pressure (Ptp) and ventilated from the outside by modifying ... [more ▼]

Eight right cranial lobes of healthy Friesian calves were suspended in an airtight box. They were inflated at a constant transpulmonary pressure (Ptp) and ventilated from the outside by modifying pressures in the box with a quasi-sinusoidal pump at a frequency of 30 counts per minute. Peak-to-peak changes were 0.5 kPa. Lobar resistance (Rl) was partitioned into three components: central airway resistance (Rc), small airway resistance (Rp) and tissue resistance (Rt). Partitioning of R1 was realised at six different lung volumes. Minimal R1 was observed for a value of Ptp between 0.5 and 0.7 kPa. At a Ptp of 0.5 kPa, Rc, Rp, Rt represent 30, 15 and 55 per cent of R1, respectively. Lobar resistance increases at high and low lung volumes. Small airway resistance is small and independent of the level of lung inflation, except at low lung volumes where a marked increase is observed. Tissue resistance is relatively high and responsible for the increase of R1 at high lung volumes. Central airway resistance does not change significantly with lung volumes [less ▲]

Partitioning of upper airway resistance in Friesian and double-muscled calves.

in Respiration Physiology (1987), 69(3), 299-306

Respiratory resistance in calves was partitioned in two components: upper airway resistance and pulmonary resistance. The former one was divided into naso-pharyngeal and laryngeal resistance. A comparison ... [more ▼]

Respiratory resistance in calves was partitioned in two components: upper airway resistance and pulmonary resistance. The former one was divided into naso-pharyngeal and laryngeal resistance. A comparison between seven healthy unsedated double-muscled calves of the Belgian White and Blue breed (BWB) and five healthy unsedated Friesian (F) calves was performed. Respiratory resistance was significantly greater in the BWB calves, due to the significantly higher values of the naso-pharyngeal and the laryngeal resistances. This finding might be related to the higher prevalence of laryngitis in this breed [less ▲]

High-frequency ventilation in cats: technical data

in 4th Comparative Respiratory Society meeting - Anaheim California - USA (1985)