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Biomedical subjects

O R Ratto

Publications and source records attributed to O R Ratto.

At least 19 recordsLinked to original sources
PubMed1989

[The role of angiotensin-converting enzyme inhibitor (captopril) on the mechanism of hypoxic pulmonary vasoconstriction. Experimental study in dogs].

In order to evaluate the action of an angiotensin converting enzyme inhibitor (Captopril) on the pulmonary hypoxic vasoconstriction, twenty one mongrel dogs were studied in two groups: group I with hypoxia, group II with normoxia. The dogs were anesthetized, intubated, and had their femoral vein and artery cannulated for blood-gas sampling and pressure records. They were mechanically ventilated with hypoxic gas mixtures (12.3% O2-87.7% N2)--group I and room air group II, at random. In both groups we measured, before and after administration of captopril 3 mg/kg intravenously, gas exchange and hemodynamic variables, as well as plasmatic levels of renin and angiotensin converting enzymes (ACE). Our results showed that the group I dogs decreased the systemic and pulmonary vascular resistances with small changes in pulmonary arterial pressures and no significant variations of pulmonary systemic resistances ratio. There were no significant variations of the same variables in the group II dogs. The gas exchange has not changed in either group of animals. In the group I dogs Captopril provoked systemic and pulmonary vasodilatation, with no gasometric and ventilation/perfusion ratio changes. In our experimental model we could not conclude that Captopril inhibited the hypoxic pulmonary vasoconstriction and/or that the angiotensin II had some action on the hypoxic pulmonary vasoconstriction mechanism, but there are some evidences favoring that hypothesis.

Analysis of Variance↗
PubMed1985

Central venous blood composition and the pulmonary ventilation during hemodialysis.

The elimination of CO2 across the dialyzer has been reported as the cause of pulmonary hypoventilation during hemodialysis. There are some evidences that the venous line blood composition could influence the central venous blood and this one the pulmonary ventilation. Our purpose was to analyze (1) the influence of the changes in composition of the venous line blood on the central venous blood and (2) the possible role of the central venous blood composition on the pulmonary ventilation of 10 chronic renal failure patients during hemodialysis performed twice in the same patients in two different conditions: acetate dialysate without (condition I) and with (condition II) constant addition of 100% CO2 bubbling into the dialysis bath. During condition I the venous line blood pH was kept in a normal range, and the PCO2 was low, whereas during condition II the pH was very low and the PCO2 extremely high. The patients during condition I decreased their pulmonary ventilation and lost CO2 across the dialyzer as the central venous blood pH and HCO3- increased, and PCO2 did not change. The same patients during condition II increased their pulmonary ventilation and absorbed CO2 across the dialyser as the central venous blood pH decreased and PCO2 increased. Thus, the venous line blood has influence on the central venous blood composition, and this plays a role on the control of pulmonary ventilation of these patients.

Adolescent↗
PubMed1983

Effect of positive pressure breathing on plasma antidiuretic hormone and renal function in dogs.

The effect of intermittent mechanical ventilation and positive end-expiratory pressure on plasma antidiuretic hormone concentration was determined in 14 pentobarbital anesthetized dogs. The study was divided into a control period (spontaneous respiration), and two consecutive 30 and 60 min periods after the start of controlled respiration: Group I - intermittent positive breathing (IPPB); Group II - positive end-expiratory pressure (PEEP) with 5 cm H2O. A decrease in urinary flow (36.9%) was observed during end-expiratory pressure breathing. An increase in plasma antidiuretic hormone in group II from 4.5 +/- 2.4 to 24.6 +/- 16.0 pg/ml (P less than 0.01) was associated with a significant reduction of free water clearance from 1.2 +/- 0.6 to 0.3 +/- 0.4 ml/min and an increase of the urine/plasma osmolality ratio (143%, P less than 0.05). The decrease in urinary output and concurrent reduction of urinary sodium excretion also suggest an influence of the fall in glomerular filtration rate and renal plasma flow on renal function. IPPB only reduced total Na+ and K+ excretion. These results indicate that the mechanisms underlying the renal response to positive end-expiratory pressure breathing may be due to an increase in antidiuretic hormone plasma levels leading to a fall in urinary flow and in part to a decrease in sodium excretion.

Animals↗
PubMed1982

Pulmonary ventilation during hemodialysis.

During hemodialysis a decrease in pulmonary ventilation has been reported. The elimination of CO2 across the dialyzer has been suggested as the cause of the pulmonary hypoventilation. Our purpose was to analyze the factors that could have influenced the pulmonary ventilation of 7 patients with chronic renal failure during hemodialysis, performed against an acetate dialysate with constant addition of CO2, bubbling into the dialysis bath. In spite of the large volume of CO2 mainly as bicarbonate, eliminated across the dialyzer there was no significant decrease of ventilation. The values of pH in the venous line were extremely low and the values of PvCO2 were artificially maintained around 35.0 mm Hg. Thus, the total CO2 delivered to the lungs, but mainly the levels of pH and PCO2 in the venous line play an important role in the control of pulmonary ventilation of these patients.

Bicarbonates↗
PubMed1982

Pulmonary gas exchange and ventilation during hemodialysis.

Hemodialysis-induced hypoxemia has been explained by several mechanisms: pulmonary microembolization, decreased pulmonary diffusing capacity, fall in alveolar oxygen tension, hypoventilation and ventilation/perfusion abnormalities. The objective of this study was to analyze the factors influencing pulmonary ventilation and gas exchange of 20 patients with chronic renal failure during hemodialysis performed under the following conditions: Group 1 (9 patients) dialyzed against an acetate dialysate with a cuprophan membrane; Group 2 (7 patients) dialyzed against acetate bubbled with CO2 with a cuprophan membrane; Group 3 (4 patients) similar to Group 1, but using a polyacrylonitrile membrane. Arterial and venous blood samples were obtained from the respective lines during the predialysis period (zero), at 30, 60, 120 180 and 240 min of hemodialysis, and 60 min post dialysis (300 min) for the measurement of pH, PCO2, PO2, HCO-3 and total CO2. The minute expired volume (VE), expired fractions of O2 (FEO2) and CO2 (FECO2), O2 consumption (VO2), CO2 elimination through the lungs (VCO2) and dialyzer, respiratory exchange ratio (R), dead space to tidal volume ratio (VD/VT), alveolar ventilation (VA) and alveolar-arterial O2 difference (delta AaPO2) were measured and a leukocyte count was performed for each period of hemodialysis. The patients in Groups 1 and 3 showed a significant drop in ventilation and PaO2, a slight decrease in PAO2 and a significant increase in delta AaPO2. The patients in Groups 1 and 2 showed a significant leukopenia at 30 min of hemodialysis. The volume of CO2 eliminated across the dialyzer was very similar for the three groups of patients. Group 2 did not show any drop in ventilation or PaO2. For Group 2 venous line pH was very low and PCO2 was within the normal range, in contrast to the normal or high pH and low PCO2 shown by Groups 1 and 3. This study indicates that the drop in PaO2 was partially the consequence of a slight decrease in PAO2, but mainly due to the increase in delta AaPO2. Thus the most likely cause of the decrease in PaO2 was the VA/Q imbalance brought about by a drop in ventilation. The drop in ventilation was linked not only to the volume of CO2 eliminated across the dialyzer, but also to the amount of CO2 delivered to the lungs, and to the pH and PCO2 of the venous line.

Adult↗
PubMed1979

[Acute respiratory insufficiency associated with the ingestion of central nervous system depressants].

The study of twenty patients with poisoning by central nervous system depressant drugs is reported. The authors emphasized clinical aspects, complications and mainly the lung function impairment. Barbiturates were the most common drugs, at least in 60% of the cases, used alone or in combination with sedatives and tranquilizers. In 55% of patients the amount of the drug ingested could not be measured. In 60% of the cases we didn't know the period of time between drug ingestion by the patients and their admission to the hospital. On admisson all patients were in coma. The coma was of varying degrees and the deeper the coma the worse was lung function and complications were more frequent. Whenever a cardiovascular collapse was present there was also a high mortality rate. The authors emphasized the importance of a follow-up of these patients in intensive care units, mainly with cardiovascular and ventilatory support.

Adolescent↗
PubMed1979

[Pulmonary function in dogs submitted to bilateral cervical vagotomy (author's transl)].

A study of the effects of cervical vagotomy on pulmonary function in two groups of dogs was done: the first group had been vagotomized and submitted to spontaneous breathing and the second had been vagotomized and submitted to mechanical ventilation. pH, partial pressure of carbonic acid in arterial blood (PaCO2), partial pressure of oxygen in arterial blood (PaO2), plasmatic bicarbonate (HCO-3), alveolar arterial oxygen difference (P(A-a)O2) while the patients breathed room air and 100% O2 and pulmonary shunting didn't change after vagotomy. There was no difference between these two groups. Hemodynamic parameters like oxygen content difference (C(a-v)O2) between arterial and venous blood, heart hate (FC), mean blood pressure (Pam) and capillary hydrostatic pressure (Pcp) didn't change after vagotomy. None of these parameters were different between the two groups.

Animals↗