Comparison of four demand oxygen delivery systems at rest and during exercise for chronic obstructive pulmonary disease.

Objectives: The aim of this study was to assess the performance of four demand oxygen delivery systems (DODS) in improving oxygenation and effort tolerance, at rest and during exercise, in chronic obstructive pulmonary disease (COPD) patients.

Materials And Methods: Thirteen COPD patients were prospectively included. Four DODS (Oxiclip, Versatile, Venture and Impulse) were compared with continuous-flow oxygen (CFO).

Use of glass capillaries avoids the time changes in high blood PO(2) observed with plastic syringes.

Study Objectives: In adults, arterial blood samples are usually drawn using plastic syringes. In contrast to glass syringes, plastic syringes let oxygen diffuse through their wall. This results in PO(2) changes during storage, especially when PO(2) is high.

Optimal handling of blood samples for routine measurement of lactate and pyruvate.

Blood lactate and pyruvate are of critical importance for the diagnosis of mitochondrial diseases. To determine guidelines for adequate blood pyruvate and lactate determinations, intraindividual studies were carried out on 10 subjects, and the influences of venostasis, delay before deproteinization, and pH in the pyruvate assay were analyzed. Delays of 1 hour or more before deproteinization of samples induced major elevations of lactate-pyruvate ratios.

Measurement of gastric intramucosal pH in patients with cirrhosis and portal hypertensive gastropathy.

Objectives: Patients with cirrhosis often have gastric mucosal lesions associated with portal hypertension. Microvascular changes due to portal hypertension may cause mucosal ischaemia. The decrease in intramucosal pH is used as an index of this condition.

Hemodynamic and gas exchange responses to infusion of acetylcholine and inhalation of nitric oxide in patients with chronic obstructive lung disease and pulmonary hypertension.

To investigate endothelium-dependent and endothelium-independent nitric oxide (NO) mediated pulmonary vasodilation in patients with chronic obstructive lung disease (COLD), we examined the responses to incremental infusion rates of acetylcholine (ACh) or inhaled NO on hemodynamic and gas exchange. In 13 patients, ACh (15 mg/min) decreased pulmonary artery pressure (Ppa) from 31 +/- 1 to 28 +/- 1 mm Hg (p < 0.01) and systemic arterial pressure while increasing cardiac index from 3.

Mechanisms of impaired arterial oxygenation in patients with liver cirrhosis and severe respiratory insufficiency. Effects of indomethacin.

The mechanisms of impaired arterial oxygenation that occur in certain patients with chronic liver cirrhosis are still debated. In the present study, we investigated nine cirrhotic patients with severe respiratory disability (mean PaO2, 64 +/- 5 mm Hg), using the inert gas elimination technique to assess the distribution of ventilation-perfusion (VA/Q) ratios. We also determined shunt fraction during pure oxygen breathing, both in supine and sitting positions.

Effects of substance P and calcitonin gene-related peptide on the pulmonary circulation.

To assess the in vivo effects of the neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP) on the pulmonary vascular bed, the hemodynamic responses to both CGRP and SP were examined in the in situ-perfused lung lobe of open-chest anesthetized pigs. Peptides were infused into the lobar artery under conditions of elevated pulmonary vascular tone by prostaglandin F2 alpha (PGF2 alpha, 20 micrograms/min). Pulmonary airway lobar dynamic compliance (Cdyn) and airway resistance (Re) were computed from simultaneously measured airway pressure and airflow entering the lobe through a Carlens endobronchial divider.

Mechanism of improvement in pulmonary gas exchange during growth in awake piglets.

Previous studies have shown a lower arterial PO2 (PaO2) in infants and young animals than in adults. To investigate the mechanism of this impairment of gas exchange we studied 13 piglets from 12 to 65 days of age. Two days after instrumentation we measured the distribution of ventilation-perfusion ratios (VA/Q) by use of the multiple inert gas technique on awake animals.

Low VA/Q areas: arterial-alveolar N2 difference and multiple inert gas elimination technique.

In 16 critically ill patients the arterial-alveolar N2 difference and data from the multiple inert gas elimination technique (MIGET) were compared in the evaluation of the contribution of low alveolar ventilation-perfusion ratio (VA/Q) lung regions (0.005 less than VA/Q less than 0.1) to venous admixture (Qva/QT).

Improvement of gas exchange during inhibition of hypoxic pulmonary vasoconstriction by nitrendipine in piglets.

To determine how nitrendipine (N), a calcium antagonist, interferes with haemodynamics and gas exchange during hypoxia, we studied 12 piglets (4-6 weeks, 4.3-9.0 kg) anaesthetized with pentobarbital (20 mg.

Chronic sodium cyanate treatment induces "hypoxia-like" effects in rats.

Three weeks of sodium cyanate (NaCNO) intraperitoneal treatment in rats (n = 15) induced high hemoglobin O2 affinity, i.e., low PO2 at 50% hemoglobin saturation (P50), 20.

Physiological effects of high-P50 erythrocyte transfusion on piglets.

Rightward shifts of the O2 dissociation curve (ODC) were experimentally obtained in lysed and resealed erythrocytes following encapsulation of inositol hexaphosphate (IHP). This continuous lysing and resealing procedure led to in vitro P50 (Po2 at 50% hemoglobin saturation) increases up to 80 Torr (pH, 7.40; Pco2, 40 Torr; temp, 37 degrees C) for both human and pig erythrocytes.

Induced low P50 in anesthetized rats: blood gas, circulatory and metabolic adjustments.

In anesthetized, normoxic or hypoxic rats the hemodynamic, metabolic and O2 transport characteristics following exchange transfusion with human erythrocytes containing a high O2 affinity hemoglobin (Hemoglobin Creteil, beta 89 Ser----Asp) have been studied. The in vivo oxygen partial pressure at 50% oxygen hemoglobin saturation (P50) decreased from 37.4 +/- 2.

Po2 temperature blood factor for blood gas apparatus.

PO2 temperature formulae supplied by manufacturers on automatic blood gas apparatus, PO2 corr. = PO2 37 degrees C X 10F X delta T were studied and compared to the experimental determination of the delta log PO2/delta T ratio (Hérigault et al. [10]).

Determination of the PO2 temperature blood factor from oxygen dissociation curves.

The variation with saturation of the temperature coefficient of PO2 in human blood (delta log PO2/delta T) was determined by continuous recording of the oxygen dissociation curve (ODC), at 37 degrees C and 25 degrees C, on the same blood samples. PCO2 and pH were held constant through an ODC run, and PCO2 was reduced at 25 degrees C to the value measured by anaerobic cooling of the same sample. delta log PO2/delta T was calculated from isosaturation points on the 37 and 25 degrees C curves.

Consequences of an acute increase in P50 in anaesthetized guinea pigs.

In anaesthetized guinea pigs, ventilated with ambient air, the peripheral haemodynamics and oxygen transport characteristics have been studied following a blood exchange transfusion with rat erythrocytes suspended in guinea pig plasma. Since the rat haemoglobin exhibited a lower oxygen affinity than guinea pig haemoglobin, the oxygen partial pressure at 50% of oxygen haemoglobin saturation (P50) increased from 25.2 +/- 1.

[Contamination of an oxygen delivery circuit by compressed air].

Routine checking of the FIO2 of a mixture delivered by a ventilator revealed large discrepancies between the FIO2 assigned and that effectively delivered, the latter being low. Measurements of FIO2 at the wall outlets showed the O2 delivery pipeline to be contaminated by compressed air. By disconnecting all the ventilators supplied by this pipeline one after the other, one ventilator, or rather its blender, was found responsible.

Effects of chronic changes in hemoglobin-O2 affinity in rats.

We have assessed the characteristics of oxygen transport following chronic intraperitoneal administration of sodium cyanate (NaCNO, 90 mg/kg; P50 decreased), o-iodosodium benzoate (OISB, 300 mg/kg; P50 increased), or sodium chloride (NaCl; P50 unchanged) to rats at a rate of 5 times/wk for 16 wk. At the end of this period, the animals were exposed to a low inspired O2 concentration and were subjected to exercise stress. Hill's n50 at pH 6.

[In vitro and in vivo study of a hemoglobin solution used as a blood substitute].

In vitro studies of a stroma free haemoglobin solution of human origin (Wx B 8326, Warner-Lambert) in comparison with fresh and stored low DPG whole human blood, was undertaken with regard to the fixation. of oxygen. Such an hemoglobin solution was shown to exhibit a high affinity for oxygen and a low Bohr effect (assessed from the delta log Po2/delta pH ratio).

[A method of continuous recording on microsamples of the Hb-O2 association curve. II. A study of Bohr effect and carbamino-formation (author's transl)].

The authors have worked out an adaptation to microsamples (200-400 mul) of the DUVELLEROY et al. method, allowing the continous registration of the O2-Hb association curve. The microsample being diluted in buffer solution, it is possible to predetermine its pH and PCO2.

A method of continuous recording on microsamples of the Hb-O2 association curve. I. Technique and direct registration of standard results.

A modified technique for continuous recording of the Hb-O2 association curve for blood samples is proposed. The following alterations to the classical method of Duvelleroy et al. (5) were studied and validated: 1) dilution of blood micro-samples (200-400 mul) to 10 ml of a buffered phosphate solution; 2) use of a (CO2, O2) mixture allowing the maintenance of standard conditions (pH=7.