Endorphins have been isolated from amniotic fluid and cord blood of mammals. To determine if these agents influence ventilation after birth, we measured ventilation (VE), tidal volume, inspiratory time, and respiratory frequency (f) in 19 rabbit pups before and after administration of naloxone (NLX), an endorphin antagonist. Tracheostomy and carotid ...

Normovolemic hemodilution produced by isovolumetric venesection was done in 8 patients with polycythemia and respiratory failure secondary to chronic obstructive pulmonary disease. The 'deformability index' was studied by means of a filtration technique. The blood flow velocity in ascending aorta and right pulmonary artery was also studied by means of ...

The relationship between cerebral oxygen consumption (CMRO2), cerebral blood flow and arterial CO2 tension was investigated during anaesthesia induced by halothane, pentobarbital, ethanol and nitrous oxide. The results obtained by halothane, pentobarbital and ethanol indicate a relationship between central suppressants and CO2 in decreasing CMRO2. During nitrous oxide anaesthesia, CMRO2 ...

The value of transcutaneous oxygen tension (tcPO2) as an oxygen parameter during uncomplicated thoracic anaesthesia was examined in ten patients anaesthetized with oxygen-nitrous oxide and enflurane or flunitrazepam/fentanyl. tcPO2 was measured with the Radiometer TCM-I monitor at 45 degrees C. Measuring interference due to the anaesthetic agents was not observed. ...

Blood acid-base balance, blood gases, respiration, ventilation, and renal function were studied in the rainbow trout during and following sustained environmental hyperoxia (PIO2 = 3.50-650 Torr). Animals were chronically fitted with dorsal aortic cannulae for repetitive blood sampling, oral membranes for the measurement of ventilation, and bladder catheters for continuous ...

Pontosubicular necrosis (PSN) is confined to a short perinatal developmental period and is apparently related to asphyxia at birth. Neuronal necrosis with karyorrhexis and proliferative changes in astrocytes are most prominent in the pontine gray matter and subiculum of the hippocampus. We have observed a striking association of PSN in ...

A method for recording complete dynamic oxygen equilibrium curves (O2EC) from microliter samples of whole blood is described. The blood sample is compressed into a thin film between two 6-micron thick Teflon membranes in order to promote rapid gas exchange with gas volume surrounding the membranes. Oxygen tension of the ...

With a Radiometer TCM-1 oxygen monitor, we followed the fluctuations in transcutaneous oxygen tension (ptcO2) during capillary blood collection from a heel prick. Thirty premature infants who presented with some respiratory compromise showed unpredictably increased (43 of 125 observations) or decreased (82 of 125 observations) values during this blood-sampling process. ...

If a small bubble gas is equilibrated with a volume of blood the partial pressures of the components of the bubble after equilibration approximate to the original tensions in the blood. A method is described in which the bubble is analysed by a respiratory mass spectrometer connected to a mini-computer. ...

In vitro contractility of isolated cylindrical segments of chorial arteries and veins from 40 human term placentas was studied. Contractility was recorded by an isometrical and axipetal method. Spontaneous contractility was observed in 75% of the arteries and in 45% of veins. In both types of vessels, contractility was similar ...

Although much information is known about the factors controlling cerebral blood flow in the adult, there are significant physiological differences between the neonate, infant, and the adult. Therefore, it is not possible directly to transfer information concerning control of cerebral blood flow in the adult to the pediatric age population. ...

Acute respiratory alkalosis decreases cerebral blood flow, increases the affinity of hemoglobin for oxygen, and can result in cerebral hypoxia. This experiment was designed to study this phenomenon in dogs, and to demonstrate the effect of an increased concentration of inspired oxygen. Seven mongrel dogs were anesthetized with pentobarbital and ...

In vivo measurements of tissue oxygen tension were made at 10-micrometer intervals through functioning in situ rabbit femoral arterial walls, using inhalation anesthesia and recessed microcathodes with approximately 4-micrometer external diameters. External environment was controlled with a superfusion well at 30 torr PO2, 35 torr PCO2. Blood pressure, gas tension ...

Ten neonates with respiratory distress requiring mechanical ventilation and supplemental oxygen were studied during a continuous 24-h period to determine the value of continuous transcutaneous oxygen (PtcO2) monitoring. All 10 infants were continuously monitored during the study with a Clark-type skin electrode (Litton) and 5 of the 10 also had ...

We have studied the serial changes in arterial blood gases in fourteen patients with acute severe asthma, all of whom received a standard therapeutic regime and had similar measurements made at identical time intervals under standard conditions. Hypoxaemia on admission was a constant finding, and the arterial oxygen tension often ...

The endocochlear potential and the scala media oxygen tension were measured from the basal coil of the guinea pig cochlea during levels of partial respiratory anoxia. This was accomplished by simultaneously positioning two electrodes (for endocochlear potential and PO2) into the endolymph by a transbasilar membrane approach, in order to ...

The cochlear blood flow was measured with the microsphere method before, during and after CO2 inhalation in anesthetized rabbits. Different gas mixtures and exposure times were used. The greatest increase of cochlear blood flow was measured after 5 min inhalation of 7% CO2 in air (115%) and the least increase ...

Blood flow regulation in the foot under a heated (43 degrees C) transcutaneous oxygen tension (tcPo2) electrode was studied in six young subjects. Blood flow under the electrode was estimated from the electrical power consumption of the thermostatistically-controlled heating element in the electrode. Changes in arterial and venous pressures, and ...

The cochlear blood flow was measured with the microsphere methods, before and during CO2-inhalation, in anesthetized rabbits. Different gas mixtures and exposure times were used. The greatest increase of cochlear blood flow was measured after 5 min inhalation of 7% CO2 in air (115%) and the least increase (44%) in ...

In a review of 210 spinal fusions, the platelet count and the arterial-alveolar oxygen tension ratio both decreased as the blood transfused increased, but were not correlated with positive fluid balance. In procedures that might require more than 70-80 ml/kg of blood, such as myelodysplastic, paralytic, and congenital spinal surgery, ...

A mathematical model of oxygen transport in the precapillary microcirculation is presented. The theory is then used to simulate oxygen distribution in the arteriolar network of the hamster cheek pouch. Theoretical prediction of transmural and longitudinal oxygen tension (PO2) gradients is in qualitative agreement with available experimental data. The effect ...

We measured ventilatory responses to CO2 (delta VI/delta PCO2) and transient hypoxia (delta VI/delta SaO2) during reductions of brain blood flow (BBF) to 70% and 50% of control in unanesthetized goats. Increase in inspiratory volume per change in CO2 tension (delta VI/delta PCO2) was measured during rebreathing with sampling of ...

Transcutaneous oxygen tension (TcPO2), arterial oxygen tension, pulse, blood pressure, cardiac output and base excess or deficit were serially measured in 18 piglets, 7 to 14 days of age, subjected to a 35% hemorrhage and reinfusion of shed blood. Eight of 18 pigs died. There is a strong correlation between ...

Continuous analysis of oxygen and carbon dioxide tension in the blood phase, over periods of 4-5 h, was carried out in the pulmonary artery (93 determinations in six anesthetized dogs) and in the aorta (29 determinations in four anaesthetized dogs). Silastic-covered stainless steel catheters attached to a mass spectrometer were ...

Measurements of maternal blood-gas tensions, (PAO2-PaO2), calculated pulmonary venous admixture (physiological shunt) and deadspace/tidal volume ratio (VD/VT) were made in 14 patients undergoing Caesarean section. Measurements were carried out after induction of general anaesthesia, and before delivery, with the patient tilted to the left. With a mean inspired oxygen concentration ...

By means of an invasive technique the relations between arterial and medullary gas tensions PO2 and PCO2), and arterial and medullary acid-base balance (pH and standard bicarbonate) were determined in long bones in seven anaesthetized dogs. A semilogarithmic correlation was found between the arterial oxygen tension and the oxygen tension ...

Baboons were bled one-third of their blood volume and then transfused with an equivalent volume of compatible donor red blood cells with 160 per cent of normal 2,3-diphosphoglycerate (2,3-DPG) levels and improved capacity to release oxygen to tissue. The mixture of baboon donor-recipient red blood cells in the circulation had ...

Effect of hypoxia was studied on the J reflex, a term used for the reflex inhibition of muscular exercise by activation of type J pulmonary endings. Hypoxia was induced by ventilating the animal with gas mixtures varying from 18 to 9% oxygen in nitrogen. The blood gas tensions of the ...

We investigated the effect on arterial blood oxygenation of exposure to 0.2 ppm of ozone in purified air for 2 hours with intermittent light exercise and heat stress. Similar exposures to purified air alone provided control data. In 12 healthy volunteers, blood gases were measured before and during exposure via ...

Eight human volunteers, individually studied in a hyperbaric chamber, breathed: 1) air at 1 ATA; 2) 80% argon and 20% oxygen and 1 ATA for 30 min; 3) air at 1 ATA for 30 min; 4) 100% 02 at 1 ATA for 30 min; 5) air at 1 ATA for ...

1. The blood flow through the forearm was measured 2 sec after single, brief isometric hand-grip contractions. The tension and duration of those contractions varied from 10 to 100% of the maximal voluntary contraction (m.v.c.) and from 2 to 12 sec, respectively. 2. The blood flow increased linearly with tension ...

Pyrenebutyric acid (PBA), the intracellular fluorescent indicator, was used to measure the partial pressure of oxygen (PO2) in the exposed cerebral cortex of anesthetized cats at hyperbaric pressures up to 4 ATA. The validity of the PBA method for determining cortical PO2 was confirmed by demonstrating a precise linear relationship ...

The effect of furosemide on renal function in patients undergoing open heart surgery was investigated, using creatinine clearance, urine flow, sodium and potassium excretion as the parameters. The effect of furosemide (2 mg/kg i.v.) on blood flow in arteria renalis and the tissue oxygen tension of the renal cortex and ...

The effects of intravenous injections of ketamine in sheep on the cardiovascular and respiratory systems are compared with the effects of intracerebroventricular injections of the same drug and also with the effects of intravenous barbiturate and steriod anaesthetics. Intravenously administered ketamine caused an initial fall in arterial blood pressure the ...

An oxygen electrode was maintained by suction on the vaginal wall in seven women. The basal value of pO2 was 9.3 mm Hg +/- 10.7 (mean +/- standard deviation) before clitoral self-stimulation was initiated. When stimulation took place the oxygen tension rose and peaked immediately after orgasm to 39.5 +/- ...

Arterial blood oxygen tensions up to 6700 m altitude (FL220) were measured polarographically while subjects breathed from various masks with constant-flow oxygen. The Sierra and Aro masks used for emergency decompression descent in commercial passenger aircraft, gave mean PaO2's of 130 +/- 7.6 and 130 +/- 12.1 torr at 6700 ...

The influence of different values of arterial oxygen partial pressure (PO2) on local tissue PO2 was investigated. Tissue PO2 was measured on the surface of the beating hearts of rabbit and cat by the multiwire surface electrode as described by Kessler and Lübbers (21). In parallel experiments, local hydrogen clearance ...

This study was undertaken to investigate influences of a new vasodilator, YC-93, a derivative of 1,4-dihydropyridine, on cerebral circulation and cerebrovascular CO2 reactivity. Cerebrocortical PO2, cerebrocortical PCO2, cerebrocortical blood flow and arterial blood pressure were continuously recorded by means of a PO2 electrode, a PCO2 electrode and a plate-type crossed ...

The development of a miniature polarographic electrode mounted in the tip of a double-lumen plastic catheter has made possible continuous in-vivo monitoring of oxygen tension. Inexpensive catheters of this type have already proved of value as a means of continuously monitoring arterial oxygen tension in the newborn. In 25 patients ...

The effect of hypoxia on cerebral blood flow in ducks was investigated by the rate at which arterially injected xenon-133 was cleared from the duck's brain. A two-component clearance curve resulted, which we have attributed to flow through the grey and white matter. Decreasing the arterial oxygen tension (PaO2) to ...

Role of serotonin in the regulation of respiratory system function. Acta Physiol. Pol., 1978, 29 (2): 131--138. This study examined respiratory centre reflector excitability, the electrical activity of respiratory muscles, outer breathing, pH and arterial blood gas composition under conditions of experimentally induced serotonin excess or deficiency in 48 dogs. ...

This study was intended to investigate the effect of high arterial oxygen tension on the peripheral circulation between normal and hypoxic area by using twelve dogs. For this purpose, acute temporary ischemia was produced at the right hindlimb by an occlusion of the right external iliac artery for 1 and ...

Determination of functional residual capacity, arterial gas tensions and pH, and arterial-alveolar differences was carried out in a group of nondistressed premature infants to determine if significant alterations in lung volumes or ventilation perfusion relationships sufficiently large to cause cyanosis could be detected after feeding. The only statistically significant changes ...

Utilizing the mass spectrometer, tissue oxygen tension (TPO2) in the resting state was measured in the extremities of ten dogs before and after lumbar sympathectomy. Although there was considerable variation between individual dogs, significant changes in tissue oxygenation were not consistently obtained in the group as a whole, althouth femoral ...

Tourniquet ischemia results in tissue hypoxia which has been measured indirectly by blood gas analysis. The Medspect mass spectrometer allows direct measurement of gas tension in different tissues and may provide more useful information regarding safe tourniquet times. Calibrated Teflon catheters were inserted into the subcutaneous tissue (11 animals), tibial ...

Transcutaneous measurement of the arterial PO2 is a practicable method for clinical routine work. The covering, calibration and placing of the electrodes are simple. If the circulation is normal, there is a strong correlation between the arterial and transcutaneous PO2. The stability of the electrode permits its employment for long-term ...

Four devices for transcutaneous PO2 (tcPO2) monitoring have been applied simultaneously in 16 infants. Both during a maximal change in PaO2 and during physiological PO2 variations, the in vivo response time of the electrodes did not show the differences observed in vitro. We compared A, a prototype of the electrode ...

The influence of halothane-oxygen mixtures on three different transcutaneous oxygen electrodes was investigated. The influence of hypotension caused by halothane and halothane-nitroprusside on transcutaneous oxygen tension measurement (tcPO2) in halothane-anaesthetized patients was examined as well. The electrodes differed with respect to polarization voltages (630 mV or 500 mV) and electrolyte ...

Red blood cell velocity was measured in capillaries of the rabbit tenuissimus muscle during exposure to a low-oxygen-tension (PO2 = 5 mmHg) and a high-oxygen-tension (room-air PO2 = 150 mmHg) suffusion solution. Control capillary red blood cell velocity was significantly reduced (44%) by elevating the suffusion solution PO2 from 5 ...

Red cell velocity and diameter were measured in arterioles of the hamster cheek pouch microvasculature. The cheek pouch tissue was exposed to two different oxygen tensions, PO2 less than 30 mmHg and PO2 greater than 150 mmHg. Blood flow was calculated from velocity and diameter measurements and was found to ...