Changes In Arterial Oxygen Tension Research Articles

Changes in Arterial Oxygen Tension after Gastric Lavage for Drug Overdose

1. Changes in arterial oxygen tension after gastric lavage were investigated in a prospective study of 55 patients admitted for drug overdose. 2. A significantly greater decrease was observed in smokers compared to non-smokers. 3. A correlation was found between the tricyclic antidepressant serum level and the observed oxygen tension decrease. 4. The usefulness, as well as the safety of the lavage procedure, in managing tricyclic antidepressants overdoses is controversial.

The Changes in Arterial Oxygen Tension ( PaO2 ) after Application of Selective Continuous Positive Airway Pressure ( CPAP ) to Nondenpendent Lung during One - Lung Ventilation

The Changes in Arterial Oxygen Tension ( PaO2 ) after Application of Selective Continuous Positive Airway Pressure ( CPAP ) to Nondenpendent Lung during One - Lung Ventilation

Histopathology of the carotid bodies in neonates and infants

A histological study was made of the carotid bodies obtained at necropsy in 40 fetuses, neonates, infants and young children, ranging in age from 23 weeks of gestation to 11 years of age. Prominence of the dark variant of chief cells was found in diseases such as bronchiolitis which are associated with sustained hypoxaemia. Such cells have copious cytoplasm known to be rich in peptides such as enkephalins. The same histological features were found in two cases clinically diagnosed as sudden infant death syndrome but in which there was associated bronchiolitis and tracheo-bronchitis respectively, thought to have given rise to hypoxaemia. In a case of sudden infant death syndrome without infection there was overgrowth of sustentacular cells with predominant progenitor cells in the absence of dark cells. We associate this appearance with inability of the carotid bodies to respond adequately to changes in arterial oxygen tension.

Low-Dose Almitrine Bismesylate Enhances Hypoxic Pulmonary Vasoconstriction in Closed-Chest Dogs

The effect of almitrine bismesylate on the hypoxic pulmonary vasoconstrictor response was studied in six closed-chest dogs anesthetized with pentobarbital and paralyzed with pancuronium. The right lung was ventilated continuously with 100% O2; the left lung was ventilated either with 100% O2 ("hyperoxia") or with an hypoxic gas mixture ("hypoxia": end-tidal oxygen tension = 60.3 +/- 0.6 mm Hg). On two consecutive days, each dog received either almitrine (Vectarion, Servier Lab) or malic acid. Consecutive almitrine doses of 0.003, 0.03, 0.3, and 3.0 micrograms.kg-1.min-1, or the equivalent volumes of malic acid without almitrine, were administered intravenously as a constant peripheral infusion for 15 min. Percent blood flow to each lung was calculated based on a variation of the traditional shunt equation. The change in percent left lung blood flow (delta %QL-VA) increased significantly between the hypoxia-no drug and the hypoxia-almitrine (3.0 micrograms.kg-1.min-1) phase. No significant changes occurred during the other almitrine doses or the respective malic acid control phases. The change in arterial oxygen tension (delta PaO2) also increased significantly between the hypoxia-no drug and the hypoxia-almitrine (3.0 micrograms.kg-1.min-1) phase. No significant changes occurred during the other almitrine doses or the respective malic acid control phases. It is concluded that in dogs low-dose almitrine enhances hypoxic pulmonary vasoconstriction and that this enhancement is dose-related.

Effect of Verapamil Inhalation on Bronchial Asthma

The effect of inhaled verapamil 20 mg on pulmonary functions and arterial blood gases in 15 patients with extrinsic bronchial asthma was studied in single-blind fashion. A significant decrease (p less than 0.05) in airway resistance and a significant increase (p less than 0.01) in specific conductance was observed after verapamil inhalation. A small increase (p less than 0.1) was observed in forced vital capacity and peak expiratory flow rate after verapamil inhalation; however, this was not statistically significant. None of the parameters of pulmonary function tests showed a significant change after normal saline inhalation. A significant fall in PaO2 (p less than 0.05) and PaCO2 (p less than 0.05) was noted after normal saline inhalation. PaCO2 showed a significant fall (p less than 0.01) after verapamil inhalation. Alveolar arterial oxygen gradient P(A-a)O2 widened significantly (p less than 0.001) after normal saline inhalation. A larger dose (20 mg) of verapamil inhalation produces a significant bronchodilator effect on large airways, but does not produce a significant change in arterial oxygen tension from the baseline value in patients with bronchial asthma.

Hyperoxemia in Newborn Infants: Detection by Pulse Oximetry

Pulse oximetry has been proposed as a noninvasive continuous method for transcutaneous monitoring of arterial oxygen saturation of hemoglobin (tcSO2) in the newborn infant. The reliability of this technique in detecting hyperoxemia is controversial, because small changes in saturation greater than 90% are associated with relatively large changes in arterial oxygen tension (PaO2). The purpose of this study was to assess the reliability of pulse oximetry using an alarm limit of 95% tcSO2 in detecting hyperoxemia (defined as PaO2 greater than 90 mm Hg) and to examine the effect of varying the alarm limit on reliability. Two types of pulse oximeter were studied alternately in 50 newborn infants who were mechanically ventilated with indwelling arterial lines. Three arterial blood samples were drawn from every infant during routine increase of inspired oxygen before intratracheal suction, and PaO2 was compared with tcSO2. The Nellcor N-100 pulse oximeter identified all 26 hyperoxemic instances correctly (sensitivity 100%) and alarmed falsely in 25 of 49 nonhyperoxemic instances (specificity 49%). The Ohmeda Biox 3700 pulse oximeter detected 13 of 35 hyperoxemic instances (sensitivity 37%) and alarmed falsely in 7 of 40 nonhyperoxemic instances (specificity 83%). The optimal alarm limit, defined as a sensitivity of 95% or more associated with maximal specificity, was determined for Nellcor N-100 at 96% tcSO2 (specificity 38%) and for Ohmeda Biox 3700 at 89% tcSO2 (specificity 52%). It was concluded that pulse oximeters can be highly sensitive in detecting hyperoxemia provided that type-specific alarm limits are set and a low specificity is accepted.

Responsiveness of the ductus arteriosus to prostaglandin E1 assessed by combined cross sectional and pulsed Doppler echocardiography.

Cross sectional echocardiography combined with Doppler echocardiography was used to record either ductal morphology or the flow profile within the ductus arteriosus before and after infusion of prostaglandin E1 in 25 newborn infants with cyanotic and acyanotic congenital heart disease with ductus dependent blood flow. The ultrasound results were compared with changes in arterial oxygen tension and the overall clinical response to prostaglandin E1 seen during the same period in 24 of the 25 patients in whom the degree of ductal narrowing could be determined with the ultrasound method. At the time of the study, the ductus was widely patent or slightly narrowed in 12 patients and was closed in two patients. These patients did not respond to prostaglandin E1. There was prominent localised narrowing of the ductus in seven patients and generalised narrowing in three. After the infusion of prostaglandin E1 there was no ductal narrowing in these patients, except for one patient who had slight residual localised narrowing. There was also a considerable change in the ductal flow profiles in each patient. In these 10 patients infusion of prostaglandin E1 resulted in an increase in arterial oxygen tension, clinical improvement, or both. The present study indicates that prostaglandin E1 is effective in patients with prominent narrowing of the ductus but is not in patients in whom the ductus is widely patent or closed. Cross sectional echocardiography combined with Doppler echocardiography was useful for predicting the responsiveness of the ductus arteriosus to the infusion.

Single Arterial Puncture vs Arterial Cannula for Arterial Gas Analysis after Exercise: Change in Arterial Oxygen Tension over Time

In an attempt to find the least invasive, safest, easiest, and cheapest method of obtaining resting and exercise samples of arterial blood, a comparison was made between samples from an arterial needle puncture and an arterial cannula. This study demonstrated that samples of arterial blood may be obtained by radial arterial puncture both at rest and during exercise in practically all cases without morbidity. Samples from arterial needle puncture provide the same results as those from arterial cannulas. In the very rare patient in whom arterial puncture during maximal exercise is unsuccessful, the arterial oxygen pressure (PaO2) measured at 10 seconds after exercise correlates very well with the PaO2 at maximal exercise, and the 15-second value correlates nearly as well. Arterial cannulas are needed in the infrequent case when arterial puncture is not accomplished during maximal exercise and the 10-second or 15-second PaO2 decreases from the resting value. In this instance, determination of the exact extent of the hypoxemia requires an exercise sample obtained by cannula; however, the decrease in PaO2 obtained by arterial needle puncture at 10 or 15 seconds will be all that is needed many times to make a clinical decision. Values obtained at 20 seconds after maximal exercise reflect less of the exercise measurement and cannot be used; however, all episodes of significant hypoxemia (PaO2 less than 60 mm Hg) were captured by the analysis at 20 seconds after exercise.

Effects of birth-related events on blood flow distribution.

At birth, the cardiovascular system changes dramatically; arterial blood pressure, heart rate, and cardiac output increase, and blood flow distribution undergoes regional changes. To determine whether these changes are related to certain events occurring at birth, we studied 18 chronically instrumented fetal sheep at 133-138 days gestational age. We measured fetal vascular pressures and heart rate and injected radionuclide-labeled microspheres to determine combined ventricular output and its distribution. Rhythmic ventilation of the fetuses with a gas mixture that produced no change in arterial blood gases decreased heart rate slightly from 173 +/- 25 to 152 +/- 16 beats/min, but changed neither mean arterial blood pressure nor combined ventricular output. Ventilation with oxygen decreased mean descending aortic and pulmonary arterial pressures, but had no significant effect on heart rate or combined ventricular output; subsequent umbilical cord occlusion had no significant effect on these variables. There was a redistribution of blood flow, however. Ventilation alone increased pulmonary blood flow from 159 +/- 68 to 641 +/- 513 ml.min-1.100 g wet weight-1, and oxygenation increased it further to 1040 +/- 426. Ventilation alone and ventilation with O2 decreased blood flow to most other fetal organs, notably the adrenal glands, brain, and heart, in a manner related to changes in arterial oxygen tension. Occlusion of the umbilical cord increased blood flow to the adrenal glands and brown fat, and also to the liver from the portal vein and hepatic artery. The changes in regional blood flow initiated by ventilation, oxygenation, and umbilical cord occlusion are similar to those occurring at birth and may play an important role in postnatal adaptation.

ARTERIAL OXYGEN TENSIONS MEASURED CONTINUOUSLY IN PATIENTS BREATHING 21% OXYGEN AND NITROUS OXIDE OR AIR

Changes in arterial oxygen tensions in nine anaesthetized patients during controlled ventilation with either 79% nitrous oxide in oxygen or air only, were measured continuously using an intra-arterial oxygen electrode. When the patients were ventilated with the mixture, there was a significant increase in PaO2 of 2.74 +/- 1.08 kPa (P less than 0.002) over control values obtained while the subjects were awake and breathing air spontaneously. Changing the inspired gas from nitrous oxide in oxygen to air while ventilation was held constant resulted in a significant decrease in PaO2 of 2.22 +/- 0.94 kPa (P less than 0.001). However, these PaO2 values were not statistically significantly different from control values. We conclude that continuous accurate measurement of arterial oxygen tension is feasible provided that corrections are made in the electrode system for anaesthetic gases. We also found that the increase in PaO2 when 79% nitrous oxide in 21% oxygen was used, when compared with air, was lower than values proposed by previous investigators. The decrease in PaO2 when the inspired gas was changed back to room air was less than that found by others and there was no evidence of hypoxia when patients were ventilated on air alone after inspiring the mixture.

Endoscopic injection sclerotherapy for bleeding esophageal varices: A new technique with a transparent over-tube : Iso Y, Kitano S, Iwanaga T, et al. Jpn J Acute Med 1987;11:207–212

Adult respiratory distress syndrome has been reported after endoscopic variceal sclerotherapy with sodium morrhuate. It has been proposed that sclerosant entering the pulmonary circulation during intravariceal injections may cause pulmonary hypertension and capillary injury. The purpose of this study was to determine whether variceal sclerotherapy with sodium morrhuate causes capillary injury or pulmonary edema in humans. We studied the effect of sclerotherapy on gas exchange and pulmonary and systemic hemodynamics in 8 patients who required endoscopic variceal sclerotherapy for treatment of variceal hemorrhage. The pulmonary vascular resistance index increased from 246 ± 67 dyn · s · cm−5/m2 (mean ± SEM) at baseline to a high of 303 ± 85 dyn · s · cm−5/m2 60 min after sclerotherapy (normal range 250–500 dyn · s · cm−5/ m2). Pulmonary artery pressure remained stable while cardiac index decreased by 12% over the same period. There were also small increases in systemic vascular resistance index and systemic arterial pressure after sclerotherapy. Although there was no change in arterial oxygen tension, the alveolararterial oxygen difference improved after sclerotherapy. These results indicate that variceal sclerotherapy with sodium morrhuate is associated with clinically insignificant changes in pulmonary and systemic hemodynamics. We did not detect evidence of acute lung injury after sclerotherapy.

Continuous monitoring of oxygen tension with a transcutaneous sensor during hypotensive anesthesia.

Transcutaneous oxygen tension (TCPO2) is a useful noninvasive technique for monitoring arterial oxygen tension under stable circulatory conditions. This study was undertaken to determine if TCPO2 is also reliable during sodium nitroprusside-induced hypotension under general anesthesia. Arterial blood gases and TCPO2 were measured prior to inducing hypotension (baseline), at 20-min intervals during hypotension, and when systemic arterial pressure had returned to within 10% of the control (pre-hypotension) value. With induced hypotension, PaO2 and TCPO2 decreased significantly (P less than 0.05), and were well correlated by linear regression (r greater than 0.85); however, regressions were strongly dependent on the individual patient. The mean regression line for all patients as a group was given by TCPO2 = 0.69 PaO2 + 20.7 mmHg (r = 0.93, P less than 0.01); significantly different regressions were obtained for each patient (P less than 0.0001). Comparing changes in TCPO2 versus those in PaO2 (relative change from baseline values) did not substantially reduce the variability among patients. It is concluded that TCPO2 reliably reflects changes in arterial oxygen tension during controlled hypotension under general anesthesia, but that a separate calibration of TCPO2 vs. PaO2, obtained prior to inducing hypotension, may be required for each individual patient.

The cardiorespiratory effects of perfluorochemicals on acute carbon monoxide poisoning in the pregnant ewe

Studies in nonpregnant animal models of carbon monoxide poisoning have demonstrated the protective effect of perfluorochemicals. Anesthetized pregnant ewes were exposed to carbon monoxide. After symptoms of toxicity were demonstrated, group 1 animals were respired with room air. Group 2 animals respired room air and were given intravenous perfluorochemicals. Group 3 animals were administered 100% oxygen. Group 4 animals were given intravenous perfluorochemicals and respired 100% oxygen. In all ewes exposure to carbon monoxide resulted in increased cardiac output, heart rate, and carboxyhemoglobin level without a significant change in arterial oxygen tension. After carbon monoxide exposure, there was no significant difference in the carboxyhemoglobin to oxyhemoglobin conversion between groups 1 and 2 although the conversion rates were more rapid in groups 3 and 4. Fetal oxygenation was improved in groups 3 and 4. All fetal lambs exhibited a progressive increase in carboxyhemoglobin and a decrease in venous pH regardless of the maternal postexposure treatment. There was no significant increase in the fetal venous oxygen content of group 4 as compared with that of group 3, suggesting that the adjunctive administration of limited quantities of perfluorochemicals to the mother offers no apparent advantage over 100% oxygen alone for acute fetal resuscitation.

Pulse oximetry during cardiac catheterization in children with congenital heart disease.

One hundred and five children with congenital heart disease were monitored by pulse oximetry during cardiac catheterization. Excellent correlation (r = 0.95) was found between oxygen saturation values obtained with pulse oximetry and those obtained from arterial blood in 133 data pairs. This correlation was described by the regression equation y = 0.91x + 8.1. The correlation was also excellent in 47 data pairs with saturation values of less than 90% (r = 0.94, y = 0.93x + 6.0) from 36 cyanotic children. The clinical usefulness of pulse oximetry in the early recognition of decreased pulmonary blood flow or partial airway obstruction was demonstrated. Early diagnosis of changes in oxygenation was especially helpful in children with cyanotic congenital heart disease, in whom small changes in arterial oxygen tension may cause large changes in oxygen saturation.

Management of a patient in respiratory failure due to chronic bronchitis

The respiratory centre situated in the medulla oblongata is responsible for regulating the rate and depth of respiration. Many factors influence the respiratory centre including impulses that are transmitted via the chemoreceptors. Green (1977) states that chemoreceptors are nerve endings found in the carotid and aortic bodies that are sensitive to changes in arterial oxygen tension. Chemoreceptors are stimulated by: (a) A fall in oxygen tension (hypoxia) (b) A rise in carbon dioxide tension (hypercapnia) and hypoxia. Stimulation of the chemoreceptors results in: Impulses being sent to the respiratory centre in the medulla oblongata to increase the rate and depth of respiration. Stimulation of the vaso-motor centre resulting in an increase in blood pressure. Depression of the cardiac accelerator centre resulting in a drop in heart rate. However, an increased respiratory rate stimulates the cardiac accelerator centre which results in an increased heart rate. (Fig. 1).

Real-time analysis of the change in arterial oxygen tension during endotracheal suction with a fiberoptic bronchoscope.

An intra-arterial Clark-type polarographic oxygen electrode was used with a fiberoptic bronchoscope for real-time analysis of the PO2 change during 1 min of suction in patients spontaneously breathing oxygen. There was a strong correlation between values obtained from the intra-arterial electrode (PiO2) and those from blood samples (PaO2), before and at the end of suction; the PiO2/PaO2 ratio was close to one. Continuous PiO2 recordings during suction without supplemental oxygen showed little change in the early period of suction, followed by a steep drop continuing even after suction. This drop in PiO2 was partially attenuated by providing oxygen with high-frequency jet ventilation and was almost completely attenuated by the use of a suction adaptor. Changes in the inspired oxygen concentration indicated the importance of keeping this variable constant during suction to prevent hypoxemia.

Effect of endoscopic variceal sclerotherapy on gas exchange and hemodynamics in humans

Adult respiratory distress syndrome has been reported after endoscopic variceal sclerotherapy with sodium morrhuate. It has been proposed that sclerosant entering the pulmonary circulation during intravariceal injections may cause pulmonary hypertension and capillary injury. The purpose of this study was to determine whether variceal sclerotherapy with sodium morrhuate causes capillary injury or pulmonary edema in humans. We studied the effect of sclerotherapy on gas exchange and pulmonary and systemic hemodynamics in 8 patients who required endoscopic variceal sclerotherapy for treatment of variceal hemorrhage. The pulmonary vascular resistance index increased from 246 ± 67 dyn · s · cm−5/m2 (mean ± SEM) at baseline to a high of 303 ± 85 dyn · s · cm−5/m2 60 min after sclerotherapy (normal range 250–500 dyn · s · cm−5/ m2). Pulmonary artery pressure remained stable while cardiac index decreased by 12% over the same period. There were also small increases in systemic vascular resistance index and systemic arterial pressure after sclerotherapy. Although there was no change in arterial oxygen tension, the alveolararterial oxygen difference improved after sclerotherapy. These results indicate that variceal sclerotherapy with sodium morrhuate is associated with clinically insignificant changes in pulmonary and systemic hemodynamics. We did not detect evidence of acute lung injury after sclerotherapy.

Dialysis hypoxemia: Role of dialyzer membrane and dialysate delivery system

Arterial blood gas values, carbon monoxide diffusion capacity, oxygen consumption, carbon dioxide production, respiratory quotient, minute ventilation, and pulmonary capillary blood flow were determined before and during hemodialysis. In addition, the effect of single passage through the dialyzer on blood carbon dioxide tension, pH, and bicarbonate concentration was evaluated. Acetate-based dialysate was used in all experiments. Cellulosic dialyzer with single-pass dialysate delivery system was used in one group, and polyacrylonitrlle dialyzers with recirculating delivery system in another. Although hypoxemia occurred in both groups, it was more severe in the former group. Dialyzer carbon dioxide loss was significantly greater with single-pass dialysate delivery system and cellulosic dialyzers than with recirculating delivery system and polyacrylonitrile dialyzer. To differentiate the role of dialysate delivery system from that of the membrane, the experiments were repeated using recirculating delivery system and cellulosic dialyzer. This resulted in marked attenuation of hypoxemia and dialyzer carbon dioxide tension losses. Since other experimental conditions were the same, the observed differences were thought to be due to the difference in the mode of dialysate delivery. It thus appears that the mode of dialysate delivery per se can modify the changes in arterial oxygen tension during hemodialysis and should be added to the list of factors implicated in the genesis of dialysis hypoxemia.

RANDOMIZED CONTROLLED TRIAL OF PHYSIOTHERAPY FOR POSTOPERATIVE PULMONARY COMPLICATIONS

A prospective randomized controlled trial was conducted in patients undergoing elective cholecystectomy to assess the value of routine chest physiotherapy. One hundred and two patients entered the study: 47 patients developed no pulmonary complications, 29 had pulmonary atelectasis and a further 26 developed chest infection. The pattern of changes in arterial oxygen tension in the period after operation supported the clinical allocation of the patients. Of 51 patients not receiving physiotherapy, 11 developed atelectasis and 19 chest infection. Of 51 treated patients, 18 developed atelectasis and seven chest infection. Routine prophylactic postoperative chest physiotherapy decreased significantly the frequency of chest infection (P less than 0.02).

Hemodynamic And Clinical Response To Three-Day Infusion Of Sulmazol (Ar-L 115 Bs) In Severe Congestive Heart Failure

Sulmazol (AR-L 115 BS) is a new positively inotropic drug with arterial and venous vasodilating properties. We studied the effects of sulmazol (three-day infusion) on clinical tolerance, hemodynamics, and blood gas levels in ten patients with severe chronic heart failure. The hemodynamic monitoring included a Swan-Ganz catheter in the pulmonary artery and a radial catheter. Blood gas levels were determined on samples of arterial and mixed venous blood. After 24 hours of infusion, there was a significant increase in cardiac index (2 to 2.5 L/min/sq m; p less than 0.005) and a significant decrease in pulmonary wedge pressure (28 to 19 mm Hg; p less than 0.001) and in right atrial pressure (7 to 4 mm Hg; p less than 0.001) without significant changes in heart rate and systolic blood pressure. These beneficial effects lasted during the three days of infusion. Oxygen delivery was significantly increased (350 to 443 ml/min/sq m; p less than 0.005) without significant change in arterial oxygen tension. The side effects included nausea, vomiting, anorexia, and mild thrombocytopenia. We conclude that sulmazol is a potent drug which may improve severely deteriorated left and right ventricular function in patients with chronic refractory heart failure without affecting the heart rate and the systolic blood pressure.