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[Continuous monitoring of blood gases in adults].

Single blood gas analysis offers only a momentary value, whereas with continuous monitoring of blood gases their development can be followed very closely. Cutaneous pO2 monitoring has not proved successful in adults, since the measured values depend very much on the condition of the skin, local perfusion, and cardiac output. On the other hand, continuous intravascular pO2 monitoring does represent a relatively safe and convenient method of supervision. At this institute a cutaneous pCO2-sensor developed by the Bio-Electronics Department of F. Hoffmann-La Roche & Co. Ltd. with sensor temperatures of 41 degrees, 43 degrees, and 44 degrees C has been tested. The coefficients of correlation are 0.95 or even higher for all three sensor temperatures. At a sensor temperature of 41 degrees C the reaction velocity is markedly reduced. Accuracy and reaction velocity for the sensor temperatures of 43 degrees and 44 degrees C are equivalent, but at a temperature of 43 degrees C there are fewer and slighter skin reactions. The authors found a slight drift of 0.2--0.3 mm Hg/h. The dependence of cutaneous pCO2 on local perfusion and cardiac output also appears to be slight.

Adult↗

[A method for the determination of O2-uptake and CO2-elimination from the respiratory gases in mechanically ventilated patients (author's transl)].

A method for the assessment of O2-uptake and CO2-elimination from respiratory gases in mechanically ventilated patients is presented, the Beckman metabolic measurement cart. It was designed for exercise measurements. In patients under respirator treatment, there are problems resulting from the pressure sensitivity of the polarographic O2-electrode. Correct measurements of O2-uptake is possible if an inspired O2-concentration of 50 per cent is not exceeded.

Anesthesia↗

[Effects of tramadol on haemodynamics and blood gases in the early postoperative period].

A variety of opioids is available for treatment of acute pain. Sometimes administration is limited due to typical side effects such as respiratory depression or pressure increase in the pulmonary circulation. Tramadol, a synthetic opioid, was investigated in a dosage of 1.5 mg/kg body weight i.v. with regard to changes in haemodynamic parameters and in blood gases. The haemodynamic parameters generally remained stable; all changes were statistically non significant. There were no signs of respiratory depression. The risk of pain therapy with opioids seems to be reduced further by the introduction of this agent.

Adolescent↗

Interrelationships between blood pressure, blood gases and plasma acetate concentrations during conventional hemodialysis.

To determine to what extent the intradialysis changes in blood pressure (BP) are related to the variations in blood gases and plasma acetate concentrations (plAc), 11 dialysed uremics were studied with measurement of plAc,pH, pCO2 and pO2 every 60' during a hemodialysis lasting 4 hrs. Dialysis resulted in significant decreases in the BP, pO2 and pCO2 and in significant increases in pH and plAc. Multiple regression analysis demonstrated that the delta % for the mean BP was closely related to plAc, pCO2 and delta-% of body weight (BW). Partial regression coefficient indicated the following rank order of correlation: plAc greater than pCO2 greater than or equal to delta-% BW greater than pO2 = O, thus demonstrating that the fall in blood pressure is related both to the increase in plAc and the decrease in pCO2. The physiological relevance of these relationships is discussed. The hypothesis is advanced that the pCO2 decrease during dialysis might contribute to the acetate-induced vascular instability.

Acetates↗

The effects of various gases on cortical and spinal somatosensory evoked potentials at pressures up to 10 bar.

The development of dog electrophysiological models for studying the treatment of cerebral arterial air embolism and spinal cord decompression sickness, required that the effects of the treatment gases on spinal and cortical somatosensory evoked potentials (SEP and CEP) be known. We found an inverse linear relationship between CEP amplitude and air pressure to 230 ft. An asymptote was approached when pressure was increased to 300 ft. This effect was not seen with 20% oxy-helium. The waves representing local cord events were depressed to a lesser extent than were the CEPs. We were able to detect an equilibration time in the EP suppression comparable to estimated inert gas wash-in time for the brain. A small depression of CEPs that did not reach significance was seen with exposure to 2.8 bar of oxygen and continuous exposure for up to 120 min caused no further diminution in amplitude than would be caused by time alone.

Air↗

Acute toxic exposure to gases from liquid manure.

Liquid manure storage is a common component of confinement systems for swine, beef, dairy, and veal operations. A mail questionnaire to a sample of swine producers indicated that more than 85,000 people in Iowa and an estimated 500,000 in the United States work in livestock confinement systems that use liquid manure storage. Deaths and illnesses in people with acute exposure to toxic gases emanating from the liquid manure have been recently reported. This communication reports results of the investigation of six such incidents. Hydrogen sulfide appears to be the main toxic substance involved, and agitation of the liquid manure is important in creating an acutely severely toxic environment. Preventive measures must include worker education and limitation of human exposure through control of environmental and human factors.

Adolescent↗

[Nocturnal changes in blood gases and pulmonary arterial pressure in chronic bronchitis patients with respiratory insufficiency (author's transl)].

Fourteen male patients with chronic bronchitis and respiratory insufficiency were monitored during nocturnal sleep by conventional polygraphy (EEG, EOG and EMG of the chin) associated with continuous recording of the mean pulmonary arterial pressure (PAP) and, in 50% of the cases, continuous measurement of O2 saturation. Six subjects were able to sleep long enough for oxygen saturation, blood gases and PAP values to be correlated with the various phases of sleep. Frequent, significant and sometimes abrupt peaks of hypoxaemia were observed; they usually, though not necessarily, occurred during paradoxical sleep. The most pronounced nocturnal changes in SaO2 were encountered in those patients who had the most severe hypoxaemia during daytime. Nocturnal fluctuations in PAP were also pronounced (with increases of more than 20 mmHg) and often paralleled changes in SaO2. Correlation between SaO2 and PAP was good in some patients ("responders") but poor or even lacking in others ("poor-or non-responders"). This preliminary study indicates that patients with chronic bronchitis may have severe exacerbations of pulmonary arterial hypertension during nocturnal sleep and warrant nocturnal oxygen therapy.

Adult↗

[Adverse effects of modern inhalation anesthetics. 2. Control of amounts and elimination of escaping anesthesia gases].

This paper presents a review on the pathological effects caused by acute or chronic exposure to the inhalation anesthetics halothane, methoxyflurane, or enflurane. Methoxyflurane has a dose-related nephrotoxicity due to its metabolic degradation with release of fluoride ions whereas suggested pathological renal effects of halothane or enflurane are still under discussion. As to the syndrome of halothane- (or enflurane-, methoxyflurane-) associated hepatitis no dose-dependent hepatotoxicity has been proven but interactions with hypoxia, hypotension, drug-pretreatment, and perhaps genetic abnormalities should be kept in mind. Severe hematologic alterations are effected by prolonged exposure to N2O or halothane and alterations of tumor immunity caused by anesthetic agents are reported, too. From clinical studies and observations of pregnant animals, a correlation between the incidence of miscarriages or malformations and chronic exposure to low doses of inhalation agents may be stated. Nevertheless, an inhalation agent is easy to control because it can be eliminated quickly in the case of complications. Therefore, one would not like to miss these inhalation agents in clinical practice but the immission into the operating room should be limited. Moreover, the best way to keep the operating room clean from waste anesthetic gases is the installation of a scavenging system which is connected to suction.

Air Conditioning↗

Understanding arterial blood gases.

Arterial blood gases are useful in establishing acid-base status, determining the degree of impairment of the lungs as a gas exchanger, diagnosing such important phenomena as pulmonary emboli and implementing or adjusting oxygen therapy. The balance among H+, HCO3- and CO2 is represented by the equation H+ + HCO3- in equilibrium CO2 + H2O. Primary alterations of either component of the left-hand side of the equation result in metabolic acid-base balance disturbances; primary alterations of CO2 result in respiratory acid-base balance disturbances.

Acid-Base Imbalance↗

Determination of the specific blood flow of the liver by inhalation of radioactive rare gases.

The technique applying the inhalation of radioactive rare gase is a new method to determine the specific blood flow of the liver. After inhalation of 133Xe, the course of activity is registered above liver and spleen as well as in the exspirated air. The perfusion is calculated from the resulting wash-out curves. The average value in healthy persons is 91 +/- 15 ml/100 g min. The reproducibility is 5 +/- 1%. The xenon wash-out is delayed in cirrhotic livers; the blood flow is significantly decreased and amounts to an average of 45 ml/100 g min. A delayed wash-out of xenon was also found in major fatty livers due to the high affinity of xenon to fat. The dependence of the partition coefficient on the fat content was investigated by Kitani and Winkler in homogenized liver tissue of different fat content. The question arises whether these in vitro findings can be transferred to in vivo wash-out curves. We therefore carried out first investigations on patients of known content of fat of the liver, applying a 85MKr-133 Xe-double measurement. According to results which have been achieved up to now, sufficient accuracy can only be obtained up to a fat content of 10%.

Fatty Liver↗

Comparison of SVO2, SpO2, and clinical parameters with arterial blood gases during ventilatory weaning after cardiac surgery.

Correlations of mixed venous and arterial oxygen saturation, heart rate, respiratory rate, and mean arterial pressure with arterial blood gas variables were computed for 57 sets of data obtained from 30 postoperative coronary artery bypass graft patients who were being weaned from mechanical ventilation. Arterial oxygen saturation and respiratory rate correlated significantly, although moderately, with blood gases.

Arteries↗

[Blood gases and pH value in swine anesthetized with barbiturate].

The influence of short term anaesthesia with the N-methyl barbiturate Eunarcon on the pH and blood gases was investigated in 19 clinical healthy male castrated pigs of the breed Large White, three months old and with a mean body weight of 30 kg. The factors of oxygen in the blood--content, saturation of hemoglobin, O2 partial pressure--are diminished continuously during anaesthesia, with a decrease of pO2 on 77% of the initial value. The pCO2 increased, and the peak value of 11% above the initial level was seen already 10 minutes after starting the anaesthesia. The pH value like a seismograph of the ionic balance is not changed significantly. The results are discussed in connection with problems of medication and control of intravenous anaesthesia.

Anesthesia↗

[The changes in blood gases, hemodynamics and oxygen delivery after weaning and the treatment of sodium nitroprusside in mechanically ventilated patients with cor pulmonale].

The change of blood gases, hemodynamics and oxygen delivery after weaning and the treatment of sodium nitroprusside were respectively studied in seven and twelve patients with cor pulmonale. Weaning resulted in decrement of pulmonary vascular resistance (from 48.4 +/- 16.6 to 37.6 +/- 18.5 kPa.s-1.L-1, P < 0.01) and increment of oxygen pressure of mixed venous blood (from 5.35 +/- 0.71 to 6.00 +/- 0.89 kPa.s-1.L-1, P < 0.01). Although artery pressure of oxygen (from 12.20 +/- 4.24 to 10.07 +/- 2.83 kPa, P < 0.01) was decreased after the treatment of sodium nitroprusside, cardiac index (from 44.5 +/- 10.3 to 53.0 +/- 13.7 ml.s-1.m-2, P < 0.05) and oxygen delivery index (from 7.9 +/- 1.6 to 9.3 +/- 2.2 ml.s-1.m-2, P < 0.05) were improved. It indicates that adequate weaning and application of vasodilator is useful to mechanically ventilated patients.

Aged↗

Arterial blood gases in elderly persons with chronic obstructive pulmonary disease (COPD).

With the increasing number of elderly people in developed countries, physicians are often confronted with patients whose arterial oxygen tension, PaO2, is lower than that of normal young adults. The normal values predicted in the literature for very old individuals are generally extrapolated from younger subjects. The purpose of the present study was to obtain PaO2 values from a large population of elderly subjects with normal and obstructive ventilatory function. We measured arterial blood gases in 274 subjects, aged 65-100 yrs (mean 82 yrs), with chronic bronchitis and moderate airways obstruction (mean forced expiratory volume in one second (FEV1), 53% pred). Mean PaO2 was 10.0 +/- 1.4 kPa (75.2 +/- 10.8 mmHg) and mean arterial carbon dioxide tension (PaCO2) was 5.4 +/- 0.8 kPa (40.5 +/- 6.1 mmHg). Both PaO2 and PaCO2 were independent of age. Blood gas abnormalities were associated with airways obstruction: PaO2 was positively correlated to FEV1 and PaCo2 was negatively correlated to FEV1. PaO2 was 10.8 +/- 1.4 kPa (81.5 +/- 10.7 mmHg) in the patients with FEV1 > or = 90% predicted versus 9.5 +/- 1.3 kPa (71.5 +/- 10.1 mmHg) in those with FEV1 < or = 35% pred. These findings suggest that the predicted PaO2 extrapolated from younger normal values are often erroneously underestimated. It is probably more accurate to accept as normal a PaO2 of 10.6-11.3 kPa (80-85 mmHg) for all subjects over 65 yrs, irrespective of their age.

Aged↗

[Effects of inhaled beta-adrenergic and anticholinergic drugs on respiratory function and arterial blood gases in patients with pulmonary emphysema].

We studied the effects of inhaled anticholinergic (oxitropium bromide, 0.2 mg) and beta-adrenergic (fenoterol 0.4 mg) drugs on respiratory function and arterial blood gases in fourteen male patients with pulmonary emphysema (age 63 +/- 8 years; FEV1/FVC 1.41 +/- 0.73 L) using a three day, randomized, double-blind placebo-controlled design. Each day, spirometry and arterial blood gas analyses were performed before and 45 min after inhalation. Both fenoterol and oxitropium bromide significantly improved FEV1 by 21% and 16%, respectively, although there was no significant difference between the two drugs. However, the mean value of PaO2 significantly decreased from 74.5 +/- 2.6 to 69.3 +/- 2.7 Torr with fenoterol, but not with oxitropium and placebo. Change of PaO2 with fenoterol was significantly correlated with %FRC, but not with FEV1 nor change of FEV1. We therefore conclude that an anticholinergic inhalant bronchodilator is more favorable for patients with COPD than a beta-adrenergic agent.

Adrenergic beta-Agonists↗

Postoperative pulmonary complications and serial pulmonary functions and arterial blood gases in patients undergoing oesophagectomy with or without a thoracotomy.

Transthoracic (TT) (n = 12) and transhiatal oesophagectomy (THE) (n = 14) were performed in 26 patients (19 males and 7 females) suffering from benign or malignant strictures of oesophagus. Nine of these patients were smokers. Preoperatively, various parameters of pulmonary functions did not differ significantly in two groups of patients. Forced vital capacity (FVC), forced expiratory volume in 1 second FEV1 (L) and forced expiratory flow between 25-75% of vital capacity (FEF 25-75%) showed a decline at second/third, seventh and 6 weeks in the postoperative period compared to preoperative values. Decrease in FVC was significant at all times. The change in FEV1 and FEF25-75% was not statistically significant at 6 weeks. The decrease in arterial oxygen tension (PaO2), maximal breathing capacity (MBC), maximal inspiratory (PImax) and expiratory (PEmax) pressures in the postoperative period was significant at second/third and seventh postoperative days. Three of 26 patients died. Of these two had TT while the third one had THE procedure. Twenty-one patients developed postoperative pulmonary complications (PPCs). Patients who developed PPCs had significantly different MBC, FEF25-75%, PEmax and FEV1 compared to those who did not have PPCs. Long-term studies involving a larger number of patients are required to document changes occurring in pulmonary functions, arterial blood gases and nutritional status of these patients.

Adult↗