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At least 793 records · Page 44Linked to original sources
PubMed1978

Lung tissue guanosine 3',5'-monophosphate: effects of ventilation and anesthesia.

In vivo levels of guanosine 3',5'-cyclic monophosphate (cGMP) in rat lung were measured by radioimmunoassay. The basal levels of this agent were found to change depending on the method of killing or anesthesia used. Lowest values were found after microwave irradiation to the head (10.2 fmol/mg wet wt). Values after pentobarbitol anesthesia, with or without atropine, were significantly higher (19-24 fmol/mg). In animals anesthetized with pentobarbital and ventilated at pressures of 7 cmH2O with no end-expiratory pressure, lung cGMP was 42-49 fmol/mg. Ventilation at higher pressures resulted in much higher levels of cGMP (20 cmH2O, 105 fmol/mg; 30 cmH2O, 233 fmol/mg). The response of cGMP to ventilation was not blocked by pretreatment of the animals with atropine. High-pressure ventilation was without effect on lung adenosine 3',5'-cyclic monophosphate.

Animals↗
PubMed1978

Passive expiration as a test of lung function.

Twenty-five normal subjects, 14 non-smokers and 11 smokers, passively expired into a spirometer after a maximal active inspiration, and after a passive inflation of the chest by a pressure cycled intermittent positive-pressure breathing (IPPB) machine. Acceptable passive expirations could be performed by all subjects after a passive inspiration but by only 12 after an active inspiration. Expired volume was found to change exponentially with time (r greater than 0.98), and the time constant of passive expiration (Tp) was obtained. There was no significant difference between the smokers and non-smokers in age, sex, forced vital capacity, FEV1 FEV1/FVC%, maximum mid-expiratory flow rate, maximum expiratory flow at 50% and 25% of the vital capacity, or the magnitude of the fall in the dynamic compliance with increasing frequency of breathing (Cdyn/f). Tp in smokers (1.06 +/- 0.47 SD) was significantly longer than in the non-smokers (0.65 +/- 0.25 SD P less than 0.02). Tp had a significant correlation with Cdyn/f(Tp = 0.6 + 161.81 Cdyn/f +/- 0.38 SE, r = 0.49, P less than 0.02). We conclude that satisfactory passive expiratory spirograms can be easily obtained after a mechanically assisted passive inspiration. Tp thus obtained is determined by the intrinsic properties of the respiratory system (lung plus thorax), and is significantly prolonged in smokers compared with non-smokers when other studies of pulmonary function including frequency dependence of compliance are unchanged.

Adult↗
PubMed1975

Assisted ventilation in infants with meconium aspiration syndrome.

In a retrospective analysis of infants born with meconium staining over an 18-month period at Cook County Hospital, 32 infants met two of the three criteria for the diagnosis of meconium aspiration syndrome: (1) history of meconium in the oropharynx or trachea; (2) clinical evidence of respiratory distress; and (3) x-ray evidence of aspiration pneumonia. Seventeen infants developed respiratory failure; nine of these infants died. One infant without respiratory failure died of sepsis. Analysis of sequential arterial blood pH and gas tension showed that nonsurviving infants had persistently high PCO2 and A-a gradient in spite of initiation of assisted ventilation. These changes seem to be related to severe right-to-left shunting and ventilation perfusion abnormalities. The data further suggest that asphyxia and acidosis occur well before the infant is born and that intrapartum monitoring to recognize fetal asphyxia may help in improving morbidity and mortality from meconium aspiration syndrome.

Blood Gas Analysis↗
PubMed1977

Effect of different respirator adjustments on central haemodynamics in open-heart surgery patients.

Changes in cardiac index (CI) mean pulmonary artery pressure (PAP), mean pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), and pulmonary artery vascular resistance (PVR), associated with spontaneous respiration (SR) and two different types of intermittent positive pressure ventilation (IPPPV and IPNPV) were studied in a total of 17 patients undergoing aortic valve replacement or myocardial revascularization. Swan-Ganz thermodilution pulmonary artery cardiac output catheters were used and the aim was to determine: whether postoperative cardiac output may paradoxically be greater during IPPPV than during IPNPV or SR; whether the use of "negative" pressure in the expiratory phase during controlled ventilation may be responsible for bringing about the central haemodynamic conditions prevailing during spontaneous respiration; and whether, in weaning from postoperative IPPPV to SR, there is a risk of pulmonary congestion as a consequence of possible autotransfusion. IPPPV connected with anaesthesia induction caused a highly significant deterioration central haemodynamics. The use of positive end-expiratory pressure (PEEP) is not to be recommended for such patients at this stage. On the first postoperative day, the mean CI was lower during IPPPV than during IPNPV (P less than 0.1) or during SR (P less than 0.05). The changes observed in CI, were, however, so slight that the authors consider the routine use of PEEP to be beneficial during controlled ventilation following major open-heart surgery. In some patients, the CI was paradoxically higher during IPPPV than during IPNPV or SR. The mean CI was nearly the same during IPNPV (3.32) as during SR (3.38). However, PAP, PCWP and PVR values were significantly higher during SR than during IPNPV. Thus, according to this study, the use of "negative" end-expiratory pressure during controlled ventilation did not in these patients produce central pressure conditions corresponding to spontaneous respiration. The present study supports the finding that in weaning from controlled ventilation with PEEP to SR there is a danger of pulmonary congestion. This could be predicted by measurement of pulmonary wedge pressure, but not by measurement of central venous pressure.

Adult↗
PubMed1978

The effect of Swan-Ganz catheter height on the wedge pressure-left atrial pressure relationships in edema during positive-pressure ventilation.

We have studied the effect of the ventrical height of the pulmonary wedge catheter in the lung on the pulmonary wedge pressure-left atrial relationship during positive end-expiratory pressure ventilation in oleic acid-induced pulmonary edema. Pulmonary wedge catheters were placed above and below the left atrium in normal dogs and in dogs with oleic acid-induced edema. Wedge pressure and left atrial pressure were measured simultaneously during positive end-expiratory pressure ventilation (range, 0 to 30 cm H2O positive end-expiratory pressure). Pulmonary wedge catheters below the left atrium correctly recorded left atrial pressure and change in left atrial pressure at all positive end-expiratory pressures studied. Pulmonary wedge catheters above the atrium consistently recorded pressures higher than the normal left atrial pressure. They did not correctly respond to increases in left atrial pressure until it was increased to a value higher than the initial upper pulmonary wedge pressure. Pulmonary arterial catheters, when properly placed, should be reliable indicators of left atrial pressure during positive-pressure ventilation in normal and edematous lungs.

Animals↗
PubMed1978

Evaluation of criteria for discontinuing mechanical ventilatory support.

Thirty-three patients who required short-term postoperative mechanical ventilatory support were studied to compare different criteria established to initiate weaning from mechanical ventilation. Intermittent mandatory ventilation criteria (i.e., decreasing mechanical respirator rate as long as the arterial (pHa) remains above 7.35) and conventional criteria (ie, vital capacity greater than 15 ml/kg and peak negative pressure greater than 20 cm H2O) were compared to determine which would more rapidly predict a patient's ability to sustain total spontaneous respiration. All patients were eventually weaned from mechanical ventilation and had their tracheas extubated. Twenty-one patients maintained a pHa of greater than 7.35 during total spontaneous ventilation before they would, or could, meet conventional criteria for initiating a trial of spontaneous respiration (P less than .001). Seven patients simultaneously met both criteria for maintaining total spontaneous ventilation and the remaining five patients met conventional criteria before intermittent mandatory ventilation criteria. In the latter group, the pHa decreased below 7.35 during spontaneous respiration but in only one patient did it fall below 7.30. Our findings suggest that a patient's ability to maintain a pHa of greater than 7.35 while decreasing the frequency of mechanical ventilator breaths is more accurate than peak negative pressure and vital capacity for predicting ability to sustan adequate spontaneous respiration.

Adolescent↗
PubMed1979

Increases in cuff volume and pressure in red rubber endotracheal tubes during anaesthesia.

Increases in endotracheal tube cell volume and pressure during anaesthesia have been reported to be due to the diffusion of nitrous oxide into the cuff. This study compared cuff volume and pressure changes in anaesthetized intubated patients who were ventilated with those allowed to breath spontaneously. The cuffs of Magill red rubber endotracheal tubes were inflated with either air or a nitrous oxide-oxygen mixture. Serial pressure and volume recordings confirmed that both parameters increased when the cuff was inflated with air. The increase in cuff pressure was however, greater during intermittent positive pressure ventilation than for spontaneous respiration. There were no significant changes when the cuff was inflated with the nitrous oxide-oxygen mixture.

Adolescent↗
PubMed1977

[Treatment of flail chest from the general surgical view. Experience with 20 cases].

Flail chest is a serious complication of multiple fractures of the ribs that needs immediate management in order to avoid its disastrous respiratory and circulatory consequences. The authors present their experience with 20 cases of flail chest injury and discuss especially some practical aspects of its treatment. Skeletal traction was used frequently to stabilize the chest wall, while intermittent positive pressure respiration was reserved only for patients with uncompensated respiratory disturbances. The authors urge that a well-organized surgical unit should be able to provide appropriate management in such cases, since most of these patients have multiple injuries that need general surgical together with more specialized treatment.

Adolescent↗
PubMed1978

Comparison of two methods of postoperative respiratory care.

After abdominal surgery, 64 patients were managed with one of the following two techniques of respiratory care: (1) deep breathing by way of a new device, an incentive spirometric three-ball, flow-measuring device (Triflo); and (2) standard episodic intermittent positive-pressure breathing (IPPB) every four hours. Both series of patients received therapy with a bronchodilator drug by nebulization. All patients had preoperative spirometric measurements followed by five consecutive days of therapy and spirometry. Chest x-ray films were obtained for all patients. There were no significant differences between the two methods of respiratory care, but 57 percent (17/30) in the group receiving therapy with IPPB developed pneumonia, atelectasis, or bronchitis, while only 29 percent (10/34) did so in the group using the incentive spirometric device (P less than 0.05). Spirometric differences were minimal, although the trend favored the incentive spirometric device. Principal conclusions were as follows: (1) deep breathing under the conditions of this investigation was equal to episodic therapy with IPPB; and (2) from an economic standpoint, IPPB, as it is currently practiced, may be disadvantageous when compared with the incentive spirometric device.

Abdomen↗
PubMed1978

Amelioration of bronchopulmonary dysplasia after vitamin E administration. A preliminary report.

We studied the effect of vitamin E on the development of bronchopulmonary dysplasis in neonates with respiratory-distress syndrome. Twenty infants received vitamin E administered intramuscularly during the acute phase of the syndrome, and 20 infants served as controls. Administration of vitamin E significantly increased the serum vitamin E concentration. Nine vitamin-treated and 13 control patients required supplemental oxygen for longer than 250 hours; all were treated with positive-pressure ventilation and endotracheal continuous distending airway pressure. Six of those 13 controls had x-ray changes consistent with bronchopulmonary dysplasia, and four died. None of the nine vitamin-treated patients had changes characteristic of bronchopulmonary dysplasia (P = 0.046), and all survived. Administration of vitamin E during the acute phase of the respiratory-distress syndrome appears to modify the development of bronchopulmonary dysplasis.

Bronchial Diseases↗
PubMed1979

Physiological responses of the newborn infant to resuscitation.

Lung ventilation, endotracheal, and intraoesophageal pressures were measured during standard resuscitation of 20 asphyxiated babies born by caesarean section. The most common response to resuscitation was the production of a large positive intraoesphageal pressure. An opening pressure greater than 2.0 kPa was required to expand the lungs of most of these babies. The need for resuscitation was associated with prolonged maternal anaesthesia before delivery.

Asphyxia Neonatorum↗
PubMed1979

Ultrasonographic evaluation of ventilatory effect on inferior vena caval configuration.

Ventilatory effect on inferior vena caval configuration was studied by ultrasonography in 14 subjects, including 5 with chronic obstructive pulmonary disease, 3 with cardiac tamponade due to carcinomatous pericardial effusion, one with tuberculous constrictive pericarditis, and 5 normal subjects. The inferior vena caval lumen decreased in the early inspiratory phase, reached a minimum at the end of inspiration, distended again during expiration, and closed transiently 2 to 3 cm below the diaphragm during maximal inspiration. These ventilatory changes of the inferior vena cava reversed with increase in intrathoracic pressure during the Valsalva maneuver and positive-pressure ventilation. When the central venous pressure was increased, as in cardiac tamponade, the inferior vena cava was fully distended through the entire phase of inspiration and expiration. Collapsibility of the inferior vena cava was inversely proportional to central venous pressure when the pressure was less than 10 cm H2O, but not when the pressure was greater than approximately 10 cm H2O. Our results suggest that the study of inferior vena caval configuration with ultrasonogrphy is a valuable noninvasive clinical aid for estimating central venous pressure and for analyzing inferior vena caval hemodynamics in various clinical conditions.

Central Venous Pressure↗