Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0476273 (respiratory distress)
 19,632 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High-frequency ventilation has been used successfully to manage life-threatening complications in premature infants with lung disease. Here we report a preliminary assessment of the efficacy and safety of high-frequency oscillatory ventilation-(HFO-A, A = active expiratory phase) when used as a primary ventilator in 11 infants of 24-34 weeks gestation who required ventilatory support. HFO-A was initiated after no more than 5.5 hr of conventional mechanical ventilation (CMV). HFO-A at 15 Hz was used for 12-203 hr following a protocol designed for rapid reduction of FI02 requirements. CO2 elimination was easily achieved in all infants. Oxygenation was satisfactory, except in one infant with congenital pneumonia. There were four deaths during HFO-A: two pulmonary (one congenital pneumonia; one pulmonary hemorrhage) and two nonpulmonary. The HFO-A protocol utilized lung volume recruitment maneuvers plus mean airway pressures (MAwP) greater than those generally used early in the course of CMV. Therefore, in a subset of infants less than or equal to 29 weeks' gestation with respiratory distress syndrome (RDS), ventilator pressures and gas exchange were compared in infants treated with either HFO-A or CMV. Maximum MAwP levels were reached earlier in six infants on HFO-A (5.2 +/- 2.5 hr; mean +/- SD) than in a comparable group of 9 CMV-treated infants (36 +/- 1 hr). This earlier use of high MAwP lowered the FI02 to less than 0.4 by 18.9 +/- 11 hr with HFO-A as compared with 64 +/- 6 hr using CMV, without any evidence of an increase in pulmonary complications. There were 17 complications in the nine CMV-treated infants; and four in the six HFO-A treated ones. We conclude that HFO-A, instituted early and used with a protocol designed for early reduction in FI02 requirements, demonstrates sufficient efficacy and safety to warrant further clinical trials in the routine management of infant RDS.
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PMID:High-frequency oscillatory ventilation in premature infants with respiratory failure: a preliminary report. 330 21

To determine the long-term pulmonary sequelae and effect on exercise tolerance of bronchopulmonary dysplasia (BPD), we studied 10 children at a mean age of 10.4 years, who had been born prematurely, survived respiratory distress syndrome, and subsequently developed BPD, and compared them with eight age-matched normal children born at term. Pulmonary function tests and graded exercise stress tests were performed. Residual volume, the ratio between residual volume and total lung capacity, vital capacity, forced expiratory volume in 1 second, forced expiratory flow between 25% and 75% of vital capacity, and maximal expiratory flows at 80%, 70%, and 60% of total lung capacity were all abnormal (P less than 0.02) in the children with BPD, compared with control values. Pre-exercise transcutaneous CO2 tension was higher (P less than 0.05) in the BPD group than in the control group. At maximal workload, tcPCO2 remained high in patients with BPD compared with control values (P less than 0.05). Arterial oxygen saturation at maximal workload fell below pre-exercise levels in the BPD group (P less than 0.05) but not in control children. There were no differences in maximal oxygen consumption between the BPD group and control children. Exercise-induced bronchospasm occurred in 50% of the BPD group, but not in the control group. We conclude that long-term survivors of BPD have evidence of airway obstruction, hyperinflation, and airway hyperreactivity, compared with a control group. Aerobic fitness was not significantly different in the BPD and control groups, but was achieved in the BPD group at the expense of a fall in SaO2 and a rise in tcPCO2.
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PMID:Childhood sequelae of infant lung disease: exercise and pulmonary function abnormalities after bronchopulmonary dysplasia. 357 20

The transcutaneous oxygen (PtcO2) monitoring technique uses a Clark electrode applied noninvasively to the skin surface. To obtain PtcO2 values that respond rapidly to physiologic changes, the electrode is heated to 44 to 45 C. Since its introduction in 1972, the PtcO2 sensor has become standard for monitoring oxygenation of neonates in respiratory distress. However, when applied to critically ill or injured adult patients, PtcO2 values often are much lower than arterial oxygen (PaO2) values. The explanation for this is that PtcO2 reflects not only arterial oxygen tension, but also cardiac output and oxygen delivery. Thus, during low-cardiac-output shock states, PtcO2, values are low, even when PaO2 is normal or high. PtcO2 monitoring in adults thus is useful in assessing oxygen delivery. Comparison to an arterial blood gas can easily differentiate whether a low PtcO2 value might be due to hypoxia or to low cardiac output. Other noninvasive monitors (conjunctival oxygen, pulse oximeter, transcutaneous CO2, end-tidal CO2) also show promise. In the emergency department, PtcO2 monitoring is useful in assessing the presence and severity of shock and hypoxia and as a physiologic monitor for titrating resuscitation.
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PMID:Noninvasive monitoring in emergency resuscitation. 377 16

Twelve sets of twin lambs were delivered prematurely by cesarean section at 133-136 days gestational age and ventilated for 3 h with either high-frequency oscillation (HFO) or conventional mechanical ventilation (CMV). Blood gases and pH values were monitored at 30-min intervals, and ventilator settings were adjusted to maintain CO2 partial pressure (PCO2) values within the normal range. There were no differences in the sequential blood gas or pH values between the HFO or CMV lambs. Mean airway pressures (MAP) between 8.0 and 20.4 cmH2O were required, indicating lung disease of variable severity in the lambs. The bidirectional protein leak from the vascular space to the airways and alveoli and vice versa was measured with radiolabeled albumins given by intravascular injection and with fetal lung fluid at birth. The albumin leaks in both directions increased as MAP required to normalize PCO2 increased, but the degree of leak was independent of type of ventilation. Pathological findings of epithelial necrosis and hyaline membranes occurred to a similar extent in lung sections from both groups of lambs. In the HFO animals less phosphatidylcholine in the alveolar wash and more of a tracer dose of radiolabeled natural surfactant that had been given at birth became tissue associated. These results indicate a decrease in the initial secretion of surfactant and/or a stimulation of reuptake in the HFO animals. HFO did not protect the immature lung from the development of large protein leaks or the pathological changes of the respiratory distress syndrome.
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PMID:Effects of high-frequency and conventional ventilation on the premature lamb lung. 384 Aug 1

The present experimental work focuses on the mechanisms involved in respiratory distress observed in the course of subarachnoid haemorrhage. For this purpose, respiratory disturbances were induced in rabbits by injecting fresh autologous blood into the subarachnoid space. For six hours after this artificially induced SAH, blood PO2 and PCO2 as well as expiratory air CO2 were regularly determined, while during the same period cerebral blood flow and cerebrospinal fluid pressure measurements were recorded. The results of this study suggest that pressure effects acting the brain structures that support respiration are principally involved in the pathogenesis of respiratory disturbances following SAH. A decrease in CBF and hypoxia with hypercapnia play a contributing secondary role adding to a vicious cycle phenomenon.
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PMID:A contribution to the pathogenesis of respiratory disturbances associated with subarachnoid haemorrhage; an experimental approach using an animal model. 393 45

Nutritional support of the patient with respiratory failure may play a key role in recovery. Nutritional intake not only indirectly influences lung function by altering body composition and most defense mechanisms but interacts directly with respiratory function in a variety of ways. This review will focus on 2 such interactions; the effect of glucose on CO2 production and the effect of protein on ventilatory drive. Glucose administration results in increases in CO2 production via 2 mechanisms; 1) a thermogenic effect and 2) an increase in the respiratory quotient (RQ). In the hypermetabolic, acutely ill patient, both the thermogenic effect and the rise in the RQ contribute to the rise in CO2 production. In the malnourished patient, a rise in the RQ is the primary mechanism for the increase. In either case, the increased need for CO2 elimination results in an increase in ventilatory demand which may precipitate respiratory distress in a patient with previously compromised pulmonary function. Infusions of amino acids, either alone or as a part of a complete nutritional support regimen, results in an enhanced ventilatory response to CO2. This seems to be a result of the thermogenic effect of protein and an increase in the ratio of the plasma concentration of the large amino acids to tryptophan. We postulate that brain uptake of tryptophan which is a precursor to serotonin (a known respiratory inhibitor) is reduced by the presence of increased amounts of the large neutral amino acids that compete with tryptophan for transport across the blood brain barrier, thereby resulting in respiratory stimulation.
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PMID:Nutrients and ventilation. 641 Jul 2

When oxygen therapy is warranted, the minimum effective dose generally should be given. Hypoxemic patients who have normal baseline ABG may be treated initially with an intermediate to high FiO2 in the range of 35% to 100%, depending on the severity of the respiratory distress. The majority of patients with exacerbations of COPD who are not in extremis may be given an initial FiO2 of 28%, especially if their previous response to oxygen is known. When treating patients who have chronic severe hypercapnia (eg, those requiring chronic home oxygen), the initial FiO2 should be 24% even though renal compensation of the respiratory acidosis has occurred. Further mild elevation of the PaCO2, due mainly to the V/Q mismatch that oxygen therapy induces, may be sufficient to precipitate unacceptable hypercapnia. Patients with exacerbations of COPD who are obviously in extremis, with severe hypoxemia and acidosis, should start with an FiO2 of 24% unless they are being mechanically ventilated. The severity of the hypoxemia and acidosis is more predictive for the development of CO2 narcosis and respiratory failure than is the degree of hypercapnia in these patients. The FiO2 can be increased to 28% and incrementally higher if low FiO2 is tolerated. The use of a high FiO2 is subject to the following guidelines for prevention of clinically significant oxygen toxicity: 100% oxygen at atmospheric pressure is safe if given for less than six hours; 70% oxygen is probably safe for 24 hours; and after this time, 45% should be the approximate upper limit to the FiO2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oxygen therapy and oxygen toxicity. 641 43

The management of status asthmaticus using a continuous iv infusion of salbutamol was studied in 14 children with a total of 16 episodes of respiratory failure, unresponsive to conventional bronchodilator therapy. The mean PaCO2 at the start of the infusion was 60 +/- 6 torr. A loading dose of 1 microgram/kg X min body weight was given over 10 min, followed by an infusion of 0.2 microgram/kg X min which was increased in 0.1-microgram/kg steps according to response. The maximum dose was 4 microgram/kg X min. On 11 (69%) occasions a sustained reduction in PaCO2 was achieved within 4 h of starting the infusion. In 5 (11%) instances no reduction in PaCO2 was seen and mechanical ventilation was instituted because of increasing respiratory distress and CO2 retention. Mean heart rate during the infusion increased from 161 to 183 beat/min. Comparison with previous data from 30 pediatric patients (40 infusions) receiving iv isoproterenol showed less effect on heart rate and a more sustained fall in PaCO2 without the recurrence of bronchospasm. We found salbutamol to be a safe and effective bronchodilator capable of reversing severe bronchospasm in most children who would otherwise require mechanical ventilation. Its greater specificity for beta 2-receptors may make it preferable to isoproterenol.
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PMID:Intravenous salbutamol in the treatment of status asthmaticus in children. 643 57

In spite of improved prophylaxis and therapy, the respiratory distress syndrome is still a major cause of morbidity and mortality in premature babies. Owing to the fact that a number of patients are unresponsive to other methods of neonatal care, an increasing number of perinatal centers have started to treat this group of patients with extracorporeal membrane oxygenation successfully. To make the extracorporeal gas exchange more practicable for the neonate directly after birth, a modification of this method using an umbilical arteriovenous shunt for CO2 removal in apneic premature lambs as an animal model was evaluated. A miniaturized low-resistance extracorporeal circuit that is totally incorporated in a regular intensive care baby incubator was developed. The benefit of using extracorporeal CO2 removal in very low birth weight newborns could be a conditioning of the premature lung during a short period of bypass, after which ventilation at nontraumatic pressures and nontoxic O2 concentrations would become possible.
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PMID:A new perfusion circuit for the newborn with lung immaturity: extracorporeal CO2 removal via an umbilical arteriovenous shunt during apneic O2 diffusion. 643 76

We tested the effectiveness of constant distending pressure applied to immature lungs in preventing respiratory distress syndrome. Fetal lambs of 131 to 134 days gestation were delivered by cesarean section, but the umbilical circulation was kept intact for CO2 removal through the natural in situ placenta. The lungs were inflated to a pressure of 35 cm H2O (Group I, 11 animals) or 25 cm H2O (Group II, 14 animals), after which the airway pressure was maintained at 15 cm H2O through apneic oxygenation until total static compliance exceeded 0.5 ml (cm H2O)- 1kg -1. After a mean of 1.1 and 5.7 h, respectively, the animals were delivered and were given mechanical ventilation for 24 h. Twenty-four animals reached this aimed-for compliance and survived the period of mechanical ventilation in excellent health. A control group of fetal lambs was delivered immediately and treated with mechanical ventilation. Three of 10 control animals developed severe respiratory distress syndrome and died; 1 additional animal survived but with central nervous system involvement from severe hypoxia. We conclude that pulmonary inflation to 35 cm H2O pressure, followed by a constant distending pressure of 15 cm H2O, held until compliance reaches 0.5 ml (cm H2O)- 1kg -1, is an important element in the prevention of respiratory distress syndrome.
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PMID:Respiratory distress syndrome in immature lambs. Prevention through antenatal accelerated conditioning of the lung. 656 74


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