Alterations In Respiratory Function Research Articles

The influence of restraint and infusion on rates of muscle protein synthesis in the rat. Effect of altered respiratory function.

1. Male rats (110-140 g body wt.) were restrained by a standard laboratory technique, by wrapping in a linen towel, and subjected to a constant intravenous infusion of saline (0.15 M-NaCl) for periods of 1 or 6 h. Fractional rates of protein synthesis (ks, %/day) were estimated at the start and at the end of the infusion period, by injection of a large concentration of [3H]phenylalanine. 2. In fed and overnight-fasted rats, restraint and infusion of saline for 1 and 6 h decreased ks in skeletal muscle by 15-20% and 30-35% respectively. Plasma glucose, insulin, glucagon and corticosterone concentrations in restrained and infused rats were not characteristic of immobilization stress. 3. Restrained rats responded to nutrient administration; ks in skeletal muscle increased by 35-40% after infusion of a mixture of amino acids and glucose for 1 or 6 h, as compared with saline-infused rats. 4. Restraint and infusion for 1 or 6 h did not overtly decrease ks and kRNA (protein synthesis per unit of RNA) in hypoxaemia-sensitive tissues, such as heart and liver. Restraint and infusion in an open cage, or in a cloth of open weave, did not decrease ks in muscle after 1 h. Blood gas measurements showed that rats restrained in a linen cloth were hypercapnic and acidotic compared with rats in an open cage. 5. It was concluded that respiratory acidosis, rather than hypoxia, resulting from restraint in a linen cloth decreases muscle protein synthesis.

Effects of postdecapitative ischemia on mitochondrial respiration in brain tissue homogenates.

Mitochondria isolated from ischemic brain characteristically show changes in respiratory function. As conventional procedures for mitochondrial isolation yield a subpopulation of the total population and require extensive manipulation, it is unclear to what extent these changes are representative of mitochondria in the unfractionated tissue. We previously showed that the oxygen uptake by unfractionated forebrain homogenates, measured under two different sets of incubation conditions, provided information on some aspects of the respiratory activity of both the free and synaptosomal pools of mitochondria. Forebrain homogenates from animals subjected to 30 min of postdecapitative ischemia exhibited large reductions in oxygen uptake rates measured in a high K+ (mitochondrial) buffer in the presence of either ADP (44% of control values) or an uncoupling agent (45% of control values). These reductions in respiratory activity were comparable to alterations observed under the same conditions for mitochondria isolated from the ischemic brains. Similar alterations were seen in homogenates from three subregions: neocortex, hippocampus, and striatum. In a physiological buffer, in which oxygen uptake by homogenates largely resulted from activity of mitochondria within synaptosomes, there was little or no change in basal glucose-supported rates (79-96% of control values) and small reductions in maximal rates (63-81% of control values) measured in the presence of an uncoupling agent. These results suggest that alterations of respiratory function seen in isolated free mitochondria provide appropriate estimates of the dysfunction in the total free mitochondrial pool but that synaptosomal mitochondria may be less affected. Measurements of respiratory function of isolated synaptosomes from ischemic tissue provided further support for the relative preservation of synaptosomal mitochondria during ischemic insult.

Primate experiments on mandibular growth direction

Induced oral respiration in eight growing rhesus monkeys led to a lowering of the chin, a steeper mandibular plane angle, and an increase in the gonial angle as compared with eight control animals. The posterior border of the mandible maintained its normal inclination relative to the skull. The mandible underwent a posterior rotation in the experimental animals and an anterior rotation in the controls. The findings suggest that the position of the chin and the inclination of the mandibular plane are controlled by the balance between the suprahyoid and the orofacial muscles. Since the posterior border of the ramus undergoes gradual remodeling and maintains its normal inclination, it is assumed that the masticatory muscles are not significantly affected by the altered respiratory function. It is therefore concluded that the ramus with the masticatory muscles and the chin with its suprahyoid and orofacial muscles represent two relatively independent systems.

Unilateral hyperlucent lung: the case for investigation.

Seventeen children with unilateral hyperlucent lungs were referred for investigation. Of the 11 who had a referring diagnosis of possible Macleod's syndrome only two were shown to have post-viral bronchiolitis. Three of the 11 had conditions that required surgical treatment and a further two with brochiectasis were treated medically. To avoid confusion we suggest that Macleod's syndrome is reserved exclusively for children with post-viral bronchiolitis. Radioisotopic regional lung function studies were useful in the investigation of the subjects from three points of view. Firstly, they distinguished children with primary perfusion abnormalities and normal ventilation, secondly, they defined the extent of altered respiratory function, and thirdly, they were able to distinguish compensatory emphysema from congenital lobar emphysema. As bronchography and bronchoscopy may be hazardous in small children with poor respiratory reserve, such regional studies may be useful in indicating which patients do not require further invasive investigation.

Cytogenetic and Other Biological Effects of 239 PuO 2 Inhaled by the Rhesus Monkey

Sixteen immature rhesus monkeys were exposed via inhalation to an insoluble, polydisperse 239PuO2 aerosol labeled with 169Yb which had an activity median aerodynamic diameter of 1.6 gm and a (0g of 1.6. Four groups with three monkeys per group were exposed to achieve initial 239pu lung burdens of 1000-2000, 200-300, 20-65, and 2-10 nCi, respectively. To determine early retention and distribution of the aerosol, four additional monkeys were exposed with initial lung burdens of 200-600 nCi and were sacrificed 4 hr and 30 days after inhalation exposure. Two monkeys were sham exposed and served as controls. Using data derived from external whole-body counting of the 169Yb label, it was estimated that the inhaled 239PuO, was retained in the body with an average effective half-life of 1000 days with some translocation from the lung to the pulmonary lymph nodes. Chromosome aberrations were scored in blood lymphocytes cultured 1, 3, 7, 19, 31, and 43 months after inhalation. Only in animals with cumulative lung doses greater than 1000 rad was there a significant increase in the frequency of rings and dicentrics when compared to the controls. An animal with an estimated initial lung burden of 1000 nCi showed marked alterations in respiratory function 30 days prior to his death from pulmonary fibrosis 990 days after inhalation exposure. Only slight respiratory changes were detected in the other animals evaluated. To date, three monkeys have died, two with initial lung burdens of 1800 and 1000 nCi '3"Pu which died from radiation pneumonitis and the third with an initial lung burden of 20 nCi which died of gastric torsion presumably not related to Pu exposure. Comparison of survival data from rhesus monkeys with those obtained from baboons and beagles indicates that rhesus monkeys, baboons, and dogs are similar in their early response to inhaled 39"PuO2.

Pharmacologic Management of Childhood Asthma

Asthma is characterized by an increased responsiveness of the airways to various stimuli, which results in narrowing of the airways and in a prolongation of the expiratory phase of respiration; in the early phase the airway obstruction is usually completely reversible, either spontaneously or as a result of therapy. There are three therapeutic approaches to asthma: the avoidance of allergens and irritants causing or aggravating the disease; the use of immunotherapy; and the use of pharmacologic agents. Increasing knowledge of the pathophysiologic aspects of bronchial asthma in the past decade has led to significant advances in its pharmacologic management. The basic alteration of respiratory function is an increased resistance to flow of air through the airway secondary to a combination of three factors: smooth muscle spasm, mucosal edema, and retained viscid secretions. In mild asthma and during remissions the airways less than 2 mm in diameter (the small airways) are obstructed, whereas during an acute attack and with chronicity, both small and large airways are involved. Although both phases of respirations are affected, the increased airway obstruction is more pronounced during expiration. EVALUATION OF THE ASTHMATIC CHILD The diagnosis of asthma is based on history, characteristic physical findings and laboratory tests. Asthmatic attacks of infants are usually associated with viral upper respiratory infections; the infants are usually febrile and frequently have otitis media.

Pulmonary physiotherapy in neonates: Physiologic changes and respiratory management

To investigate physiologic alterations in respiratory function associated with chest physiotherapy, arterial blood gases, respiratory patterns, lung mechanics, and functional residual capacity were measured in 13 neonates (weights 1.25 to 3.20 kg) during the control period, after vibration of the chest and suctioning, after hyperventilation, and two hours after suctioning. Compared to control values, mean PO2decreased significantly after suctioning to 43 mm Hg and increased significantly after hyperventilation to 78 mm Hg. There was a significant decrease in inspiratory resistance and a trend toward decrease in expiratory resistance after suctioning, with return to control levels after hyperventilation. Respiratory rate increased significantly after suctioning. Functional residual capacity, dynamic lung compliance, and tidal volume, as well as PCO2 and base excess, were not changed appreciably throughout the protocol. Because of potentially severe hypoxemia, this study suggests that suctioning and hyperventilation are not warranted on a routine basis in infants recovering from respiratory diseases.

ALTERATIONS IN NEONATAL RESPIRATORY FUNCTION FOLLOWING CHEST PHYSIOTHERAPY

Percussion, suctioning and hyperventilation have been recommended for airway management in neonates requiring endotracheal tubes. To investigate physiological alterations in respiratory function due to chest physiotherapy, we measured arterial blood gases, respiratory patterns, lung mechanics, and functional residual capacity (FRC) in 10 neonates, weights (1.25 to 3.20 kg) during the control period, post vibration of the chest and suctioning, after hyperventilation, and 2 hours post suctioning. Post suctioning compared to controls mean (± SEM) PaO2 decreased 75.2 (± 9.3) to 44.0 (±3.1) mm Hg (P<0.01) while lung compliance and FRC were unchanged. There was a decrease in inspiratory resistance (RI) from 81.8 (± 14.6) to 59.0 (± 10.6) cm H2O/L/sec. (P<0.02) and I:E ratio increased from 0.93 (± 0.04) to 1.04 (± 0.06) (P<0.07). Hyperventilation compared to post suctioning resulted in an increase in mean (± SEM) PaO2 to 63.9 (± 10.0) mmHg (P<0.01), and RI to 98.3 (± 22.0) cm H2O/L/sec. (P<0.05). FRC, CL, VT were unchanged. Two hour followup values for all parameters studied were similar to control values except for a trend toward increased compliance. There were no significant differences at any stage of the study for PaCO2, pH, base excess, VT, or minute ventilation. This study indicates that there is a significant decrease in PaO2 after chest vibration and suctioning increase in PaO2 after hyperventilation but these changes do not appear to be related to alterations in lung volume.

Experimental effects of acutely increased intracranial pressure on respiration and blood gases.

VER the last 10 years there has been a growing number of clinical observations concerning the alteration of respiratory function with disease of the central nervous system. 1~,~8,34 37,55 Within the specific field of head injury and increased intracranial pressure, improved monitoring techniques have called attention to the relationship of intracranial pressure waves and respiratory patterns. ~s Equally important, and intimately related, have been the observations concerning blood gas and acid-base alterations in head injury, and their prognostic significance. 5,1s,33,5~ These changes in the blood gases and acid-base balance alter the caliber of the cerebral vessels and the rate of cerebral blood flow. These in turn further increase the intracranial pressure. Clinical observations of our own have led us to believe that alterations in respiratory pattern may well be one of the earliest signs of increased intracranial pressure, far preceding the classical symptoms of clinically observed changes in pulse and blood pressure. This paper reports an investigation of the interrelationship of intracranial pressure, respiration, and blood gases under a controlled situation, using an extradural balloon to simulate compression of an epidural hematoma. 19,2~ Such a model, while subject to the criticism that relatively slow compression by a balloon simulates only one form of acute injury, is nevertheless controllable and repeatable. The absence of other factors in acute injury, such as acceleration, deceleration, contusion, hemorrhage, and laceration, limits the injurious effects studied primarily to those caused by compression and its resultant distortion; the method also provides means for careful monitoring of these effects.

Alterations in Pulmonary Functions

There is probably no other area of clinical medicine in which alterations in respiratory function occur so often, so quickly, and for such varied reasons as in the patient subject to anesthesia and operative treatment. In this area, then, there is a definite and important but unfortunately, insufficiently emphasized relationship between surgery and basic biology. To further establish this relationship, some elements of basic respiratory physiology need to be considered. Respiratory function is dependent upon a very complex arrangement which includes at least (1) neurosensory elements, (2) central integration in the brain, (3) neuromuscular effectors (neurotransmission, neuromuscular transmission, musculoskeletal function), and (4) ventilation of the lung (movement of gas, circulation). The neurosensory elements detect changes of a chemical or physical nature in the bloodstream or in special cells, send these to brain centers where the signal is integrated with signals from other areas of the body, and the brain centers,