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Biomedical subjects

R M Goldring

Publications and source records attributed to R M Goldring.

46 records · Page 3Linked to original sources
PubMed1968

Respiratory adjustment to chronic metabolic alkalosis in man.

This study examined the ventilatory adjustment to chronic metabolic alkalosis induced under controlled conditions in normal human volunteers. Metabolic alkalosis induced by buffers (sodium bicarbonate, trishydroxymethylamine methane) or ethacrynic acid was associated with alveolar hypoventilation, as evidenced by a rise in arterial Pco(2), a fall in arterial Po(2), a reduced resting tidal volume, and a diminished ventilatory response to CO(2) inhalation. Alveolar hypoventilation did not occur when metabolic alkalosis was induced in the same subjects by thiazide diuretics or aldosterone despite comparable elevations of the arterial blood pH and bicarbonate concentration.The different ventilatory responses of the two groups could not be ascribed to differences among individuals comprising each group, pharmacological effects of the alkalinizing agents, differences in the composition of the lumber spinal fluid, changes in extracellular fluid volume, or sodium and chloride balance.The differences in ventilatory adjustments were associated with differences in the patterns of hydrogen and potassium ion balance during the induction of alkalosis. Alveolar hypoventilation occurred when hydrogen ions were buffered (sodium bicarbonate, trishydroxymethylamine methane) or when renal hydrogen ion excretion was increased (ethacrynic acid). Alveolar hypoventilation did not occur when induction of similar degrees of extracellular alkalosis was accompanied by marked potassium loss and no demonstrable increase in external hydrogen loss (thiazides and aldosterone).These observations suggest that respiratory depression does not necessarily accompany extracellular alkalosis but depends on the effect of the mode of induction of the alkalosis on the tissues involved in the control of ventilation.

Journal Article↗
PubMedDate not supplied

The influence of lung volume on expiratory flow rates in diffuse interstitial lung disease.

This study evaluated maximum expiratory flow rates with respect to lung volume and maximum recoil pressure in selected patients with diffuse interstitial lung disease who had normal large airway function by standard technique. Coefficient of retraction was normal or greater than normal in all. Peak flow varied directly with lung volume as in normals. At 50% vital capacity (VC) and 25% VC, the absolute flow rates varied from higher to lower than normal. However, when flow was adjusted to volume, the flow/volume ratio was normal or high in all. Flow/volume ratio at mid-lung volume appeared to increase with increase in coefficient of retraction. Patients with frequency dependence of compliance had lower flow/volume ratios at 25% VC than those without, although still within normal range. Thus, despite recognized wide variations in normals, the flow/volume ratio is pertinent to the evaluation of reduced air flow rates in in interstitial lung disease to distinguish abnormal upstream airway resistance from volume-dependent reduction of flow rate. An effort-independent flow rate that yields a supernormal flow/volume ratio suggests increased recoil properties of the respiratory system.

Adult↗
PubMedDate not supplied

Relationship of functional residual capacity to static pulmonary mechanics in chronic obstructive pulmonary disease.

Static pulmonary mechanics may not be the sole determinant of the functional residual capacity (FRC) in the chronic obstructive pulmonary diseases (COPD). To assess the relationship of FRC to pulmonary mechanics, pulmonary function tests such as spirometry, lung volumes, maximum expiratory flow volume curves, and single-breath diffusing capacity were related to compliance measurements in 65 patients with stable COPD. Compliance studies were examined over the range of tidal volume and at maximum lung inflation. The results showed that there was a poor correlation between the degree of hyperinflation at FRC and static compliance in the tidal range. However, there was a highly significant correlation between FRC and static lung mechanics at maximum lung inflation, as well as between FRC and diffusing capacity. Thus, in patients with stable COPD, FRC is a useful guide to static recoil properties of the lung as assessed at maximum lung inflation. Lung compliance measurement in tidal range may not reflect this relationship. An increase in FRC remains a useful index of pulmonary emphysema, even in the presence of chronic airway disease.

Adult↗
PubMedDate not supplied

Nasal CPAP in obstructive sleep apnea: mechanisms of action.

Sixteen patients with the obstructive sleep apnea syndrome (OSAS) were studied for 1-2 h while receiving continuous positive airway pressure (CPAP) delivered via a nasal mask. Obstructive apneas were obliterated in all. Eight patients had studies of genioglossal muscle activity (GG EMG) and one patient had computed tomograms (CT) of the upper airway while on nasal CPAP. The GG EMG studies showed two patterns: suppression and augmentation of GG EMG while on CPAP. The CT scan showed the airway to be narrowed while the patient was awake off CPAP. It returned to a normal caliber when CPAP was applied, despite sleep. These results are interpreted to suggest three potential mechanisms of action for nasal CPAP in OSAS: 1) reduced upper airway resistance due to prevention of sleep-induced collapse of the airway; 2) reduced upper airway resistance due to dilatation of the airway by nasal CPAP beyond its dimension in the awake state; and 3) possible stimulation of mechanoreceptors leading to an increase in airway tone while CPAP is applied.

Airway Resistance↗