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P J Fahey

Publications and source records attributed to P J Fahey.

34 records · Page 2Linked to original sources
PubMed1987

Key issues in nutrition. From conception through infancy.

Pregnant and lactating women and infants are at nutritional risk because of their special needs; both require adequate dietary nutrition and, often, dietary supplementation. For example, the mother's increased requirements for iron, calcium, folic acid, and vitamin D usually must be met with increased milk intake and multivitamin-with-mineral supplements. Since the pregnant and the lactating woman can pass both nutrients and nonnutrients to the child, she should be advised on a well-balanced, high-quality diet that is free of drugs or other additives that may be harmful. Although either breastfeeding or the use of formula may fulfill energy and protein needs, the infant may require supplemental vitamins K and C, fluoride, and iron.

Bottle Feeding↗
PubMed1987

Key issues in nutrition. During childhood and adolescence.

Good nutrition is important between ages 2 and 18, because growth and maturation are taking place and because future eating habits are being established. The primary care physician can assist children and adolescents by evaluating high-risk factors, such as a family history of cardiovascular disease or hypercholesterolemia, and by recommending supplemental nutrients as indicated. Possibly more important, though, is the counseling the physician can give these patients and their parents to promote a life-style that may prevent disease.

Adolescent↗
PubMed1987

Key issues in nutrition. Disease prevention through adulthood and old age.

Certain dietary practices are valid methods of lowering the risk of disease. Others, while popular, have unproven benefits or may even be associated with risks of their own. Careful evaluation of hypercholesterolemia is necessary. Persons with a high level of low-density lipoprotein (LDL) cholesterol and a low level of high-density lipoprotein (HDL) cholesterol need diet therapy, because they are at increased risk of cardiovascular disease. Weight reduction and fat restriction can lower blood pressure, help control hyperglycemia, and improve the LDL cholesterol-HDL cholesterol ratio. Some evidence indicates a protective role of beta carotene against cancer in animals. However, hypervitaminosis A is dangerous and relatively easy to accomplish, so supplementation beyond a multivitamin tablet is discouraged. Data about inhibition of cancer in humans through use of high doses of vitamin E or C or selenium are inconclusive, and studies of effects of long-term ingestion are not available. In general, megadoses of even healthy substances are thought to be dangerous. Decreased consumption of fat, increased consumption of foods high in fiber, and elimination of alcohol and tobacco are sensible recommendations. Consumption of cruciferous vegetables has not been proven to reduce the incidence of cancer, but a moderate amount of them in the diet would seem reasonable.

Adult↗
PubMed1987

Office-based assessment of pulmonary function.

PFT is a valuable tool for evaluating the patient with respiratory complaints and for screening the high-risk population. It is no longer only a hospital-based test, but, with current technology, is an efficient, practical procedure that can be performed in an office at minimal cost to the patient. In addition, serial spirometry can be used to identify high-risk populations and gauge response to bronchodilator therapy. Spirometry should be performed routinely in all smokers older than 40.

Adult↗
PubMed1986

Measurement of lung gas volume and regional density by computed tomography in dogs.

To determine if computed tomography (CT) can accurately measure lung volume, we compared lung gas volume measured by helium dilution with the equivalent volume calculated from CT total lung volume and density in 13 supine dogs. CT lung gas volume underestimated helium volume by 34% (range: -63 to 0%). Studies of wooden lung phantoms varying in density from 0.082g/cc to 0.776g/cc showed that only 15% of this error could be mimicked by the phantoms. The rest of the discrepancy is attributed to the lung's irregular borders, and the sharp density gradients surrounding and within the lung that result in x-ray beam hardening, sampling limitations, and partial volume measurement errors. Serial biweekly measurements in three dogs for 14 weeks showed CT gas volume to be highly reproducible with less scatter than seen in the helium measurements. Density in the lungs of all dogs showed a uniform gradual decrease from approximately 0.60g/cc at the dependent surface to 0.20g/cc at the superior surface with relatively constant density at any horizontal level. These studies show that whereas CT underestimates gas volume in the lungs, serial measurements are highly reproducible in experimental studies and are a promising technique to monitor diseases or response to therapy. Density gradients in the lungs were sufficiently uniform so that disruption of the normal gradient may be an indicator of early lung disease.

Animals↗
PubMed1986

Relationship of tracheal size to maximal expiratory airflow and density dependence.

Wave-speed theory predicts that maximal expiratory flow (MEF) at high lung volumes depends strongly on size of central airways. We tested this prediction by correlating MEF and tracheal cross-section area (T-XSA) in 15 (11 males, 4 females) healthy never-smoking volunteers. T-XSA was determined by planimetric analysis of contiguous 1-cm computerized tomographic scans of the intrathoracic trachea. We found a significant correlation between T-XSA at total lung capacity (TLC) and flow at 75% of vital capacity (V75) (r = 0.88, P less than 0.001). This contrasted to the correlation found between lung volume at TLC and V75 (r = 0.60). Density dependence of airflow (percent increase in V75 in air) was 35 +/- 17% and showed a significant inverse relationship to T-XSA (r = 0.70). These results confirm predictions of wave-speed theory and demonstrate the importance of cross-sectional area of central airways in determining MEF at high lung volumes. The large variability of MEF in normal individuals partly represents variations in tracheal size. Poor correlation between lung size and airway size suggests only a loose coupling between airways and lung parenchyma consistent with dysanaptic growth. Our findings indicate that changes in density dependence of airflow are not solely determined by the status of small airways and that differences in tracheal size contribute to its variability.

Adult↗
PubMed1985

Effect of the rebreathing pattern on pulmonary tissue volume and capillary blood flow.

Noninvasive rebreathing measurements of pulmonary tissue volume (Vt) and pulmonary capillary blood flow (Qc) theoretically and experimentally vary with the rebreathing maneuver. To determine the cause of these variations and identify ways to minimize them, we examined the consequences of varying the volume inspired (VI), rebreathing rate (f), volume rebreathed (Vreb), and alveolar volume (VA) on the observed Vt and Qc in six normal sitting subjects. When VA was increased by progressively larger VI and Vreb, Vt increased 50 ml/l of VA. Increasing VA while keeping VI and Vreb constant did not significantly alter Vt. Diminishing Vreb while VA and VI constant caused Vt to fall 108 ml/l decrease in Vreb. Therefore the observed Vt is not simply a function of VA but increased with greater penetration of the inspired gas into the lungs. Diminishing f from 40 to 12 breaths/min caused the observed Vt to rise 27%, indicating time allowed for alveolar mixing is an important determinant of Vt. The observed Qc, in contrast, was essentially independent of the same variations in rebreathing. The above findings were similar regardless of solubility of the tracer gas (dimethyl ether instead of acetylene) or changing to the supine position. A two-compartment series lung model derived from the anatomy and rates of gas mixing in normal human pulmonary lobules produced similar changes in Vt. Thus the degree of uneven distribution between ventilation, VA, Vt, and Qc within the normal lung lobule can account for variations in the observed Vt with different ventilatory maneuvers. Slow deep breathing maneuvers tended to reduce variations in Vt. Unlike Qc, the observed value of Vt can be expected to vary substantially with pathological processes that alter pulmonary gas distribution.

Acetylene↗
PubMed1985

Oxygen cost of breathing. Changes dependent upon mode of mechanical ventilation.

We describe a patient with respiratory failure who demonstrated marked increases in O2 consumption (VO2) when breathing with synchronized intermittent mandatory mechanical ventilation (SIMV). When the mode of ventilation was changed to facilitate inspiratory gas flow (pressure-support) during spontaneous breathing, O2 consumption decreased 27 percent. Several important factors contributing to the increased O2 cost of breathing in patients requiring mechanical ventilation are reviewed, including the high internal resistance of demand-flow SIMV systems.

Aged↗
PubMed1984

Raynaud's phenomenon of the lung.

To determine if pulmonary vessels develop vasospasm during Raynaud's phenomenon, digital vasospasm was induced by hand immersion in 15 degrees C water (cold pressor test) in 17 subjects, and pulmonary function was measured during the subsequent 120 minutes. Five healthy persons were control subjects, seven subjects had well documented systemic disorders associated with Raynaud's phenomenon (secondary Raynaud's), and five subjects had a history of Raynaud's phenomenon but no evidence of an associated disorder (primary Raynaud's). The only measure of pulmonary function that changed significantly following cold pressor testing was carbon monoxide diffusing capacity. Subjects with primary Raynaud's phenomenon had normal baseline carbon monoxide diffusing capacity (23.7 +/- 4.6 ml/minute/mm Hg) but demonstrated significant decreases (p less than 0.05) at 15 minutes (21.2 +/- 3.5 ml/minute/mm Hg), 45 minutes (19.5 +/- 3.7 ml/minute/mm Hg), and 120 minutes (17.1 +/- 2.1 ml/minute/mm Hg) after cold pressor testing. Subjects with secondary Raynaud's phenomenon had low baseline carbon monoxide diffusing capacity (71 percent predicted) and showed no significant change following cold pressor testing. These findings indicate that digital vasospasm in patients with primary Raynaud's phenomenon is part of a systemic vascular response that includes a decrease in the size of the pulmonary capillary bed.

Adult↗
PubMed1984

Clinical experience with continuous monitoring of mixed venous oxygen saturation in respiratory failure.

The amount of oxygen in mixed venous blood (SvO2) is a reliable indicator of the status of oxygenation of tissue in most clinical settings. Monitoring levels of SvO2 might, therefore, aid in managing critically ill patients. A recently developed adult pulmonary arterial catheter provides continuous measurement of SvO2 via fiberoptic bundles incorporated into the catheter, in addition to measuring hemodynamic pressures and cardiac output by thermodilution. We evaluated 100 consecutive fiberoptic catheters for accuracy and reliability of the system in 86 critically ill adult patients and determined the clinical usefulness that knowledge of SvO2 provided. Over a range of hemoglobin saturations from 24 to 85 percent, the correlation coefficient between in vivo SvO2 vs photometrically measured samples for 199 paired measurements was 0.95. Mean duration of usage for 33 catheters in the medical intensive care unit was 6.1 days; all catheters functioned normally until clinical conditions permitted removal. Continuous measurements of SvO2 detected unsuspected increases in tissue oxygen consumption during coughing spasms and positioning of the patient. In nine of 13 patients with hypoxemic respiratory failure requiring positive end-expiratory pressure (PEEP), we found a strong correlation (r = 0.88) between oxygen delivery and SvO2. Of the four patients not showing correlation, two had sepsis, and two had nearly normal values of SvO2 and oxygen delivery at all levels of PEEP studied. Continuous measurement of SvO2 improves monitoring of patients, facilitates titration of respiratory therapies, detects abrupt changes in tissue oxygen consumption, and identifies levels of PEEP associated with greatest oxygen delivery.

Adult↗
PubMed1983

"Won't breathe" vs "can't breathe". Detection of depressed ventilatory drive in patients with obstructive pulmonary disease.

Impaired pulmonary mechanics or depression of the respiratory centers can limit the ventilatory response to inhaled carbon dioxide in patients with chronic obstructive pulmonary disease (COPD). We devised a method able to detect depressed neurogenic and chemical ventilatory drive during expiratory airflow obstruction. In 14 normal subjects, we impeded expiratory airflow while measuring the resultant decline in maximum voluntary ventilation (MVV) and the ventilatory response to rebreathing 7 percent CO2 (delta V/delta PCO2). The MVV and delta V/delta PCO2 fell proportionately and were closely correlated (r = 0.88). The lower limit for delta V/delta PCO2 during airway obstruction equalled 1.2 L/min/mm Hg X (observed MVV divided by predicted MVV). Nine patients with COPD and normal arterial carbon dioxide tension (PaCO2) all had normal values for delta V/delta PCO2 corrected for MVV; however, nine of 12 patients with COPD and elevated PaCO2 and bicarbonate levels had depressed values for delta V/delta PCO2. These data indicate that neurogenic and chemical depression to ventilation can be detected in patients with mechanical obstruction to expiratory airflow if delta V/delta PCO2 is corrected for changes in MVV.

Adolescent↗
PubMed1981

Spontaneous lysis of mycetomas after acute cavitating lung disease.

Pulmonary mycetomas (fungus balls) caused by mucormycosis and aspergillus developed in 2 patients after aspiration pneumonia and septic lung infarction. No specific therapy was initiated and both fungus balls underwent spontaneous lysis. These patients and the descriptive literature of other patients with fungus balls secondary to acute lung damage suggest that mycetomas forming in acutely damaged but previously healthy lung tissue have a high incidence of spontaneous resolution. Therapy with antifungal agents or resectional surgery is not required unless hemoptysis or chronic suppurative infection develops.

Acute Disease↗