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Biomedical subjects

D J Pierson

Publications and source records attributed to D J Pierson.

At least 73 records · Page 4Linked to original sources
PubMed1984

Subcutaneous and mediastinal emphysema. Pathophysiology, diagnosis, and management.

Subcutaneous emphysema and pneumomediastinum occur frequently in critically ill patients in association with blunt or penetrating trauma, soft-tissue infections, or any condition that creates a gradient between intra-alveolar and perivascular interstitial pressures. A continuum of fascial planes connects cervical soft tissues with the medlastinum and retroperitoneum, permitting aberrant air arising in any one of these areas to spread elsewhere. Diagnosis is made in the appropriate clinical setting by careful physical examination and inspection of the chest roentgenogram. While the presence of air in subcutaneous or mediastinal tissue is not dangerous in itself, prompt recognition of the underlying cause is essential. Certain trauma-related causes may require surgical intervention, but the routine use of chest tubes tracheostomy, or mediastinal drains is not recommended.

Emphysema↗
PubMed1983

Monitoring hemodynamics in the critically ill.

Intelligent, safe patient management based on hemodynamic monitoring requires that the right measurements be made, that the data so generated be accurate, and that the clinician's judgment and understanding of their use be appropriate. This article discusses the catheterization of systemic and pulmonary arteries, with an emphasis on the purposes to be served by monitoring rather than on specific measurements, techniques, or devices.

Cardiac Catheterization↗
PubMed1983

Effect of acetazolamide on normoxic and hypoxic exercise in humans at sea level.

Acetazolamide (A) is a potent inhibitor of carbonic anhydrase. It has been shown to be efficacious in preventing acute mountain sickness as well as decreasing the O2 desaturation that occurs during sleep in individuals with chronic mountain sickness who live at altitude. Very little data, however, are available about its effect on exercise. We studied six healthy males in a double-blind cross-over design using acetazolamide and placebo (P) during normoxic and hypoxic (fractional inspired O2 = 0.118) progressive work exercise to exhaustion on a bicycle ergometer. A metabolic acidosis was documented in all subjects on A (P less than 0.045). Before exercise, subjects on A had 2.0 and 3.5 l/min increase in minute ventilation (VE) during normoxia (P = not significant) and hypoxia (P less than 0.005), respectively, and a 2.2% increase in arterialized O2 hemoglobin saturation (SaO2) during hypoxia. During normoxic and hypoxic exercise, VE/kpm and SaO2/kpm were significantly higher while the respiratory exchange ratio (R) was significantly lower on A. These effects were greater on hypoxia. During normoxia, maximal O2 consumption (1/min) was lower on A [3.1 +/- 0.4 (A) vs. 3.8 +/- 0.2 (P), P less than 0.025] and higher during hypoxia on A[2.6 +/- 0.7 (A) vs. 2.4 +/- 0.1 (P), P less than 0.05]. The increase in exercise VE on A may result in an increased alveolar and subsequent arterial O2 tension which may be important for exercise at altitude. Carbonic anhydrase inhibition may also affect CO2 transport in the lung, which may explain the lower R.

Acetazolamide↗
PubMed1983

Variability of arterial blood gas values in stable patients in the ICU.

To establish guidelines for the interpretation of changes in arterial blood gas (ABG) values, we studied 29 clinically stable ICU patients for spontaneous variability in PaO2, PaCO2 and pH. ABGs were sampled six times over a 50-minute period, during which all patients received a fixed FIO2 of 0.5 via endotracheal tube and underwent no therapeutic interventions. Each sample was analyzed in duplicate with careful attention to method of collection and measurement. The range separating the lowest and highest PaO2 varied from 1 to 45 mm Hg (16.2 +/- 10.9 mm Hg [mean +/- SD] ). For PaCO2 this range was from 1 to 8 mm Hg (3.0 +/- 1.9 mm Hg). Coefficient of variation for PaO2 and PaCO2 averaged 5.1 +/- 3.2 percent (mean +/- SD) and 3.0 +/- 1.5 percent respectively. pH varied within 0.03 +/- 0.02 units. Percentage change in PaO2 between sequential intrapatient samples averaged 5.3 +/- 2.8 percent (mean +/- SD) and 7.1 +/- 7.9 percent over ten- and 50-minute intervals, respectively. Various clinical features were analyzed by multiple regression analysis for their relation to PaO2 variation. Only leukocyte count and mean arterial oxygen content were statistically significant associations (p less than 0.05), but together explained less than 35 percent of the variation observed. Because considerable spontaneous variation occurs, even in stable patients, clinicians should base therapeutic decisions on trends in PaO2 values rather than on isolated changes interpreted without appropriate clinical correlation.

Adult↗
PubMed1983

Confirmation of EMIT cannabinoid assay results by bonded phase adsorption with thin layer chromatography.

Clinical urine specimens were screened for the presence of cannabinoids using the EMIT Cannabinoid Assay. Aliquots of these samples were also analyzed for 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THCA), the major cannabis metabolite in urine, by a technique which combines bonded phase adsorption (BPA) and thin layer chromatography (TLC). A 100% agreement between EMIT and BPA-TLC results was observed when at least 20 mL of urine was assayed by BPA-TLC. Bonded phase adsorption coupled with thin layer chromatography appears to be a suitable technique for the confirmation of positive EMIT Cannabinoid Assay results.

Adsorption↗
PubMed1982

Augmentation of exercise ventilation by medroxyprogesterone acetate.

The influence of medroxyprogesterone acetate (MPA) on exercise performance was studied in a double-blind cross-over trial using six normal males to compare the exercise performance changes to those observed in a previous study of exercise responses of female subjects during the follicular and luteal phase of the menstrual cycle. A maximal progressive work exercise test on a cycle ergometer was performed after 2 weeks of placebo or MPA administration. Although five of six subjects spontaneously complained of increased exertional dyspnoea on MPA, no significant decreases were documented in maximal exercise time or in maximal oxygen consumption. A mean increase in exercise ventilation of 19% at low levels of exertion and 26% at high levels of exertion was documented, but no subject demonstrated evidence of ventilatory limitation. The increases in exercise ventilation observed in these male subjects after MPA administration were larger than those observed in the previous study comparing exercise ventilatory responses during follicular and luteal phases of the menstrual cycle. It seems possible that some other exercise-related modulator of the ventilatory response to exercise under the influence of progesterone is present in either male subjects receiving MPA or women with normal hormonal cycles.

Adult↗
PubMed1982

Asthma in the elderly: special challenge.

It is important both prognostically and therapeutically to recognize the "asthmatic component" in COPD. When this component is significant, the outlook is better and impressive improvement can be attained. Wheezing in the elderly must be differentiated from a number of conditions other than asthma. Excluding other causes is especially important in this age group, particularly when wheezing is of acute or recent onset.

Adrenal Cortex Hormones↗
PubMed1981

A practical procedure for measuring functional residual capacity during mechanical ventilation with or without PEEP.

The measurement of functional residual capacity (FRC) in patients receiving mechanical ventilation may provide valuable data in the assessment and management of acute respiratory failure. Previous descriptions of apparatus and techniques for FRC measurement have either been inapplicable to patients receiving positive end-expiratory pressure (PEEP), or insufficiently detailed to allow convenient duplication in the clinical setting. The authors describe a helium rebreathing method for bedside determination of FRC which can be performed during ventilation with PEEP and which is applicable in patients with prolonged equilibration times. The method is both reproducible in patients (variation from mean FRC: +/- 2.2%) and accurate (coefficient of variation from in vitro FRC of 3000 ml: +/- 1.7%). The apparatus and assembly are described in detail and require only components which are readily available commercially, so that they may be applicable to clinical use in a general hospital.

Adult↗
PubMed1981

Respiratory drives and exercise in menstrual cycles of athletic and nonathletic women.

To investigate the influence of the midluteal and midfollicular phases of the menstrual cycle on exercise performance and ventilatory drives, we studied six outstanding female athletes, six controls with normal menstrual cycles, and six outstanding athletes who were amenorrheic. In all menstruating subjects resting minute ventilation (Ve) and mouth occlusion pressures (P0.1) were higher in the luteal phase (p less than k0.0001 and p less than 0.02, respectively),. Hypoxic (expressed as the hyperbolic shape parameter A) and hypercapnic (expressed as S, deltaVE/delta PAco2) ventilatory responses were increase in the luteal phase (p less than 0.01). The athletes had lower A values during the luteal phase than the nonathletes (p less than 0.001). Maximal exercise response, expressed either as total exercise time or maximum O2 consumption or CO2 production (VO2 max or Vco2 max) was decreased during the luteal phase but was significantly different at a p less than 0.05 level only among the nonathletes. Ventilatory equivalent (VE/VO2) during progressive exercise on a bicycle ergometer was significantly increased during the luteal phase. The amenorrheic athletes showed no changes between the two test periods. The luteal phase of the menstrual cycle induced increases in ventilatory drives and exercise ventilation in both athletes and controls, but the athletes, in contrast to controls, demonstrated no significant decrease in exercise performance in the luteal phase.

Adolescent↗
PubMed1979

Acute lobar atelectasis: a prospective comparison of fiberoptic bronchoscopy and respiratory therapy.

To evaluate the usefulness of fiberoptic bronchoscopy for treatment of acute lobar atelectasis, 31 subjects were randomly allocated to fiberoptic bronchoscopy followed by respiratory therapy for 48 hours, or to respiratory therapy alone for the same period. No significant differences between groups with regard to restoration of volume loss were detected after the first treatment intervention, at 24 or at 48 hours (P greater than 0.20). Specifically, the mean percentage resolution of volume loss immediately after bronchoscopy (38 per cent) closely approximated that after the first respiratory therapy treatment in subjects who had not undergone bronchoscopy (37 per cent). An air bronchogram proved to be a predictor of delayed resolution for both groups. At 24 hours, 26 per cent of the air bronchograms demonstrated 83 per cent resolution (P less than 0.001). These results suggest that fiberoptic bronchoscopy does not add to respiratory therapy in the treatment of acute lobar atelectasis and that an air bronchogram predicts delayed resolution of collapse.

Adolescent↗
PubMed1979

The significance of wheezing in chronic airflow obstruction.

Eighty-three patients with chronic airflow obstruction were examined prospectively to determine the relationships among wheezing intensity, severity of obstruction, and response to inhaled isoproterenol. For each patient, expiratory wheezing scores were assigned during deep unforced breathing and during forced vital capacity efforts at spirometry. Unforced wheezing scores were independently correlated with severity of obstruction (r = 0.42) and bronchodilator response (r = 0.46), but these correlations did not permit consistent prediction of either variable for clinical purposes. The highest wheezing scores, however, were uniformly associated with moderate or severe obstruction. Twenty-nine of 48 patients with wheezing but only 3 of 35 patients without wheezing demonstrated 15% or greater improvement in one-second forced expiratory volume after bronchodilator inhalation (p less than 0.001). Wheezing during forced exhalation was not correlated with either degree of obstruction or bronchodilator response.

Aged↗