Search PubMed⌕ Search

Biomedical subjects

D J Pierson

Publications and source records attributed to D J Pierson.

At least 55 records · Page 3Linked to original sources
PubMed1987

Severe precocious emphysema in intravenous methylphenidate (Ritalin) abusers.

Intravenous (IV) drug abuse is known to cause pulmonary tale granulomatosis. Reports have documented a syndrome of pulmonary vascular sclerosis in long-term IV methylphenidate users. Although this would be expected to produce restrictive lung disease, we hereby report six patients who have severe obstructive lung disease. All had used IV methylphenidate for at least four years. One of these patients died of progressive respiratory insufficiency and the others are clinically disabled. Their symptoms and airflow obstruction are more severe than those of most patients with chronic obstructive pulmonary disease. In these individuals, we cannot say that precocious obstructive lung disease is not due to a combination of smoking and other factors, nor can we be certain that methylphenidate is the offending agent. However, this cluster of cases among methylphenidate abusers suggests that long-term IV exposure to this drug might lead to early severe obstructive lung disease.

Adult↗
PubMed1987

Comparison of high-frequency jet ventilation with conventional mechanical ventilation for bronchopleural fistula.

In seven patients with acute respiratory failure and a bronchopleural fistula, the authors compared gas exchange and volume of gas lost via the chest tube during conventional mechanical ventilation (CV) and high-frequency jet ventilation (HFJV). After the initial comparison, patients were randomized to HFJV or CV, unless one mode of ventilation was clearly superior based on preestablished criteria. In six of the seven patients, oxygenation deteriorated after the switch from CV to HFJV. The ratio of PaCO2 to FI02 declined from 227 +/- 167 to 133 +/- 100 (mean +/- SD, P less than 0.05), and the PaCO2 increased from 47 +/- 13 to 56 +/- 18 mm Hg (P less than 0.05). The mean chest tube leak did not change significantly. Randomization of the mode of ventilation was not performed in any patient because CV was superior by a priori criteria. We conclude that when acute respiratory failure is complicated by a bronchopleural fistula, HFJV with mean airway pressures comparable to those provided during conventional ventilation does not provide satisfactory gas exchange.

Acute Disease↗
PubMed1986

Influence of body size and gender on control of ventilation.

Hypoxic (HVR) and hypercapnic (HCVR) ventilatory responses are influenced by both metabolic activity and hormonal factors. By studying 67 subjects of both sexes, including those at the extremes of stature, we examined the influence of gender, CO2 production (VCO2), O2 consumption (VO2), body surface area (BSA), and vital capacity (VC) on resting ventilation (VE), HVR, and HCVR. We measured resting VE, VO2, and VCO2 and then performed isocapnic progressive hypoxic and hypercapnic ventilatory responses. The effect of stature was reflected in higher VE and metabolic rate (both P less than 0.001) in tall men compared with short men that was ablated by correction for BSA. Perhaps because their heights vary less than those of the men, tall women were not statistically distinguishable from short women in any of these measured parameters. Tall men tended to have greater hypoxic chemosensitivity than short men but this was not significantly different (P = 0.07). Gender affected the control of ventilation in a number of ways. Men had higher VE (P less than 0.05) and metabolic rate (P less than 0.001) than women. Even after correction for BSA men still had higher metabolic rates. Women had higher VE/VCO2 than men (P less than 0.05) and lower resting end-tidal Pco2 (PETCO2) values (P less than 0.05). Both A, the shape parameter of the hyperbolic HVR curve, and HVR determined from mouth occlusion pressure (AP) were greater in women than in men, although only AP reached statistical significance. However, corrections of A for BSA (P less than 0.05), VCO2 (P less than 0.01), and VC (P less than 0.001) amplified these differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Persistent bronchopleural air leak during mechanical ventilation. A review of 39 cases.

Bronchopleural fistula (BPF), or bronchopleural air leak, is regarded as an ominous complication of ventilator management in acute respiratory failure, but data on its natural course and prognosis are lacking. We reviewed all instances of mechanical ventilation at a major trauma center during a four-year period, and found that 39 of the 1,700 mechanically-ventilated patients developed BPF lasting at least 24 hrs. Overall mortality in these 39 patients was 67 percent, and this was higher when BPF developed late in the illness (16 of 17, or 94 percent, when mean onset was hospital day 13), than when it occurred within 24 hours of admission (ten of 22, or 45 percent, p = 0.002). Survival in patients with chest trauma (12 of 27, 44 percent), most of whom had air leaks on or just after admission, was better than in those with other primary diagnoses (one of 12, 8 percent, p less than 0.005). All eight patients whose maximum air leak exceeded 500 ml per breath died, whereas 13 of 30 with smaller maximum leaks survived (p less than 0.05). Despite leaks as large as 900 ml per breath, however, conventional ventilator adjustments permitted avoidance of severe respiratory acidosis (pH less than 7.30) in all but two patients. We conclude that the occurrence of BPF during mechanical ventilation identifies patients with high mortality, but that unmanageable respiratory acidosis from this complication is rare.

Acidosis, Respiratory↗
PubMed1986

A simple technique for pulmonary function testing in patients with permanent tracheostomies.

UNLABELLED: In patients with permanent tracheostomies, the clinician can encounter difficulty in creating a satisfactory seal between the patient and pulmonary function testing (PFT) equipment. We have developed a simple apparatus and procedure for effecting a tight seal during testing. MATERIALS AND METHODS: The seal around the tracheostomy is made with a newborn-size resuscitation mask, the hole of which is larger than the tracheal stoma. A sealing lubricant is applied to the soft rim of the mask and around the tracheostomy site, and adapters enable connection of the resuscitation mask and the large-bore PFT-equipment tubing. After affixing the adapters to the mask, we check that the seal is tight; if airleak is evident, more lubricant or a mask of different size or style may be necessary. Once a tight seal is achieved without airway compromise, the mask is attached to the PFT equipment and testing can begin. During testing, the patient should wear nose clips to prevent volume loss through the upper airway. COMMENTS: This equipment is simple, inexpensive, and readily available. Further, it permits pulmonary function testing whether or not a tracheostomy tube is in place, an advantage if variable extrathoracic upper airway obstruction is a consideration. If the patient has a cuffed tracheostomy tube in place, the PFT equipment can be connected directly to the tube. We have found that this apparatus and technique are well tolerated and that test results are reproducible.

Equipment and Supplies, Hospital↗
PubMed1986

Contamination of a multiple-use suction catheter in a closed-circuit system compared to contamination of a disposable, single-use suction catheter.

UNLABELLED: Multiple-use (M-U) closed-system endotracheal suction catheters are effective in preventing arterial oxygen desaturation in patients on positive end-expiratory pressure (PEEP) and may lessen the frequency of bradycardia and hypotension in unstable patients who are prone to these complications of suctioning. However, because M-U catheters remain attached to the ventilator circuit and are reintroduced repeatedly into the patient's airway over 24 hours or longer, they could become heavily contaminated with pathogens. We hypothesized a risk of autocontamination to the patient by re-inoculation of the respiratory tract with organisms that flourished on the M-U catheter while it was isolated from the patient's immune defenses or antibiotic therapy. METHODS: We tested this hypothesis in 30 mechanically ventilated adult patients with positive sputum cultures. We measured and compared the amount of bacteria present on an M-U catheter at the end of a 24-hour use period, the amount of bacteria present in the patient's sputum at that time, and the amount of bacteria present on a single-use (S-U) catheter at that time, after it had made one pass into the patient's airway. Organisms recovered and colony counts were also compared to results of a sputum culture obtained before the study began. RESULTS: Fourteen different pathogens or potential pathogens were recovered, in numbers of 2 x 10(1) to 2 x 10(7)colony-forming units. The greatest number of colonies was most often recovered from the sputum specimen, and statistical analysis showed no differences in rate or magnitude of contamination between M-U and S-U catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Design and evaluation of a nitrous oxide scavenging system for use in nontraditional hospital settings.

Analgesic use of nitrous oxide (N2O) in nontraditional settings requires safe and effective scavenging systems to rid the work area of hazardous waste gas. Significant health risks to health care workers are associated with repetitive exposure to excessive levels of N2O. Regulations limit the exposure level to 25 parts per million and also require the use of effective scavenging systems. We tested the existing room ventilation and a suction-powered scavenging system in our burn unit's hydrotherapy room and found them to be inadequate in maintaining safe room air levels. We therefore developed a fan-powered scavenging system using a ceiling-mounted hood, under which N2O is administered, and found it to maintain safe levels while requiring little patient cooperation and allowing complete access to the patient.

Burn Units↗
PubMed1986

Confirmation of Syva enzyme multiple immunoassay technique (EMIT) d.a.u. and Roche Abuscreen radioimmunoassay (RIA) (125I) urine cannabinoid immunoassays by gas chromatographic/mass spectrometric (GC/MS) and bonded-phase adsorption/thin-layer chromatographic (BPA-TLC) methods.

Thirty human urines screened positive by the Syva enzyme multiple immunoassay technique (EMIT) d.a.u. urine cannabinoid assay were also positive for the major marijuana urinary metabolite 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) when assayed by gas chromatographic/mass spectrometric (GC/MS) and a noninstrumental qualitative bonded-phase adsorption/thin-layer chromatographic (BPA-TLC) technique. The noninstrumental BPA-TLC procedure was the simpler of the two techniques to perform and interpret. Assay of these same samples by the Roche Abuscreen radioimmunoassay (RIA) for cannabinoids (125I) revealed that reliance on the 100-ng/mL equivalent positive calibrator yielded a high incidence of false negative results (10 out of 30). The performance of these same 4 assays on 30 true negatives also was evaluated. All samples were negative for cannabinoids by EMIT and RIA, and for THC-COOH by BPA-TLC. GC/MS assay, however, detected spurious low levels of approximately 5-ng/mL THC-COOH in two instances. Because of this, a reliability level of 10 ng/mL was set for the routine quantitative confirmation of THC-COOH by the GC/MS method.

Chromatography, Thin Layer↗
PubMed1986

Ventilatory management in acute lung injury.

Practical theoretic aspects of the adult respiratory distress syndrome and its application to the patient are presented. Rational utilization of mechanical ventilation and positive end-expiratory pressure in the management of hypoxemia is discussed in detail.

Humans↗
PubMed1985

The matching of ventilation and perfusion in the lung of the Tegu lizard, Tupinambis nigropunctatus.

Ventilation-perfusion (VA/Q) distribution was evaluated in the Tegu lizard, Tupinambis nigropunctatus, using the multiple inert gas elimination technique (MIGET) in order to define the limitations to gas exchange in the large chambered unicameral lung. The lizards (0.52-1.1 kg) were anesthetized with halothane and ventilated. Body temperature was maintained at 35 degrees C. Arterial and sinus venosus PO2 averaged 79.4 +/- 5.9 and 47.3 +/- 6.4 torr while breathing air and 232.1 +/- 31 and 64.8 +/- 11.5 torr while breathing oxygen. VA/Q distributions were broad and right-to-left shunt averaged 21% while breathing air and 27% while breathing oxygen. Gas exchange was significantly impaired due to the presence of both shunt and VA/Q heterogeneity. The walls of the lung enclose a large axial air chamber. Microscopic examination revealed approximately three generations of septa which subdivided the wall into tubular-shaped gas-exchange chambers. Wall thickness averages 2.8 mm at the anterior end of the lung, 2.1 mm in the middle portion of the lung and 1.4 mm at the posterior end. The thickness of the blood-air barrier (epithelial-basal lamina-endothelial cell layer) ranged from 0.35 to 0.90 micron. Although this barrier is slightly thicker than in the mammalian lung (0.1-0.5 micron), it is unlikely to be a source of diffusion limitation in gas exchange at rest.

Animals↗
PubMed1985

Testosterone replacement in hypogonadal men: effects on obstructive sleep apnoea, respiratory drives, and sleep.

The obstructive sleep apnoea syndrome occurs predominantly in men. To determine the effect of testosterone on ventilatory function and whether testosterone may play a role in the development of obstructive apnoea, we performed waking ventilatory drive studies and sleep studies in five hypogonadal men. These androgen-deficient subjects were studied both while receiving no treatment and after six weeks of testosterone replacement therapy (testosterone oenanthate 200 mg i.m. every 2 weeks). Hypoxic ventilatory drive decreased significantly, from 158 +/- 39 (mean +/- SEM) off testosterone to 88 +/- 19 on testosterone therapy (P less than 0.05). Hypercapnoeic ventilatory drive did not change significantly on testosterone. Obstructive sleep apnoea developed in one man and markedly worsened in another man in association with testosterone administration. Both of these subjects also exhibited marked decreases in oxygen saturation with the development of cardiac dysrhythmias during sleep and large increases in haematocrit. The remaining three hypogonadal men did not demonstrate significant sleep apnoea either on or off testosterone. The percentage of sleep time spent in REM sleep increased from 14 +/- 3% to 22 +/- 2% when the men were receiving testosterone (P less than 0.01), but the episodes of sleep apnoea tended to occur during non-REM sleep. We conclude that in some hypogonadal men, replacement dosages of testosterone may affect ventilatory drives and induce or worsen obstructive sleep apnoea. The obstructive sleep apnoea syndrome is a potential complication of testosterone therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Pulmonary function in subjects at the extremes of stature.

Normal indexes of pulmonary function are based on data from large numbers of persons, using sex, size, and age as independent determinants. The influence of aging has been well examined, but few subjects at the extremes of stature have been included in previous studies. The predicted normal values are extrapolated from data acquired in studies of persons of average height. To evaluate these predictions at the extremes of stature, we performed full pulmonary function testing in 49 healthy, nonsmoking Caucasian subjects (28 men, 21 women) who were either above the 99th or below the 5th percentile for height. Nineteen subjects of average height (9 men, 10 women) performed spirometric testing. The techniques and equipment used met the American Thoracic Society's recommendations. We demonstrated that predicted values of pulmonary function testing can be extended to include those persons at the extremes of stature.

Adult↗
PubMed1985

Does intermittent mandatory ventilation correct respiratory alkalosis in patients receiving assisted mechanical ventilation?

One of the claimed advantages of intermittent mandatory ventilation (IMV) over assisted mechanical ventilation (AMV) (assist-control) is the avoidance or correction of acute respiratory alkalosis, ostensibly by allowing patients to achieve normal alveolar ventilation (VA) and PaCO2 through the function of an intact ventilatory drive. However, although respiratory alkalosis in patients being hyperventilated with controlled mechanical ventilation (CMV) can be corrected by a change to IMV, CMV is seldom appropriate for patients with acute respiratory failure, and whether IMV affects respiratory alkalosis in patients triggering the ventilator in the AMV mode has not previously been tested. We studied 26 patients with acute respiratory alkalosis (pH greater than or equal to 7.48) while receiving AMV. Measurements of arterial blood gases and CO2 production (VCO2), and calculation of VA, were performed after 30 min of AMV, repeated after 30 min of IMV at a mandatory rate one half the previous AMV rate, and then repeated again 30 min after a return to the original AMV settings. Mean arterial pH decreased slightly from 7.51 during AMV to 7.48 during IMV, and returned to 7.51 on resumption of AMV (p less than 0.05 for both changes); corresponding mean values for PaCO2 were 28.6, 29.7, and 27.5 mmHg, respectively. These changes were related to an increase in VCO2 during IMV as compared with AMV (p less than 0.05), without a significant alteration in VA. When the mandatory rate was further reduced during IMV from one half to one fourth the prior, triggered AMV rate in 10 patients, no additional reduction in pH occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Cardiac asystole during an hypoxic drive study in a normal subject.

A healthy 31-year-old man who had previously sojourned to an altitude of 5,000 meters with no detrimental effect developed sudden cardiac asystole during a progressive hypoxic ventilatory response ( HVR ) test. At the moment of asystole, his alveolar PO2 (PAO2) was 41 mm Hg and his arterial oxygen saturation (SaO2) was 81 percent. Cardiopulmonary resuscitation was initiated, and after 20 seconds of asystole and apnea, he recovered normal sinus rhythm and spontaneous respiration. A subsequent ECG and cardiac enzyme levels were normal. During testing, he demonstrated depressed ventilation in response to hypoxia and a slowing of the heart rate. Careful observation of heart rate and breath-by-breath ventilation during HVR tests may predict this potentially fatal complication.

Adult↗
PubMed1984

Prospective evaluation of amiodarone pulmonary toxicity.

Reports of pulmonary infiltrates in patients taking amiodarone, initiated the study of 69 patients for pulmonary toxicity using serial chest roentgenograms (CXRs), pulmonary function tests (PFTs), and symptoms before and during therapy. Mean PFTs did not significantly change from their baseline normal values, but 10 percent of patients had a greater than or equal to 15 percent fall in total lung capacity, and 28 percent a greater than or equal to 15 percent fall in diffusion capacity (DCO) following treatment. Initial abnormalities in pulmonary function or CXR were predictive of risk of developing pulmonary toxicity. Degree of exposure to amiodarone (dose plus duration) correlated only weakly with development of pulmonary toxicity, which could occur in patients taking relatively small doses of the drug. Pulmonary complications of amiodarone are common, in most cases reversible, and often confused with congestive heart failure or pneumonia. Patients should be evaluated before treatment by assessing symptoms, CXRs, and DCO. Patients with initial abnormalities in these parameters, particularly both CXR and DCO abnormalities, should be considered for alternative therapy.

Adult↗