Foreign-body aspiration, asthma and chronic bronchitis.
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Asthma↗
Biomedical subjects
T K Aldrich
Publications and source records attributed to T K Aldrich.
Effects of fire fighting uniform (modern, modified modern, and traditional) design changes on exercise duration in New York City Firefighters.
Fire departments have replaced traditional uniforms with modern, more thermal protective gear. Although the new uniforms afford superior burn protection, they may reduce work time. Our purpose was to determine if exercise time was (1) reduced by wearing the modern versus traditional uniform, and (2) increased by a design change to a modified modern uniform (T-shirt and short pants rather than a shirt and long pants under the outer uniform). Male firefighters (n = 23; age 27 to 59) performed a maximum exercise test in gym clothes (maximal oxygen consumption = 46 +/- 9 ml/kg/min) and then returned on separate days to exercise using a moderately high intensity, constant work rate treadmill protocol while wearing fire fighting breathing apparatus and each of three uniforms. Firefighters exceeded anaerobic threshold by 1 minute and eventually reached or exceeded maximum heart rate and maximal oxygen consumption. Exercise time in modern (15 +/- 3 min) was significantly less than in traditional (18 +/- 5 min) uniform. Exercise time in modified modern (17 +/- 5 min) was significantly greater than in modern and not significantly different than in traditional uniforms. The rate of change in oxygen consumption and water loss were significantly affected by uniform type, with faster rates in modern compared with modified modern or traditional uniforms. These findings show the impact that design changes have on energy demands and exercise duration.
Adult↗
Accuracy of pulse oximetry in sickle cell disease.
Pulmonary complications and hypoxemia are common in sickle cell disease (SCD) and may exacerbate microvascular occlusive phenomena. Thus, detecting hypoxemia is of particular importance in SCD. To assess the accuracy of pulse oximetry in the diagnosis of hypoxemia in SCD, we compared 22 pulse oximetric measurements of arterial oxygen saturation (SpO2) in adult patients with SCD and acute vasoocclusive crisis with simultaneously drawn arterial saturation (SaO2 = oxyhemoglobin divided by oxyhemoglobin plus reduced hemoglobin) measured by co-oximetry. We accepted SpO2 readings only if they were stable and characterized by strong and regular photoplethysmographic waves on the oximeter screen. To assess the position of these patients' oxyhemoglobin dissociation curves, we plotted arterial and venous oxygen saturation (SaO2 and SvO2 ) against oxygen tension. We found right-shifted oxyhemoglobin dissociation curves, with pH-corrected p50s ranging from 28 to 38 mm Hg. Pulse oximetry slightly overestimated oxyhemoglobin percentage (by an average of 3.4 percentage points), but it almost always accurately estimated SaO2 (underestimating on average by 1.1 percentage points). The error in SpO2 was never enough to classify a hypoxemic patient erroneously as normoxemic or a normoxemic patient as hypoxemic. We conclude that, as long as strong and regular photoplethysmographic waves are present, pulse oximeters can be relied upon not to misdiagnose either hypoxemia or normoxemia in SCD.
Acute Disease↗
The incidence, prevalence, and severity of sarcoidosis in New York City firefighters.
OBJECTIVE: The etiology of sarcoidosis is unknown, but epidemiology suggests that environmental agents are a factor. Because firefighters are exposed to numerous toxins, we questioned whether sarcoidosis was increased in this cohort. SETTING: The New York City Fire Department (FDNY), employing > 11,000 firefighters and nearly 3,000 emergency medical services (EMS) health-care workers (HCWs). DESIGN: In 1985, FDNY initiated a surveillance program to determine the incidence, prevalence, and severity of biopsy-proven sarcoidosis in firefighters. In 1995, EMS HCWs were added as control subjects. RESULTS: Between 1985 and 1998, 4 prior cases and 21 new cases of sarcoidosis were found in FDNY firefighters. Annual incidence proportions ranged from 0 to 43.6/100,000, and averaged 12.9/100,000. On July 1, 1998, the point prevalence was 222/100,000. For EMS HCWs, annual incidence proportions were zero. Radiographic stage 0 or stage 1 sarcoidosis was found in 19 firefighters (76%), and stage 3 was found in 1 firefighter (4%). Pulmonary function (FVC, FEV(1), and diffusing capacity for carbon monoxide) was normal in 17 firefighters (68%), and reduced to </= 65% predicted in 2 firefighters (8%). Maximum oxygen consumption (MVO(2)) was normal in 10 of 17 firefighters (59%), and reduced to 65% predicted in 3 firefighters (12%). Five of seven firefighters (71%) with abnormal MVO(2) had gas exchange abnormalities, and none had O(2) desaturation. All returned to fire fighting. CONCLUSIONS: Annual incidence proportions and point prevalence were increased in FDNY firefighters as compared to EMS HCWs and historical controls. Radiographs and physiologic measurements demonstrated only minimal impairment.
Adult↗
Inhibition of capsaicin-induced cough by the gamma-aminobutyric acid agonist baclofen.
Gamma-aminobutyric acid (GABA) is a central inhibitory neurotransmitter that also exists in the lungs. The GABA-agonist baclofen has been shown to have antitussive activity via a central mechanism in animals. Recently it was demonstrated that a 14-day course of baclofen given three times daily significantly inhibits the cough reflex in healthy volunteers. Because of the prolonged antitussive effect of baclofen that has been previously observed, the present study was conducted to evaluate the antitussive effect of low-dose, oral baclofen given once daily. Forty-one healthy volunteers were randomly assigned in a double-blind manner to receive a 28-day course of baclofen, either 10 mg or 20 mg once daily, or placebo. Subjects underwent cough challenge testing with inhaled capsaicin to establish baseline cough reflex sensitivity, and subsequently after 14 and 28 days of therapy. Subjects receiving baclofen 20 mg daily demonstrated significant inhibition of cough sensitivity after 14 days and after 28 days of therapy compared with baseline. Neither placebo nor baclofen 10 mg daily had a significant effect on cough sensitivity. No serious side effects were experienced by any study participant. These results confirm the recent observation that baclofen has significant antitussive activity in humans. Further, once-daily administration of a relatively low dose of baclofen is sufficient to achieve significant cough inhibition, although at least 14 to 28 days of therapy may be required to attain maximal antitussive effect. These results support further investigation of baclofen or other GABA-agonists as potential therapeutic agents for chronic, nonproductive cough.
Administration, Oral↗
Assessment of diaphragm function.
Assessment of diaphragm function begins with the physical examination, but neither the physical examination nor radiography is sensitive enough to detect subtle abnormalities of diaphragm function. Maximal static transdiaphragmatic pressure and maximal static inspiratory mouth pressure have been widely used as measures of diaphragm and inspiratory muscle strength, respectively. Both are useful as rough indications of muscle strength, but, because they are highly effort dependent, they should not be relied upon for absolute accuracy. Objective measurement of diaphragm function requires phrenic nerve stimulation.
Diaphragm↗
Emergency treatment of acute asthma with albuterol metered-dose inhaler plus holding chamber: how often should treatments be administered?
STUDY OBJECTIVE: To determine the optimal treatment interval for administering albuterol metered-dose inhaler (MDI) with a holding chamber to patients presenting to the emergency department (ED) with acute asthma. DESIGN: Prospective, randomized, double-blind study. SETTING: EDs of two affiliated teaching hospitals in the Bronx, NY. PATIENTS: One hundred adult patients with acute asthma and FEV1 <60% predicted of normal. INTERVENTIONS: At entry (T=0 min), eligible patients all openly received inhaled albuterol (six puffs) via MDI with a spacer. Subsequently, in a double-blind fashion, they received six puffs of albuterol or placebo with new MDIs and spacers at 30, 60, and 90 min such that group 1 (n=34) received albuterol every 30 min, group 2 (n=33) every 60 min, and group 3 (n=33) at 120 min only. FEV1 and vital signs were measured at T=0 and at 15, 30, 60, 90, and 120 min following initial treatment. Potassium levels were measured at T=0 and 120 min. Adverse events, the use of additional inhaled beta-agonists or systemic corticosteroids, and hospitalization rates were recorded. MEASUREMENTS AND RESULTS: At T=0, the groups did not differ in age, FEV1, or prescribed asthma medications. All groups showed significant improvement in FEV1 (p<0.05; T=120 vs 0 min). The conditions of groups 1 and 2 improved significantly more than those of group 3, but did not differ compared to each other. The mean+/-SEM change in FEV1 (T=120 vs 0 min) was 0.993+/-0.108, 0.858+/-0.135, and 0.321+/-0.056 L, respectively, for the three groups. Separate analysis for patients with FEV1% <40% or >40% predicted showed similar results. However, patients who initially were low responders to albuterol treatment (<15 percentage point increase at 15 min) improved significantly with 30-min treatments compared to the other two treatment regimens. Patients who initially responded with >15 percentage point increase in FEV1 at 15 min following initial albuterol inhalation benefited equally from 30- or 60-min treatments compared to 120 min. Potassium levels did not change significantly during the study. Adverse events and hospitalization rates were equivalent. After the conclusion of the study, group 3 patients required a greater number of beta-agonist treatments prior to eventual discharge from the ED. CONCLUSIONS: For acute asthma, albuterol MDI with a holding chamber can be given optimally at 60-min intervals with minimal adverse effects for the majority of patients. However, patients who initially demonstrate a low or poor bronchodilator response to albuterol should be given subsequent treatments at 30-min intervals. This will optimize care and conserve resources for patients who will benefit the most.
Administration, Inhalation↗
Pulmonary entrapment of sickle cells: the role of regional alveolar hypoxia.
Pulmonary microvascular occlusion by abnormally adherent and/or nondeformable sickle red blood cells (SS cells) may contribute to the pathogenesis of acute chest syndrome of sickle cell disease. We hypothesized that regional alveolar hypoxia reduces SS cell deformability and, by causing regional vasoconstriction, slows regional perfusion, facilitating endothelial adhesion and mechanical entrapment of cells. In isolated rat lungs perfused at constant average flow with physiological salt solution, we separately ventilated the two lungs: one with 95% O2 and the other with 0, 2.5, 5, or 21% O2. We infused a bolus of 99mTc-labeled SS cells or normal human AA cells along with 113Sn-labeled 15-mu m microspheres as a perfusion marker, then sliced the lungs and counted 99mTc and 113Sn. Weight-normalized perfusion decreased with hypoxia (P < 0.02). Retention of AA cells (perfusion-normalized) averaged approximately 1% in lungs ventilated with 95% O2 and increased only twofold with 0% O2. In contrast, retention of SS cells averaged 3-fold higher than that of AA cells at 95 and 5% O2, 15-fold higher at 2.5% O2, and 25-fold higher at 0% O2 (P < 0.01). Histological examination demonstrated entrapment of individual SS cells in alveolar capillaries of hypoxic but not well-oxygenated lungs. Relief of hypoxia, but not increased perfusate flow, caused prompt efflux of most entrapped cells, which were primarily high-density (high mean corpuscular hemoglobin concentration) cells. Thus substantial retention of SS cells does not occur without hypoxia, but regional hypoxia and/or the resulting vasoconstriction causes extraordinary regional retention of dense SS cells, a phenomenon that appears to be due more to mechanical entrapment of nondeformable cells in capillaries than to endothelial adhesion.
Anemia, Sickle Cell↗
Maximal inspiratory pressure: does reproducibility indicate full effort?
BACKGROUND: Maximal inspiratory pressure (MIP) is often relied upon as an index of inspiratory muscle strength, and reproducibility of MIP taken to indicate maximal effort. This study was designed to determine whether reproducibility is a valid indicator of maximal effort. METHODS: Ten normal subjects were studied, all of whom were familiar with the MIP test but none was an experienced subject. They were told that the purpose was to measure how accurately they could generate 50% of their MIP. Each performed nine MIP efforts and nine submaximal efforts. Means and coefficients of variation of peak negative inspiratory pressure (Pmax) and the ranges of the best three efforts were calculated for each type. RESULTS: Mean (SE) Pmax averaged-93.8 (6.0) cm H2O for the maximal efforts and -60.6 (7.7) cm H2O for the submaximal trials, with coefficients of variation averaging 8.71 (1.75)% and 14.58 (2.63)%, respectively and the ranges averaging 6.5 (1.1)% and 13.4 (3.5)%, respectively. There was no clear separation between the coefficients of variation or ranges of maximal and submaximal efforts. In four cases the ranges of the best three submaximal efforts were less than 5 cm H2O and less than 5% -criteria that have been used to validate MIP results. These four subjects had lower ranges for submaximal than maximal efforts, even when expressed as percentages of the means. CONCLUSION: Reproducibility should not be relied upon to indicate a valid MIP test, especially for research purposes when relatively small changes in inspiratory muscle strength must be discriminated.
Female↗
Single, high-dose intramuscular triamcinolone acetonide versus weekly oral methotrexate in life-threatening asthma: a double-blind study.
Effective and less toxic treatments are needed for patients with severe, steroid-dependent asthma. Both low-dose oral methotrexate and high-dose intramuscular triamcinolone have been recommended for these patients. We compared the effects of these two medications on pulmonary function, peak flow rates, airway reactivity, oral steroid use, emergency room (ER) visits, and hospitalizations in patients with steroid-dependent, life-threatening asthma. In a randomized, placebo-controlled, double-blind study, we investigated 19 such patients. Six of the patients (Group I) received a single dose of 360 mg triamcinolone intramuscularly with placebo methotrexate; seven patients (Group II) received placebo triamcinolone followed by low-dose oral methotrexate (a first dose of 7.5 mg followed by 15 mg weekly); and six patients (Group III) received placebo triamcinolone with placebo methotrexate. All patients used the same high-dose inhaled steroids. The patients took tapering courses of oral steroids when needed, but attempted to reduce their oral steroid use whenever possible. Methacholine challenge testing was performed every 6 wk, pulmonary function tests every 4 wk, and home peak-flow measurements twice daily. Oral steroid use, ER visits, and hospitalizations were also monitored. The patients in the triamcinolone treatment group showed a significant and sustained increase in home peak-flow rates, and their FEV1 persistently improved by a mean of 40% (p < 0.05), whereas the FEV1 of the patients in the methotrexate treatment and placebo groups remained near baseline. The PC20 in the triamcinolone group increased progressively (p > 0.05), and the improvements in total mean reactivity were greater in this group than in either of the other two groups (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
Effect of long-term undernutrition on male and female rat diaphragm contractility, fatigue, and fiber types.
The effects of long-term undernutrition (10 wk) on diaphragm contractility, fatigue, and fiber type proportions were studied in male and female rats. Contractility and fatigue resistance indexes were measured in an in vitro diaphragm costal strip preparation by using direct stimulation at 37 degrees C. Undernutrition allowed for continued growth in males and females but with substantial reductions in weight gain. Relative to control rats of the same sex, final weights were significantly lower in undernourished males (74 +/- 3%) than females (90 +/- 5%), but weight gain was not significantly different between undernourished males (58 +/- 5%) and females (60 +/- 3%). Only in males did undernutrition significantly reduce costal diaphragm weight (to 77 +/- 5% of control). Diaphragm forces, normalized for cross-sectional area, were not significantly different from male or female control values. Fatigue resistance indexes (fatigue/baseline force) were increased at all stimulation frequencies in undernourished males but not in undernourished females. Costal diaphragm atrophy, involving types I and II fibers, occurred in undernourished males but not in undernourished females. In conclusion, despite long-term undernutrition reducing weight gain to similar levels in males and females (relative to control), there was excellent preservation of diaphragm weight, function, and structure in females but, although diaphragm atrophy occurred, there was preserved contractility and increased fatigue resistance in males.
Animals↗
Effects of long-term continuous respiratory resistive loading on rat diaphragm function and structure.
The effects of long-term (24- to 28-wk) continuous respiratory resistive loading on diaphragm mass, contractility, fatigue, and fiber types were studied in male rats. Increased respiratory resistance was produced by extratracheal banding, and results were compared with sham-operated pair-fed controls. At the time the animals were killed, banded tracheal segment internal diameter was reduced by 57% of control values. Diaphragm surface area and muscle mass (normalized for body mass) increased by 19% of control values. Isometric diaphragm contractility and fatigue resistance indexes were measured using an in vitro diaphragm costal strip preparation at 37 degrees C. Twitch and tetanic stimulations were evoked using direct stimulation. Compared with controls, baseline tensions (normalized for diaphragm cross-sectional area) were significantly decreased at low frequencies. Fatigue resistance (endurance) indexes were significantly increased at all frequencies. These findings were consistent with observed increases in number and cross-sectional area of type I (low-tension high-endurance) fibers. We conclude that the diaphragm adapts to chronic long-term resistive loads by sacrificing peak tensions for an increase in endurance capacity.
Airway Resistance↗
Intrinsic positive end-expiratory pressure in ambulatory patients with airways obstruction.
In patients with severe expiratory airflow limitation, dynamic hyperinflation often occurs when inspiratory efforts are initiated at a thoracic volume above the relaxation point of the respiratory system. The result is intrinsic positive end-expiratory alveolar pressure (PEEPi). To determine whether PEEPi occurs in ambulatory patients, we measured alveolar pressure (Palv) noninvasively during tidal breathing in 8 normal subjects, 15 asthmatic subjects, and 19 patients with COPD, using a body plethysmographic technique that includes computerized corrections for nonlinear pneumotachometer output and for plethysmograph leakage. In all 8 normal subjects, 9 asthmatic subjects, and 3 COPD patients, Palv descended smoothly to zero at end expiration. In contrast, among each of the remaining 22 patients, there was an abrupt change in slope of the Palv tracing near end expiration, identifying the onset of the next inspiratory effort and indicating the presence of PEEPi, ranging from 0.2 to 9.5 cm H2O. PEEPi was significantly correlated with FRC (% of predicted); PEEPi = (0.040 x %FRC) - 3.65, r = 0.73, p < 0.001, and with the reciprocal of FEV1 (% of predicted), PEEPi = (138/%FEV1) - 1.34, r = 0.69, p < 0.001. PEEPi could be elicited in normal subjects by severe expiratory resistive loading but not by the increased expiratory muscle activity occurring during an MVV maneuver. We conclude that PEEPi is common in patients with airways obstruction, even without overt ventilatory failure, and that its severity is generally in proportion to the severity of the hyperinflation and the airways obstruction.
Adult↗
Comparison of the Raja and the Abrams pleural biopsy needles in patients with pleural effusion.
In 31 patients with exudative pleural effusions, we compared the diagnostic yield of the Abrams pleural biopsy needle with that of a new instrument, the Raja pleural biopsy needle. Each patient was randomly biopsied with both needles, and a total of 153 pleural biopsies were done, 73 with the Abrams needle and 80 with the Raja needle. No complications resulted from biopsies with either needle. Etiologic diagnoses were possible in 38 (52%) biopsies obtained using the Abrams needle, compared with 66 (82.5%) for those using the Raja needle; the difference in proportions for the diagnostic yield was statistically significant (p < 0.01, two-tailed Fisher's exact test). There were no significant differences between the needles in obtaining etiologic diagnoses in any specific disease category. The difference between the mean size of the pleural specimens obtained with the two needles was also statistically significant (p < 0.001, Mann-Whitney U test). The Raja pleural biopsy needle is easy and safe to use, and despite its smaller external diameter yields a significantly larger pleural tissue sample and significantly increases the diagnostic yield of pleural biopsies compared with the Abrams pleural biopsy needle.
Adult↗
Nutritional factors in the pathogenesis and therapy of respiratory insufficiency in neuromuscular diseases.
Malnutrition is a serious threat to patients with neuromuscular disease and marginally-compensated respiratory muscle weakness. It causes atrophy of inspiratory muscles, further weakening them. It reduces respiratory drive, potentially aggravating respiratory failure, either directly or indirectly, by promoting atelectasis and pneumonia, and it contributes strongly to such patients' risk of infection, their most common cause of death. In treating such patients, it must be remembered that abrupt increases in nutritional support, particularly with high percentages of carbohydrates, will increase CO2 production, potentially worsening ventilatory failure. Certain selected neuromuscular disease patients benefit from specific nutritional treatments (carnitine for carnitine deficient patients, high-calorie diets for muscular dystrophy and acid-maltase deficiency). Finally, the amino acid, fat, and nucleic acid content of the diet affects the immune response in beneficial or harmful ways, that are just now being elucidate. The potential for useful nutritional interventions in patients with neuromuscular diseases has never looked better, but is not yet fully realized. The challenges for the future will be to work out the beneficial and harmful effects of the various nutrients in the various diseases, to find ways to rapidly identify patients who will benefit, and to determine the safest, least uncomfortable, and most effective methods of delivery of the required nutrients.
Humans↗
High-dose intramuscular triamcinolone in severe, chronic, life-threatening asthma.
BACKGROUND: Despite oral corticosteroid therapy, some patients with asthma have frequent exacerbations requiring emergency room visits, hospitalization, and occasionally, mechanical ventilation. We compared the effects of high-dose intramuscular triamcinolone with oral prednisone in patients with severe chronic asthma. METHODS: In a double-blind, placebo-controlled, cross-over study that spanned all seasons, we treated 12 patients with high-dose intramuscular triamcinolone (360 mg over the first three days of the treatment period) or low-dose oral prednisone (median dose, 12.5 mg per day throughout the period; range 0 to 30). The two three-month treatment periods were separated by a three-month washout period. During all periods the patients were allowed to take additional doses of prednisone for acute exacerbations of asthma. RESULTS: After receiving triamcinolone, the patients had significantly better peak expiratory flow rates than while receiving prednisone (the average [+/- SEM] weekly percent of the predicted value during the triamcinolone period was 91.5 +/- 6.9, as compared with 75.0 +/- 5.9 for the prednisone period; P less than 0.05). During the prednisone period there were 21 emergency room visits and 10 hospitalizations, but there were none during the triamcinolone period (P less than 0.05). There were two episodes of ventilatory failure during the prednisone period. Total steroid doses were significantly smaller during the triamcinolone period than during the prednisone period (P less than 0.04). Steroidal side effects were more pronounced after treatment with triamcinolone than after treatment with prednisone (P less than 0.1). CONCLUSIONS: We conclude that high-dose intramuscular triamcinolone is more effective than low-dose prednisone in patients with severe, chronic, life-threatening asthma, but steroidal side effects are somewhat worse.
Administration, Oral↗
An evaluation of the accuracy of Assess and MiniWright peak flowmeters.
With the advent of small inexpensive peak flowmeters, the at-home monitoring of peak flow rates has become an invaluable aid in the treatment of asthmatic patients. In this study, we evaluated the performance of the MiniWright and Assess peak flowmeters for accuracy and reproducibility. Measurements were made at varying peak flow rates and compared with those obtained simultaneously by a calibrated pneumotachograph. When this segment of the study was completed, the peak flow devices were subjected to 200 uses and were then retested. Four MiniWright peak flowmeters that had been extensively used in our clinic were tested as well. The Assess peak flowmeter was more accurate than the MiniWright at low flow rates (less than 300 L/min), while the MiniWright meter was more accurate at high flow rates (greater than 400 L/min). We also found that the accuracy of the MiniWright meter deteriorated after 200 uses and worsened further after extensive use, while the Assess meter retained its accuracy after 200 uses.
Evaluation Studies as Topic↗
The effects of short- and long-term corticosteroid treatment on rat diaphragm contractility and fatigue.
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Animals↗