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Biomedical subjects

Richard M Schwartzstein

Publications and source records attributed to Richard M Schwartzstein.

5 recordsLinked to original sources
PubMed2006

Expiratory abdominal rounding in acute dyspnea suggests congestive heart failure.

Patients in acute respiratory distress require rapid assessment of the cause of dyspnea. We have observed that many of those patients who are in congestive heart failure (CHF) exhibit rounding of the abdominal cross-section during expiration. We sought to evaluate the diagnostic utility of this breathing pattern in dyspneic patients presenting to an emergency department. Twenty-six subjects with dyspnea due to a variety of conditions were recruited from the emergency department at Beth Israel Deaconess Medical Center. Subjects ranged in age from 21 to 94 years and 81% were female. We measured variation in the anteroposterior and transverse diameters of the rib cage and abdomen using respiratory magnetometers and determined phase of respiration with a pneumotachometer. Investigators blinded to the subjects' identities and diagnoses interpreted measurements as indicating normal respiratory movement without expiratory abdominal rounding, slight expiratory rounding, or pronounced expiratory rounding. The likely cause of dyspnea was determined from discharge diagnoses in the medical record. Expiratory rounding was observed in 12/14 subjects with CHF and 5/12 subjects without CHF (p = 0.0186), and pronounced expiratory rounding was present in 11/14 patients with CHF and 2/12 patients without CHF (p = 0.0016). Test characteristics for the association of CHF with pronounced expiratory rounding were sensitivity 79%, specificity 83%, and predictive accuracy 81%. In patients with acute respiratory distress, expiratory abdominal rounding suggests CHF as the primary cause of dyspnea; a greater degree of rounding suggests a greater likelihood of CHF. The clinical utility of this diagnostic sign remains to be determined in a prospective study.

Abdomen↗
PubMed2006

Effect of inhaled furosemide on air hunger induced in healthy humans.

Recent evidence suggests that inhaled furosemide relieves dyspnoea in patients and in normal subjects made dyspnoeic by external resistive loads combined with added dead-space. Furosemide sensitizes lung inflation receptors in rats, and lung inflation reduces air hunger in humans. We therefore hypothesised that inhaled furosemide acts on the air hunger component of dyspnoea. Ten subjects inhaled aerosolized furosemide (40 mg) or placebo in randomised, double blind, crossover experiments. Air hunger was induced by hypercapnia (50+/-2 mmHg) during constrained ventilation (8+/-0.9 L/min) before and after treatment, and rated by subjects using a 100 mm visual analogue scale. Subjects described a sensation of air hunger with little or no work/effort of breathing. Hypercapnia generated less air hunger in the first trial at 23+/-3 min after start of furosemide treatment (58+/-11% to 39+/-14% full scale); the effect varied substantially among subjects. The mean treatment effect, accounting for placebo, was 13% of full scale (P=0.052). We conclude that 40 mg of inhaled furosemide partially relieves air hunger within 1h and is accompanied by substantial diuresis.

Administration, Inhalation↗
PubMed2003

Utility of daily routine portable chest radiographs in mechanically ventilated patients in the medical ICU.

STUDY OBJECTIVES: To determine whether there is any difference in diagnostic, therapeutic, and outcome efficacy between protocols utilizing daily (ie, routine) chest radiographs (CXRs) and those utilizing clinically indicated (ie, nonroutine) CXRs in mechanically ventilated patients. DESIGN: Prospective, randomized, observational study. SETTING: A 20-bed medical ICU at a university hospital. PATIENTS: Adult patients who had been receiving mechanical ventilation for > 48 h. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Ninety-four patients who had been intubated for at least 48 h were randomized to receive either routine or nonroutine CXRs and were observed until extubation or death. The percentage of CXRs with new findings was significantly larger in the nonroutine CXR group (53.1%; 120 CXRs) compared to that in the routine CXR group (33.4%; 98 CXRs; odds ratio [OR], 1.59; 95% confidence interval [CI], 1.16 to 2.18; p = 0.004). The number of CXRs with new findings that resulted in interventions was significantly larger in the nonroutine CXR group (26.5%; 60 CXRs) compared to that in the routine CXR group (13.3%; 39 CXRs; OR, 2.0; 95% CI, 1.29 to 3.08; p = 0.002). There was no difference in the mean duration of mechanical ventilation (routine CXR arm, 7.93 days; nonroutine CXR arm, 6.76 days; p = 0.2606), length of ICU stay (routine CXR arm, 11.93 days; nonroutine CXR arm, 9.55 days; p = 0.1936), and total length of hospital stay (routine CXR arm, 19.34 days; nonroutine CXR arm, 16.45 days; p = 0.2199) between the two groups. Although patients in the nonroutine arm of the study received fewer CXRs, adverse outcomes (eg, length of mechanical ventilation, length of hospital stay, length of ICU stay, and mortality) did not increase (p = 0.818). Using the number of CXRs per patient as a surrogate, there was a statistically significant cost savings and decreased radiation exposure in the nonroutine CXR group. CONCLUSIONS: For mechanically ventilated patients, a strategy calling for daily routine CXRs compared to CXRs obtained based on clinical indications alone was not associated with reduced ICU or hospital length of stay or with reduced mortality.

Female↗
PubMed2002

"Tightness" sensation of asthma does not arise from the work of breathing.

Asthma evokes several uncomfortable sensations including increased "effort to breathe" and chest "tightness." We have tested the hypotheses that "effort" and "tightness" are due to perception of increased work performed by the respiratory muscles. Bronchoconstriction was induced by inhaled methacholine in 15 subjects with mild asthma (FEV(1)/FVC baseline = 81.9% +/- 5.8; bronchoconstriction = 64.0% +/- 8.6). To relieve the work of breathing, and thereby minimize activation of respiratory muscle afferents and motor command, subjects were mechanically ventilated. Subjects separately rated effort to breathe and tightness during mechanical ventilation and during spontaneous breathing. Bronchoconstriction produced elevated end-expiratory lung volume (279 +/- 62 ml); in a control study, end-expiratory lung volume was increased equally in the absence of bronchoconstriction by increasing end-expiratory pressure. During bronchoconstriction, ratings of effort were greater during spontaneous breathing than during mechanical ventilation (p < 0.05). Ratings of tightness were unchanged by the absence of respiratory muscle activity (p = 0.12). Hyperinflation alone did not produce tightness or effort. We conclude that tightness is not related to the increase in respiratory work during bronchoconstriction.

Adult↗