Biomedical subjects

James W Leatherman

Publications and source records attributed to James W Leatherman.

4 recordsLinked to original sources

PubMed2004

Effect of prolongation of expiratory time on dynamic hyperinflation in mechanically ventilated patients with severe asthma.

OBJECTIVE: To assess the effect of a decrease in respiratory rate on dynamic hyperinflation, as determined by changes in plateau airway pressure, in patients with status asthmaticus whose baseline minute ventilation approximated 10 L/min. DESIGN: Observational descriptive study. SETTING: Medical intensive care unit. PATIENTS: Twelve patients with severe asthma mechanically ventilated in the assist control mode with a tidal volume of 613 +/- 100 mL and an inspiratory flow rate of 79 +/- 4 L/min. INTERVENTIONS: A decrease in respiratory rate from 18 to 12 and 6 breaths/min. MEASUREMENTS AND MAIN RESULTS: Plateau airway pressure decreased by approximately 2 cm H2O (25.4 +/- 2.8 vs. 23.3 +/- 2.6 cm H2O, p <.01) when respiratory rate was decreased from 18 to 12 breaths/min (increase in expiratory time 1.7 secs) and by a similar amount (23.3 +/- 2.6 vs. 21.3 +/- 2.9 cm H2O, p <.01) when respiratory rate was decreased from 12 to 6 breaths/min (increase in expiratory time 5 secs). Peak airway pressure was similar at the three respiratory rates (66.8 +/- 8.7 vs. 66.4 +/- 9.5 vs. 67.8 +/- 11.1 cm H2O at 18, 12, and 6 breaths/min, respectively). End-expiratory flow rates (n = 7) were 61.4 +/- 12.6, 38.6 +/- 4.5, and 23.1 +/- 5.8 mL/sec at respiratory rates of 18, 12, and 6 breaths/min, respectively. CONCLUSIONS: Prolongation of expiratory time decreases dynamic hyperinflation in patients with status asthmaticus, as evidenced by a reduction in plateau airway pressure, but the magnitude of this effect is relatively modest when baseline minute ventilation is < or = 10 L/min, because of the low end-expiratory flow rates. Since flow progressively decreases throughout expiration, the reduction in dynamic hyperinflation resulting from a given prolongation of expiratory time will depend on the baseline respiratory rate (i.e., less reduction in dynamic hyperinflation at a lower respiratory rate). Changes in peak airway pressure may not always reflect the changes in dynamic hyperinflation that result from prolongation of expiratory time.

Adult↗

PubMed2003

Overestimation of pulmonary artery occlusion pressure in pulmonary hypertension due to partial occlusion.

OBJECTIVE: To evaluate partial occlusion in patients with pulmonary hypertension with regard to a) the degree to which it leads to overestimation of pulmonary artery occlusion pressure (Ppao) and b) identification of factors that could enhance its recognition. DESIGN: Observational descriptive study. SETTING: Medical intensive care unit. PATIENTS: Fourteen patients with pulmonary hypertension and an increased pulmonary artery diastolic pressure (Ppad) - Ppao gradient (> or = 10 mm Hg). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The Ppao was recorded during partial occlusion (partial Ppao) and after catheter repositioning to obtain a lower, more accurate value (best Ppao). The error due to partial occlusion, defined as the difference between the partial Ppao and the best Ppao, was 13 +/- 5 mm Hg (range, 6-21 mm Hg). The previously widened Ppad - Ppao gradient invariably narrowed during partial occlusion and then increased by 13 +/- 5 mm Hg (range, 5-23) during the best Ppao measurement. There was a moderate correlation between the error due to partial occlusion (partial Ppao - best Ppao) and both the mean pulmonary artery pressure (r =.77, <.01) and the Ppad - Ppao gradient (r =.79, <.01). CONCLUSIONS: Partial occlusion in patients with pulmonary hypertension may lead to significant overestimation of the Ppao and should be suspected when there is a substantial increase in the Ppao without a concomitant increase in the Ppad, as reflected by a marked narrowing of a previously widened Ppad - Ppao gradient.

Catheterization, Swan-Ganz↗

PubMed2002

Rheumatology.

Explore the source record for details and available documents.

Humans↗

PubMed2002

Neuromuscular disorders in the intensive care unit.

Neuromuscular disorders encountered in the ICU can be categorized as muscular diseases that lead to ICU admission and those that are acquired in the ICU. This article discusses three neuromuscular disorders can lead to ICU admission and have a putative immune-mediated pathogenesis: the Guillian-Barré syndrome, myasthenia gravis, and dermatomyositis/polymyositis. It also reviews critical care polyneuropathy and ICU acquired myopathy, two disorders that, alone or in combination, are responsible for nearly all cases of severe ICU acquired muscle weakness.

Critical Care↗