American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jul 1995
Variability of patient-ventilator interaction with pressure support ventilation in patients with chronic obstructive pulmonary disease.
In 12 patients with chronic obstructive pulmonary disease (COPD) receiving pressure support ventilation (PSV), we studied the variability of respiratory muscle unloading and defined its physiologic determinants using a modified pressure-time product (PTP). Inspiratory PTP/min decreased as PSV was increased (p < 0.001), but there was considerable interindividual variation: coefficients of variations of up to 96%. ⋯ At PSV of 20 cm H2O, expiratory effort, quantitated by an expiratory PTP, was clearly evident in five patients before the cessation of inspiratory flow, signifying that the patient was "fighting" the ventilator; of note, these five patients had a frequency of < or = 30 breaths/min. In conclusion, patient-ventilator interactions in patients with COPD are complex, and events in expiration need to be considered in addition to those of inspiration.
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Am. J. Respir. Crit. Care Med. · Jul 1995
Progress at the interface of inflammation and asthma. Report of an ATS-sponsored workshop November, 1993.
Most attendees agreed that the workshop achieved it goal of bringing together individuals with a number of distinct scientific approaches to consider new ways of thinking about asthma.
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Am. J. Respir. Crit. Care Med. · Jul 1995
Arterial oxygenation time after an FIO2 increase in mechanically ventilated patients.
The time for arterial PO2 to reach equilibrium after a 0.2 increase in the fraction of inspired oxygen (FIO2) was studied, using arterial blood gases measured at 1, 2, 3, 4, 5, 7, 9, and 11 min in 30 stable, mechanically ventilated medical intensive care unit (ICU) patients. Eight patients also underwent a 0.4 increase in FIO2. Each patient's rise in PO2 over time [PO2(t)] was fit to the following exponential equation: PO2(t) = PO2i + (PO2f-PO2i) (1-e-kt), where t refers to time, PO2i and PO2f refer to the initial and final equilibrated PO2. ⋯ The mean t90% (+/- SD) was 6.0 (+/- 3.4) min for all patients (range 1.7 to 14.3 min); 7.1 +/- 2.1 min for 18 patients with chronic obstructive pulmonary disease (COPD) and 4.4 +/- 2.0 min for 12 patients without COPD (p < 0.05). In the subgroup of patients undergoing both an FIO2 increase of 0.2 and 0.4, there was no significant difference in the mean t90%'s for the two FIO2 changes (7.7 versus 7.7 min). We conclude that after a 0.2 or 0.4 increase of FIO3, a 15-min equilibration time period is adequate for 90% of the increase in PO2 to occur, in stable, mechanically ventilated medical ICU patients.
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Am. J. Respir. Crit. Care Med. · Jul 1995
A dual-binding antibody to E- and L-selectin attenuates sepsis-induced lung injury.
Many studies indicate a pivotal role for neutrophil adhesion in sepsis-associated lung injury. Neutrophil adhesion to endothelium depends on activation and expression of selectin and integrin adhesion receptors. We studied the effects of pretreatment with a dual-binding porcine anti-E- and anti-L-selectin monoclonal antibody (EL-246) on a porcine model of sepsis-induced lung injury. ⋯ There was no significant difference in pulmonary and systemic hemodynamics between Groups 2 and 3. Group 4 animals exhibited a transient neutropenia, but otherwise no other differences in measured parameters were found compared with Group 1 control animals. In conclusion, EL-246 significantly reduced neutrophil accumulation in lung and attenuated sepsis-induced lung injury, but failed to attenuate deranged pulmonary and systemic hemodynamics.(ABSTRACT TRUNCATED AT 250 WORDS)