American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Aug 1995
Efficacy of expiratory tracheal gas insufflation in a canine model of lung injury.
Tracheal gas insufflation (TGI) improves the efficiency of CO2 elimination by reducing the CO2-laden dead space of the airways. The effect of TGI on PaCO2 diminishes in the setting of acute lung injury (ALI) because an increased alveolar component dominates the total physiologic dead space. Nevertheless, adopting a strategy of permissive hypercapnia should partially offset the decreased efficacy of TGI by increasing CO2 concentration in the proximal airways. ⋯ The corresponding decrements in PaCO2 produced by TGI at a flow rate of 10 L/min were 16 +/- 3, 24 +/- 10, and 10 +/- 2 mm Hg, respectively. TGI decreased total physiologic dead space per breath (VD) by 56, 31, and 28 ml during the pre-OAI, post-OAI, and post-OA/VT stages, respectively. Despite a smaller reduction in VD during the post-OAI stage, the effect of TGI on PaCO2 was preserved because of the relatively high PaCO2 prior to its initiation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Aug 1995
Randomized Controlled Trial Comparative Study Clinical TrialA randomized, double-blind comparison of methoxamine and epinephrine in human cardiopulmonary arrest.
The beneficial effect of epinephrine has been attributed to its alpha-adrenergic properties. The present study was designed to compare the effects of epinephrine and methoxamine in witnessed cardiac arrests. Consecutive, witnessed cardiac-arrest victims presenting to the emergency room or from the inpatient population of our institution were enrolled in this study. ⋯ Of the 145 patients remaining, 77 received methoxamine (M) and 68 epinephrine (E). There was no difference in rate of successful resuscitation (42% versus 53%, M versus E, respectively), or in neurologic outcome as measured by the Glasgow-Pittsburgh Coma Score (GPCS). This study failed to demonstrate any difference in the rate of initial resuscitation, survival to discharge from the hospital, or neurologic status with methoxamine as opposed to epinephrine in the setting of cardiac arrest.
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Am. J. Respir. Crit. Care Med. · Aug 1995
Multicenter Study Comparative StudyPulmonary function tests in HIV-infected patients without AIDS. Pulmonary Complications of HIV Infection Study Group.
To determine the prevalence, incidence, and types of lung diseases that occur in association with HIV infection, 1,353 subjects, including HIV-seropositive homosexual men, injection drug users, female sexual partners of HIV-positive men, and HIV-seronegative control subjects from the first two transmission categories were evaluated prospectively in a multicenter study. Patients with AIDS at the time of initial evaluation were excluded. One thousand two-hundred ninety-four subjects who had no AIDS-defining diagnosis within 3 mo of enrollment had measurements of FVC, FEV1 and DLCO at the time of enrollment. ⋯ Part of the reduction in DLCO in drug users was attributable to factors other than HIV infection, especially cigarette smoking and race. Using predicted values that take cigarette smoking into account, the prevalence of abnormality in DLCO was higher among injection drug users (33.3%) than among homosexual men (11.2%) and female sexual partners (12.7%). These results show that advanced HIV infection, characterized by CD4 count < 200/mm3 or HIV-associated symptoms, and factors unrelated to HIV infection, including race, cigarette smoking, and injection drug use, are all associated with reductions in DLCO measurements.
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Am. J. Respir. Crit. Care Med. · Aug 1995
Randomized Controlled Trial Comparative Study Clinical TrialNasal pressure support ventilation plus oxygen compared with oxygen therapy alone in hypercapnic COPD.
Non-invasive ventilation has been used in chronic respiratory failure due to chronic obstructive pulmonary disease (COPD), but the effect of the addition of nasal positive-pressure ventilation to long-term oxygen therapy (LTOT) has not been determined. We report a randomized crossover study of the effect of the combination of nasal pressure support ventilation (NPSV) and domiciliary LTOT as compared with LTOT alone in stable hypercapnic COPD. Fourteen patients were studied, with values (mean +/- SD) of Pao2 of 45.3 +/- 5.7 mm Hg, PaCO2 of 55.8 +/- 3.6 mm Hg, and FEV1 of 0.86 +/- 0.32 L. ⋯ Quality of life with oxygen plus NPSV was significantly better than with oxygen alone. The degree of improvement in daytime PaCO2 was correlated with the improvement in mean overnight PaCO2. Nasal positive-pressure ventilation may be a useful addition to LTOT in stable hypercapnic COPD.
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Am. J. Respir. Crit. Care Med. · Aug 1995
Comparative StudyAlterations of lung and chest wall mechanics in patients with acute lung injury: effects of positive end-expiratory pressure.
In 16 mechanically ventilated patients with acute lung injury (ALI) (eight patients with moderate ALI [moderate group], eight patients with severe ALI [adult respiratory distress syndrome, ARDS group]) and in eight normal anesthetized-paralyzed subjects (control group), we partitioned the total respiratory system mechanics into the lung (L) and chest wall (w) mechanics using the esophageal balloon technique together with the airway occlusion technique during constant flow inflation. We measured lung elastance (Est,L), chest wall elastance (Est,w), and total lung (Rmax, L) and chest wall (Rmax,w) resistance. Rmax,L includes airway (Rmin,L) and "additional" lung resistance (DR,L). ⋯ The end-expiratory lung volume (EELV) was measured at each level of PEEP. Specific total lung (sRmax,L), airway (sRmin,L), and "additional" lung (sDR,L) resistances were obtained as Rmax,L x EELV, Rmin,L x EELV, and DR,L x EELV, respectively. At PEEP 0 cm H2O, we found that both Est,L (23.7 +/- 5.5 and 13.8 +/- 3.3 versus 9.3 +/- 1.7 cm H2O/L; p < 0.01) and Est,w (13.2 +/- 5.4 and 9.9 +/- 2.1 versus 5.6 +/- 2.3 cm H2O/L; p < 0.01) were markedly increased in patients with ARDS and moderate ALI compared with control subjects, with a significant (p < 0.01) effect of the severity of the disease on Est,L (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)