• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.201-209
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• 1996

Background : Auto-PEEP which develops when expiratory lung emptying is not finished until the beginning of next inspiration is frequently found in patients on mechanical ventilation. Its presence imposes increased risk of barotrauma and hypotension, as well as increased work of breathing (WOB) by adding inspiratory threshold load and/or adversely affecting to inspiratory trigger sensitivity. The aim of this study is to evaluate the relationship of auto-PEEP with WOB and to evaluate the effect of PEEP applied by ventilator (external PEEP) on WOB in patients with auto-PEEP. Method : 15 patients, who required mechanical ventilation for management of acute respiratory failure, were studied. First, the differences in WOB and other indices of respiratory mechanics were examined between 7 patients with auto-PEEP and 8 patients without auto-PEEP. Then, we applied the 3 cm $H_2O$ of external PEEP to patients with auto-PEEP and evaluated its effects on lung mechanics as well as WOB. Indices of respiratory mechanics including tidal volume ($V_T$), repiratory rate, minute ventilation ($V_E$), peak inspiratory flow rate (PIFR), peak expiratory flow rate (PEFR), peak inspiratory pressure (PIP), $T_I/T_{TOT}$, auto-PEEP, dynamic compliance of lung (Cdyn), expiratory airway resistance (RAWe), mean airway resistance (RAWm), $p_{0.1}$, work of breathing performed by patient (WOB), and pressure-time product (PTP) were obtained by CP-100 Pulmonary Monitor (Bicore, USA). The values were expressed as mean $\pm$ SEM (standard error of mean). Results : 1) Comparison of WOB and other indices of respiratory mechanics in patients with and without auto-PEEP : There was significant increase in WOB ($l.71{\pm}0.24$ vs $0.50{\pm}0.19\;J/L$, p=0.007), PTP ($317{\pm}70$ vs $98{\pm}36\;cm$ $H_2O{\cdot}sec/min$, p=0.023), RAWe ($35.6{\pm}5.7$ vs $18.2{\pm}2.3\;cm$ H2O/L/sec, p=0.023), RAWm ($28.8{\pm}2.5$ vs $11.9{\pm}2.0cm$ H2O/L/sec, p=0.001) and $P_{0.1}$ ($6.2{\pm}1.0$ vs 2.9+0.6 cm H2O, p=0.021) in patients with auto-PEEP compared to patients without auto-PEEP. The differences of other indices including $V_T$, PEFR, $V_E$ and $T_I/T_{TOT}$ showed no significance. 2) Effect of 3 cm $H_2O$ external PEEP on respiratory mechanics in patients with auto-PEEP : When 3 cm $H_2O$ of external PEEP was applied, there were significant decrease in WOB ($1.71{\pm}0.24$ vs $1.20{\pm}0.21\;J/L$, p=0.021) and PTP ($317{\pm}70$ vs $231{\pm}55\;cm$ $H_2O{\cdot}sec/min$, p=0.038). RAWm showed a tendency to decrease ($28.8{\pm}2.5$ vs $23.9{\pm}2.1\;cm$ $H_2O$, p=0.051). But PIP was increased with application of 3 cm $H_2O$ of external PEEP ($16{\pm}2$ vs $22{\pm}3\;cm$ $H_2O$, p=0.008). $V_T$, $V_E$, PEFR, $T_I/T_{TOT}$ and Cdyn did not change significantly. Conclusion : The presence of auto-PEEP in mechanically ventilated patients was accompanied with increased WOB performed by patient, and this WOB was decreased by 3 cm $H_2O$ of externally applied PEEP. But, with 3 cm $H_2O$ of external PEEP, increased PIP was noted, implying the importance of close monitoring of the airway pressure during application of external PEEP.

• Tuberculosis and Respiratory Diseases
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• v.60 no.6
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• pp.653-662
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• 2006

Background: The changes in the pulmonary function observed in burn patients with an inhalation injury are probably the result of a combination of airway inflammation, chest wall and muscular abnormalities, and scar formation. In addition, it appears that prolonged ventilatory support and an episode of pneumonia contribute to the findings. This study investigated the changes in the pulmonary function in patients with inhalation injury at the early and late post-burn periods. Methods: From August 1, 2002, to August 30, 2005, surviving burn patients who had an inhalation injury were enrolled prospectively. An inhalation injury was identified by bronchoscopy within 48hours after admission. Spirometry was performed at the early phase during admission and the recovery phase after discharge, and the changes in the pulmonary function were compared. Results: 37 patients (M=28, F=9) with a total burn surface area (% TBSA), ranging from 0 to 18%, were included. The initial $PaO_2/$FiO_2$ratio and COHb were $286.4{\pm}129.6mmHg$ and $7.8{\pm}6.6%$. Nine cases (24.3%) underwent endotracheal intubation and 3 cases (8.1%) underwent mechanical ventilation. The initial X-ray findings revealed abnormalities in, 18 cases (48.6%) with 15 (83.3%) of these being completely resolved. However, 3 (16.7%) of these had residual sequela. The initial pulmonary function test, showed an obstructive pattern in 9 (24.3%) with 4 (44.4%) of these showing a positive bronchodilator response, A restrictive pattern was also observed in 9 (24.3%) patients. A lower DLco was observed in only 4 (17.4%) patients of which 23 had undergone DLco. In the follow-up study, an obstructive and restrictive pattern was observed in only one (2.7%) case each. All the decreased DLco returned to mormal. Conclusions: Most surviving burn patients with an inhalation injury but with a small burn size showed initial derangements in the pulmonary function test that was restored to a normal lung function during the follow up period.

• Journal of Chest Surgery
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• v.39 no.3 s.260
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• pp.184-193
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• 2006

Background: Off-pump coronary artery bypass grafting (OPCAB) has been proven to result in less morbidity. The patients who have left ventricular dysfunction may have benefits by avoiding the adverse effects of the cardiopulmonary bypass. The present study compared early and midterm outcomes of off-pump versus on-pump coronary artery bypass grafting (On pump CABG) in patients with severe left ventricular dysfunction. Material and Method: Ninety hundred forth six patients underwent isolated coronary artery bypass grafting by one surgeon between January 2001 and Febrary 2005.. Data were collected in 100 patients who had left ventricular ejection fraction (L VEF) less than $35\%$ (68 OPCAB; 32 On pump CABG). Mean age of patients were 62.9$\pm$9.0 years in OPCAS group and 63.8$\pm$8.0 years in On pump CABG group. We compared the preoperative risk factors and evaluated early and midterm outcomes. Result: In OPCAB and On pump CABG group, mean number of used grafts per patient were 2.75$\pm$0.72, 2.78$\pm$0.55 and mean number of distal anastomoses were 3.00$\pm$0.79, 3.16$\pm$0.72 respectively. There was one perioperative death in OPCAB group ($1.5\%$). The operation time, ventilation time, ICU stay time, CK-MB on the first postoperative day, and occurrence rate of complications were significantly low in OPCAB group. Mean follow-up time was 26.6$\pm$12.8 months (4${\~}$54 months). Mean LVEF of OPCAB and On pump CABG group improved significantly from $27.1\pm4.5\%$ to $40.7\pm13.0\%$ and $26.9\pm5.4\%$ to $33.3\pm13.7\%$. The 4-year actuarial survival rate of OPCAB and On pump CABG group were $92.2\%,\;88.3\%$ and the 4-year freedom rates from cardiac death were $97.7\%,\;96.4\%$ respectively. There were no significant differences between two groups in 4 year freedom rate from cardiac event and angina. Conclusion: OPCAS improves myocardial function and favors early and mid-term outcomes in patients with severe left ventricular dysfunction compared to On pump CABG group. Therefore, OPCAB is a preferable operative strategy even in patients with severe left ventricular dysfunction.