• Tuberculosis and Respiratory Diseases
• /
• v.40 no.6
• /
• pp.631-637
• /
• 1993

Background: In normal adults, ventilation is uneven and greater in the base than the apex of the lung in tidal volume breathing. However infants have fragile chest wall and reduced elastic recoil, resulting in easy closure of peripheral airways especially in the dependent portion of the lung. So ventilation in infants is greater in the apex than the base of the lung. We assumed that in adults whose closing volume is increased, dependent portion could be easily collapsed during tidal breathing and ventilation could be greater in the uppear than than the lower portion of the lung. Methods: We measured spirometry and closing volume(CV) in normal controls and in patients with chronic lung disease. Also we measured fractional distribution of ventilation at supine, left lateral and right lateral decubitus with $^{133}Xe$ ventilation scan in normal controls, patients with normal closing volume and patients with increased closing volume. Results: The subjects consisted of 7 normal controls(mean $age{\pm}SD$, $62.9{\pm}6.1$ years). 6 patients with normal CV($62.8{\pm}8.2$ years) and 7 patients with increased CV($63.0{\pm}15.3$ years). 1) Normal controls have mean(${\pm}SD$) FVC $104{\pm}11%$ of predicted value, $FEV_1\;120{\pm}16%,\;FEV_1/FVC\;112{\pm}5%$ and CV $86.9{\pm}12.5%$. Patients with normal CV have FVC $62{\pm}11%,\;FEV_1\;54{\pm}17%,\;FEV_1/FVC\;84{\pm}23%$ and CV $92.6{\pm}15.5%$. Patients with increased CV, have FVC $53{\pm}9%,\;FEV_1\;38{\pm}13,\;FEV_1/FVC\;69{\pm}16%$ and CV $176.1{\pm}36.6%$, CV was significantly different between two patient groups(p<0.02) 2). In normal controls mean fractional ventilation to left lung was $48.1{\pm}5.3%$ at supine, $54.1{\pm}9.8%$ at dependent and $40.9{\pm}6.5%$ at left uppermost position. In patients with normal CV mean fractional ventilation to left lung was $44.6{\pm}2.1%$ at supine, $59.7{\pm}5.6%$ at left dependent and $31.7{\pm}8.3%$ at left uppermost position. In patients with increased CV mean fractional ventilation to left lung was $48.7{\pm}4.5%$ at supine, $41.7{\pm}6.6%$ at left dependent and $60.9{\pm}15.7%$ at left uppermost position. In normal controls and patients with normal CV, ventilation to left lung at left dependent position tends to be higher than that at supine position but without statisitical significance and it was significantly lower at left uppermost than at left lung dependent position. In patients with increased CV, ventilation to left at left dependent position tends to be higher than that at supine position but without significance and it was significantly higher at left uppermost than that at left dependent position. Conclusion: These data suggest that in patients with increased CV ventilation to one side of lung could be higher at uppermost than at dependent position on lateral decubitus during tidal breathing and this fact should be taken into account in positioning of patients with unilateral lung disease.

• Journal of Chest Surgery
• /
• v.35 no.6
• /
• pp.420-429
• /
• 2002

Moderate hypothermic cardiopulmonary bypass (CPB) has commonly been used in cardiac surgery. Several cardiac centers recently practice normothermic CPB in cardiac surgery, However, the clinical effect and safety of normothermic CPB on cerebral metabolism are not established and not fully understood. This study was prospectively designed to evaluate the clinical influence of normothermic CPB on brain metabolism and to compare it with that of moderate hypothermic CPB. Material and Method: Thirty-six adult patients scheduled for elective cardiac surgery were randomized to receive normothermic (nasopharyngeal temperature ＞34.5 $^{\circ}C$, n=18) or hypothermic (nasopharyngeal temperature 29~3$0^{\circ}C$, n=18) CPB with nonpulsatile pump. Middle cerebral artery blood flow velocity (VMCA), cerebral arteriovenous oxygen content difference (CAVO$_{2}$), cerebral oxygen extraction (COE), modified cerebral metabolic rate for oxygen (MCMRO$_{2}$), cerebral oxygen transport (TEO$_{2}$), cerebral venous desaturation (oxygen saturation in internal jugular bulb blood$\leq$50 %), and arterial and internal jugular bulb blood gas analysis were measured during six phases of the operation： Pre-CPB (control), CPB-10 min, Rewarm-1 (nasopharyngeal temperature 34 $^{\circ}C$ in the hypothermic group), Rewarm-2 (nasopharyngeal temperature 37 $^{\circ}C$ in the both groups), CPB-off and Post-CPB (skin closure after CPB-off). Postoperaitve neuropsychologic complications were observed in all patients. All variables were compared between the two groups. Result： VMCA at Rewarm-2 was higher in the hypothermic group (153.11$\pm$8.98%) than in the normothermic group (131.18$\pm$6.94%) (p＜0.05). CAVO$_{2}$ (3.47$\pm$0.21 vs 4.28$\pm$0.29 mL/dL, p＜0.05), COE (0.30$\pm$0.02 vs 0.39$\pm$0.02, p＜0.05) and MCMRO$_{2}$ (4.71 $\pm$0.42 vs 5.36$\pm$0.45, p<0.05) at CPB-10 min were lower in the hypothermic group than in the normothermic group. The hypothermic group had higher TEO$_{2}$ than the normothermic group at CPB-10 (1,527.60$\pm$25.84 vs 1,368.74$\pm$20.03, p＜0.05), Rewarm-2 (1,757.50$\pm$32.30 vs 1,478.60$\pm$27.41, p＜0.05) and Post-CPB (1,734.37$\pm$41.45 vs 1,597.68$\pm$27.50, p＜0.05). Internal jugular bulb oxygen tension (40.96$\pm$1.16 vs 34.79$\pm$2.18 mmHg, p＜0.05), saturation (72.63$\pm$2.68 vs 64.76$\pm$2.49 %, p＜0.05) and content (8.08$\pm$0.34 vs 6.78$\pm$0.43 mL/dL, p<0.05) at CPB-10 were higher in the hypothermic group than in the normothermic group. The hypothermic group had less incidence of postoperative neurologic complication (delirium) than the normothermic group (2 vs 4 patients, p＜0.05). Lasting periods of postoperative delirium were shorter in the hypothermic group than in the normothermic group (60 vs 160 hrs, p<0.01). Conclusion: These results indicate that normothermic CPB should not be routinely applied in all cardiac surgery, especially advanced age or the clinical situations that require prolonged operative time. Moderate hypothermic CPB may have beneficial influences relatively on brain metabolism and postoperative neuropsychologic outcomes when compared with normothermic CPB.