PubMed Health⌕ Search

Biomedical subjects

F Cordova

Publications and source records attributed to F Cordova.

10 recordsLinked to original sources
PubMed2000

Correlation of changes in quality of life after lung volume reduction surgery with changes in lung function, exercise, and gas exchange.

STUDY OBJECTIVES: To evaluate correlations between improvement in quality of life (QOL) in patients with severe COPD before and after they undergo lung volume reduction surgery (LVRS) with changes in pulmonary function tests, gas exchange, exercise performance, and alterations in medical management. DESIGN: Case-series analysis. SETTING: University hospital. PATIENTS: Forty-two patients (mean [+/- SD] age, 56+/-8 years; 53% women) with severe airflow obstruction (FEV(1), 0.62+/-0.2 L), and moderate to severe hyperinflation (total lung capacity [TLC], 6.9+/-1.7 L). INTERVENTION AND MEASUREMENTS: All patients underwent bilateral LVRS via median sternotomy. Measurements of lung function, symptom-limited cardiopulmonary exercise testing, the total distance the patient was able to walk in 6 min in a corridor, and sickness impact profile (SIP) scores were made before and 3 months after LVRS. SIP scores are inversely proportional to the level of function and QOL. RESULTS: Compared to baseline, FEV(1) increased (0.87+/-0.3 vs. 0.62+/-0.2 L, respectively; p<0.01) while residual volume significantly decreased (3.2+/-1.8 vs. 6.3+/-1.2 L, respectively; p<0.004) at 3 months post-LVRS. On cardiopulmonary exercise testing, values increased from baseline to post-LVRS for total exercise time (9.0+/-2.2 vs. 6.0+/-1.5 min, respectively; p = 0.045), maximum oxygen uptake (VO(2)) (16+/-3 vs. 11+/-2 mL/kg/min, respectively; p = 0.01), and maximum minute ventilation (VE) (33+/-9 vs. 28+/-5 L/min, respectively; p = 0.03). The percentage change in the oxygen cost of breathing (VO2/VE ratio) from low to high workloads during exercise was significantly lower after LVRS (p = 0.002). There was no significant change in oxygenation after LVRS (PaO(2)/fraction of inspired oxygen, 331+/-27 vs. 337+/-39, respectively; p = 0.76), but PaCO(2) tended to be lower (41+/-9 vs. 48+/-6 mm Hg, respectively; p = 0.07). Overall SIP scores were significantly lower after LVRS than before (8+/-4 vs. 15+/-2, respectively; p = 0.002). Changes in SIP scores correlated with the change in VO2/VE ratio from low to high workloads, with patients having the smallest changes in VO2/VE ratio having the smallest changes in SIP scores after LVRS (r = 0.6; p = 0.01). Improved or lower SIP scores also tended to correlate with a reduction in residual volume/TLC ratio (r = 0.45; p = 0.09), and there was a linear correlation with a statistically significant Pearson r value with decreased steroid requirements (r = 0.7; p = 0.001). Moreover, changes in psychological SIP subscore tended to correlate with diminished oxygen requirements post-LVRS (r = 0.45; p = 0.09). However, there was no significant correlation between changes in SIP scores and routine measurements of lung function, exercise performance, or gas exchange. CONCLUSION: There is an association between an improvement in QOL and reduced hyperinflation after LVRS. Reduced hyperinflation may lead to more efficient work of breathing during exercise and, therefore, to an increased ability to perform daily activities. Changes in QOL scores correlate best with behaviorally based variables that directly affect the patient's well-being, such as systemic steroid administration.

Case-Control Studies↗
PubMed1999

Relationship between resting hypercapnia and physiologic parameters before and after lung volume reduction surgery in severe chronic obstructive pulmonary disease.

Patients with severe chronic obstructive pulmonary disease (COPD) have varying degrees of hypercapnia. Recent studies have demonstrated inconsistent effects of lung volume reduction surgery (LVRS) on PaCO2; however, most series have excluded patients with moderate to severe hypercapnia. In addition, no study has examined the mechanisms responsible for the reduction in PaCO2 post-LVRS. We obtained spirometry, body plethysmography, diffusion capacity, respiratory muscle strength, 6-min walk test, and incremental symptom-limited maximal exercise data in 33 consecutive patients pre- and 3 to 6 mo post-LVRS, and explored the relationship between changes in PaCO2 and changes in the measured physiologic variables. All patients underwent bilateral LVRS via median sternotomy and stapling resection by the same cardiothoracic surgeon. Patients were 57 +/- 8 yr of age with severe COPD, hyperinflation, and air trapping (FEV1, 0.73 +/- 0.2 L; TLC, 7.3 +/- 1.6 L; residual volume [RV], 4.8 +/- 1.4 L), and moderate resting hypercapnia (PaCO2, 44 +/- 7 mm Hg; range, 32 to 56 mm Hg). Post-LVRS, PaCO2 decreased by 4% (PaCO2 pre 44 +/- 7 mm Hg, PaCO2 post 42 +/- 5 mm Hg; p = 0.003). Patients with higher baseline values of PaCO2 had the greatest reduction in PaCO2 post-LVRS (r = -0.61, p < 0.001). Significant correlations existed between reduction in PaCO2 and changes in FEV1 (r = -0.56; p = 0.0007), maximal inspiratory pressure (PImax) (r = -0.46; p = 0.009), diffusing capacity of the lungs for carbon monoxide (DLCO) (r = -0.47; p = 0.008), and RV/TLC (r = 0.41; p = 0. 02). Correlation existed also between reduction in PaCO2 and breathing pattern at maximal exercise: maximal minute ventilation (V Emax) (r = -0.47; p = 0.009), and tidal volume (VT) (r = -0.40; p = 0.02). The changes in PaCO2 post-LVRS showed marked intersubject variability. We conclude that LVRS, by reducing hyperinflation, air trapping, and improving respiratory muscle function, enables the lung and chest wall to act more effectively as a pump, thereby increasing alveolar ventilation and reducing baseline resting PaCO2. In addition, patients with higher baseline levels of PaCO2 demonstrate the greatest reduction in PaCO2 post-LVRS, and should not be excluded from receiving LVRS.

Aged↗
PubMed1999

Improvements in lung function, exercise, and quality of life in hypercapnic COPD patients after lung volume reduction surgery.

STUDY OBJECTIVE: To determine the impact of preoperative resting hypercapnia on patient outcome after bilateral lung volume reduction surgery (LVRS). METHODS: We prospectively examined morbidity, mortality, quality of life (QOL), and physiologic outcome, including spirometry, gas exchange, and exercise performance in 15 patients with severe emphysema and a resting PaCO2 of > 45 mm Hg (group 1), and compared the results with those from 31 patients with a PaCO2 of < 45 mm Hg (group 2). RESULTS: All preoperative physiologic and QOL indices were more impaired in the hypercapnic patients than in the eucapnic patients. The hypercapnic patients exhibited a lower preoperative FEV1, a lower diffusing capacity of the lung for carbon monoxide, a lower ratio of PaO2 to the fraction of inspired oxygen, a lower 6-min walk distance, and higher oxygen requirements. However, after surgery both groups exhibited improvements in FVC (group 1, p < 0.01; group 2, p < 0.001), FEV1 (group 1, p=0.04; group 2, p < 0.001), total lung capacity (TLC; group 1, p=0.02; group 2, p < 0.001), residual volume (RV; group 1, p=0.002; group 2, p < 0.001), RV/TLC ratio (group 1, p=0.03; group 2, p < 0.001), PaCO2 (group 1, p=0.002; group 2, p=0.02), 6-min walk distance (group 1, p=0.005; group 2, p < 0.001), oxygen consumption at peak exercise (group 1, p=0.02; group 2, p=0.02), total exercise time (group 1, p=0.02; group 2, p=0.02), and the perceived overall QOL scores (group 1, p=0.001; group 2, p < 0.001). However, because the magnitude of improvement was similar in both groups, and the hypercapnic group was more impaired, the spirometry, lung volumes, and 6-min walk distance remained significantly lower post-LVRS in the hypercapnic patients. There was no difference in mortality between the groups (p=0.9). CONCLUSIONS: Patients with moderate to severe resting hypercapnia exhibit significant improvements in spirometry, gas exchange, perceived QOL, and exercise performance after bilateral LVRS. The maximal achievable improvements in postoperative lung function are related to preoperative level of function; however, the magnitude of improvement can be expected to be similar to patients with lower resting PaCO2 levels. Patients should not be excluded from LVRS based solely on the presence of resting hypercapnia. The long-term benefit of LVRS in hypercapnic patient remains to be determined.

Aged↗
PubMed1997

Effect of N-acetylcysteine on human diaphragm strength and fatigability.

Free radical injury is believed to be important in diaphragm dysfunction. N-Acetylcysteine (NAC) is a potent free radical scavenger shown in animal models to attenuate diaphragm fatigue; however, its effects on human diaphragm function are unknown. We assessed diaphragm function by electrophrenic twitch stimulation (PdiT) and twitch occlusion (to yield Pdimax) in four healthy subjects 35 +/- 3 yr of age (mean +/- SD). We intravenously administered NAC (150 mg/kg in 250 ml D5W) or placebo (CON) (250 ml D5W) in a randomized manner after subjects were premedicated with antihistamines. There were no significant side effects with the infusion. After infusion, we measured baseline Pdimax and PdiT at FRC. Diaphragm fatigue was then induced by subjects breathing through an inspiratory resistive load. Pdimax and PdiT were then measured at 15 to 30 min and 1, 2, 3, 4, and 20-25 h after fatigue. Times to fatigue were 13 +/- 4 min (CON) and 21 +/- 6 min (NAC) (p = 0.04). At 15 min after fatigue, PdiT was reduced to 40% (CON) compared with 30% (NAC) initial PdiT value (p = 0.05). Other twitch characteristics (maximal rate of relaxation and maximal contraction rate) were reduced to a greater degree after placebo compared with NAC. There were no significant differences in the rate of recovery between CON and NAC. Pdimax at 30 min after fatigue was significantly greater with NAC; however, at 1 h after fatigue, Pdimax for CON and NAC were not different, suggesting similar rates of recovery in high-frequency fatigue. These data suggest that NAC may attenuate low-frequency human diaphragm fatigue.

Acetylcysteine↗
PubMed1997

Stability of improvements in exercise performance and quality of life following bilateral lung volume reduction surgery in severe COPD.

STUDY OBJECTIVE: To evaluate the long-term stability of improvements in exercise capacity and quality of life (QOL) after lung volume reduction surgery (LVRS). DESIGN: Case-series analysis. SETTING: University hospital. PATIENTS: Twenty-six patients with severe airflow obstruction (mean FEV1 of 0.67+/-0.18 L) and moderate to severe hyperinflation (mean total lung capacity of 7.30+/-1.90 L). INTERVENTION AND MEASUREMENTS: All patients underwent bilateral LVRS via median sternotomy. Serial measurement of lung function, symptom-limited cardiopulmonary exercise tests, 6-min walk distances (6MWD), and sickness impact profile (SIP) scores were done before, and at 3, 6, 12, and 18 months after surgery. RESULTS: FEV1 (0.93+/-0.29 vs 0.68+/-0.19 L, p<0.001) increased while residual volume (3.47+/-1.2 vs 4.77+/-1.5 L, p<0.001) decreased significantly at 3 months post-LVRS compared to baseline, and these changes were maintained at 12 to 18 months follow-up. Similarly, the increase in 6MWD at 3 months post-LVRS (340+/-84 vs 251+/-114 m, p<0.001) was sustained at all follow-up times. On cardiopulmonary exercise testing, total exercise time (9.0+/-1.8 vs 6.1+/-1.9 min, p<0.001), oxygen uptake at peak exercise (VO2 peak) (14.9+/-4 vs 11.9+/-3 mL/kg/min, p<0.001), maximum oxygen pulse (7.43+/-2.37 vs 5.85+/-1.96 mL/beat, p<0.005), and maximum minute ventilation (VEmax) (30.3+/-10 vs 23.5+/-7.1 L/min, p<0.001) increased significantly at 3 months post-LVRS. On serial study following LVRS, total exercise time remained significantly greater at 6 (8.5+/-1.38 min) and 12 months (8.71+/-2.0 min) post-LVRS compared to baseline (5.81+/-1.9 min, p<0.05). VO2 peak tended to be higher at all follow-up periods (3 months, 16.1+/-4.3; 6 months, 14.5+/-2.6; 12 months, 14.1+/-3.5 mL/kg) compared to baseline (12.6+/-3.9 mL/kg, p=0.08). Similarly, maximum O2 pulse tended to be higher in all follow-up studies (3 months, 8.45+/-2.7; 6 months, 7.6+/-1.7; 12 months, 7.42+/-2.1 mL/beat) compared to baseline (6.39+/-2.5 mL/beat, p=0.06). Higher VEmax continued to be observed at 6 (30+/-10 L/min) and 12 months (28+/-10 L/min) post-LVRS, compared to baseline (23+/-7 L/min, p=0.02). VEmax post-LVRS was significantly higher at 3 and 6 months compared to baseline on post-hoc analysis (p<0.05). Overall SIP scores were lower at 3 months (7 vs 18, p<0.0002) post-LVRS and were sustained in long-term follow-up. CONCLUSION: We conclude that bilateral LVRS via median sternotomy in selected patients with severe, diffuse emphysema improves exercise performance and QOL at 3 months following LVRS and these improvements are maintained for at least 12 to 18 months in follow-up.

Airway Obstruction↗
PubMed1996

Lung volume reduction surgery in ventilator-dependent COPD patients.

BACKGROUND: Lung volume reduction surgery has been advocated recently as adjunctive surgical therapy to improve lung and chest wall mechanics in selected patients with diffuse emphysema. Although clear-cut guidelines to select candidates have not been fully established, patients decompensated with significant pulmonary artery hypertension and hypercapnic respiratory failure are currently not considered suitable subjects. Accordingly, ventilator-dependent COPD patients are not considered candidates for this procedure. However, because ventilator-dependent COPD patients have an exceptionally poor prognosis, we elected to offer them this promising, but unproved surgical intervention. Herein, we describe the outcome of these three patients. PATIENTS: The 3 patients had recurrent exacerbations of COPD precipitating respiratory failure, and following aggressive medical therapy remained mechanically ventilated for 11 to 16 weeks (1 patient had a brief period of successful weaning before returning to mechanical ventilation). Prior to surgery, the patients had severe hypercapnia and cor pulmonale. Compared with preoperative values, surgery resulted in improvements in PaO2/FIO2, 304 +/- 80 (SD) vs 229 +/- 48 mm Hg, reductions in PaCO2, 44 +/- 3 vs 60 +/- 9 mm Hg, increases in FVC, 1.63 + 0.52 vs 1.09 +/- 0.05 L, and maximum inspiratory pressure, 57 +/- 22 vs 29 +/- 12 cm H2O. Postoperative complications included persistent air leaks and one tension pneumothorax. Patients weaned from mechanical ventilation after 10 to 21 days all were discharged home and they continue to demonstrate improved gas exchange and functional status. CONCLUSIONS: Lung volume reduction surgery in select, ventilator-dependent COPD patients can result in improved gas exchange and respiratory mechanics that enable successful weaning and overall improved functional status.

Female↗
PubMed1993

Epilepsy and sport.

Sport and epilepsy are not mutually exclusive, providing the disease has been properly diagnosed and managed and adequate safeguards are taken. The author also outlines specific contraindications for the sports-minded person with epilepsy.

Child↗
PubMed1986

[Digital image processing: fundamental techniques and applications in biological research].

Digital image processing represents a relatively new but very dynamic domain. Its importance is still growing due to the rapid development in related computer equipment. In this paper basics concepts are introduced and a survey of problems and methods is presented. Starting with techniques used for the capture of data, it continues with techniques applied to coding new data, image enhancement and pattern recognition. Special attention is given to pattern recognition techniques which provide the basics for classification of data according to established criteria. Finally, two applications are presented; the reconstruction of 3-D volumes from serial cutting and a survey of chlorophyll concentration on Lake Aculeo using remote images obtained by the LANDSAT satellite.

Analog-Digital Conversion↗