Passive smoking acutely affects the microcirculation in healthy non-smokers.

OBJECTIVE: Acute effects of passive smoking on microcirculation have not been sufficiently studied. The aim of the present study was to detect microcirculatory alterations in healthy non-smokers after passive exposure to cigarette smoke, utilizing the Near Infrared Spectroscopy method combined with the vascular occlusion technique. METHODS: Sixteen (9 females, age: 34 ±â€¯9 years) non-smoking, healthy volunteers were exposed to passive smoking for 30 min in a temperature-controlled environment. Smoke concentration was monitored with a real-time particle counter. The following microcirculatory parameters were estimated: baseline tissue oxygen saturation (StO2); StO2 decrement after vascular occlusion (indicating the oxygen consumption rate); StO2incremental response after vascular occlusion release (reperfusion rate); the time period where the StO2 signal returns to the baseline values after the hyperemic response. RESULTS: Baseline StO2 (79.6 ±â€¯6.4 vs. 79 ±â€¯8%, p = 0.53) as well as the time needed for StO2 to return to baseline levels (138.2 ±â€¯26.5 vs. 142.1 ±â€¯34.6 s, p = 0.64) did not significantly differ before vs. after passive smoking exposure. Oxygen consumption rate decreased after 30 min exposure to passive smoking (from 12.8 ±â€¯4.2 to 11.3 ±â€¯2.8%/min, p = 0.04); Reperfusion rate also significantly decreased (from 5.6 ±â€¯1.8 to 5 ±â€¯1.7%/s, p = 0.04). CONCLUSIONS: Our results suggest that acute exposure to passive smoking delays peripheral tissue oxygen consumption and adversely affects microcirculatory responsiveness after stagnant ischemia in healthy non-smokers.

Clinical factors affecting costs in patients receiving systemic antifungal therapy in intensive care units in Greece: Results from the ESTIMATOR study.

Invasive fungal infections are common in intensive care units (ICUs) but there is a great variability in factors affecting costs of different antifungal treatment strategies in clinical practice. To determine factors affecting treatment cost in adult ICU patients with or without documented invasive fungal infection receiving systemic antifungal therapy (SAT) we have performed a prospective, multicentre, observational study enrolling patients receiving SAT in participating ICUs in Greece. During the study period, 155 patients received SAT at 14 participating ICUs: 37 (23.9%) for proven fungal infection before treatment began, 10 (6.5%) prophylactically, 77 (49.7%) empirically and 31 (20.0%) pre-emptively; 66 patients receiving early SAT (55.9%) were subsequently confirmed to have proven infection with Candida spp. (eight while on treatment). The most frequently used antifungal drugs were echinocandins (89/155; 57.4%), fluconazole (31/155; 20%) and itraconazole (20/155; 12.9%). Mean total cost per patient by SAT strategy was €20 458 (proven), €15 054 (prophylaxis), €23 594 (empiric) and €22 184 (pre-emptive). Factors associated with significantly increased cost were initial treatment failure, length of stay (LOS) in ICU before starting SAT (i.e. from admission until treatment start), fever and proven candidaemia (all P≤.05). CONCLUSION: Early administration of antifungal drugs was not a substantial component of total hospital costs. However, there was a significant adverse impact on costs with increasing LOS in febrile patients in ICU for whom diagnosis of fungaemia was delayed before starting SAT, and with initial treatment failure. Awareness of potential candidaemia and initiation of pre-emptive or empirical strategy as early appropriate treatment may improve ICU patient outcomes while reducing direct medical costs.

Left ventricular diastolic dysfunction--an independent risk factor for weaning failure from mechanical ventilation.

The objective of this study was to investigate the contribution of left ventricular (LV) diastolic dysfunction to weaning failure, along with the levels of the currently used cardiac biomarkers. Forty-two mechanically ventilated patients, who fulfilled criteria for weaning from mechanical ventilation (MV), underwent a two-hour spontaneous breathing trial (SBT). Transthoracic echocardiography (TTE) was performed before the start of the SBT. The grade of LV diastolic dysfunction was assessed by pulsed-wave Doppler and tissue Doppler imaging at the level of the mitral valve. Haemodynamic and respiratory parameters were recorded. Blood levels of B-type natriuretic peptide (BNP), troponin I, creatine kinase-MB, and myoglobin were measured on MV and at the end of the SBT. Weaning success was defined as the patient's ability to tolerate spontaneous breathing for more than 48 hours. Fifteen patients failed to wean. LV diastolic dysfunction was significantly associated with weaning failure (P<0.001). The grade of diastolic dysfunction was significantly correlated with BNP levels both on MV and at the end of the SBT (P<0.001, r=0.703 and P<0.001, r=0.709, respectively). BNP levels on MV were lower in patients who successfully weaned compared to those who did not (361±523 ng/l versus 643±382 ng/l respectively, P=0.008). The presence of diastolic dysfunction was independently associated with weaning failure (odds ratio [OR] 11.23, confidence interval [CI] 1.16-109.1, P=0.037) followed by respiratory frequency/tidal volume (OR 1.05, CI 1.00-1.10, P=0.048). Therefore, assessment of LV diastolic function before the start of weaning could be useful to identify patients at risk of weaning failure.

Early response roles for prolactin cortisol and circulating and cellular levels of heat shock proteins 72 and 90α in severe sepsis and SIRS.

OBJECTIVE: To evaluate the early heat shock protein (HSP) and hormonal stress response of intensive care unit (ICU) patients with severe sepsis/septic shock (SS) or systemic inflammatory response syndrome (SIRS) compared to healthy subjects (H). METHODS: Patients with early (first 48 hrs) SS (n = 29) or SIRS (n = 29) admitted to a university ICU and 16 H were enrolled in the study. Serum prolactin, cortisol, and plasma ACTH were determined using immunoassay analyzers. ELISA was used to evaluate extracellular HSPs (eHSP90α, eHSP72) and interleukins. Mean fluorescence intensity (MFI) values for intracellular HSPs (iHSP72, iHSP90α) were measured using 4-colour flow-cytometry. RESULTS: Prolactin, cortisol, and eHSP90α levels were significantly increased in SS patients compared to SIRS and H (P < 0.003). ACTH and eHSP72 were significantly higher in SS and SIRS compared to H (P < 0.005). SS monocytes expressed lower iHSP72 MFI levels compared to H (P = 0.03). Prolactin was related with SAPS III and APACHE II scores and cortisol with eHSP90α, IL-6, and lactate (P < 0.05). In SS and SIRS eHSP90α was related with eHSP72, IL-6, and IL-10. CONCLUSION: Prolactin, apart from cortisol, may have a role in the acute stress response in severe sepsis. In this early-onset inflammatory process, cortisol relates to eHSP90α, monocytes suppress iHSP72, and plasma eHSP72 increases.

Changes in thenar muscle tissue oxygen saturation assessed by near-infrared spectroscopy during weaning from mechanical ventilation.

BACKGROUND: Tissue oxygen saturation (StO2) measured by near-infrared spectroscopy (NIRS) has been used to provide information on local tissue oxygenation in different clinical settings. This study aims to determine the effect of weaning from mechanical ventilation on thenar muscle StO2. METHODS: In consecutive critically ill mechanically ventilated patients, StO2 at the thenar eminence, along with a vascular occlusion test (VOT), were measured by NIRS, on mechanical ventilation and during a 2-hour T-piece spontaneous breathing trial (SBT). Hemodynamic, gas exchange and respiratory variables were recorded. RESULTS: Forty-four patients were included in this study, 25 tolerated the SBT and 19 failed. On mechanical ventilation, no differences in any measured variable were observed between patients who succeeded or failed. Two minutes after SBT start, StO2 was decreased in patients who failed whereas it did not change in patients who succeeded (P<0.001). For all data, 2 minutes after the start of SBT, StO2 significantly correlated with SaO2 (r=0.32, P=0.037) and with the respiratory frequency/tidal volume (f/VT) index (r=-0.34, P=0.023). VOT-derived StO2 downslope and StO2 upslope did not change significantly along the SBT test. The maximum StO2 value, its ratio to minimum StO2, and the post-VOT StO2 value decreased significantly in patients who failed whereas no change was found in those who succeeded the SBT (P=0.003, P=0.025 and P<0.001 respectively). StO2 and f/VT at the second minute of SBT yielded a receiver operator characteristics curve area value of 0.77 and 0.80, P=0.002, respectively, in detecting the SBT outcome. CONCLUSION: SBT failure was associated with a significant impairment of thenar muscle StO2. A decrease of StO2 at 2 minutes after disconnection from the ventilator was associated with SBT failure. Further validation is warranted.

Resting respiratory variables and exercise capacity in adult patients with cystic fibrosis.

INTRODUCTION: Cystic fibrosis (CF) is the most common life-limiting, recessively inherited disease in the white population, associated with significantly high morbidity and mortality rates; CF pulmonary disease, assessed by pulmonary function tests, arterial blood gases and the Schwachman score, remains the most prevalent in terms of morbidity in the adult CF population. OBJECTIVES: The aim of the present study was to evaluate the relationship between resting respiratory variables and exercise capacity in adult patients with CF. RESULTS: Study investigations undertaken in 18 CF patients and 11 healthy volunteers showed that among the resting lung function parameters, inspiratory capacity (IC) at rest was the only significant predictor of VO(2) peak (r=0.67, p<0.007) and VO(2)/t-slope (r=0.86, p<0.0001). The percentage of predicted FEV(1) in adult CF patients was 77+/-33% pred. vs 104+/-16% pred. in healthy subjects (p<0.006); the corresponding percentage of IC at rest was 82+/-36% pred. in patients vs 116+/-20% pred. in healthy (p<0.003). CF patients presented with a significantly prolonged rapid breathing after exercise (32br per minute at recovery for CF vs 22 for healthy; p<0.001), as well as a shortened inspiratory time. CONCLUSION: Adult patients with CF show a limited exercise capacity with lower peak oxygen consumption and prolonged oxygen kinetics. Interestingly, decreased IC qualified as the only significant predictor of exercise capacity in our study.

Carbapenem-resistant versus carbapenem-susceptible Acinetobacter baumannii bacteremia in a Greek intensive care unit: risk factors, clinical features and outcomes.

BACKGROUND: There has been an increasing incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) infections in recent years. The objective of this study was to determine specific risk factors for and outcome of bacteremia due to CRAB isolates among our ICU patients with A. baumannii bacteremia. PATIENTS AND METHODS: Among 96 patients with ICU-acquired A. baumannii bacteremia, 30 patients with CRAB were compared with the remaining 66 with carbapenem-susceptible A. baumannii (CSAB) isolates. RESULTS: Recent ventilator-associated pneumonia (VAP) due to CRAB (OR 16.74, 95% CI 3.16-88.79, p = 0.001) and a greater number of intravascular devices (OR 3.93, 95% CI 1.9-13.0, p = 0.025) were independently associated with CRAB bacteremia acquisition. Patients with CRAB bacteremia had a lower severity of illness on admission than those with CSAB. Although, by univariate analysis, patients with CRAB were more likely to have had exposure to colistin, carbapenems and linezolid, multivariate analysis did not revealed any significant association. The mortality was not different between patients with CRAB and CSAB bacteremia (43.3 vs. 46.9%, p = 0.740). Severity of organ failure (OR 1.42, 95% CI 1.20-1.67, p = 0.001), and increased white blood cell (WBC) count (OR 1.09, 95% CI 1.01-1.19, p = 0.036), at bacteremia onset were independently associated with mortality. CONCLUSION: VAP due to CRAB and excess use of intravascular devices are the most important risk factors for CRAB bacteremia in our ICU. Severity of organ failure and WBC count at A. baumannii bacteremia onset are independently associated with mortality.

Non-invasive assessment of the microcirculation in critically ill patients.

Sepsis is associated with abnormalities of muscle tissue oxygenation and of microvascular function. We investigated whether the technique of near-infrared spectroscopy can evaluate such abnormalities in critically ill patients and compared near-infrared spectroscopy-derived indices of critically ill patients with those of healthy volunteers. We studied 41 patients (mean age 58 +/- 22 years) and 15 healthy volunteers (mean age 49 +/- 13 years). Patients were classified into one of three groups: systemic inflammatory response syndrome (SIRS) (n = 21), severe sepsis (n = 8) and septic shock (n = 12). Near-infrared spectroscopy was used to continuously measure thenar muscle oxygen saturation before, during and after a three-minute occlusion of the brachial artery via pneumatic cuff. Oxygen saturation was significantly lower in patients with SIRS, severe sepsis or septic shock than in healthy volunteers. Oxygen consumption rate during stagnant ischaemia was significantly lower in patients with SIRS (23.9 +/- 7.7%/minute, P < 0.001), severe sepsis (16.9 +/- 3.4%/minute, P < 0.001) or septic shock (14.8 +/- 6%/minute, P < 0.001) than in healthy volunteers (35.5 +/- 10.6%/minute). Furthermore, oxygen consumption rate was significantly lower in patients with septic shock than patients with SIRS. Reperfusion rate was significantly lower in patients with SIRS (336 +/- 141%/minute, P < 0.001), severe sepsis (257 +/- 150%/minute, P < 0.001) or septic shock (146 +/- 101%/minute, P < 0.001) than in healthy volunteers (713 +/- 223%/minute) and significantly lower in the septic shock than in the SIRS group. Near-infrared spectroscopy can detect tissue oxygenation deficits and impaired microvascular reactivity in critically ill patients, as well as discriminate among groups with different disease severity.

Effect of heliox breathing on flow limitation in chronic heart failure patients.

Patients with chronic heart failure (CHF) exhibit orthopnoea and tidal expiratory flow limitation in the supine position. It is not known whether the flow-limiting segment occurs in the peripheral or central part of the tracheobronchial tree. The location of the flow-limiting segment can be inferred from the effects of heliox (80% helium/20% oxygen) administration. If maximal expiratory flow increases with this low-density mixture, the choke point should be located in the central airways, where the wave-speed mechanism dominates. If the choke point were located in the peripheral airways, where maximal flow is limited by a viscous mechanism, heliox should have no effect on flow limitation and dynamic hyperinflation. Tidal expiratory flow limitation, dynamic hyperinflation and breathing pattern were assessed in 14 stable CHF patients during air and heliox breathing at rest in the sitting and supine position. No patient was flow-limited in the sitting position. In the supine posture, eight patients exhibited tidal expiratory flow limitation on air. Heliox had no effect on flow limitation and dynamic hyperinflation and only minor effects on the breathing pattern. The lack of density dependence of maximal expiratory flow implies that, in CHF patients, the choke point is located in the peripheral airways.

New insights into the exercise intolerance of beta-thalassemia major patients.

The purpose of our study was assessment of the relative contribution of the systems involved in blood gas exchange to the limited exercise capacity in patients with beta-thalassemia major (TM) using integrative cardiopulmonary exercise testing (CPET) with estimation of oxygen kinetics. The study consisted of 15 consecutive TM patients and 15 matched controls who performed spirometric evaluation, measurement of maximum inspiratory pressure (Pimax) and an incremental symptom-limited CPET on a cycle ergometer. Exercise capacity was markedly reduced in TM patients as assessed by peak oxygen uptake (pVO(2), mL/kg/min: 22.1+/-6.6 vs 33.8+/-8.3; P<0.001) and anaerobic threshold (mL/kg/min: 13.0+/-3.0 vs 18.7+/-4.6; P<0.001) compared with controls. No ventilatory limitation to exercise was noted in TM patients (VE/VCO(2) slope: 23.4+/-3.2 vs 27.8+/-2.6; P<0.001 and breathing reserve, %: 42.9+/-17.0 vs 29.5+/-12.0; P<0.005) and no difference in oxygen cost of work (peak VO(2)/WR, mL/min W: 12.2+/-1.7 vs 12.2+/-1.5; P=NS). Delayed recovery oxygen kinetics after exercise was observed in TM patients (VO(2)/t slope, mL/kg/min(2): 0.67+/-0.27 vs 0.93+/-0.23; P<0.05) that was significantly correlated with Pimax at rest (r: 0.81; P<0.001). The latter was also significantly correlated to pVO(2) (r: 0.84; P<0.001) and inversely correlated to ferritin levels (r: -0.6; P<0.02). Exercise capacity is markedly reduced in TM patients and this reduction is highly associated with the limited functional status of peripheral muscles.

Impaired oxygen kinetics in beta-thalassaemia major patients.

AIM: Beta-thalassaemia major (TM) affects oxygen flow and utilization and reduces patients' exercise capacity. The aim of this study was to assess phase I and phase II oxygen kinetics during submaximal exercise test in thalassaemics and make possible considerations about the pathophysiology of the energy-producing mechanisms and their expected exercise limitation. METHODS: Twelve TM patients with no clinical evidence of cardiac or respiratory disease and 10 healthy subjects performed incremental, symptom-limited cardiopulmonary exercise testing (CPET) and submaximal, constant workload CPET. Oxygen uptake (VO2), carbon dioxide output and ventilation were measured breath-by-breath. RESULTS: Peak VO2 was reduced in TM patients (22.3 +/- 7.4 vs. 28.8 +/- 4.8 mL kg(-1) min(-1), P < 0.05) as was anaerobic threshold (13.1 +/- 2.7 vs. 17.4 +/- 2.6 mL kg(-1) min(-1), P = 0.002). There was no difference in oxygen cost of work at peak exercise (11.7 +/- 1.9 vs. 12.6 +/- 1.9 mL min(-1) W(-1) for patients and controls respectively, P = ns). Phase I duration was similar in TM patients and controls (24.6 +/- 7.3 vs. 23.3 +/- 6.6 s respectively, P = ns) whereas phase II time constant in patients was significantly prolonged (42.8 +/- 12.0 vs. 32.0 +/- 9.8 s, P < 0.05). CONCLUSION: TM patients present prolonged phase II on-transient oxygen kinetics during submaximal, constant workload exercise, compared with healthy controls, possibly suggesting a slower rate of high energy phosphate production and utilization and reduced oxidative capacity of myocytes; the latter could also account for their significantly limited exercise tolerance.

Predisposing factors for critical illness polyneuromyopathy in a multidisciplinary intensive care unit.

OBJECTIVE: To investigate risk factors of critical illness polyneuromyopathy (CIPM) in a general multidisciplinary intensive care unit (ICU). PATIENTS AND METHODS: Prospective observational study in a 28-bed university multidisciplinary ICU. Four hundred and seventy-four (323 M/151 F, age 55 +/- 19) consecutive patients were prospectively evaluated. All patients were assigned admission Acute Physiology and Chronic Health Evaluation (APACHE II; 15 +/- 7) and Sequential Organ Failure Assessment (SOFA; 6 +/- 3) scores and were subsequently evaluated for newly developed neuromuscular weakness. Other potential causes of new-onset weakness after ICU admission were excluded before CIPM was diagnosed. RESULTS: Forty-four (23.8%) of 185 patients developed generalized weakness that met the criteria for CIPM. Patients with CIPM had higher APACHE II (18.9 +/- 6.6 vs 15.6 +/- 6.4, P = 0.004) and SOFA scores (8.4 +/- 2.9 vs 7.1 +/- 2.9, P = 0.013). According to multivariate logistic regression analysis, the following risk factors were independently associated with the development of CIPM: severity of illness at the time of ICU admission, administration of aminoglycoside antibiotics and high blood glucose levels. Analysis according to severity of illness stratification revealed the emergence of Gram (-) bacteremia as the most important independent predisposing factor for CIPM development in less severely ill patients. CONCLUSIONS: CIPM has a high incidence in the ICU setting. Our study revealed the association of aminoglycosides, hyperglycemia and illness severity with CIPM development, as well as the association between Gram (-) bacteremia and development of CIPM in less severely ill patient population.

Propofol-induced hyperamylasaemia in a general intensive care unit.

This study examined the incidence of hyperamylasaemia, in the absence of other plausible causes of pancreatic dysfunction, in intensive care unit (ICU) patients who received propofol. One-hundred-and-seventy-two consecutive patients of a general ICU who stayed for more than 24 hours were studied. Patients with a diagnosis consistent with elevated serum amylase levels at admission were excluded from the study, as were patients who had received medications known to raise serum amylase levels. Forty-four patients 53 +/- 20 years of age and median duration of ICU stay of five days (range two to 55) were eligible. Thirty of those, aged 54 +/- 21 years and median duration of ICU stay of five days (range two to 27) received continuous infusion of propofol for sedation (maximum dose 45 microg/kg/min). Of the 30 patients who received propofol, 16 (53%) developed hyperamylasaemia (125 to 466 IU/l) after two to nine days of continuous infusion. Liver and kidney function remained normal throughout the observation period. Of the 14 patients who did not receive propofol (aged 51 +/- 18 years), only two (14%) developed hyperamylasaemia, a significantly lower incidence (P = 0.021). Propofol infusion is associated with biochemical evidence of pancreatic injury. Amylase levels monitoring of propofol-sedated patients is warranted.

Patterns of dynamic hyperinflation during exercise and recovery in patients with severe chronic obstructive pulmonary disease.

BACKGROUND: Not all patients with severe chronic obstructive pulmonary disease (COPD) progressively hyperinflate during symptom limited exercise. The pattern of change in chest wall volumes (Vcw) was investigated in patients with severe COPD who progressively hyperinflate during exercise and those who do not. METHODS: Twenty patients with forced expiratory volume in 1 second (FEV(1)) 35 (2)% predicted were studied during a ramp incremental cycling test to the limit of tolerance (Wpeak). Changes in Vcw at the end of expiration (EEVcw), end of inspiration (EIVcw), and at total lung capacity (TLCVcw) were computed by optoelectronic plethysmography (OEP) during exercise and recovery. RESULTS: Two significantly different patterns of change in EEVcw were observed during exercise. Twelve patients had a progressive significant increase in EEVcw during exercise (early hyperinflators, EH) amounting to 750 (90) ml at Wpeak. In contrast, in all eight remaining patients EEVcw remained unchanged up to 66% Wpeak but increased significantly by 210 (80) ml at Wpeak (late hyperinflators, LH). Although at the limit of tolerance the increase in EEVcw was significantly greater in EH, both groups reached similar Wpeak and breathed with a tidal EIVcw that closely approached TLCVcw (EIVcw/TLCVcw 93 (1)% and 93 (3)%, respectively). EEVcw was increased by 254 (130) ml above baseline 3 minutes after exercise only in EH. CONCLUSIONS: Patients with severe COPD exhibit two patterns during exercise: early and late hyperinflation. In those who hyperinflate early, it may take several minutes before the hyperinflation is fully reversed after termination of exercise.

Dynamic hyperinflation and tolerance to interval exercise in patients with advanced COPD.

Dynamic hyperinflation (DH) contributes importantly to the limitation of constant-load exercise (CLE) in patients with chronic obstructive pulmonary disease (COPD). However, its role in the limitation of interval exercise (IE) remains to be explored. The change (Delta) in inspiratory capacity (IC) was measured to reflect changes in DH in 27 COPD patients (forced expiratory volume in one second mean+/-SEM % predicted: 40+/-3) at the end of a symptom-limited CLE test at 80% of peak work capacity (WRmax) and an IE test at 100% WRmax (30 s of work, alternated with 30 s of unloaded pedalling). At the limit of tolerance in both IE and CLE, patients exhibited similar DH (DeltaIC: 0.39+/-0.05 L and 0.45+/-0.05 L, respectively). However, exercise endurance time (t end) for IE (32.7+/-3.0 min) was significantly greater than for CLE (10.3+/-1.6 min). The IE t end correlated with resting IC, expressed as % pred normal. At 30 and 90% of total IE t end, DeltaIC (0.43+/-0.06 and 0.39+/-0.05 L, respectively) and minute ventilation (31.1+/-1.6 and 32.7+/-2.2 L.min(-1), respectively) were not significantly different. Resting hyperinflation helps to explain the limitation of interval exercise. Implementation of interval exercise for rehabilitation should provide important clinical benefits because it prolongs exercise endurance time and allows sustaining higher stable ventilation.

Interval training as an alternative modality to continuous exercise in patients with COPD.

Understanding of what constitutes a training load adequate to induce training effects in patients with chronic obstructive pulmonary disease (COPD) is still evolving. The present study investigated whether interval training (IT) is effective in terms of inducing measurable improvements in physiological response and compared its effects on exercise tolerance (ET) and quality of life to those of continuous training (CT). Thirty-six COPD patients, with a forced expiratory volume in one second of 45+/-4% of the predicted value (mean+/-SEM), were randomly assigned to CT (exercise at 50% of baseline peak work-rate) or IT (work for 30 s at 100% of peak work-rate alternating with 30-s rest intervals) groups that cycled 40 min x day(-1) and 2 days x week(-1) for 12 weeks. After training, both groups showed significantly improved ET (IT, 57+/-6 to 71+/-8 W; CT, 57+/-5 to 70+/-6 W) and total quality-of-life score of the Chronic Respiratory Disease Questionnaire (IT, 77+/-3 to 88+/-2; CT, 78+/-3 to 93+/-2). At identical levels of exercise, minute ventilation was significantly reduced (IT, 35.8+/-2.5 to 31.7+/-2.5 L x min(-1); CT, 36.4+/-2.7 to 32.5+/-2.7 L x min(-1)). The magnitude of improvement in these variables was not significantly different among groups. The present data expand on the principles of exercise prescription for chronic obstructive pulmonary disease patients by demonstrating that interval training elicits substantial training effects, which are similar in magnitude to those produced by continuous training at half the exercise intensity but double the exercise time.

Early recovery of oxygen kinetics after submaximal exercise test predicts functional capacity in patients with chronic heart failure.

BACKGROUND: Oxygen (O2) uptake at peak exercise (VO2 peak) is an objective measurement of functional capacity in patients with chronic heart failure (CHF). The significance of recovery O2 kinetics parameters in predicting exercise capacity, and the parameters of submaximal exercise testing have not been thoroughly examined. METHODS AND RESULTS: Thirty-six patients (mean age = 48+/-14 years) with CHF and New York Heart Association functional class I, II, or III, and eight healthy volunteers (mean age = 39+/-13 years) were studied with maximal and submaximal cardiopulmonary exercise testing (CPET). The first degree slope of O2 uptake decay during early recovery from maximal (VO2/t-slope), and submaximal exercise (VO2/t-slope)(sub), were calculated, along with VO2 half-time (T(1/2)VO2). Patients with CHF had a longer recovery of O2 uptake after exercise than healthy volunteers, expressed by a lower VO2/t-slope (0.616+/-0.317 vs. 0.956+/-0.347 l min(-1) min(-1), P=0.029) and greater T(1/2)VO2 (1.28+/-0.30 vs. 1.05+/-0.15 min, P = 0.005). VO2/t-slope correlated with the VO2 peak (r = 0.84, P<0.001), anaerobic threshold (r = 0.79, P<0.001), and T(1/2)VO2, a previously established estimate of recovery O2 kinetics (r = -0.59, P<0.001). (VO2/t-slope)(sub) was highly correlated with VO2/t-slope after maximal exercise (r=0.87, P<0.001), with the VO2 peak (r=0.87, P<0.001) and with T(1/2)VO2 after maximal exercise (r=-0.62, P<0.001). VO2/t-slope after maximal and submaximal exercise was reduced in patients with severe exercise intolerance (F=9.3, P<0.001 and F=12.8, P<0.001, respectively). CONCLUSIONS: Early recovery O2 kinetics parameters after maximal and submaximal exercise correlate closely with established indices of exercise capacity in patients with CHF and in healthy volunteers. These findings support the use of early recovery O2 kinetics after submaximal exercise testing as an index of functional capacity in patients with CHF.

Limitation of infarct size by fixed coronary arterial stenosis maintained during reperfusion.

BACKGROUND: The effect on infarct size of a pre-infarction high-grade, fixed coronary arterial stenosis maintained during reperfusion, was evaluated. METHODS: This experimental study was carried out in the research laboratory of a University Hospital. A canine occlusion-reperfusion model was used. Twenty-eight dogs underwent proximal left anterior descending (LAD) coronary artery occlusion (O). In Group 1 (n=6) the O lasted for 6 hours. In Group 2 (n=6) the O lasted for 2 hours followed by 4 hours of reperfusion (R). In Group 3 (n=3), LAD was stenosed for 30 minutes followed by O for 6 hours. In Group 4 (n=7) LAD was stenosed for 30 minutes followed by O for 2 hours and then 4 hours of R during which the artery was kept stenosed at the same degree (fixed) as the initial one. In Group 5 (n=6) the protocol was identical to Group 4 with the additional use of the intra-aortic balloon pump during R. RESULTS: The infarcted myocardium was almost the same in Groups 1 and 3 (80.0+/-10.6% vs 77.3+/-3.8%, respectively, p=NS), but less in Group 2 (59.0+/-19.9%, p=0.046 vs Group 1). There were no hemodynamic differences between Groups 4 and 5 and the infarcted myocardium was almost identical in both groups (37.7+/-18.8% and 38.7+/-19.1%, respectively, p=NS). The combined results of Groups 4 and 5, regarding the infarcted myocardium, was 38.1+/-18% (p=0.037 vs Group 2). CONCLUSIONS: In this acute coronary occlusion model, a pre-existing high-grade stenosis that maintained during reperfusion increased the amount of salvaged ischemic myocardium.