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Minute Ventilation (minute + ventilation)
Selected AbstractsMechanisms by which systemic salbutamol increases ventilationRESPIROLOGY, Issue 2 2006Antony E. TOBIN Background and objective: Salbutamol (SAL) has systemic effects that may adversely influence ventilation in asthmatic patients. The authors sought to determine the magnitude of this effect and mechanisms by which i.v. SAL affects ventilation. Methods: A prospective study of nine healthy subjects (eight men, one woman; age 23 ± 1.4 years (SD)) was undertaken. Each subject received i.v. SAL at 5, 10 and 20 µg/min each for 30 min at each dose and was observed for 1 h post infusion. Minute ventilation (V,E), oxygen consumption (V,O2), CO2 production (V,CO2), occlusion pressure (P0.1), heart rate, blood pressure, respiratory rate, glucose, arterial blood gases, lactate and potassium (K+) were recorded at baseline and at 30-min intervals. The effect of 100% oxygen on V,E and P0.1 during SAL infusion at 20 µg/min was observed. Results are expressed as mean ± SEM. Results: V,E was significantly increased at 20 µg/min SAL (37.8 ± 12.1%, P = 0.01), as were V,O2 (22.5 ± 5.1%, P < 0.01) and V,CO2 (40.9 ± 10.6%, P < 0.01). Ventilation was in excess of metabolic needs as demonstrated by a rise in the respiratory exchange ratio (0.87 ± 0.03 to 0.99 ± 0.04, P < 0.05). Serum lactate rose by 124 ± 30.4% from baseline to 20 µg/min (1.1 ± 0.1 to 2.3 ± 0.25 mmol/L, P < 0.01) and base excess decreased (0.89 ± 0.56 to vs. ,1.75 ± 0.52 mmol/L, P < 0.01) consistent with a lactic acidosis contributing to the excess ventilation. There was no significant differences in V,E or P0.1 with FIO2 = 1.0, suggesting peripheral chemoreceptor stimulation was not responsible for the rise in V,E. At 20 µg/min SAL, K+ fell significantly from baseline (3.8 ± 0.06 to 2.8 ± 0.09 mmol/L, P < 0.001). Conclusion: Systemic SAL imposes ventilatory demands by increasing metabolic rate and serum lactate. This may adversely affect patients with severe asthma with limited ventilatory reserve. [source] A Single Ventilator for Multiple Simulated Patients to Meet Disaster SurgeACADEMIC EMERGENCY MEDICINE, Issue 11 2006Greg Neyman MD Objectives To determine if a ventilator available in an emergency department could quickly be modified to provide ventilation for four adults simultaneously. Methods Using lung simulators, readily available plastic tubing, and ventilators (840 Series Ventilator; Puritan-Bennett), human lung simulators were added in parallel until the ventilator was ventilating the equivalent of four adults. Data collected included peak pressure, positive end-expiratory pressure, total tidal volume, and total minute ventilation. Any obvious asymmetry in the delivery of gas to the lung simulators was also documented. The ventilator was run for almost 12 consecutive hours (5.5 hours of pressure control and more than six hours of volume control). Results Using readily available plastic tubing set up to minimize dead space volume, the four lung simulators were easily ventilated for 12 hours using one ventilator. In pressure control (set at 25 mm H2O), the mean tidal volume was 1,884 mL (approximately 471 mL/lung simulator) with an average minute ventilation of 30.2 L/min (or 7.5 L/min/lung simulator). In volume control (set at 2 L), the mean peak pressure was 28 cm H2O and the minute ventilation was 32.5 L/min total (8.1 L/min/lung simulator). Conclusions A single ventilator may be quickly modified to ventilate four simulated adults for a limited time. The volumes delivered in this simulation should be able to sustain four 70-kg individuals. While further study is necessary, this pilot study suggests significant potential for the expanded use of a single ventilator during cases of disaster surge involving multiple casualties with respiratory failure. [source] Rate Responsive Pacing Using Transthoracic Impedance Minute Ventilation Sensors: A Multicenter Study on Calibration StabilityPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2002FIRAT DURU DURU, F., et al.: Rate Responsive Pacing Using Transthoracic Impedance Minute Ventilation Sensors: A Multicenter Study on Calibration Stability. Previous studies showed that transthoracic impedance. Previous studies showed that transthoracic impedance minute ventilation (IMV), as measured by a pacemaker sensor, is closely correlated to actual minute ventilation (VE·) determined by standard methods. The aim of this study was to analyze the changes in the calibration between IMV and VE· at rest and during exercise over time. Fifteen patients (age 60 ± 13 years) with Medtronic Kappa 400 pacemakers completed a baseline visit followed by two visits separated by 1 month and 1 week, respectively. In each patient, VE· (L/min) was monitored at rest in the supine and sitting positions and during graded bicycle ergometer exercise using a standard cardiopulmonary metabolic gas analysis system with simultaneous recording of IMV (,/min) using DR-180 extended telemetry monitors. Calibration at rest was defined as the ratio of IMV to VE·, calculated from 1-minute average values in the supine and sitting positions. Calibration during bicycle exercise was defined as intercept (IMV value at VE·= 10 L/min-typical VE· value at beginning of exercise), and slope of the IMV/VE· regression line. The calibration of IMV showed individual variability over time. The magnitude (absolute value) of observed fractional changes in calibration at 1 month was 0.23 ± 0.20 (rest-supine), 0.20 ± 0.15 (rest-sitting), 0.18 ± 0.19 (exercise-intercept), 0.28 ± 0.35 (exercise-slope), and 0.18 ± 0.15, 0.15 ± 0.09, 0.28 ± 0.39, and 0.27 ± 0.15, respectively, at 1 week. The magnitude of change at 1 month was not statistically different from the magnitude of change at 1 week. In conclusion, the calibration of IMV, as measured by a pacemaker sensor, versus actual VE· may demonstrate variability. However, this study also suggests that the observed changes are not cumulative over time. These results have implications for patient monitoring applications using these sensors and for development of future pacemaker rate response algorithms. [source] The repeatability of submaximal endurance exercise testing in cystic fibrosis,PEDIATRIC PULMONOLOGY, Issue 1 2007MB BCh BAO, Sinead C. Barry BSc Abstract Submaximal endurance cycle ergometer exercise tests are used to measure the efficacy of an exercise intervention, but the repeatability of these tests in patients with cystic fibrosis (CF) has not been established. The purpose of this study was to examine the repeatability of submaximal endurance testing in stable CF. Fifteen adults with CF underwent two submaximal endurance tests carried out over a 7-day period. A subset of six subjects returned 28 days later for a third submaximal endurance test. Workload was set at 80% of maximum workload and exercise was performed to exhaustion. Oxygen consumption, minute ventilation, tidal volume, carbon dioxide output, respiratory rate, heart rate, and oxygen saturation were measured at rest, at end exercise and at four matched times during the submaximal endurance tests (20, 40, 60, and 80% of exercise duration calculated from the first endurance test). Submaximal endurance test time was highly repeatable with no significant learning effect identified on multiple testing. Submaximal endurance exercise time demonstrated a variability of 5.7% which is consistent with high levels of repeatability. Metabolic, ventilatory and cardiac variables were all also highly reproducible between test days. Submaximal endurance testing is repeatable in stable CF, confirming that submaximal endurance tests are a reliable tool for assessment of therapeutic benefit in patients with CF. Pediatr Pulmonol. 2007; 42:75,82. © 2006 Wiley-Liss, Inc. [source] Influence of body fat distribution on oxygen uptake and pulmonary performance in morbidly obese females during exerciseRESPIROLOGY, Issue 1 2001Jing Li Objective: The aim of this study was to determine the effects of fat distribution on aerobic and ventilatory response to exercise testing in morbidly obese (MO) females. Methodology: The study population consisted of 164 MO females, 55% (n = 90) with upper body or abdominal adiposity (UBD), as defined by waist,hip circumference ratio (WHR) , 0.80, and 45% (n = 74) with lower body fat distribution (LBD) (WHR < 0.80). An incremental exercise testing on cycle ergometer was performed to determine the effect of exercise on oxygen consumption (V·O2), carbon dioxide production (V·CO2), minute ventilation (V·E), tidal volume ( T), respiratory rate (fb) and heart rate (HR). Results: Upper body adiposity individuals had significantly higher O2 and V·CO2 than LBD subjects (P < 0.05) from 0 watt (W) of pedalling up to their anaerobic threshold (AT) and maximal exercise. E was significantly higher in UBD subjects compared with LBD subjects, from 20 W during exercise up to AT and peak work levels (P < 0.05). Upper body adiposity group also had a significantly higher fb than the LBD group at rest, after each workload and at AT and peak exercise work rates (P < 0.05). T was lower in UBD subjects at free pedalling and up to AT and peak workload with significant difference at 60 and 80 W (P < 0.05). The anaerobic threshold, expressed as work rate, was significantly lower in the UBD subjects (P < 0.05) and peak workload achieved did not differ significantly between the two groups. Conclusions: Upper body adiposity subjects had higher oxygen requirement, more rapid and shallow breathing, higher ventilatory demand, but lower anaerobic threshold than the LBD individuals during progressive exercise. It suggests that the cardiopulmonary endurance to exercise in MO patients with upper body fat distribution is lower than in those with lower body fat distribution. [source] Treatment with leuprolide acetate decreases the threshold of the ventilatory response to carbon dioxide in healthy malesTHE JOURNAL OF PHYSIOLOGY, Issue 2 2004Jason H. Mateika This investigation was designed to determine if suppression of testosterone alters the ventilatory response to carbon dioxide in the presence of high and low levels of oxygen. Eleven healthy male subjects completed a series of rebreathing trials during wakefulness, before and after treatment with a long-acting gonadotropin-releasing hormone agonist. Five subjects also completed studies during non-rapid eye movement (NREM) sleep. During wakefulness, subjects initially hyperventilated to reduce the partial pressure of carbon dioxide (PET,CO2) below 25 Torr. Subjects then rebreathed from a bag containing a normocapnic (42 Torr), low (50 Torr) or high oxygen (140 Torr) gas mixture. During each trial PET,CO2 increased while oxygen was maintained at a constant level. The threshold of the ventilatory response to carbon dioxide was considered to be the point at which minute ventilation began to rise in a linear fashion as PET,CO2 increased. The slope of the ventilatory response above the threshold was used as a measure of sensitivity to carbon dioxide. During NREM sleep, hypocapnia was induced via nasal mechanical ventilation. Several trials were completed until the cessation of mechanical ventilation resulted in a central apnoea which demarcated the threshold of the ventilatory response to carbon dioxide. In response to treatment with leuprolide acetate, the threshold measured in wakefulness decreased during carbon dioxide rebreathing in the presence of low (41.05 ± 0.77 versus 39.40 ± 0.83 Torr; P= 0.01) and high (46.32 ± 0.56 versus 44.78 ± 0.83 Torr; P= 0.01) oxygen levels. An increase in sensitivity (4.82 ± 0.61 versus 7.17 ± 1.20 l min,1 Torr,1; P= 0.02) was also observed during rebreathing in the presence of high but not low oxygen levels. The increase in sensitivity was accompanied by an increase in carbon dioxide production. The findings observed during NREM sleep were similar to those observed during wakefulness, since the PET,CO2 that demarcated the threshold was decreased after leuprolide treatment (42.1 ± 0.6 versus 39.6 ± 0.6 Torr; P= 0.002). Additionally, the decrease in PET,CO2 required to induce an apnoea was greater after treatment with leuprolide (2.56 ± 0.25 versus 4.06 ± 0.29 Torr; P= 0.004). We conclude that suppression of testosterone decreases the threshold of the ventilatory response to carbon dioxide during both wakefulness and sleep. [source] A comparison of the respiratory effects of oxycodone versus morphine: a randomised, double-blind, placebo-controlled investigation,ANAESTHESIA, Issue 10 2010S. H. Chang Summary Oxycodone's respiratory profile (particularly the extent of respiratory depression in comparison to morphine) remains to be fully characterised in the peri-operative period. We randomly assigned ASA 1-2 adults for elective surgery under general anaesthesia to receive saline, morphine 0.1 mg.kg,1, or oxycodone 0.05 mg.kg,1, 0.1 mg.kg,1, or 0.2 mg.kg,1. Results were obtained from six patients in the saline group, 12 patients in the groups receiving morphine 0.1 mg.kg,1, oxycodone 0.05 mg.kg,1 and 0.1 mg.kg,1, and from 10 patients who received oxycodone 0.2 mg.kg,1. Patients were breathing spontaneously and minute ventilation monitored with a wet wedge spirometer for 30 min. All active groups demonstrated significant respiratory depression compared to saline (p < 0.0001 for all groups). The mean (SD) reduction in minute volume from baseline was 22.6% (10.4%) for the morphine 0.1 group and 53.3% (27.2%), 74.4% (12.9%) and 88.6% (13.5%) for the oxycodone 0.05, 0.1 and 0.2 groups, respectively, with significant dose dependent differences between oxycodone groups (p = 0.0007). The extent and speed of onset of oxycodone induced respiratory depression was dose dependent and greater than an equivalent dose of morphine. [source] Physiologic Effects of the TASER After ExerciseACADEMIC EMERGENCY MEDICINE, Issue 8 2009Gary M. Vilke MD Abstract Objectives:, Incidents of sudden death following TASER exposure are poorly studied, and substantive links between TASER exposure and sudden death are minimal. The authors studied the effects of a single TASER exposure on markers of physiologic stress in humans. Methods:, This prospective, controlled study evaluated the effects of a TASER exposure on healthy police volunteers after vigorous exercise, compared to a subsequent, identical exercise session that was not followed by TASER exposure. Subjects exercised to 85% of predicted heart rate (HR) on an ergometer and then were given a standard 5-second TASER activation. Measures before and for 60 minutes after the TASER activation included minute ventilation, tidal volume, respiratory rate, end-tidal pCO2, oxygen saturation, HR, blood pressure (systolic BP/diastolic BP), 12-lead electrocardiogram, and arterialized blood for pH, pO2, pCO2, and lactate. Each subject repeated the exercise and data collection session on a subsequent data, without TASER activation. Data were analyzed using paired Student's t-tests with differences and 95% confidence intervals (CIs). Statistical significance was adjusted for multiple comparisons. Results:, A total of 25 officers (21 men and 4 women) completed both portions of the study. After adjusting for multiple comparisons, the TASER group was significantly higher for systolic BP at baseline (difference of 14.1, 95% CI = 8.7 to 19.5, p < 0.001) and HR at 5, 30, and 60 minutes with the largest difference at 30 minutes (difference of 7.0, 95% CI = 2.5 to 11.5, p = 0.004). There were no other significant differences between the two groups in any other measure at any time. Conclusions:, A 5-second exposure of a TASER following vigorous exercise to healthy law enforcement personnel does not result in clinically significant changes in ventilatory or blood parameters of physiologic stress. 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