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Biomedical subjects

C K Mahutte

Publications and source records attributed to C K Mahutte.

At least 19 recordsLinked to original sources
PubMed1996

Resolution of recurrent atelectasis in spinal cord injury patients with administration of recombinant human DNase.

Atelectasis occurs frequently in patients with spinal cord injury (SCI). Impaired cough leads to ineffective clearance of secretions. If the secretions cannot be cleared and become thick and purulent, atelectasis may occur. Recombinant human DNase (rhDNase) has been shown to decrease purulent sputum viscosity in vitro. We report two SCI patients with respiratory failure due to recurrent atelectasis from purulent secretions in whom conventional treatment methods had failed. Administration of rhDNase resulted in successful resolution of atelectasis. These results suggest the need for a controlled clinical trial.

Deoxyribonucleases↗
PubMed1996

Relationship of changes in cardiac output to changes in heart rate in medical ICU patients.

OBJECTIVE: To determine whether changes in cardiac output are correlated with changes in other commonly measured covariables (heart rate, respiratory rate, mean arterial pressure, mean pulmonary artery pressure, pulmonary artery occlusion pressure, and temperature). DESIGN: Case series. SETTING: Medical intensive care unit (ICU) in a Veterans Administration Medical Center. PATIENTS: Twenty-three patients with Swan-Ganz catheters placed by the primary care team were studied on 25 occasions. Patients were managed by the primary team as clinically indicated. INTERVENTIONS: Thermodilution cardiac output and covariables were determined at baseline and at hourly intervals for the next 5 h. Each cardiac output measurement was calculated by averaging the last four of five individual measurements at each time point. RESULTS: The mean cardiac output (9.21/min), heart rate (107/min), and pulmonary artery occlusion pressure (19 mmHg) were elevated. The hourly mean change in cardiac output was 10.2%. Using least-squares linear regression analysis, we found clinically significant changes in cardiac output (> 6.4%) to be most closely correlated with changes in heart rate (R2 = 0.29, p < 0.001). Stepwise linear regression analysis showed that none of the other covariables added significantly to this relationship. No significant relationship was found between changes in cardiac output and changes in pulmonary artery occlusion pressure. Despite these correlations clinically significant changes in cardiac output were accompanied by changes in heart rate in the same direction only 62% of the time. CONCLUSION: Changes in cardiac output were best correlated with changes in heart rate. Changes in pulmonary artery occlusion pressure were not correlated with changes in cardiac output in this population of medical ICU patients. A change in any of the covariables (alone or in combination) cannot be reliably used to indicate a simultaneous change in cardiac output.

Adult↗
PubMed1996

Arterial blood gas changes during breath-holding from functional residual capacity.

Breath-holding serves as a model for studying gas exchange during clinical situations in which cessation of ventilation occurs. We chose to examine the arterial blood gas changes that occurred during breath-holding, when breath-holding was initiated from functional residual capacity (FRC) while breathing room air. Eight normal subjects who had a radial artery catheter placed for another study were taught to breath-hold on command from FRC. FRC was determined using respiratory inductance plethysmography. Arterial blood gas specimens were obtained at 5-s intervals until the termination of breath-holding. The average breath-holding time (+/-SD) was 35 (+/-10 s). The PaO2, PaCO2, and pH values were plotted against time and individually fit to logistic equations for each subject. The arterial PaO2 fell by a mean of 50 mm Hg during the first 35 s of breath-holding under these conditions, while the arterial PCO2 rose by a mean of 10.2 mm Hg during the first 35 s and the pH fell by a mean of 0.07 in the first 35 s. The rapid decline in PaO2 is greater than that previously reported using different methods and should be considered in clinical situations in which there is an interruption of oxygenation and ventilation at FRC while breathing room air. The changes in PaCO2 and pH are similar to those previously reported in paralyzed apneic patients.

Adolescent↗
PubMed1995

Effect of measurement errors on cardiac output calculated with O2 and modified CO2 Fick methods.

We have investigated the effect of measurement errors on cardiac output, calculated via three different Fick methods. In method 1, the classic O2 Fick equation is expressed in terms of oxygen uptake (VO2), arterial pulse (SaO2) and venous oximetry (SVO2) saturations. The second method, a modified CO2 Fick method, is obtained by replacing VO2 in method 1 with carbon dioxide production (VCO2) divided by the respiratory quotient. In method 3, cardiac output is expressed as VCO2 divided by the product of the SaO2-SVO2 difference and a constant. This constant is determined from initial measurements of VCO2, SaO2, SVO2, and thermodilution cardiac output (Qth). This determination of the constant results in equality of the initial cardiac output of method 3 with the simultaneously determined Qth and, therefore, is similar to performing an autocalibration. For each of the three preceding Fick methods, we derive general expressions that explicitly show how measurement errors (random and systematic) in the Fick variables (VO2, VCO2, SaO2, and SVO2) propagate into errors in calculated cardiac output. The errors in theoretically calculated cardiac output decrease as the SaO2-SVO2 difference increases, except for the systematic error in method 3. The systematic error of method 3 is constant and depends only upon the accuracy of the initial Qth. Analytic expressions for the sensitivity of calculated cardiac output to errors in individual Fick variables are also obtained. Using estimates from the literature for typical systematic and random measurement errors in the Fick variables, the resultant errors in cardiac output are numerically calculated. The effect of random measurement errors on errors in calculated cardiac output was comparable among the three methods. However, the systematic error was least with method 3. Total errors (random and systematic) were comparable among the three methods. Using these numerical measurement errors, we conclude that continuous cardiac output may be calculated with comparable accuracy with each of these methods.

Bias↗
PubMed1995

Arterial oxygenation time after an FIO2 increase in mechanically ventilated patients.

The time for arterial PO2 to reach equilibrium after a 0.2 increase in the fraction of inspired oxygen (FIO2) was studied, using arterial blood gases measured at 1, 2, 3, 4, 5, 7, 9, and 11 min in 30 stable, mechanically ventilated medical intensive care unit (ICU) patients. Eight patients also underwent a 0.4 increase in FIO2. Each patient's rise in PO2 over time [PO2(t)] was fit to the following exponential equation: PO2(t) = PO2i + (PO2f-PO2i) (1-e-kt), where t refers to time, PO2i and PO2f refer to the initial and final equilibrated PO2. The time constant k and PO2f were determined by a nonlinear curve fitting technique. The 90% oxygenation times (t90%), defined as the time required to reach 90% of the final equilibrated PO2, were calculated. The mean t90% (+/- SD) was 6.0 (+/- 3.4) min for all patients (range 1.7 to 14.3 min); 7.1 +/- 2.1 min for 18 patients with chronic obstructive pulmonary disease (COPD) and 4.4 +/- 2.0 min for 12 patients without COPD (p < 0.05). In the subgroup of patients undergoing both an FIO2 increase of 0.2 and 0.4, there was no significant difference in the mean t90%'s for the two FIO2 changes (7.7 versus 7.7 min). We conclude that after a 0.2 or 0.4 increase of FIO3, a 15-min equilibration time period is adequate for 90% of the increase in PO2 to occur, in stable, mechanically ventilated medical ICU patients.

Aged↗
PubMed1994

Oxygen Fick and modified carbon dioxide Fick cardiac outputs.

OBJECTIVE: To compare cardiac outputs estimated from the classical oxygen Fick and modified CO2 Fick methods with thermodilution cardiac output. The modified CO2 Fick cardiac output was obtained by replacing the oxygen uptake (VO2) in the Fick equation with the CO2 production (VCO2) divided by either an assumed or measured value of the respiratory exchange ratio or with an independently determined constant (Crit Care Med 1991; 19:1270-1277). DESIGN: Criterion standard study. SETTING: The medical and surgical intensive care unit (ICU) in a Veterans Affairs Medical Center. PATIENTS: A total of 17 patients (26 studies) and 11 surgical patients (13 studies), predominantly mechanically ventilated using the intermittent mandatory ventilation mode, were studied over a period of 4.3 hrs. MEASUREMENTS: A respiratory gas exchange monitor was used to measure VO2, VCO2, and respiratory exchange ratio at 3-min intervals. Calculations were performed with arterial and venous oxygen saturations measured with both a laboratory cooximeter and bedside pulse and venous reflectance oximeters. In the oxygen Fick method, cardiac output was calculated from VO2 together with arterial and venous oxygen saturations. In the modified CO2 Fick methods, cardiac output values were calculated from arterial and venous oxygen saturations with VCO2, divided by either: a) an assumed value of the respiratory exchange ratio equal to 0.8 for all patients (method 1); b) the patient's measured value of the respiratory exchange ratio (method 2); or c) a constant, determined from an initial, simultaneous measurement of thermodilution cardiac output, VCO2, and oximetry saturations. Data were examined by linear regression analysis and bias and precision calculations. MAIN RESULTS: Thermodilution cardiac output was more related to cardiac outputs calculated with the 3 modified CO2 Fick methods than to the oxygen Fick cardiac output. Thermodilution cardiac output was closely related to the modified CO2 Fick cardiac output calculated via method 3. For this method, with pulse and venous reflectance oximetry saturations, linear regression yielded an r2 = .85, a standard error of the estimate of 0.88 L/min (n = 111) and a bias and precision of 0.11 and 0.97 L/min, respectively. Thermodilution cardiac output was less closely related to oxygen Fick cardiac output, which, when calculated with pulse and venous reflectance oximetry saturations, yielded an r2 = .50, a standard error of the estimate of 1.47 L/min (n = 128), and a bias and precision of 0.01 and 1.85 L/min, respectively. CONCLUSIONS: We conclude from this study that thermodilution cardiac output is more closely related to cardiac output calculated from modified CO2 Fick methods than to oxygen Fick cardiac output. Since cardiac output calculated with the modified CO2 Fick method 3 obviates the difficulties associated with measuring VO2 accurately and requires neither an assumption of nor measurement of the respiratory exchange ratio, method 3 may prove to be clinically useful for continuous cardiac output monitoring via oximetry in ICU patients.

Adult↗
PubMed1994

Variability of cardiac output over time in medical intensive care unit patients.

OBJECTIVES: To determine the amount of spontaneous variability of cardiac output over time in critically ill patients, and to determine the effect of mechanical ventilation on cardiac output variability over time. DESIGN: Case series. SETTING: Medical intensive care unit in a Veterans Affairs Medical Center. PATIENTS: Twenty-two patients with indwelling pulmonary artery flotation catheters were studied. Two patients were studied twice. INTERVENTIONS: During a 1-hr time period in which no interventions were required or made, thermodilution cardiac output was determined at baseline and then every 15 mins for 1 hr. At each time point, five individual cardiac output measurements were made and a mean was computed. The covariables of heart rate, respiration rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary artery occlusion pressure, and temperature were also recorded at each time point. MEASUREMENTS AND MAIN RESULTS: The variability of the five cardiac output measurements made at each time point was expressed by calculating for each patient a coefficient of variation of the measurements. The overall mean coefficient of variation of the measurements was 5.8%. The variability of the cardiac output measurements over time was expressed by calculating for each patient a coefficient of variation over time. The overall mean coefficient of variation over time was 7.7%. A subgroup of 15 "covariable stable" patients (defined as those patients with covariables within +/- 5% of the mean covariable values during the hour) had a mean coefficient of variation over time of 6.4%, whereas "covariable unstable" patients (with > +/- 5% changes in any covariable) had a mean coefficient of variation over time of 9.9% (p < .05). Patients breathing spontaneously had a mean coefficient of variation over time of 10.1%, whereas mechanically ventilated patients had a mean coefficient of variation over time of 6.3% (p < .05). CONCLUSIONS: The spontaneous variability of cardiac output should be considered when interpreting two cardiac output determinations made at separate times. Due to spontaneous variability alone, a patient with a baseline cardiac output of 10.0 L/min would be expected (95% confidence interval) to have a cardiac output range of 9.2 to 10.8 L/min if covariables were stable, and a range of at least 8.8 to 11.2 L/min if covariables were unstable. Patients who were mechanically ventilated displayed less variability than patients who were breathing spontaneously.

Adult↗
PubMed1994

Development of a patient-dedicated, on-demand, blood gas monitor.

A new monitor (CDI 2000) that brings blood gas measurements to the patient's bedside has been developed. To measure blood gases, blood is drawn into the patient's arterial pressure-monitoring line past in-line fluorescent-based sensors. After measurement, the blood is returned to the patient, avoiding blood loss and delays in sample turnaround and reducing the risk of infection to both patient and operator. We assessed this system's performance in vitro with tonometered bovine blood. Bias (mean difference between monitor and tonometered gas or measured pH values) +/- the standard deviation (SD) were 0.01 +/- 0.02 at pH = 7.39; 0.0 +/- 0.7 mm Hg at Pco2 = 39 mm Hg; and 2.4 +/- 3.2 mm Hg at a Po2 = 100 mm Hg (n = 54). Changes in hematocrit, blood temperature, or serum sodium concentration did not have clinically significant effects on system performance. Studies in normal volunteers, in whom large changes in blood gases were induced, showed a bias (mean difference between monitor and IL 1306 values) +/- SD of 0.00 +/- 0.02 for pH, -0.4 +/- 2.0 mm Hg for Pco2, and -3.6 +/- 7.7 mm Hg for Po2 (n = 69). We conclude from the present study that the performance of this system is comparable to that of conventional blood gas analyzers.

Animals↗
PubMed1994

Performance of a patient-dedicated, on-demand blood gas monitor in medical ICU patients.

We examined the performance characteristics of a new bedside blood gas monitor. This monitor's fluorescent pH, PCO2, and PO2 sensors are embedded in a cassette, which is calibrated in vitro and then inserted into the patient's radial artery tubing set. In 50 medical ICU patients, 683 paired monitor and conventional blood gas analyzer values were obtained. Performance was assessed via calculations of bias (mean monitor and analyzer difference) and its standard deviation (SD), plots of monitor and analyzer differences against the means (of monitor and analyzer), and linear regression analysis of the sequential changes in monitor values versus the corresponding sequential changes in analyzer values. The ex vivo calibration, assessed using the initial paired blood samples, showed a bias +/- SD of 0.02 +/- 0.02 for pH, -0.1 +/- 1.9 mm Hg for PCO2, and 4.3 +/- 6.0 mm Hg for PO2. For all paired samples (n = 683), the biases +/- SD were 0.004 +/- 0.023 for pH, 0.6 +/- 2.4 mm Hg for PCO2, and 2.7 +2- 6.4 mm HG for PO2. The PO2 bias increased as PO2 increased. The standard deviations (imprecision) of both PCO2 and PO2 also increased as the magnitudes of these variables increased. Sequential changes in monitor values versus the corresponding sequential changes in analyzer values revealed regression lines close to the line of identity. Serum sodium had no effect on pH bias. Daily drift of the sensors was inconsequential, with values of -0.01/d for pH, 1.7 mm Hg/d for PCO2, and 1.1 mm Hg/d for PO2. We conclude that the performance of this monitor is comparable to that of conventional blood gas analyzers.

Blood Gas Analysis↗
PubMed1994

Variability of arterial blood gas values over time in stable medical ICU patients.

The spontaneous variability of arterial blood gas and pH values (ABGs) was examined in a group of 28 typical stable medical ICU patients under a variety of ventilatory conditions. In each patient, 13 ABG specimens were measured at 5-min intervals during a 1-h study period using a new bedside, extravascular fluorescent blood gas monitor. For all patients, the mean coefficient of variation (C) was 6.1 percent for PO2 and 4.7 percent for PCO2. The average SD for pH was 0.012. We conclude that the spontaneous variability for ABG values over a 1-h period is substantial and that this variability should be taken into account when making clinical decisions based on ABG values.

Adult↗
PubMed1994

Acquired laryngomalacia as a cause of obstructive sleep apnea.

We describe a patient who, 4 years after a radical neck dissection and radiotherapy, presented with obstructive sleep apnea; upon bronchoscopy, he was found to have acquired laryngomalacia. Inspiration induced upper airway obstruction due to a large flaccid epiglottis, large aryepiglottic folds, and edema of the supraglottic area. We suggest that acquired laryngomalacia can lead to obstructive sleep apnea. Patients with obstructive sleep apnea after radical neck dissection need to be evaluated for laryngomalacia with fiberoptic laryngobronchoscopy. Examination of the upper airway is useful to determine the nature and extent of any upper airway collapse.

Adult↗
PubMed1994

Influence of pressure- and flow-triggered synchronous intermittent mandatory ventilation on inspiratory muscle work.

OBJECTIVE: To determine the effect of pressure- and flow-triggered synchronous intermittent mandatory ventilation on inspiratory muscle work. DESIGN: Consecutive clinical, prospective, randomized trial. SETTING: Medical intensive care unit (ICU) of a U.S. Veterans Affairs Medical Center. PATIENTS: Eight patients recovering from acute respiratory failure of various etiologies. INTERVENTIONS: Assist control, followed by randomized application of pressure- and flow-triggered synchronous intermittent mandatory ventilation at 60%, 40%, 20% of the assist-control rate, and flow-triggered continuous positive airway pressure. A total of eight settings were maintained for 10 mins each. MEASUREMENTS AND MAIN RESULTS: Total work rate (joules/min), inspiratory muscle work (joules/L), and pressure time-product per breath (cm H2O-sec) were measured. During pressure- or flow-triggered synchronous intermittent mandatory ventilation, total work rate increased as the mandatory rate was decreased. The method of ventilator triggering had a significant effect on the total work rate. With pressure-triggered synchronous intermittent mandatory ventilation, the total work rate at 60% of the assist-control rate was similar to that with assist-control; whereas with flow-triggered synchronous intermittent mandatory ventilation, this result was achieved at 40% of the assist-control rate. At a machine support level of 20%, total work rate with pressure-triggered synchronous intermittent mandatory ventilation was significantly greater than with flow-triggered synchronous intermittent mandatory ventilation. The method of ventilator triggering had no significant effect on the inspiratory muscle work of the mandatory breaths. This finding was in contrast to the effect on inspiratory muscle work of spontaneous breaths. With pressure-triggered synchronous intermittent mandatory ventilation, inspiratory muscle work of the spontaneous breaths was greater than with the flow-triggered at machine support of 40% and 20%. With either pressure- or flow-triggered synchronous intermittent mandatory ventilation, inspiratory muscle work of the mandatory breaths was not significantly different from that of the corresponding spontaneous breaths, except at the lower machine support levels with the pressure-triggered synchronous intermittent mandatory ventilation. Pressure-time product followed a trend similar to that of inspiratory muscle work. CONCLUSIONS: During synchronous intermittent mandatory ventilation, the method of ventilator triggering has a significant effect on the total work rate and inspiratory muscle work of the spontaneous breaths, particularly at lower machine support levels. Conversely, the method of ventilator triggering has no significant effect on inspiratory muscle work of the mandatory breaths.

Acute Disease↗
PubMed1993

Experimental and predicted dual oximetry variability.

OBJECTIVE: We wished to determine whether the individual bias (mean difference) and precision (standard deviation of the difference) values of 2 variables, arterial oxygen saturation (SaO2) and mixed venous oxygen saturation (SvO2), could be used to predict the bias and precision values of the combined dual oximetry variable (SaO2-SvO2). METHODS: We simultaneously measured SaO2 by pulse oximetry and arterial blood gas co-oximetry and SvO2 by fiberoptic reflectance oximetry pulmonary artery catheter and venous blood gas co-oximetry in 238 data sets from 55 patients. Three different methods were used to predict the standard deviation of the difference of (SaO2-SvO2) [s delta(SaO2-SvO2)]: simple sum, root mean square (RMS) error, and RMS error with correction term. We derived the equation for the RMS error with correction term because initial results showed that the simple sum and RMS error methods did not predict s delta(SaO2-SvO2) well. The correction term accounts for the non-independence of simultaneous SaO2 and SvO2 measurements. RESULTS: The observed overall bias of the SaO2, SvO2, and (SaO2-SvO2) measurement methods were 0.17, -1.76, and 1.94, respectively. The observed overall s delta(SaO2-SvO2) of the (SaO2-SvO2) measurement method was 5.12. The simple sum method overestimated the actual s delta(SaO2-SvO2) by 38%, the RMS error method differed from the actual s delta(SaO2-SvO2) by 3%, and the RMS error with correction term method matched the actual s delta(SaO2-SvO2). CONCLUSION: The bias of a (SaO2-SvO2) measurement method is simply the bias of the SaO2 measurement method less the bias of the SvO2 measurement method. s delta(SaO2-SvO2) is best predicted by the derived equation, RMS error with correction term. The same principles and equations also apply to other situations in which 2 variables with the same dimensions are combined into 1 variable, such as (PaCO2-EtCO2) gradients and perfusion-pressure gradients. Although the difference between the s delta(SaO2-SvO2) predicted by the RMS error equation and the derived RMS error equation with correction term was small, the difference may be significant for other combined variables.

Oximetry↗
PubMed1993

Clinical performance of a blood gas monitor: a prospective, multicenter trial.

OBJECTIVE: To prospectively assess the clinical performance of a fluorescent optode-based blood gas monitoring system that is designed to perform arterial pH, PCO2, and PO2 measurements as frequently as clinically required without violating the integrity of the arterial catheter tubing system or permanently removing blood from the patient. DESIGN: A prospective, multicenter study to compare modern blood gas analyzer measurements with the coinciding measurements of the blood gas monitoring system. SETTING: Four intensive care units (ICUs) in academic centers with varying patient populations, blood gas measurement routines, and blood gas laboratory facilities. PATIENTS: Adult ICU patients (n = 117), with appropriately functioning radial arterial catheters in place, who were assessed as likely to require multiple arterial blood gas measurements for > or = 2 days. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 117 patients had 1,341 concurrent blood gas analyzer and monitor measurements of arterial pH, PCO2, and PO2 over a 1- to 4-day period. The range of values were 7.14 to 7.64 for arterial pH, 19 to 98 torr (2.5 to 13.0 kPa) for PaCO2, and 38 to 413 torr (5.1 to 54.9 kPa) for PaO2. Linear regression analysis of the optode-based monitor compared with the electrode-based blood gas analyzer demonstrated r2 values of .85 for pH, .92 for PCO2, and .94 for PO2. Comparative statistical analyses for bias (mean difference between analyzer and monitor) and precision (standard deviation of the mean difference [+/- SD] between analyzer and monitor) were respectively:-0.004 and +/- 0.027 for pH; -0.8 torr (-0.11 kPa) and +/- 2.4 torr (0.32 kPa) for PCO2; -2.2 torr (-0.31 kPa) and +/- 8.7 torr (1.2 kPa) for PO2. CONCLUSIONS: Clinical performance of this fluorescent, optode-based blood gas monitoring system demonstrates stability, consistency, and accuracy comparable to modern blood gas analyzers. This system withstood the normal abuse and rigors of clinical conditions common to the ICU while reliably performing in critically ill patients for up to 80 hrs. Use of the device did not significantly alter the function or longevity normally expected from a 20-gauge radial artery catheter. We submit that this blood gas monitoring system can replace the use of blood gas analyzers for ICU patients with indwelling arterial catheters.

Adolescent↗
PubMed1993

Effect of hypercapnia on the arousal response to airway occlusion during sleep in normal subjects.

The effect of an acute increase in PCO2 on the arousal response to occlusion of a mask covering the nose with the mouth sealed during non-rapid-eye-movement sleep was studied in six normal males aged 28.3 +/- 8.3 (SD) yr. Baseline occlusions, while subjects breathed a room air-O2 mixture adjusted to produce an arterial O2 saturation of 98%, were alternated with hypercapnic occlusions in which a small amount of 100% CO2 was added to increase the preocclusion end-tidal PCO2 by 3.5 +/- 0.59 Torr above the baseline value. The maximum deflections in supraglottic airway pressure (Pmax) were measured on the initial occluded breath (PmaxI) and the final breath preceding arousal (PmaxF). In the hypercapnic occlusions, the time to arousal was shorter (23.7 +/- 13.9 vs. 35.2 +/- 15.9 s, P < 0.03) and PmaxI and rate of change in Pmax were higher. However, the PmaxF in the baseline (20.2 +/- 4.1 cmH2O) and hypercapnic occlusions (20.4 +/- 4.4 cmH2O) did not differ. We conclude that an increase in PCO2 before airway occlusion shortens the time to arousal by increasing the initial occluded inspiratory effort (suction pressure) and the rate of increase in effort but does not change the arousal threshold.

Adolescent↗
PubMed1993

Airway occlusion pressure and breathing pattern as predictors of weaning outcome.

Airway occlusion pressure (P0.1) and the ratio of breathing frequency (f) to tidal volume (VT) (f/Vt) are good predictors of weaning outcome. However, the specificity of f/VT in predicting weaning success is relatively low. We postulated that the product of P0.1 and f/VT (P0.1*f/VT) would better predict weaning outcome than either variable alone. In 45 male patients, we prospectively evaluated P0.1*f/VT, P0.1, and f/VT in predicting weaning outcome. The threshold values of each variable were determined from published data. The sensitivity, specificity, and positive and negative predictive values in detecting weaning success, and the area under the receiver operating characteristic (ROC) curves were calculated. Ten (22%) of the 45 patients failed weaning. P0.1*f/VT yielded the highest specificity and positive and negative predictive values. P0.1*f/VT, P0.1, and f/VT were all highly sensitive (0.97); but they were less specific, 0.60 for P0.1*f/Vt and 0.40 for P0.1 and f/VT. The areas under the ROC curves for P0.1*f/VT, P0.1, and f/VT were not significantly different. We conclude that P0.1*f/VT has equivalent sensitivity as P0.1 and f/VT. P0.1 slightly improves the specificity of f/VT in predicting weaning success.

Acute Disease↗