Non-invasive Estimation of Cardiac Output in Mechanically Ventilated Patients: A Prolonged Expiration Method

Cecchini, S.; Schena, Emiliano; Notaro, M.; Carassiti, Massimiliano; Silvestri, Sergio

doi:10.1007/s10439-012-0534-3

Cited by 4 publications

(8 citation statements)

References 25 publications

(33 reference statements)

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“…These features make VOM reliable for measurements also in other medical applications. For instance, this kind of sensor may be employed in the field of noninvasive methods for cardiac output estimation [3] in application related to the monitoring of human intestinal gases [30] and in other industrial processes in particular when bidirectional air flow rate must be measured.…”

Section: Discussionmentioning

confidence: 99%

“…Their output is used to estimate minute volume and tidal volume; therefore their accuracy is crucial to perform a correct diagnosis and to avoid common side effects related to uncorrected mechanical ventilation [1]. Moreover, flowmeters play a crucial role in the noninvasive assessment of metabolic gas exchange of mechanically ventilated patients by indirect calorimetry [2] and in noninvasive techniques for cardiac output monitoring [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Assessment of a Variable Orifice Flowmeter for Respiratory Monitoring

et al. 2015

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Accurate measurement of gas exchanges is essential in mechanical ventilation and in respiratory monitoring. Among the large number of commercial flowmeters, only few kinds of sensors are used in these fields. Among them, variable orifice meters (VOMs) show some valuable characteristics, such as linearity, good dynamic response, and low cost. This paper presents the characterization of a commercial VOM intended for application in respiratory monitoring. Firstly, two nominally identical VOMs were calibrated within ±10 L·min−1, to assess their metrological properties. Furthermore, experiments were performed by humidifying the air, to evaluate the influence of vapor condensation on sensor’s performances. The condensation influence was investigated during two long lasting trials (i.e., 4 hours) by delivering 4 L·min−1and 8 L·min−1. Data show that the two VOMs’ responses are linear and their response is comparable (sensitivity difference of 1.4%, RMSE of 1.50 Pa); their discrimination threshold is <0.5 L·min−1, and the settling time is about 66 ms. The condensation within the VOM causes a negligible change in sensor sensitivity and a very slight deterioration of precision. The good static and dynamic properties and the low influence of condensation on sensor’s response make this VOM suitable for applications in respiratory function monitoring.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Assessment of a Variable Orifice Flowmeter for Respiratory Monitoring

et al. 2015

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“…This method was used to calculate the denominator of Eq. 1 without any invasive measurement [8]. The system, schematically reported in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The non-invasive technique for measuring CO using a modified Fick principle [11] applied to CO 2 , already described in detail [8], allows an estimation of the CO by calculating the PBF from the mass conservation of CO 2 . By considering a linear CO 2 dissociation curve, Eq.…”

Section: Cardiac Output Measured By Prolonged Expiration Technique (Cmentioning

confidence: 99%

“…Some techniques based on the Fick method, employ the pulmonary blood flow (PBF) to estimate CO [4][5][6][7]. We proposed a non-invasive method, already described in our previous study [8], which calculates CO applying the differential application of the Fick principle to the CO 2 . The expired gas content was monitored during both normal breathing and prolonged expiration in order to noninvasively estimate PaCO 2 and PvCO 2 .…”

Section: Introductionmentioning

confidence: 99%

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Non-invasive cardiac output evaluation in postoperative cardiac surgery patients, using a new prolonged expiration-based technique

Mattei

Schena

Cecchini

et al. 2014

J Clin Monit Comput

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The gold standard methods to measure cardiac output (CO) are invasive and expose the patient to high risks of various complications. The aim of this study is to assess an innovative non-invasive method for CO monitoring in mechanically ventilated patients after cardiac surgery and its agreement with values obtained by thermodilution technique. Continuous monitoring of respiratory gas concentrations and airflow allows the estimation of CO through a newly developed algorithm derived from a modified version of the Fick equation. It consists of two phases: the first involves measurements during steady breathing state, and the second starts when a sudden perturbation into the carbon dioxide elimination process is introduced by a prolonged expiration. This prospective clinical study involved thirty-five adult patients, undergone cardiac surgery. The measurements were performed in curarized and haemodynamically stable patients, during the post-surgery recovery in intensive care unit. The study protocol, which lasted 1 h for each patient, consisted of 20 measurements obtained by prolonged expiration-based method and 10 by thermodilution. The estimation of CO using the proposed method (COK) agreed with the thermodilution (COT) as demonstrated by: a low mean bias between COK and COT considering all patients (i.e., -0.11 L min(-1)); a best fitting line having slope = 0.98, r = 0.81, p < 0.0001; the lower and upper limits of agreement were -0.77 and +0.54 L min(-1), respectively. COK shows a mean percentage error of 34 %. In stable mechanically ventilated patients, undergone cardiac surgery, the proposed method is reliable if compared to the thermodilution. Considering the non-invasivity of the technique, further evaluations of its performances are encouraged.

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Cardiac output estimation in mechanically ventilated patients: A comparison between prolonged expiration method and thermodilution

Cecchini

Schena

Saccomandi

et al. 2012

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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A non-invasive method to estimate cardiac output (CO) in mechanically ventilated patients, based on prolonged expiration, has been previously described. With the aim to assess its performances, we prospectively enrolled fifteen cardiac surgery patients, and compared the results obtained with the non-invasive method with the ones obtained using two invasive approaches based on thermodilution. The correlations between the prolonged expiration method with both the thermodilution-based ones show high values (ρ(2)>0.77 and ρ(2)>0.89). This encouraging agreement is also confirmed by the closeness between the measured values of CO: the mean differences considering all patients and the two reference invasive techniques are -0.8 % and -7.5 %. These values show the slight underestimation of CO by the proposed non-invasive method with respect to the gold standard. On the other hand the described method could represent a good compromise between accuracy and non-invasiveness, which fosters the implementation of a new monitoring tool suitable for a semi-continuous CO assessment.

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Non-invasive Estimation of Cardiac Output in Mechanically Ventilated Patients: A Prolonged Expiration Method

Cited by 4 publications

References 25 publications

Experimental Assessment of a Variable Orifice Flowmeter for Respiratory Monitoring

Experimental Assessment of a Variable Orifice Flowmeter for Respiratory Monitoring

Non-invasive cardiac output evaluation in postoperative cardiac surgery patients, using a new prolonged expiration-based technique

Cardiac output estimation in mechanically ventilated patients: A comparison between prolonged expiration method and thermodilution

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