Comparison of aortic pulse-wave contour analysis and thermodilution methods of measuring cardiac output during anesthesia in the dog

Efficacy of Stroke Volume Variation, Cardiac Output and Cardiac Index as Predictors of Fluid Responsiveness using Minimally Invasive Vigileo Device in Intracranial Surgeries

Introduction:

Functional hemodynamic monitoring using dynamic parameters such as stroke volume variations (SVVs) based on pulse contour analysis is considered more accurate than central venous pressure and mean arterial pressure (MAP) in predicting fluid responsiveness. New device, i.e., Vigileo system, allows automatic and continuous monitoring of cardiac output (CO) based on pulse contour analysis and respiratory stroke volume.

Aim:

The study aims to test the above hypothesis using graded volume loading step (VLS) to assess the accuracy of SVV as a predictor of fluid responsiveness in patients undergoing intracranial surgery.

Materials and Methods:

After taking ethical committee approval and informed consent, 60 patients aged between 18 and 55 years belonging to the American Society of Anesthesiologists physical status Class I and II, of either sex, scheduled for brain surgery were included in the study. In this study, 5 min after intubation, with stable hemodynamics, patients received volume loading in successive steps (VLS) of 200 ml of lactated Ringer's solution until the stroke volume increased to <10%. Blood pressure (BP), heart rate (HR), stroke volume (SV), and SVV were measured before and after each VLS. Optimal preload augmentation required by each patient was measured by the number of VLS after which an increase in SV was <10%.

Results:

There was a significant decrease in the baseline BP and SV in responsive and nonresponsive groups for the first VLS, but there is no change in HR statistically. There was a significant change in SV after first VLS. Receiver operating characteristic analysis showed a larger area under the curve of 0.758 for SVV compared to other measured variables. The median number of VLS administered were 2 per patient equating to a mean ± SD requirement of 368 ± 176 ml of crystalloid per patient as the optimal preoperative infusion volume.

Conclusion:

SVV is a better predictor of preload responsiveness measured with third-generation Vigileo device when compared to BP and HR.

Edwards FloTrac™ sensor and Vigileo™ monitor: easy, accurate, reliable cardiac output assessment using the arterial pulse wave

Edwards Lifesciences has recently introduced the FloTrac sensor and Vigileo monitor system for monitoring cardiac output continuously. It does not require thermodilution or dye dilution, but rather bases its calculations on arterial waveform characteristics in conjunction with patient demographic data. It is unique among arterial waveform cardiac output systems in that it does not require calibration with another method. Studies thus far indicate that it is robust and accurate over a wide range of cardiac output and clinical conditions. It will be valuable in the care of many patients, such as those with critical illness, cardiovascular dysfunction, trauma or undergoing major surgery.

Comparison of continuous arterial pressure waveform analysis with the lithium dilution technique to monitor cardiac output in conscious dogs with systemic inflammatory response syndrome

OBJECTIVE

To assess the agreement between cardiac output (CO) measured by use of arterial pressure waveform analysis (PulseCO) and lithium dilution (LiDCO) in conscious dogs with systemic inflammatory response syndrome (SIRS).

ANIMALS

14 dogs with naturally occurring SIRS.

PROCEDURES

Pulse power analysis was performed on critically ill patients with a PulseCO monitor. All measurements were obtained with an indwelling arterial line and in accordance with the manufacturer's instructions. Intermittent measurements of CO were obtained with the LiDCO method to validate the PulseCO measurements at initial calibration (baseline; time 0) and at 4, 8, 16, and 24 hours. The 2 methods for measuring CO were compared by use of Bland-Altman analysis. An error rate for the limits of agreement between the 2 methods of < 30% was defined as being acceptable.

RESULTS

Bland-Altman analysis did not indicate good agreement between measurements obtained by use of the PulseCO and LiDCO methods, despite no significant change in cardiac index (CI) over time as measured with the LiDCO method. The percentage error for the overall difference in CI values between the PulseCO and LiDCO measurements was 122%, which indicated that the PulseCO method was not an acceptable means of CO measurement when compared with the LiDCO method for this patient population.

CONCLUSIONS AND CLINICAL RELEVANCE

Agreement between the PulseCO and LiDCO methods for measurement of CO was not acceptable at 4- and 8-hour intervals after calibration in conscious dogs with naturally occurring SIRS.

Is radial artery pressure waveform derived cardiac index is reliable during cardiac surgery with hypothermic cardiopulmonary bypass?

BACKGROUND

Discrepancy of central-peripheral arterial pressure after cardiopulmonary bypass may affect the reliability of arterial pressure waveform derived cardiac index (APCI) monitoring.

METHODS

In 15 elective cardiac surgeries employing moderate hypothermic cardiopulmonary bypass (CPB), APCI from radial arterial cannula and pulmonary artery catheter derived cardiac index from thermodilution method (PACI) were measured 1) after anesthesia induction (T1), 2) before CPB (T2), 3) immediately after CPB (T3) and 4) 1 hour after CPB (T4). APCI and PACI were analyzed by using the Bland-Altman analysis.

RESULTS

Biases of APCI and PACI at T1, T2, T3 and T4 were 0.093 L/min/m2, -0.053 L/min/m2, 0.485 L/min/m2 and -0.09 L/min/m2, respectively. The limits of agreement (2 SD) at T1, T2, T3 and T4 were from -2.285 to 2.471 L/min/m2, -2.475 to 2.369 L/min/m2, -2.255 to 3.225 L/min/m2 and -2.609 to 2.423 L/min/m2, respectively. Bias of APCI and PACI during entire period (T1-T4) was 0.095 L/min/m2 and 2 SD was from -2.387 to 2.557 L/min/m2. However, mean error % (2 SD/mean) of APCI at T1, T2, T3, and T4 were greater than 30%.

CONCLUSIONS

Our results were not able to show that APCI measured from radial artery is comparable to PACI for hemodynamic monitoring during cardiac surgery employing moderate hypothermic CPB. Considering the limitations of PACI as a gold standard of hemodynamic monitoring in a certain clinical circumstance, further investigation employing other monitoring method than PACI may be followed to get more definitive conclusion.

Cardiac Output Determination From the Arterial Pressure Wave: Clinical Testing of a Novel Algorithm That Does Not Require Calibration

OBJECTIVE

The purpose of this study was to evaluate the accuracy and precision of a novel algorithm that evaluates cardiac output by using arterial pressure waveform characteristics.

DESIGN

Prospective, observational study comparing the cardiac output values of intermittent thermodilution, continuous thermodilution, and continuous arterial pressure wave assessment.

SETTING

The intensive care unit in a tertiary care university hospital.

PARTICIPANTS

Fifty postoperative cardiac surgical patients, within the first 12 hours after surgery.

INTERVENTIONS

All patients received a pulmonary artery catheter (PAC) and at least 1 systemic arterial pressure catheter. The data from the arterial catheter were processed by using a new arterial pressure cardiac output (APCO) algorithm. The data from the PAC (continuous and intermittent assessments) were collected for comparison with the APCO.

MEASUREMENTS

Two hundred ninety-five cardiac output measurements using intermittent thermodilution (ICO), continuous thermodilution (CCO), and arterial pressure-based output (APCO) were obtained during various times during the first 12 postoperative hours. The measurements of each method at each time point were compared by using Bland-Altman analysis.

RESULTS

The mean cardiac output ranged from 2.77 to 9.60 L/min. APCO, compared with ICO, revealed a bias of 0.55 L/min and precision of 0.98 L/min. APCO, compared with CCO, revealed a bias of 0.06 L/min and precision of 1.06 L/min. The APCO agreement between femoral and radial arterial catheters was close; the bias was -0.15 L/min, and the precision was 0.56 L/min.

CONCLUSIONS

This novel arterial pressure cardiac output algorithm provides cardiac output assessments that agree satisfactorily for clinical purposes with intermittent and continuous thermodilution techniques in postoperative cardiac surgical patients. Further study is required for other patient populations and clinical situations.

Comparison of arterial pressure waveform analysis with the lithium dilution technique to monitor cardiac output in anesthetized dogs

OBJECTIVE

To assess agreement between arterial pressure waveform-derived cardiac output (PCO) and lithium dilution cardiac output (LiDCO) systems in measurements of various levels of cardiac output (CO) induced by changes in anesthetic depth and administration of inotropic drugs in dogs.

ANIMALS

6 healthy dogs.

PROCEDURE

Dogs were anesthetized on 2 occasions separated by at least 5 days. Inotropic drug administration (dopamine or dobutamine) was randomly assigned in a crossover manner. Following initial calibration of PCO measurements with a LiDCO measurement, 4 randomly assigned treatments were administered to vary CO; subsequently, concurrent pairs of PCO and LiDCO measurements were obtained. Treatments included a light plane of anesthesia, deep plane of anesthesia, continuous infusion of an inotropic drug (rate adjusted to achieve a mean arterial pressure of 65 to 80 mm Hg), and continuous infusion of an inotropic drug (7 microg/kg/min).

RESULTS

Significant differences in PCO and LiDCO measurements were found during deep planes of anesthesia and with dopamine infusions but not during the light plane of anesthesia or with dobutamine infusions. The PCO system provided higher CO measurements than the LiDCO system during deep planes of anesthesia but lower CO measurements during dopamine infusions.

CONCLUSIONS AND CLINICAL RELEVANCE

The PCO system tracked changes in CO in a similar direction as the LiDCO system. The PCO system provided better agreement with LiDCO measurements over time when hemodynamic conditions were similar to those during initial calibration. Recalibration of the PCO system is recommended when hemodynamic conditions or pressure waveforms are altered appreciably.

The new pulmonary arterial catheters. Right ventricular ejection fraction and continuous cardiac output

The flow-directed pulmonary artery catheter is the mainstay of hemodynamic monitoring in critically ill and injured patients. During its 25-year history, the catheter has been modified to measure mixed venous oxygen saturation, right ventricular ejection fraction, and recently, continual thermodilution cardiac output. The clinical application of the new generations of pulmonary artery catheters is reviewed in this article.

The cardiovascular effects of high-dose butorphanol-nitrous oxide anaesthesia before and during operation

The cardiovascular effects of high doses of butorphanol (0.3-0.45 mg . kg-1) plus 60 per cent N2O anaesthesia were measured at unconsciousness, following tracheal intubation, and immediately before and at one and ten minutes after surgical stimulation in 17 A.S.A. class I and II patients undergoing elective gastric or gall bladder surgery. Butorphanol and N2O produced unconsciousness with only small decreases in heart rate and cardiac output but did not result in sufficient analgesia to block or treat stimulation of the cardiovascular system secondary to tracheal intubation or surgical incision, even when supplemented with additional butorphanol to high cumulative dose levels (1.0 mg . kg-1). The data suggest that even high dose butorphanol - N2O anaesthesia requires supplementation with other anaesthetics or anaesthetic adjuvants to prevent cardiovascular stimulation during general abdominal surgery.