Transthoracic echocardiographic assessment of cardiac output in mechanically ventilated critically ill patients by intensive care unit physicians

Bergamaschi, Valentina; Vignazia, Gian Luca; Messina, Antonio; Colombo, Davide; Cammarota, Gianmaria; Corte, Francesco Della; Traversi, Egidio; Navalesi, Paolo

doi:10.1016/j.bjane.2018.09.003

Abstract

Background and objectives:

Transthoracic echocardiography may potentially be useful to obtain a prompt, accurate and non-invasive estimation of cardiac output. We evaluated whether non-cardiologist intensivists may obtain accurate and reproducible cardiac output determination in hemodynamically unstable mechanically ventilated patients.

Methods:

We studied 25 hemodynamically unstable mechanically ventilated intensive care unit patients with a pulmonary artery catheter in place. Cardiac output was calculated using the pulsed Doppler transthoracic echocardiography technique applied to the left ventricular outflow tract in apical 5 chamber view by two intensive care unit physicians who had received a basic Transthoracic Echocardiography training plus a specific training focused on Doppler, left ventricular outflow tract and velocity-time integral determination.

Results:

Cardiac output assessment by transthoracic echocardiography was feasible in 20 out of 25 enrolled patients (80%) and showed an excellent inter-operator reproducibility (Pearson correlation test r = 0.987; Cohen's K = 0.840). Overall, the mean bias was 0.03 L.min^-1, with limits of agreement -0.52 and +0.57 L.min^-1. The concordance correlation coefficient (ρ_c) was 0.986 (95% IC 0.966-0.995) and 0.995 (95% IC 0.986-0.998) for physician 1 and 2, respectively. The value of accuracy (C_b) of CO_TTE measurement was 0.999 for both observers. The value of precision (ρ) of CO_TTE measurement was 0.986 and 0.995 for observer 1 and 2, respectively.

Conclusions:

A specific training focused on Doppler and VTI determination added to the standard basic transthoracic echocardiography training allowed non-cardiologist intensive care unit physicians to achieve a quick, reproducible and accurate snapshot cardiac output assessment in the majority of mechanically ventilated intensive care unit patients.

KEYWORDS
Cardiac output; Transthoracic echocardiography; Pulmonary artery catheter; Intensive Care Unit

[1] * Corresponding author. E-mail:mess81rc@gmail.com (A. Messina).

Patient	Age (y)	M/F	BSA	Diagnosis	PEEP	Inotropes/vasopressors	Dose (mcg.kg⁻¹.min⁻¹)
1	67	M	2.15	ARDS	15	Dopamine	7.0
2	53	M	1.97	AMI	5	Epinephrine	0.1
3	71	M	2.31	Septic shock	12	Norepinephrine	0.7
4	26	F	1.49	Septic shock	15	Norepinephrine	0.8
5	61	M	1.95	AMI	7	Dopamine	8.2
6	54	F	1.73	PE	5	Epinephrine	0.1
7	69	M	1.78	AMI	8	Dobutamine	7.7
8	70	M	2.26	ARDS	20	Norepinephrine	1.1
9	29	F	1.60	Septic shock	15	Norepinephrine	1.0
10	74	M	2.09	AMI	7	Dopamine	8.0
11	72	F	1.78	ARDS	12	Dopamine	9.0
12	78	M	2.07	Septic shock	11	Norepinephrine	1.2
13	19	M	1.68	ARDS	15	Dopamine	9.0
14	73	M	2.06	Septic shock	18	Norepinephrine	0.5
15	74	M	1.97	ARDS	12	Norepinephrine	0.7
16	64	M	2.21	Septic shock	10	Norepinephrine	0.8
17	41	M	2.04	Septic shock	10	Norepinephrine	1.2
18	75	F	1.69	Septic shock	5	Norepinephrine	0.5
19	67	M	1.94	ARDS	15	Norepinephrine	0.4
20	41	M	2.01	ARDS	14	Norepinephrine	0.8

Patient	O₁-CO_TTE (L.min⁻¹)	O₂-CO_TTE (L.min⁻¹)	O_1-2avg-CO_TTE (L.min⁻¹)	CO_PAC (L.min⁻¹)
1	7.57	6.76	7.16	6.65
2	4.40	4.51	4.45	4.47
3	8.09	8.28	8.18	8.18
4	4.89	5.34	5.11	5.18
5	3.43	3.58	3.50	3.79
6	2.89	2.90	2.89	2.77
7	3.61	3.49	3.55	3.55
8	8.54	8.35	8.44	8.12
9	7.15	7.15	7.15	7.32
10	5.62	5.35	5.48	5.25
11	4.12	4.12	4.12	4.58
12	8.90	8.81	8.85	8.89
13	5.60	5.61	5.60	5.42
14	7.75	8.40	8.07	8.12
15	4.40	4.64	4.52	4.42
16	8.59	9.28	8.93	8.98
17	9.05	8.85	8.95	8.77
18	7.84	8.03	7.93	8.22
19	6.31	6.58	6.44	6.39
20	4.27	4.61	4.44	4.26

Mean ± SD	6.15 ± 2.00	6.23 ± 2.01	6.18 ± 1.99	6.14 ± 2.02