T6 - Choque e Monitorização Hemodinâmica (2)

Question 1

Volumetric parameters?

Answer 1

✓ Transpulmonary thermodilution has enabled measurement of several new volumetric parameters, which can be obtained with the PiCCO and VolumeView devices. (permite avaliação de pré-carga e outros parâmetros)

Question 2

Basic Principles of Thermodilution (pulmonary/transpulmonary)?

Answer 2

✓ Atualmente menos utilizadas
✓ For thermodilution methods (e.g. pulmonary artery catheter, PiCCO, VolumeView) a drop in temperature is used. A temperature–time curve is thus produced.
✓ Permitem em alguns doentes, particularmente naqueles com disfunção ventricular direita significativa, uma avaliação adequada de múltiplos parâmetros que vão para além da análise da pré-carga e que incluem o índice de permeabilidade vascular pulmonar
✓ Dynamic measures are more accurate than static measurements for assessing fluid responsiveness in mechanically ventilated patients.
✓ In simple terms, assessing fluid responsiveness asks the question: Will the cardiac output increase with fluid administration?

Question 3

PVPI?

Answer 3

✓ Pulmonary vascular permeability index
✓ This reflects the permeability of the capillary-alveolar barrier
✓ PVPI is higher (>3) in ALI/ARDS than in hydrostatic pulmonary edema
✓ Importante para distinguir edema pulmonar hidrostático (ex. IC esq) de edema pulmonar não hidrostático (não pulmonar)

Question 4

Cardiac output monitoring?

Answer 4

Cardiac output (CO) monitoring plays an essential role in critical care.

✓ Direct measurement of CO should be considered when a patient remains hypotensive despite adequate fluid resuscitation or when there is ongoing evidence of global tissue hypoperfusion.

Question 5

Pulmonary artery catheter (PAC or Swan-Ganz Catheter)?

Answer 5

✓ Has long been considered the optimal form of hemodynamic monitoring.
✓ It allows for near continuous, simultaneous measurement of pulmonary artery and cardiac filling pressures, cardiac output, and SvO2 (mixed venous oxygen saturation).

✓ Despite the relatively low risk of complications with the PAC (2-9%), the technique is invasive and its use has not been shown to clearly improve outcomes of critically ill patients
✓ Atualmente preferem-se técnicas menos invasivas e com menos complicações

Question 6

Continuous cardiac output measurement: arterial pressure waveform analysis?

Answer 6

✓ The PiCCO® and other systems provide continuous CO measurement using the arterial pressure waveform.
✓ These systems analyze the arterial waveform and use algorithms to calculate the CO.

Question 7

Echocardiography and Doppler technology?

Answer 7

✓ Cardiac output can be measured by 2D echocardiography and Doppler technology, using either a transthoracic (TTE) or transoesophageal (TOE) technique.
✓ TTE has the advantage of being rapid and non-invasive, but images may sometimes be limited in ventilated ICU patients.
✓ TOE provides high-quality images but is more invasive than TTE.
✓ Stroke volume is calculated using Doppler to measure the velocity time integral (VTi) of the flow signal at a given site, and 2D echo to measure the cross-sectional area of the same site.
– These measurements of flow and diameter are usually obtained at the level of the left ventricular outflow tract (LVOT), and then used to calculate CO.
✓ Echo-Doppler calculation of CO is operator-dependent, and continuous measurement of CO cannot be performed using this technique.

Question 8

Esophageal Doppler (ODM)?

Answer 8

✓ Measures blood flow velocity in the descending aorta by using a Doppler transducer at the tip of a probe, which is inserted into the esophagus via the mouth or nose

Question 9

Assessment of cardiac contractility?

Answer 9

✓ Assessing cardiac contractility is important in establishing the etiology of shock, and in guiding further therapy.
✓ For example, a patient in cardiogenic shock with poor LV function is likely to require inotropy with adrenaline or dobutamine infusion, whereas a septic patient with a hyperdynamic heart is more likely to benefit from a vasopressor infusion such as noradrenaline

Question 10

Assessment of cardiac contractility - Echocardiography?

Answer 10

✓ A visual assessment of LV function will often reveal any significant abnormality.
✓ Formal estimation of LV contractility can be performed by measuring ejection fraction (EF). The EF is the percentage of LV diastolic volume ejected with each heartbeat (normal >55%).

EF (%) = {(EDV- ESV)/ EDV} x 100

✓ Echocardiography should not be viewed simply in the context of cardiac output or ejection fraction. It can provide an assessment of preload and diagnose potentially reversible ventricular or valvular pathologies, cardiac tamponade, or massive pulmonary embolism

Question 11

Conclusions?

Answer 11

✓ Shock means that the oxygen delivery is insufficient for oxygen consumption
✓ Due to decreased delivery, increased consumption and/or inadequate utilization (extração; ou uma combinação de 2 ou 3 destas)
✓ We monitor and treat shock on the basis of several variables
✓ Followed and interpreted dynamically (com mais do que uma medição e procurando avaliar o efeito de determinadas intervenções)
✓ Less invasive variables are being used (aumentar segurança do doente)