A REVIEW OF FUNCTIONAL
HAEMODYNAMIC MONITORING
AJ van den Berg
Definition

The assessment of the dynamic interactions of
haemodynamic variables in response to a defined
intervention.
Goals
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
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To use proactive interventions to create parameters
of robust sensitivity and specificity
To monitor and identify cardiovascular insufficiency,
volume responsiveness and vasomotor tone
To define end-points to guide early goal-directed
therapy
Predicting Volume Responsiveness

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Defined as at least a 15% increase in Cardiac
Output following a 500ml bolus.
During positive pressure ventilation, various
measures have been found to be good indicators of
volume responsiveness
 Pulse
Pressure Variation (PPV)
 Left Ventricular Stroke Volume Variation (SVV)
 Systolic Pressure Variation
 Change in inferior and superior vena cavae diameters
Predicting Volume Responsiveness


SVV > 10% or PPV > 13-15% on a tidal volume of
8ml/kg highly predictive of volume responsiveness
Problems:
 Influenced
by tidal volume, chest wall compliance and
contractility
 In the presence of spontaneous breathing or irregular
heartbeats, PPV and SVV become inaccurate
Predicting Volume Responsiveness

Problems (continued)

Ventilation with low tidal volumes
the cyclical changes in flow are dependent on changes in intrathoracic pressures
 Tidal volume is a major determinant of intrathoracic pressure and
therefore needs to be great enough to alter central venous
pressure
 Tidal volumes of 6 ml/kg alter the sensitivity but not the specificity
of these parameters


Intra-abdominal Hypertension
Reduced chest wall compliance
 PPV and SVV remain reliable if tidal volume is maintained
 Passive Leg Raise (PLR) has reduced sensitivity

Predicting Volume Responsiveness

Marik et al (2013):
 cardiac
output measured by bioreactance, cerebral
blood flow measured by carotid Doppler in 34
critically ill patients.
 Volume responsiveness assessed by PLR induced
changes in stroke volume index (SVI)
 PLR had a sensitivity of 94% and a specificity of 100%
for predicitng volume responsiveness
Predicting Volume Responsiveness

Marik et al (continued):
 Carotid
blood flow increased by 79±32% in fluid
responders, compared to 0.1±14% in non-responders
(P < 0.0001)
 If carotid blood flow was used as an estimate of
volume responders, a value of 20% seperated
responders from non-responders with a sensitivity of
94% and a specificity of 86%.
Predicting Volume Responsiveness


Improved assessment of fluid responsiveness
Study by Lopes
 High-risk
surgery patients
 Volume loading guided by PPV minimisation
 Improved postoperative outcome,
 decreased length of hospital stay,
 lower duration of mechanical ventilation,
 lower length of stay in ICU
Assessing Arterial Tone



Dynamic central arterial elastance (Ea)
If the arterial circuit becomes stiffer, then for the
same stroke volume change, there will be a larger
pulse pressure change
Ea = PPV/SVV
Assessing Arterial Tone
Assessing Arterial Tone

Monge et al (2011)
 Assessed
the effect of volume loading in hypotensive
septic shock patients who’s PPV indicated that they
were volume responsive
 All patients increased cardiac output
 Only patients with normal or increased Ea increased
their arterial pressure
 Only the PPV/SVV (Ea) slope predicted responders
from non-responders
 Ea < 0.9 reflects a severely vasodilated state
Identifying Cardiovascular Insufficiency

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Inadequate oxygen delivery relative to metabolic
demands
In compensated shock, arterial pressure and cardiac
output are often within normal ranges
Therefore insensitive as early predictors of
decompensation
Microcirculatory changes already occur
Tissue cardiovascular reserve should therefore be a
sensitive early warning sign
Identifying Cardiovascular Insufficiency




Near-infrared spectroscopy has used to evaluate
tissue oxygen saturation (StO2)
A dynamic ischaemic challenge (vascular occlusion
test) improves the ability of StO2 to identify tissue
hypoperfusion
Deoxygenation rate reflects local metabolic rate
Reoxygenation rate reflects local cardiovascular
reserve and microcirculatory flow
Identifying Cardiovascular Insufficiency




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Study comparing septic patients to
haemodynamically stable non-septic patients
Reoxygenation rate lower in septic patients
Reoxygenation rates were higher in survivors
Reoxygenation rates tended to increase during
resuscitation in survivors but not in nonsurvivors
The reoxygenation slope was found to be a good
predictor of ICU death (cut-off value 2.55%/s,
sensitivity 85%, specificity 73%)
Identifying Cardiovascular Insufficiency


Reoxygenation rate is related more to the severity
of the sepsis than to MAP or vasopressor dose
Other studies:
 Reoxygenation
rate predicted organ failure as well as
failure of SBT’s
 In acute trauma patients, when lactate > 1.7,
reoxygenation rate was 100% specific for patients in
need of life-saving intervention
References
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Pinsky MR. Functional Haemodynamic Monitoring. Curr Opin Crit Care 2014; 20:
288-293
Lopes RL, Oliveira MA, Pereira VOS, et al. Goal-directed fluid management based
on pulse pressure variation monitoring during high-risk surgery: a pilot randomized
controlled trial. Crit Care 2007; 11:R100.
Marik PE, Levitov A, Young A, Andrews L. The use of bioreactance and carotid
doppler to determine volume responsiveness and blood flow redistribution following
passive leg raising in hemodynamically unstable patients. Chest 2013; 143:364–
370.
Monge MI, Gil A, Garcia RM. Dynamic arterial elastance to predict arterial
pressure response to volume loading in preload-dependent patients. Crit Care
2011; 15:R15.
Giraud R, Slegenthaler N, Bendjelid K. Pulse pressure variation, stroke volume
variation and dynamic arterial elastance. Crit Care 2011; 15:414.
Creteur J, Carollo T, Soldati G, et al. The prognostic value of muscle StO2 in septic
patients. Intensive Care Med 2007; 33:1549–1556.