Shock Syndromes I
Device or
Category
Obtainable
Parameters
Advantages
Limitations
Arterial pulse
pressure wave-
form analysis
(FloTrac/Vigileo,
PiCCOplus,
PulsioFlex,
LiDCO plus,
PRAM-MostCare,
Nexfin)
CO and CI, SV, SVR
(calculated), SVV,
PPV
| • | Continuous |
|---|
measurement of values
| • | Allows for assessment |
|---|
of SVV and PPV, which
are dynamic markers of
fluid responsiveness in
mechanically ventilated
patients (see later in the
chapter)
| • | Minimally invasive |
|---|
(Nexfin is noninvasive)
| • | Accuracy relies on optimal arterial |
|---|
waveform from arterial catheter
| • | Inaccurate in patients with mitral or |
|---|
aortic valve disease or when used
concomitantly with an intra-aortic
balloon pump
| • | Arrhythmias reduce the accuracy of |
|---|
reported CO and CI (though this may
be accounted for by internal software
with some devices)
| • | Accuracy may be limited during rapid |
|---|
changes in vascular resistance
| • | Some devices require a CVC in |
|---|
addition to an arterial pressure catheter
| • | Interpretation of SVV and PPV is |
|---|
limited by the need for positive
pressure ventilation, no spontaneous
breaths being triggered by the patient,
and relatively large tidal volumes
| • | SVV and PPV are not accurate |
|---|
predictors of fluid responsiveness in
the setting of arrhythmias
Bioimpedance/
bioreactance
(NICOM, BioZ,
ECOM)
Continuous CO and
| • | Noninvasive |
|---|---|
| • | NICOM CO correlates |
well with CO values
from thermodilution
and pulse pressure
waveform analysis
| • | Conflicting validation results with |
|---|
BioZ and ECOM, particularly in
patients with septic shock
| • | ECOM requires endotracheal |
|---|
intubation
aIncludes manual sphygmomanometry and automated oscillometric (cuff) techniques.
BP = blood pressure; CVC = central venous catheter; CVP = cental venous pressure; IVC = inferior vena cava; LV = left ventricular; LVOT VTI = left ventricular outflow
tract velocity time integral; mPAP = mean pulmonary artery pressure; PAC = pulmonary artery catheter; PADP = pulmonary artery diastolic pressure; PAOP = pulmonary
artery occlusion pressure; PASP = pulmonary artery systolic pressure; PCWP = pulmonary capillary wedge pressure PPV = pulse pressure variation; RAP = right atrial
pressure; RVSP = right ventricular systolic pressure; Scvo2 = central venous oxygen saturation; SVR = systemic vascular resistance; SVV = stroke volume variation.
Global perfusion
End-organ function (altered mental status, low urinary output, and mottled skin, as noted earlier)
Elevated blood lactate concentration (above 2 mmol/L)
Lactate is produced from pyruvate by lactate dehydrogenase as an end product of glycolysis
under anaerobic conditions.
ii.
Most lactate is cleared by the liver by conversion back to pyruvate in the Cori cycle, with a
small amount cleared by the kidneys. Severe liver dysfunction may impair lactate clearance
and accentuate lactate concentration elevations in shock.