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Monitoring ensures rapid detection of changes in the clinical status
Allows for accurate assessment of progress and response to therapy
When clinical signs and monitored parameters disagree, assume that clinical assessment is correct
Trends are generally more important than a single reading
Use non-invasive techniques when possible
Alarms are crucial for patient safety

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Blood Pressure
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Can be measured intermittently with a cuff or continuously with an arterial line
BP does not reflect CO – BP can be high with a low CO if vasoconstriction occurs and vice versa
Central Venous Pressure (CVP)
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Measured in internal jugular vein or subclavian vein, reflecting right atrial pressure
May be used to assess volume

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Pulmonary Artery Wedge Pressure (PAWP)
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Reflects left atrial pressure
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Normal is 6-12 mm Hg
Cardiac Output (CO)
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Usually measured by thermodilution PA catheter
Can also be measured by dye dilution, transesophageal Doppler, echo, or impedence plethysmography
EKG
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Monitors rate and rhythm of heart

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ABG
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Monitors acid-base balance, PaO2, and
PaCO2
Oxygen Saturation
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SpO2, using a finger or other probe, measures the proportion of saturated to desaturated hemoglobin
Requires adequate perfusion for accuracy
Oxygenatio is OK if SpO2 >90%

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Mixed venous O2 saturation (SvO2)
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Measured with PA catheter
Normal is 65-75%
Low SvO2 may indicate inadequate tissue O2 delivery (even if arterial O2 is OK)
Lung Function
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Aa gradient and PaO2/FiO2 ratio measure the adequacy of gas exchange
Arterial to end-tidal CO2 gradients indicate the adequacy of ventilation
PF, FEV1, and FVC help assess patients with lung dx
MIP/NIF is used to determine readiness for extubation

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Respiratory compliance
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Vt/PIP-PEEP
A measure of the ease of inflation
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High airway pressures during mechanical ventilation may be caused by low compliance
Capnography
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End-tidal CO2 concentration is close to artrial
PaCO2 levels
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Indicates the adequacy of alveolar ventilation

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Global measures
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Reflect the adequacy of total tissue perfusion but could be normal with local perfusion abnormalities
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Increased lactate concentration and metabolic acidosis suggests anaerobic metabolism and inadequate tissue oxygenation…lactate also increases with liver failure and sepsis, though
SvO2 <55% indicates global tissue hypoxia

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Organ-specific Measures
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Urine flow
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A sensitive indicator of renal perfusion provided the kidneys aren’t damaged
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Normal is 1ml/kg
Core-peripheral temperature
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The gradient between peripheral (skin) temp and core (rectal) is often used as an index of peripheral perfusion
The less perfusion, the colder the periphery

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Organ-specific Measures
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Gastric tonometry
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Used to detect shock-induced splanchnic ischemia by measure gastric luminal PCO2 and deriving the mucosal pH
Neurological monitoring
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Utilizes GCS, ICP measurement, and jugular venous bulb saturation