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Monitoring in Critical Care Dr. Abdul-Monim Batiha. General Guidelines. Monitoring ensures rapid detection of changes in the clinical status Allows for accurate assessment of progress and response to therapy
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General Guidelines • 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
Hemodynamic Monitoring • Blood Pressure • 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) • Measured in internal jugular vein or subclavian vein, reflecting right atrial pressure • May be used to assess volume
Hemodynamic Monitoring, cont… • Pulmonary Artery Wedge Pressure (PAWP) • Reflects left atrial pressure • Normal is 6-12 mm Hg • Cardiac Output (CO) • Usually measured by thermodilution PA catheter • Can also be measured by dye dilution, transesophageal Doppler, echo, or impedence plethysmography • EKG • Monitors rate and rhythm of heart
Respiratory Monitoring • ABG • Monitors acid-base balance, PaO2, and PaCO2 • Oxygen Saturation • 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%
Respiratory Monitoring, cont… • Mixed venous O2 saturation (SvO2) • Measured with PA catheter • Normal is 65-75% • Low SvO2 may indicate inadequate tissue O2 delivery (even if arterial O2 is OK) • Lung Function • 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
Respiratory Monitoring, cont… • Respiratory compliance • Vt/PIP-PEEP • A measure of the ease of inflation • High airway pressures during mechanical ventilation may be caused by low compliance • Capnography • End-tidal CO2 concentration is close to artrial PaCO2 levels • Indicates the adequacy of alveolar ventilation
Organ and Tissue Oxygenation • Global measures • Reflect the adequacy of total tissue perfusion but could be normal with local perfusion abnormalities • 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
Organ and Tissue oxygenation • Organ-specific Measures • Urine flow • A sensitive indicator of renal perfusion provided the kidneys aren’t damaged • Normal is 1ml/kg • Core-peripheral temperature • 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
Organ and Tissue Oxygenation • Organ-specific Measures • Gastric tonometry • Used to detect shock-induced splanchnic ischemia by measure gastric luminal PCO2 and deriving the mucosal pH • Neurological monitoring • Utilizes GCS, ICP measurement, and jugular venous bulb saturation