Assessment

Cardiac assessment

Which basic investigations may be used in assessing cardiovascular function?

Following basic clinical examination of the praecordium during a cardiovascular examination, investigations may include

Non-invasive

• Pulse: this is a clinical assessment of rate and rhythm, e.g. radial artery, and volume and character, e.g. carotid artery

• Non-invasive blood pressure (NIBP): this employs a sphygmomanometer, e.g.manual measurement, or a Dinamap®, e.g. automated monitoring.The Dinamap® can measure absolute values, mean and pulse pressure, but mercury measurement is more accurate

• Electrocardiograph (ECG):measures the rate, rhythm, intervals, axis and waveforms

• Transthoracic echocardiography (TTE):measures systolic function, cardiac filling, valve function general morphology and

• blood flow

• Radiology: plain chest radiography (cardiothoracic ratio), CT, MRI

Other non-invasive assessments include the clinical evaluation of GCS, as a marker of cerebral perfusion, capillary refill time and urine output as markers of cardiac index (CI) and organ function, e.g. renal function.

Invasive

• Intra-arterial blood pressure (IABP): e.g. radial arterial line, exhibits a continuous arterial waveform and beat to beat variation

• Central venous catheter (CVC): e.g. internal jugular vein, measures the central venous pressure (CVP) or its response to fluid challenges and inotropes.The waveform may be continuously displayed

• Pulmonary artery flotation catheter (PAFC): provides both direct and derived measures of left heart function, e.g. cardiac output. It also measures systemic and pulmonary vascular resistance, e.g. pulmonary artery capillary wedge pressure (PACWP), oxygen delivery, SaO2 and demand

• Transoesophageal echocardiography (TOE [TEE]): Gives a more detailed picture of the left heart and thoracic aorta than transthoracic echocardiography

• Cardiac catheterisation and coronary angiography: is the gold standard diagnostic procedure regarding the structure and function of the heart

Other invasive assessments of cardiac index and peripheral organ perfusion include

• Arterial blood gases (ABGs): to assess the acidosis and base excess associated with anaerobicmetabolism following poor tissue perfusion

• Biochemistry: rising serum lactate levels indicate a poor cardiac index

• Gastric tonometry: adequacy of splanchnic perfusion is estimated fromgastric intramucosal pH measurements using a gastric probe.The gut is the first organ system to reflect a poor peripheral perfusion

• Arteriovenous oxygen difference (a–vO2): oxygen extraction is increased in cases of poor organ perfusion due to relative stagnation

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