The Circulation

Abstract

Adequate systemic perfusion is the endpoint of shock resuscitation and the therapeutic goal in all critically ill patients. In view of this, it is important to remember that it is not the numbers on a monitor (e.g. arterial blood pressure, cardiac output) but mostly clinical signs which determine whether systemic blood flow is adequate or not. The skin, mental state, kidneys and the general appearance are readily available bedside indicators to assess the adequacy of systemic perfusion.

To all the students who listen, look, touch and reflect: may they hear, see, feel and comprehend

Professor John Brereton Barlow

Clinical Practices

Box 1 Clinical Stratification of Acute Heart Failure

Green, compensated; yellow, pulmonary congestion with adequate systemic blood flow; orange, no pulmonary congestion but inadequate systemic blood flow; red, pulmonary congestion and inadequate systemic blood flow

Box 2 Verifying the Presence of a Paradoxical Pulse with the Sphygmomanometer

Step 1 Inflation of the sphygmomanometer cuff above the systolic arterial blood pressure

Step 2 Slow deflation of cuff while examiner listens for Korotkoff sounds over the brachial artery

Step 3 Identification of the peak systolic pressure during expiration

Step 4 Further slow deflation of the cuff to identify the blood pressure at which Korotkoff sounds are audible during both inspiration and expiration

If the difference between the two blood pressure levels exceeds 10 mmHg during normal inspiration, a paradoxical pulse is present. A difference in blood pressure levels >20 mmHg is usually only found in pericardial tamponade and severe dynamic hyperinflation (such as in status asthmaticus).

Box 3 Quote by Adolf Jarisch Junior, Austrian Physician and Pharmacologist, 1928

“It was fatal for the development of our understanding of circulation that blood flow is relatively difficult while blood pressure so easy to measure: This is the reason why the sphygmomanometer has gained such a fascinating influence, although most organs do not need blood pressure but flow”.

Box 4 The Valsalva Manoeuvre to Diagnose Left Heart Failure

In selected critically ill patients who are monitored with an arterial line and can hold their breath for at least 5–10 s, the Valsalva manoeuvre can be performed. The physiological blood pressure response to the increase in intrathoracic pressure during the Valsalva manoeuvre is a short increase followed by a gradual fall of arterial blood pressure. With (expiration and) release of intrathoracic pressure, venous return increases leading to an overshoot of the systolic blood pressure. It is the amplitude of this increase of systolic arterial blood pressure after the end of the Valsalva manoeuvre which correlates directly with left ventricular ejection fraction and function.

Box 5 Clinical Signs of Increased Left Ventricular Filling Pressures (LVFP) and Decreased Left Ventricular Ejection Fraction (LVEF)

Clinical signs	Increased LVFP	Decreased LVEF
Positive abdominojugular reflux	+++	+
Abnormal Valsalva response	++	+++
Displaced apical impulse	++	+++
Tachycardia	++	+
Third heart sound	+	++
Distended neck veins	+	+++

Box 6 Cardiac Murmurs: Summary of Timing of Murmurs and Associated Heart Lesions

Timing of murmur	Associated heart lesion
Pansystolic	Mitral regurgitation, tricuspid regurgitation, ventricular septal defect
Ejection and mid-systolic	Aortic stenosis, aortic sclerosis (related to the stiffness of the valve cusps and aortic walls with normal pulse pressure), pulmonary stenosis, pulmonary flow murmur of atrial septal defect, Fallot’s syndrome/right outflow tract obstruction
Late systolic	Mitral valve prolapse (click-murmur syndrome/Barlow’s syndrome), hypertrophic cardiomyopathy, papillary muscle dysfunction (ischaemia), coarctation of the aorta (extending into diastole to a “machinery murmur”)
Early diastolic	Aortic regurgitation, pulmonary regurgitation, Graham Steell murmur (functional pulmonary regurgitation in mitral stenosis or other causes of pulmonary hypertension)
Mid-late diastolic	Mitral stenosis, tricuspid stenosis, Austin Flint murmur in aortic regurgitation, atrial myxoma
Continuous	Patent ductus arteriosus, arteriovenous fistula, aorta pulmonary connection (e.g. congenital, Blalock shunt), rupture of sinus of Valsalva into the right ventricle or atrium, “mammary soufflé”—described in later pregnancy or early post-partum period, venous hum usually most audible over right supraclavicular fossa and abolished by ipsilateral internal jugular vein compression