Describe the cardiovascular changes that occur following the loss of 1000ml of blood in an adult.
A structured approach that included mentioning that 1000mls of blood was
substantial – being approximately 20% of the blood volume of a 70 kg person was
required for a good answer. Candidates were expected to also include changes in
systolic and diastolic blood pressure, pulse pressure, heart rate, cardiac output and
the neuronal (eg sympathetic nervous system response on the various circulations)
and hormonal responses (eg rennin aldosterone, Anti-Diuretic Hormone,
catecholamines, etc). Candidates were also expected to discuss differences in
responses according to rate of blood loss. Flow diagram could have been used to
illustrate some of these concepts.
References: Textbook of Medical Physiology, Guyton pg 278 – 282, Principles of
Physiology for the Anaesthetist, Power & Kam pg 154
Flow diagram could have been used, but
Kirkman, E., and S. Watts. "Haemodynamic changes in trauma." British journal of anaesthesia 113.2 (2014): 266-275.
Guyton, Arthur C. "Determination of cardiac output by equating venous return curves with cardiac response curves." Physiological reviews 35.1 (1955): 123-129.
Jacobsen, J., et al. "Cardiovascular and endocrine responses to haemorrhage in the pig." Acta physiologica scandinavica 138.2 (1990): 167-173.
Schadt, James C., and John Ludbrook. "Hemodynamic and neurohumoral responses to acute hypovolemia in conscious mammals." American Journal of Physiology-Heart and Circulatory Physiology 260.2 (1991): H305-H318.
Freeman, J. "Physiological effects of haemorrhage." Annals of the Royal College of Surgeons of England 33.3 (1963): 138.
B A Foex Systemic responses to trauma British Medical Bulletin 1999, 55 (No 4) 726-743
Gutierrez, Guillermo, HDavid Reines, and Marian E. Wulf-Gutierrez. "Clinical review: hemorrhagic shock." Critical care 8.5 (2004): 1-9.
Chien, Shu, and Stuart Billig. "Effect of hemorrhage on cardiac output of sympathectomized dogs." American Journal of Physiology-Legacy Content 201.3 (1961): 475-479.
Evans, David, and H. W. Boyes. "The effects of rapid massive haemorrhage and retransfusion on various cardiovascular parameters in the dog." Canadian Anaesthetists’ Society Journal 16.5 (1969): 385-394.
Shen, Tao, and Keith Baker. "Venous return and clinical hemodynamics: how the body works during acute hemorrhage." Advances in physiology education 39.4 (2015): 267-271.
Mutschler, M., et al. "A critical reappraisal of the ATLS classification of hypovolaemic shock: does it really reflect clinical reality?." Resuscitation 84.3 (2013): 309-313.
Lawton, Luke D., et al. "The utility of Advanced Trauma Life Support (ATLS) clinical shock grading in assessment of trauma." Emergency Medicine Journal 31.5 (2014): 384-389.
Scully, Christopher G., et al. "Effect of hemorrhage rate on early hemodynamic responses in conscious sheep." Physiological Reports 4.7 (2016): e12739.