D6.ii · Blood Pressure Monitoring

This VIVA will examine blood pressure physiology and measurement What are the changes in the arterial blood pressure waveform as it moves from the level of the ascending aorta to the peripheral blood vessels and what accounts for this?

This viva will explore your knowledge of invasive arterial monitoring systems. What are the features of an invasive arterial monitoring system that improve accuracy of the waveform display? (Image removed from report.)

This viva will explore your knowledge of cardiovascular physiology and measurement. This is an arterial waveform in a healthy young adult. Indicate the points from A to D, and what determines the shape of the waveform? . (Image removed from report.)

This viva will explore your knowledge of the following areas: The pharmacology of common anticoagulants and the physics of arterial lines. What is the mechanism of action of un-fractionated heparin?

This viva tested knowledge of the measurement of arterial blood pressure and the pharmacology of beta blocking drugs.

This viva discussed fluid flow and related physical principles around turbulent and laminar flow and then the invasive measurement of arterial blood pressure.

Tested knowledge of coronary perfusion and blood pressure measurement. It began by asking candidates to describe the coronary artery blood flow.

This viva will test your knowledge of cardiac physiology and blood pressure measurement. Outline the factors that affect cardiac output. This viva tested the candidates’ knowledge of cardiovascular physiology, specifically determinants of cardiac output, ventricular stroke work, volume loops, etc. It also tested knowledge of invasive arterial pressure measurement, including that relating to ideal design features of measuring systems and sources and types of errors of measurement. Candidates seemed to only have a superficial understanding of cardiac output and it’s determinants, they lacked depth in their explanations and were less familiar with right sided heart pressures and function. Measurement principles were much better covered.

This station will explore cardiovascular physiology, positive pressure ventilation and aspects of measurement. This is a trace of the arterial blood pressure in a mechanically ventilated patient. It is well known that variations in blood pressure can occur with respiration. Outline the physiology that explains why these blood pressure changes occur? Candidates were asked to explain the physiological principles that contribute to these blood pressure changes, in addition to the cardiovascular consequences of positive pressure ventilation, regulation of myocardial contractility and a series of questions relating to invasive pressure monitoring. These included being asked to describe a transducer, accuracy and calibration

The initial information given to the candidates was - You were asked by an intensive care nurse whether you would like to start some anti- hypertensive treatment for an ICU patient who had a very high arterial blood pressure (systolic 180mmHg, diastolic 60mmHg) displayed on the invasive haemodynamic monitor at the bedside. The ICU nurse said that the non-invasive oscillometric blood pressure monitor (systolic 140mmHg and diastolic 80mmHg) was much lower than the invasive blood pressure. Can you explain how a non-invasive oscillometric blood pressure monitor works? This viva explored the candidates’ knowledge in relation to the following points Principles of oscillometric blood pressure measurements, factors affecting accuracy Principles of invasive blood pressure measurement, factors affecting accuracy, resonance and damping Examination feedback: All candidates had a good understanding of the principles behind oscillometric blood pressure monitoring and its pitfalls. A good understanding on invasive blood pressure monitoring was also essential to pass this viva. The common weaknesses were 1) the effects of the intra-arterial catheter size or bore, catheter length, and compliance of the tubing on resonance and damping; 2) how to assess the damping factor at the bed side; and 3) what is the minimal requirement in terms of natural frequency of the measuring system in relation to the frequency of the blood pressure waveform to prevent resonance. Most candidates found it difficult to convert a heart rate of 60 per minute into frequency in Hz.

techniques? An understanding of the principles of monitoring in clinical practice including the evaluation of the accuracy, reliability, convenience and hazards of methods of monitoring (S 1) was the subject of this viva. This question required candidates to describe the components of a thermodilution cardiac output catheter system (R 2.e) and invasive blood pressure transducer (R 2.d). Detailed knowledge of the physics of accurately reproducing biological waveforms, including discussion of natural resonant frequency and damping co-efficient was essential. Understanding of the sources of error such as zeroing, baseline drift, suboptimal damping and performance of a “flush test” was assessed (C1h 2.b, S 2.b). Candidates were expected to discuss the Fick Equation and the Stewart-Hamilton Equation related to cardiac output measurement by the indicator method (C1h 2.c, S 2.c). Better answers incorporated a labelled diagram of the thermodilution curve. Additional marks were awarded for a discussion of the sources of error in cardiac output measurement, computation constant and potential complications of pulmonary artery catheterisation. Syllabus: S 1, R 2.e, R 2.d, C1h 2.b, S 2.b, C1h 2.c, S 2.c 2 candidates (100%) passed this question. A detailed syllabus has been developed and forms the foundation for the knowledge base for the JFIC Primary Examination. All questions are sourced directly from that syllabus and candidates should have a sound understanding of those topics, and confidence to express their understanding of the subject material in both written and oral form. The candidates should also be able to integrate and express the general basic, and the topic specific, physiological and pharmacological principles detailed within the syllabus. Dr Gillian Bishop Chair Dr Arthas Flabouris Deputy Chair Primary Examination Circulation: Board of joint faculty Panel of Examiners Supervisors of Intensive Care Training Course Supervisors Regional Education Offices Registered Trainees