(BQ) Part 2 book Examination anaesthesia - A guide to intensivist and anaesthetic training has contents: Data interpretation for the final examination, useful reference and review articles.
Chapter Data interpretation for the final examination Never trust anything that can think for itself if you can’t see where it keeps its brain J K ROWLING Overview Prior to 2007 one of three clinical medical vivas in the final FANZCA examination was solely devoted to the interpretation of clinical data This viva required rapid spot diagnosis of radiographs, electrocardiographs, spirometry results, arterial blood gases and biochemical data (among others), and usually involved a flurry of X-rays and papers to and fro across the examination table One of the major changes in format of the clinical examination in 2007 was the restructuring of the clinical viva process and removal of this medical viva as an isolated entity However, candidates should not regard interpretation of investigations as any less critical to their exam preparation Any commonly used data modality may appear in any section of the examination Multiple choice questions using biochemical data and ECG features are very common; recent years have seen the appearance of several short-answer written questions that specifically relate to interpretation of test results Most commonly, candidates are asked to interpret such data in the clinical vivas, either as a component of a clinical scenario given in an anaesthesia viva, or as part of the assessment of a patient in the medical vivas The advantage of using these latter clinical formats is that they give candidates the opportunity to correlate facets of a clinical situation, or features elicited on history and examination, with appropriate medical investigations Always consider the clinical scenario before you, and keep the following questions in mind when reviewing clinical tests: Is this the most appropriate investigation in this situation? How will the results of the test influence my management? Does my interpretation of the test result correlate with the clinical picture? Does the test result solve a clinical problem or raise new concerns? It is expected that candidates will possess reasonable proficiency at reviewing common modalities and frequently encountered conditions When faced with a baffling radiograph or ECG it is not appropriate in the examination to defer to the opinion of a radiologist or electrophysiologist In such situations a comprehensive system for examining each of these is vital and may provide insight that was 100 6 • Data interpretation for the final examination 101 lacking on initial perusal of the test The need to practise a technique for reviewing and verbalising results of data interpretation cannot be overemphasised Many hospitals have libraries of X-rays and ECGs, which in conjunction with major relevant texts provide an invaluable resource This chapter contains a discussion of commonly encountered investigations and several clinical examples, including practice cases with the types of questions that might be expected in the exam (for which answers or descriptions are given in the last section of this chapter, commencing on page 192) A comprehensive description of all pathologies that may be encountered is obviously beyond the scope of this book and candidates are urged to read widely around all of these topics in relevant dedicated texts It is also useful to obtain tutorials from other specialists, such as radiologists and cardiologists, to improve your approach to investigations Electrocardiography Interpreting electrocardiographs (ECGs) is a critical skill required of the anaesthetist It is presumed that candidates understand the physiological principles of ECG generation, and expected that they are familiar with a wide range of ECG abnormalities that may be encountered perioperatively Be mindful that an ECG in the examination (and in real life) may contain more than one abnormality A system for assessing the ECG is useful when no obvious abnormality exists on initial perusal of the trace, or when the trace is unusually complicated with multiple pathological processes One such system is presented in Box 6.1 (overleaf) It is possible to describe the ECG to the examiners using the format of a comprehensive system (which can also be a stalling tactic while desperately searching for a hidden abnormality) However, you may be interrupted and asked to comment on an obvious abnormal feature You should also be aware that commonly generated computer indices (such as axis, QRS duration and segment lengths) are very likely to appear on the ECG tracings you receive in the examination (as they usually in real life) A computer-generated diagnosis will most probably be deleted Always consider the ECG in conjunction with the clinical situation presented or the patient you have seen, all of which may provide clues to help your interpretation of the trace Similarly, use the information you gain from the ECG to comment on likely diagnoses and required treatment options for that patient Some examples of clinical scenarios and associated ECG traces are provided in the following pages Brief answers to these appear on pages 192–94 102 Examination anaesthesia BOX 6.1 Systematic assessment of the ECG Demographic and technical aspects • Patient details, date and time • Tracing speed (normally 25 mm/s) • Tracing amplitude (normally 10 mm/mV) Computer-generated data • Axis • Segment intervals • Heart rate • Diagnoses (may be misleading) Rate and rhythm • Approximate heart rate is 300 divided by the number of large (0.2 sec) squares between successive R waves • Rhythm may be regular, regularly irregular or irregularly irregular • Take particular note of the relationship of P waves and QRS complexes (are both always present and related?) Cardiac axis • Computer-generated value may be given • Downward overall deflection in lead I implies right axis deviation • Downward overall deflection in all inferior leads implies left axis deviation • Axis determination is frequently useful, even diagnostic Interval duration • PR interval normally 0.12–0.2 sec • QRS complex duration normally