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ACCURACY OF PARAMEDIC DIAGNOSIS OF ACUTE CARDIOGENIC PULMONARY OEDEMA A prospective diagnostic audit of 1,334 patients Emma Jenkinson*, Malcolm Woollard**, Robert Newcombe†, Iain Robertson-Steel†† *Heartlands Hospital/West Midlands Ambulance Service, **Faculty of Pre-hospital Care Research Unit, †Medical Statistics Department, University of Cardiff, ††West Midlands Ambulance Service NHS Trust United Kingdom BACKGROUND psychiatric haematology lungs trauma RESPIRATORY DISTRESS cardiac renal PATHOPHYSIOLOGY OF LVF CPAP IN LVF “…single greatest advance in the management of these [LVF] patients in the past decade…” Cohen Solal et al 1, 2004 CPAP is effective in patients with pulmonary oedema who remain hypoxic despite maximal medical treatment BTS Guidelines 2, 2002 Some UK ambulance services are looking to introduce CPAP for paramedic use, one service already has. PRE-HOSPITAL DIAGNOSIS OF ACPO Seven main studies 3 Overall error rates 9-23% Additional study found 92% accuracy 4 Paramedic identification of common lung sounds found to be unreliable in 40% of cases 5 STUDY AIM A prospective diagnostic audit to assess the accuracy of paramedic diagnosis of acute cardiogenic pulmonary oedema DATA COLLECTION Prospective audit Population: patients brought to Heartlands (BHH) by West Midlands Ambulance Service (WMAS) Publicised beforehand 2 stages, 2 teams to allow for blinding An estimated 1,300 patients required Data collected between 4 Dec 05 until 31 Mar 06 DATA COLLECTION – STAGE 1 WMAS PRFs searched to identify patients taken to BHH with: Diagnosis of ACPO OR Furosemide given OR Presenting complaint of respiratory distress OR Any of the following diagnoses: Acute asthma Croup SOB ?cause Exacerbation COPD Chest infection Pulmonary oedema Haemoptysis Excluded if seen by Dr DATA COLLECTION – STAGE 2 Demographics matched to hospital records to obtain: Emergency department (ED) diagnosis (Hospital discharge diagnosis) Investigator then unblinded Diagnoses matched DATA ANALYSIS Two-by-two tables produced in SPSS: Positive or negative pre-hospital diagnosis of ACPO Positive or negative ED diagnosis of ACPO Results then entered into StatsDirect to calculate: Sensitivity Specificity PPV NPV PLR NLR Proportion of patients with ACPO correctly identified by ambulance staff as having ACPO Proportion of patients without ACPO correctly identified by ambulance staff as not having ACPO By how much does the probability of having ACPO increase with a positive pre-hospital diagnosis? How much the probability of ACPO decreases with a negative pre-hospital diagnosis of ACPO RESULTS Eligible patients (n=1,334) No record (n=102) GP referrals (n=34) Transfer in (n=1) Did not wait (n=16) To primary care (n=19) Patients seen by ED doctor (n=1,162) ED diagnosis not recorded (n=7) Complete data (n=1,155) RESULTS Complete data (n=1,155) PRE-HOSPITAL DIAGNOSIS: ACPO (n=59) Not ACPO (n=1096) ED DIAGNOSIS: ED DIAGNOSIS: ACPO Not ACPO ACPO Not ACPO (n=24) (n=35) (n=50) (n=1046) RESULTS ALL PATIENTS Pre-hospital diagnosis ED diagnosis ACPO Not ACPO Total: ACPO 24 35 59 Not ACPO 50 1046 1096 Total: 74 1081 1155 95% Confidence intervals Prevalence Sensitivity 6.41% 32.43 % 5.06-7.98% Specificity 96.76% 95.53-97.73% Positive predictive value 40.68% 28.07-54.25% Negative predictive value 95.44% 94.03-96.60% Likelihood ratio of +ve result 10.02% 6.25-15.58% Likelihood ratio of –ve result 0.70% 0.58-0.80% 22.00-44.32% RESULTS PARAMEDIC TECHNICIAN 6.39% 6.43% 4.70-8.46% 4.35-9.1% 46.67 % 10.34% 31.66-62.13% 2.19-27.35% 95.30% 99.05% 93.39-96.78% 97.59-99.74% 40.38% 42.86% 27.01-54.90% 9.90-81.59% 96.32% 94.14% 94.57-97.63% 91.54-96.14% 9.92% 10.91% 6.14-15.50% 2.78-40.98% 0.56% 0.91% 0.41-0.70% 0.74-0.97% (n = 704) Prevalence Sensitivity Specificity +ve predictive value -ve predictive value LR +ve result LR –ve result (n = 451) RESULTS ED diagnoses for patients with incorrect pre-hospital diagnosis of ACPO No. % total (95% CI) RESPIRATORY 22 63% (45-79%) Infection 8 23% (10-40%) Chronic obstructive pulmonary disease 5 14% (5-30%) Other respiratory disease 5 14% (5-30%) Respiratory failure 3 9% (2-23%) Asthma 1 3% (0-15%) CARDIOVASCULAR 7 20% (8-13%) Chest pain ?cause 3 9% (2-23%) Syncope and collapse 1 3% (0-15%) Angina/unstable angina 2 6% (0-19%) Ischaemic heart disease – other 1 3% (0-15%) OTHER 6 17% (6-35%) TOTAL 35 100% Diagnosis CONCLUSIONS Sensitivity low, specificity high A positive diagnosis carried some predictive value If patients are treated for ACPO by pre-hospital staff this is likely to be appropriate A large proportion of patients with ACPO are likely to be missed Further training is required to improve diagnosis REFERENCES 1. Cohen Solal A. et al (2004) Traitement médical de l’insufficance cardiaque aigüe décompensée. Annales de Cardiologie et d’Angéiologie 53: 200-208 2. British Thoracic Society Standards of Care Committee (2002) Non-invasive ventilation in acute respiratory failure. Thorax 57: 192-211 3. Shapiro S.E. (2005) Evidence review: Emergency medical services treatment of patients with congestive heart failure/acute pulmonary edema: do risks outweight the benefits? J Emerg Nursing 31(1): 51-57 4. Durham B., Aguilera P., Dale K., Neimen H. (1999) Accuracy of pre-hospital diagnosis of primary respiratory distress. Acad Emerg Med 6(5): 474 5. Widger H.N., Johnson D.R., Cohan S., Felde R., Colella R. (1996) Assessment of lung auscultation by paramedics. Ann Emerg Med 28(3): 309-312