Bjørn Olav Haugen

Feasibility and reliability of point-of-care pocket-sized echocardiography

Aims To study the reliability and feasibility of point-of-care pocket-sized echocardiography (POCKET) at the bedside in patients admitted to a medical department at a non-university hospital. Methods and results One hundred and eight patients were randomized to bedside POCKET examination shortly after admission and later high-end echocardiography (HIGH) in the echo-lab. The POCKET examinations were done by cardiologists on their ward rounds. Assessments of global and regional left ventricular (LV) function, right ventricular (RV) function, valvular function, left atrial (LA) size, the pericardium and pleura were done with respect to effusion and measurements of inferior vena cava (IVC) and abdominal aorta (AA) were performed. Correlations between POCKET and HIGH/appropriate radiological technique for LV function, AA size and presence of pericardial effusion were almost perfect, with r ≥ 0.92. Strong correlation (r ≥ 0.81) was shown for RV and valvular function, except for grading of aortic stenosis (r = 0.62). The correlations were substantial for IVC and LA dimensions. Median time used for bedside screening with POCKET was 4.2 min (range: 2.3–13.0). There was excellent feasibility for cardiac structures and pleura, which was assessed to satisfaction in ≥94% of patients. Lower feasibility (71–79%) was seen for the abdominal great vessels. Conclusion Point-of-care semi-quantitative evaluation of cardiac anatomy and function showed high feasibility and correlation with the reference method for most indices. Pocket-sized echocardiographic examinations of ∼4 min length, performed at the bedside by experts, offers reliable assessment of cardiac structures, the pleural space and the large abdominal vessels. Clinical trial registration: http://www.clinicaltrials.gov; unique ID: NCT01081210.

Routinely adding ultrasound examinations by pocket-sized ultrasound devices improves inpatient diagnostics in a medical department.

BACKGROUND We aimed to investigate the potential benefit of adding a routine cardiac and abdominal diagnostic examination by pocket-sized ultrasound device in patients admitted to a medical department. METHODS A random sample of 196 patients admitted to the medical department at a non-university hospital in Norway between March and September 2010 was studied. The patients underwent cardiac and abdominal screening with a pocket-sized ultrasound device with B-mode and color flow imaging after a principal diagnosis was set. Three internists/cardiologists experienced in ultrasonography performed the examinations. Diagnostic corrections were made and findings were confirmed by high-end echocardiography and examinations at the radiologic department. RESULTS 196 patients were included (male=56.6%, mean±SD; 68.1±15.0 years old). The time spent doing the ultrasound screening was mean±SD 4.3±1.6 min for the cardiac screening and 2.5±1.1 min for the abdominal screening. In 36 (18.4%) patients this examination resulted in a major change in the primary diagnosis. In 38 (19.4%) patients the diagnosis was verified and in 18 (9.2%) patients an important additional diagnosis was made. CONCLUSION By adding a pocket-sized ultrasound examination of <10 min to usual care, we corrected the diagnosis in almost 1 of 5 patients admitted to a medical department, resulting in a completely different treatment strategy without delay in many of the patients. Routinely adding a cardiac and abdominal ultrasound screening has the potential to rearrange inpatients workflow and diagnosis.

Feasibility and reliability of point-of-care pocket-size echocardiography performed by medical residents

Aims To study the feasibility and reliability of pocket-size hand-held echocardiography (PHHE) by medical residents with limited experience in ultrasound. Methods and results A total of 199 patients admitted to a non-university medical department were examined with PHHE. Six out of 14 medical residents were randomized to use a focused protocol and examine the heart, pericardium, pleural space, and abdominal large vessels. Diagnostic corrections were made and findings were confirmed by standard diagnostics. The median time consumption for the examination was 5.7 min. Each resident performed a median of 27 examinations. The left ventricle was assessed to satisfaction in 97% and the pericardium in all patients. The aortic and atrioventricular valves were assessed in at least 76% and the abdominal aorta in 50%, respectively. Global left-ventricular function, pleural, and pericardial effusion showed very strong correlation with reference method (Spearmans r ≥ 0.8). Quantification of aortic stenosis and regurgitation showed strong correlation with r = 0.7. Regurgitations in the atrioventricular valves showed moderate correlations, r = 0.5 and r = 0.6 for mitral and tricuspid regurgitation, respectively, similar to dilatation of the left atrium (r = 0.6) and detection of regional dysfunction (r = 0.6). Quantification of the abdominal aorta (aneurysmatic or not) showed strong correlation, r = 0.7, while the inferior vena cava diameter correlated moderately, r = 0.5. Conclusion By adding a PHHE examination to standard care, medical residents were able to obtain reliable information of important cardiovascular structures in patients admitted to a medical department. Thus, focused examinations with PHHE performed by residents after a training period have the potential to improve in-hospital diagnostic procedures.

Antiplatelet effect of clopidogrel is reduced in patients treated with therapeutic hypothermia after cardiac arrest

BACKGROUND The platelet inhibitor clopidogrel is administered to patients treated with therapeutic hypothermia following cardiac arrest due to acute coronary syndromes. Interactions with proton pump inhibitors and genetics are factors with a known potential to attenuate the platelet inhibition of clopidogrel. In patients treated with therapeutic hypothermia, reduced gastrointestinal function and hypothermia may also reduce the effect of clopidogrel. To investigate the net platelet inhibition of clopidogrel, we have measured the platelet reactivity index in patients treated with therapeutic hypothermia. METHODS AND RESULTS Twenty-five Caucasian patients treated with clopidogrel and therapeutic hypothermia were prospectively included. Therapeutic hypothermia was defined as 33-34°C and delivered for 24h. Clopidogrel loading doses (300-600 mg) were administered enterally the day of admission and followed by 75 mg daily. Blood samples were collected on day 1 (n=25) and day 3 (n=16). The samples were analysed for inhibition by clopidogrel with a vasodilator stimulated phosphoprotein phosphorylation kit. On day 1 and day 3, platelet reactivity index was 0.77±0.09 and 0.57±0.16, respectively. The number of patients with a satisfactory antiplatelet effect (defined as platelet reactivity index <0.5) were 0 (0%) and 5 (31%), respectively. CONCLUSION In patients treated with therapeutic hypothermia after cardiac arrest, the effect of clopidogrel on platelets was virtually nonexistent on day 1 after administration, with some improvement on day 3.

Effects of Hypothermia on the Disposition of Morphine, Midazolam, Fentanyl, and Propofol in Intensive Care Unit Patients

Therapeutic hypothermia (TH) may induce pharmacokinetic changes that may affect the level of sedation. We have compared the disposition of morphine, midazolam, fentanyl, and propofol in TH with normothermia in man. Fourteen patients treated with TH following cardiac arrest (33–34°C) were compared with eight matched critically ill patients (36–38°C). Continuous infusions of morphine and midazolam were stopped and replaced with infusions of fentanyl and propofol to describe elimination and start of infusion pharmacokinetics, respectively. Serial serum and urine samples were collected for 6–8 hours for validated quantification and subsequent pharmacokinetic analysis. During TH, morphine elimination half-life (t1/2) was significantly higher, while total clearance (CLtot) was significantly lower (median [semi-interquartile range (s-iqr)]): t1/2, 266 (43) versus 168 (11) minutes, P < 0.01; CLtot, 1201 (283) versus 1687 (200) ml/min, P < 0.01. No significant differences were seen for midazolam. CLtot of fentanyl and propofol was significantly lower in hypothermic patients [median (s-iqr)]: fentanyl, 726 (230) versus 1331 (678) ml/min, P < 0.05; propofol, 2046 (305) versus 2665 (223) ml/min, P < 0.05. Compared with the matched, normothermic intensive care unit patients, t1/2 of morphine was significantly higher during TH. CLtot was lower during TH for morphine, fentanyl, and propofol but not for midazolam. Reducing the infusion rates of morphine, fentanyl, and propofol during TH is encouraged

Semiautomatic contour detection in ultrasound M-mode images.

We have developed a method for semiautomatic contour detection in M-mode images. The method combines tissue Doppler and grey-scale data. It was used to detect: 1. the left endocardium of the septum, the endocardium and epicardium of the posterior wall in 16 left ventricular short-axis M-modes, and 2. the mitral ring in 38 anatomical M-modes extracted pair-wise in 19 apical four-chamber cine-loops (healthy subjects). We validated the results by comparing the computer-generated contours with contours manually outlined by four echocardiographers. For all boundaries, the average distance between the computer-generated contours and the manual outlines was smaller than the average distance between the manual outlines. We also calculated left ventricular wall thickness and diameter at end-diastole and end-systole and lateral and septal mitral ring excursions, and found, on average, clinically negligible differences between the computer-generated indices and the same indices based on manual outlines (0.8-1.8 mm). The results were also within published normal values. In conclusion, this initial study showed that it was feasible in a robust and efficient manner to detect continuous wall boundaries in M-mode images so that tracings of left ventricular wall thickness, diameter and long axis could be derived.

Diagnostic influence of cardiovascular screening by pocket-size ultrasound in a cardiac unit

Aims We aimed to study the diagnostic influence of adding a routine cardiovascular ultrasound screening of the cardiac anatomy and function, the pericardium, the pleura and the abdominal great vessels by the new pocket-size ultrasound device (pUS) with grey scale and colour Doppler imaging. Methods and results In 119 randomly selected patients admitted to a cardiac unit at a non-university hospital, routinely adding a cardiovascular ultrasonography of only 4.4 min with a pocket-size device corrected the primary diagnosis in 16% of patients. In addition, 29% had the primary diagnosis verified and in 10% an additional important diagnosis was made. Higher age predicted any diagnostic influence of pUS screening with an increase of 61% (P = 0.003) per 10 years of higher age. Overall, the pUS screening had a sensitivity and specificity with respect to detecting at least moderate pathology of 97 and 93%. Positive and negative predictive values were 93 and 87%, respectively. In the sub-group of subjects with a change in the primary diagnosis following pUS there was no false-negative or false-positive findings. Conclusion Screening by pUS assessed vascular and cardiac anatomy and function accurately and enabled correction of the diagnosis in 16% of patients admitted to a cardiac unit. In 55% of the participants, the cardiovascular ultrasound screening had important diagnostic influence. We suggest that it would be appropriate to implement strategies and systems for routinely adding an ultrasound cardiovascular examination to patients in cardiac units.

Volumetric Blood Flow Measurement with the Use of Dynamic 3-Dimensional Ultrasound Color Flow Imaging

We describe a new method for measuring blood volume flow with the use of freehand dynamic 3-dimensional echocardiography. During 10 to 20 cardiac cycles, the ultrasonographic probe was slowly tilted while its spatial position was continuously recorded with a magnetic position sensor system. The ultrasonographic data were acquired in color flow imaging mode, and the separate raw digital tissue and Doppler data were transferred to an external personal computer for postprocessing. From each time step in the reconstructed 3-dimensional data, one cross-sectional slice was extracted with the measured and recorded velocity vector components perpendicular to the slice. The volume flow rate through these slices was found by integrating the velocity vector components, and was independent of the angle between the actual flow direction and the measured velocity vector. Allowing the extracted surface to move according to the movement of anatomic structures, an estimate of the flow through the cardiac valves was achieved. The temporal resolution was preserved in the 3-dimensional reconstruction, and with a frame rate of up to 104 frames/s, the reconstruction jitter artifacts were reduced. Examples of in vivo blood volume flow measurement are given, showing the possibilities of measuring the cardiac output and analyzing blood flow velocity profiles.

Quantification of mitral regurgitation using high pulse repetition frequency three-dimensional color Doppler.

BACKGROUND The aim of this study was to validate a novel method of determining vena contracta area (VCA) and quantifying mitral regurgitation using multibeam high-pulse repetition frequency (HPRF) color Doppler. METHODS The Doppler signal was isolated from the regurgitant jet, and VCA was found by summing the Doppler power from multiple beams within the vena contracta region, where calibration was done with a reference beam. In 27 patients, regurgitant volume was calculated as the product of VCA and the velocity-time integral of the regurgitant jet, measured by continuous-wave Doppler, and compared with regurgitant volume measured by magnetic resonance imaging (MRI). RESULTS Spearmans rank correlation and the 95% limits of agreement between regurgitant volume measured by MRI and by multibeam HPRF color Doppler were r(s) = 0.82 and -3.0 +/- 26.2 mL, respectively. CONCLUSION For moderate to severe mitral regurgitation, there was good agreement between MRI and multibeam HPRF color Doppler. Agreement was lower in mild regurgitation.

Causes of in-hospital cardiac arrest – Incidences and rate of recognition ☆

BACKGROUND AND METHODS Do emergency teams (ETs) consider the underlying causes of in-hospital cardiac arrest (IHCA) during advanced life support (ALS)? In a 4.5-year prospective observational study, an aetiology study group examined 302 episodes of IHCA. The purpose was to investigate the causes and cause-related survival and to evaluate whether these causes were recognised by the ETs. RESULTS In 258 (85%) episodes, the cause of IHCA was reliably determined. The cause was correctly recognised by the ET in 198 of 302 episodes (66%). In the majority of episodes, cardiac causes (156, 60%) or hypoxic causes (51, 20%) were present. The cause-related survival was 30% for cardiac aetiology and 37% for hypoxic aetiology. The initial cardiac rhythm was pulseless electrical activity (PEA) in 144 episodes (48%) followed by asystole in 70 episodes (23%) and combined ventricular fibrillation/ventricular tachycardia (VF/VT) in 83 episodes (27%). Seventy-one patients (25%) survived to hospital discharge. The median delay to cardiopulmonary resuscitation (CPR) was 1min (inter-quartile range 0-1min). CONCLUSIONS Various cardiac and hypoxic aetiologies dominated. In two-thirds of IHCA episodes, the underlying cause was correctly identified by the ET, i.e. according to the findings of the aetiology study group.