Hand-carried Ultrasound Performed by Hospitalists: Does It Improve the Cardiac Physical Examination?

Article Outline

• Abstract
• Materials and Methods
  • Study Populations
  • Training of Hospitalists
  • Physical Examination Plus Hand-Carried Ultrasound versus Physical Examination Alone
  • Statistics
• Results
  • Study Populations
  • Does Hand-carried Ultrasound Add to the Accuracy of the Cardiac Physical Examination?
• Discussion
• Conclusions
• Acknowledgments
• References
• Copyright

Abstract 

Objective

The traditional physical examination of the heart is relatively inaccurate. There is little information regarding whether cardiac hand-carried ultrasound performed by noncardiologists adds to the accuracy of physical examinations. The purpose of this study was to determine whether hand-carried ultrasound can add to the accuracy of hospitalists' cardiac physical examinations.

Methods

During a focused training program in hand-carried echocardiography, 10 hospitalists performed cardiac examinations of 354 general medical inpatients first by physical examination and then by hand-carried ultrasound. Eligible inpatients included those for whom a conventional hospital echocardiogram was ordered. We measured how frequently the hospitalists' cardiac examination with or without hand-carried ultrasound matched or came within 1 scale level of an expert cardiologist's interpretation of the hospital echocardiogram.

Results

Adding hand-carried ultrasound to the physical examination improved hospitalists' assessment of left ventricular function, cardiomegaly, and pericardial effusion. For left ventricular function, using hand-carried ultrasound increased the percentage of exact matches with the expert cardiologist's assessment from 46% to 59% (P=.005) and improved the percentage of within 1-level matches from 67% to 88% (P=.0001). The addition of hand-carried ultrasound failed to improve the assessments of aortic stenosis, aortic regurgitation, and mitral regurgitation.

Conclusion

Adding hand-carried ultrasound to physical examination increases the accuracy of hospitalists' assessment of left ventricular dysfunction, cardiomegaly, and pericardial effusion, and fails to improve assessment of valvular heart disease. The clinical benefit achieved by improved immediacy of this information has not been determined. An important limitation is that the study assessed only 1 level of training in hand-carried ultrasound.

Keywords: Echocardiography, Hand-carried ultrasound, Hospitalist, Physical examination

Echocardiography can provide valuable information about a patient's cardiac anatomy and function that is difficult or impossible to obtain reliably through the traditional physical examination.¹, ², ³ For example, one study showed that physical examinations performed by cardiologists detected only 57% of the important cardiac abnormalities that were identified by echocardiography.⁴ Recent technologic advances have made available hand-carried ultrasound devices that weigh only 2 to 4 kg and provide high-quality 2-dimensional and Doppler images that are closely comparable to images obtained by conventional echocardiography machines.⁵, ⁶, ⁷, ⁸, ⁹ Studies have suggested that hand-carried ultrasound can improve the accuracy of the cardiac physical examination by cardiologists,⁴ medical residents,¹⁰, ¹¹ and medical students.¹² However, less is known about what hand-carried ultrasound can add to the physical examination by internists. Each of 2 previous studies involved only 1 general internist performing hand-carried ultrasound examinations without concurrent physical examinations for comparison.¹³, ¹⁴

One group of internists for whom hand-carried ultrasound might be especially valuable is those who concentrate on inpatient medicine, also known as hospitalists. As the most rapidly growing physician group in the United States¹⁵ who are caring for an increasing percentage of hospitalized patients, hospitalists may especially benefit from enhanced cardiac diagnostic skills. There is no information on whether hand-carried ultrasound would add to the physical examination by this large group of noncardiologists. Therefore, we sought to determine whether hand-carried ultrasound can add to the accuracy of the cardiac physical examinations by hospitalists.

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Materials and Methods 

Study Populations 

Study populations and hospitalist training have been described.¹⁶ Briefly, the study took place on the inpatient medical service at the Johns Hopkins Bayview Medical Center, an academic medical center, between March 2004 and August 2005. The hospitalists in this study spend most of their clinical time on the inpatient medical service, and each hospitalist admits an average of 623 patients per year. Hospitalists gave informed consent to participate in the study and completed a Johns Hopkins University training program on human investigation before participating.

Adult patients admitted to the medical service were eligible to participate if they were scheduled to have a conventional echocardiogram within 24 hours of the hand-carried ultrasound and provided informed, written consent. Study patients were selected as follows. The names of the patients scheduled to have an echocardiogram as part of their clinical care were identified by a research echocardiography technician (CM) who also determined whether the patients were appropriate on the basis of the inclusion criteria above. If several patients were appropriate for the study concurrently, the patient studied was selected preferentially if the participating hospitalist was the patient's responsible physician. Otherwise, the patient studied was selected randomly from among eligible patients. The Johns Hopkins University School of Medicine Institutional Review Board approved the study protocol.

Training of Hospitalists 

Hospitalists were introduced to echocardiography by the research echocardiography technician and by online resources. Hospitalists then performed 5 training echocardiograms, during which the research technician taught them to obtain and interpret 2-dimensional and Doppler images using a hand-carried device (SonoSite Elite, 2.6 kg; SonoSite Inc, Bothell, Wash). These hand-carried ultrasound examinations were not included in the current study. Color Doppler obtained in the apical 4-chamber view was used to assess the severity of mitral and aortic regurgitation. Hospitalists were taught to grade mitral regurgitation as “mild” if the regurgitant color Doppler jet occupied less than 20% of the left atrium, “moderate” if the jet occupied 20% to 40% of the left atrium, and “severe” if the jet occupied more than 40% of the left atrium and extended into the pulmonary veins.¹⁷ Hospitalists graded aortic regurgitation on the basis of the width of the regurgitant jet in the left ventricular outflow tract.¹⁸ The severity of aortic stenosis was graded semiquantitatively on the basis of the extent of calcification and degree of restricted leaflet motion as seen in 2-dimensional long- and short-axis views. On the basis of the left ventricular motion visualized on the long-axis, short-axis, and apical 4-chamber views, hospitalists were taught to grade left ventricular function as normal, mildly reduced, moderately reduced, or severely reduced. Hospitalists then spent 6 hours interpreting conventional echocardiograms with a cardiologist, and they also were encouraged to review a CD-ROM–based teaching file of 20 echocardiography cases and to spend additional time reading echocardiograms with a cardiologist.

Hospitalists performed hand-carried ultrasound examinations on eligible inpatients. They were encouraged to function independently, but the research technician remained at the bedside to give additional training if requested. The technician recorded how long it took the hospitalists to complete each hand-carried ultrasound examination. On the basis of the hand-carried ultrasound examination, hospitalists recorded 6 cardiac measurements (ie, left ventricular size in systole and diastole, interventricular septum thickness, posterior wall thickness, left atrial size, and aortic root size) and graded left ventricular dysfunction, pericardial effusion, mitral regurgitation, aortic stenosis, and aortic regurgitation as absent/normal, mild, moderate, severe, or unable to assess. After finishing a hand-carried ultrasound examination, hospitalists could request further training or review from the technician, including review of the corresponding conventional echocardiogram. Hospitalists were expected to perform approximately 30 hand-carried ultrasound examinations during this study.

Physical Examination Plus Hand-Carried Ultrasound versus Physical Examination Alone 

Immediately before each hand-carried ultrasound, hospitalists performed a physical examination relevant to the heart, and on the basis of the physical examination performed in the customary fashion, they were asked to complete a study form in which they indicated the presence (and degree) or absence of cardiomegaly, left ventricular dysfunction, pericardial effusion, aortic regurgitation, aortic stenosis, and mitral regurgitation. Assessments were made on the same graded scale used for hand-carried ultrasound-based assessments (absent/normal, mild, moderate, severe, or unable to assess).

Immediately after performing the physical examination and recording the assessments, the hospitalists performed the hand-carried ultrasound examination as described above. All hand-carried ultrasound examinations were recorded on videotape and saved for evaluation and comparison with the conventional echocardiogram as interpreted by an expert cardiologist (EPS) who reviewed recordings of the hand-carried and conventional echocardiograms, grading quality of image acquisition and recording the same assessments and measurements on the same scales used by the hospitalists. For hand-carried ultrasound, cardiomegaly was defined as left ventricular diastolic size of 5.7 cm or greater. The expert cardiologist was blind with regard to hospitalist identity and hospitalist physical examination results.

Statistics 

We calculated the percentages of matches between the expert cardiologist's interpretation of the conventional echocardiogram and either the physical examination alone or the physical examination plus hand-carried ultrasound with respect to several prespecified cardiac abnormalities. A weighted McNemar's test for paired proportions was used to compare these pairs of percentages. To compensate for infrequently occurring results, cases were weighted by (1-p), where p is the proportion of cases with a particular assessment as determined by the expert cardiologist. Such percentages and P values were computed for cardiomegaly, left ventricular dysfunction, aortic regurgitation, aortic stenosis, pericardial effusion, and mitral regurgitation. All confidence intervals (CIs) are 95%. SAS version 8.02 (SAS Institute Inc, Cary, NC) was used in all analyses. Data resulting from cases in which the hospitalists were assisted by the research technician were not included in our calculations.

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Results 

Study Populations 

Ten hospitalists were enrolled in the study, each certified by the American Board of Internal Medicine, with an average of 2.9 (range: 0-9) years of postresidency experience. Several hospitalists had limited previous experience with echocardiography. Two hospitalists had been involved in a previous study of hand-carried ultrasound training, and each had performed 10 training scans. One hospitalist had 40 hours of previous didactic echocardiography training and 40 hours of supervised echocardiography reading experience. The 10 hospitalists completed 354 supervised hand-carried ultrasound examinations (mean=35.4, range=28-50). Supervised hand-carried ultrasound examinations averaged 22 minutes in duration (13 minutes to perform the study, 9 minutes to set up and record findings).

All patients (n=354) were admitted to the general medical service of the Johns Hopkins Bayview Medical Center. The research technician enrolled all of the patients, selecting at random most from all eligible patients admitted to the medical service (n=319) and a minority from eligible patients for whom the hospitalist performing the hand-carried ultrasound was the responsible physician (n=35). The mean patient age was 63.0 years (standard deviation 18.7), the mean patient weight was 75.5 kg (standard deviation 14.0), and 53.0% were female. Their admission diagnoses represented the wide spectrum of internal medicine disorders.

Does Hand-carried Ultrasound Add to the Accuracy of the Cardiac Physical Examination? 

Table 1, Table 2 display the percentage of hand-carried ultrasound plus physical examination findings that match those of the conventional echocardiogram (as interpreted by the expert cardiologist). Two standards of matching are shown: The hand-carried ultrasound plus physical examination or physical examination alone finding exactly matched that of the expert cardiologist assessment, which was made on a 4-point scale (normal, mild, moderate or severe) plus unable to assess; and the hand-carried ultrasound plus physical examination or physical examination alone approximately matched, defined as coming within 1 scale level of matching the expert cardiologist assessment, based on the 4-point severity of abnormality scale defined above. As can be seen from the table, results were mixed or inconclusive for the assessments of aortic regurgitation, aortic stenosis, and mitral regurgitation.

Table 1. Physical Examination Plus Hand-carried Ultrasound Versus Physical Examination

PE = physical examination; HCU = hand-carried ultrasound.

Table 2. Ninety-five Percent Confidence Intervals for Matching Percentages

Cases	Aortic Regurgitation				Aortic Stenosis				Mitral Regurgitation				Cardiomegalyc				Left Ventricular Function				Pericardial Effusion
	%	LCL	UCL	N	%	LCL	UCL	N	%	LCL	UCL	N	%	LCL	UCL	N	%	LCL	UCL	N	%	LCL	UCL	N
		Matching Expert Cardiologist's Assessment Exactlya
All
HCU	52	46	57	290	73	68	77	336	42	36	48	290	90	86	93	311	59	54	64	336	79	75	84	336
PE	63	58	69	290	74	69	79	336	40	34	46	290	59	53	64	311	46	41	51	336	49	44	54	336
Normal
HCU	59	52	65	206	79	75	84	286	54	44	63	114	93	90	96	271	73	67	79	219	84	80	89	269
PE	86	82	91	206	84	79	88	286	79	71	86	114	59	54	65	271	64	58	70	219	61	55	66	269
Abnormalb
HCU	35	24	45	84	34	21	47	50	35	28	42	176	70	56	84	40	32	24	41	117	60	48	71	67
PE	7	2	13	84	20	9	31	50	15	10	20	176	53	37	68	40	12	6	18	117	3	0	7	67
		Matching Expert Cardiologist's Assessment Within 1 Assessment Levela
All
HCU	74	69	79	290	83	79	87	336	77	72	82	290	90	86	93	311	88	84	91	336	96	93	98	336
PE	83	79	88	290	90	87	93	336	77	72	82	290	59	53	64	311	67	62	72	336	59	54	64	336
Normal
HCU	73	67	79	206	85	81	89	286	80	72	87	114	93	90	96	271	89	85	94	219	95	92	97	269
PE	89	85	94	206	94	91	97	286	89	83	94	114	59	54	65	271	77	71	82	219	62	56	68	269
Abnormal
HCU	76	67	85	84	70	57	83	50	76	69	82	176	70	56	84	40	85	78	91	117	99	96	100	67
PE	69	59	79	84	68	55	81	50	70	63	77	176	53	37	68	40	49	40	58	117	48	36	60	67

PE = physical examination; HCU = hand-carried ultrasound; LCL = lower 95% confidence limit; UCL = upper 95% confidence limit; N = number of cases.

PE and HCU rows contain the percent of all cases that matched the result of the expert cardiologist's interpretation of the conventional echocardiogram. The percent matching normal values represent the percent of true negatives. The percent matching abnormal values represent the percent of the true positives.

Compared with physical examination alone, the addition of hand-carried ultrasound increased the overall percentage of correct pericardial effusion assessments from 49% to 79% for exact matches and from 59% to 96% for within 1-level matches. For cases with pericardial effusions, the percentage of correct pericardial effusion assessments increased from 3% to 60% when exact matches were required and from 48% to 99% for within 1-level matches. In both cases, this shows an improvement of greater than 50 percentage points.

In the case of assessing left ventricular function, gains with hand-carried ultrasound were uniform in all categories calculated. They were modest overall: from 46% to 59% (difference 13%) when exact matches were required and from 67% to 88% (difference 21%) for within 1-level matches. By assessing only the cases with abnormal left ventricular function, the percentage point gains are greater: 20% and 36%, respectively. Only 59% (CI, 54-64) of hand-carried ultrasound assessments exactly matched those of the expert cardiologist, and 88% (CI, 84-91) were within 1 scoring level.

Cardiomegaly was more accurately assessed by hand-carried ultrasound than by physical examination alone. The overall percentage correct increased from 59% on physical examination alone to 90% by hand-carried ultrasound.

Hand-carried ultrasound was more accurate than physical examination in detecting aortic regurgitation (35% vs 7%) but less accurate in detecting its absence (59% vs 86%), indicating that the hospitalists were over-reading aortic regurgitation. Similar results were found for mitral regurgitation (Table 1).

Exactly correct assessment rates for abnormal results with exact matching of cardiologist assessment were 32% to 35% for all but pericardial effusion (60%; CI, 48-71) and cardiomegaly (70%; CI, 58-84), which was only assessed dichotomously. However, when matching is required within only 1 assessment level, the results improved to the 70% to 85% range for all types of assessment except pericardial effusion (99%; CI, 96-100).

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Discussion 

The traditional cardiac physical examination often misses important findings that are detectable by echocardiography.¹, ⁴ The current study reveals for the first time what hand-carried echocardiography can add to the physical examinations of internists. Our study shows that adding hand-carried ultrasound to physical examination increases the accuracy of hospitalists' assessments of left ventricular dysfunction, cardiomegaly, and pericardial effusions, and fails to improve the accuracy of assessments of aortic stenosis, aortic regurgitation, and mitral regurgitation (Table 1, Table 2). It is noteworthy that hand-carried ultrasound did not always improve the accuracy of hospitalist assessments. In particular, for aortic regurgitation and mitral regurgitation, hospitalists often over-read normal examinations. These studies require color Doppler, and previous studies have shown that this technique is difficult for inexperienced users to interpret adequately.¹⁹ These valvular assessments were probably limited by the hospitalists' relative difficulty in acquiring adequate images in the apical view,¹⁶ as well as by the semiquantitative methods by which valvular abnormalities were evaluated. The results also confirm the limitations of the physical examination, particularly for left ventricular function and pericardial effusion assessments.

This study adds considerably to what little is known about hand-carried ultrasound in the hands of general internists and builds on prior studies suggesting that hand-carried ultrasound can supplement the physical examinations of other health care providers. However, both of the 2 previous studies of general internists involved only 1 physician performing hand-carried ultrasound examinations, and neither examined what hand-carried ultrasound could add to the physical examination.¹³, ¹⁴ Our study consisted of a substantial number of internist subjects: 10 hospitalists. The training program in both prior studies required internists to complete 20 hours of didactic instruction and 30 to 40 hand-carried ultrasound examinations.¹³, ¹⁴ Studies of other health care providers suggest that hand-carried ultrasound can add information to the cardiac physical examination. Manasia et al²⁰ showed that 6 surgical intensivists gained valuable information in 76 of 90 critically ill patients (85%) after adding hand-carried ultrasound to physical examination to assess left ventricular function and pericardial effusion. In addition, the information gained by hand-carried ultrasound affected immediate patient management in 37% of patients. Spencer et al⁴ showed that when cardiologists added hand-carried ultrasound to the physical examination, the rate of missing important cardiac abnormalities (as defined by conventional echocardiography) decreased from 43% to 21%. In a similar study, 10 of 13 medical residents correctly modified their physical examination-based diagnosis after using hand-carried ultrasound to help detect left ventricular dysfunction in 12 model patients.¹⁰ DeCara et al¹² demonstrated that even after a 10-day review of cardiac physical examination skills, medical students performing hand-carried ultrasound more accurately diagnosed cardiac abnormalities than by physical examination alone. Illustrating dramatically the value of ultrasound and the inherent limitations of the physical examination, Kobal et al²¹ showed that first-year medical students performing hand-carried echocardiography examinations were superior to cardiologists performing physical examinations in detecting valvular disease and left ventricular dysfunction and enlargement and hypertrophy. Specifically, students identified 86% of left ventricular dysfunction and 89% of significant valvular lesions, whereas cardiologists diagnosed only 45% and 50%, respectively.

Our study shows that hand-carried ultrasound in the hands of hospitalists does not replace conventional echocardiography. At the level of training reached in this study, hospitalists using hand-carried ultrasound still missed many cardiac abnormalities. For example, even after adding hand-carried ultrasound to physical examination, hospitalists correctly identified the degree of left ventricular dysfunction 32% of the time (CI, 24-41). However, when within 1-level of severity was required, they correctly identified 88% (CI, 84-91) of cases of left ventricular dysfunction. Hand-carried ultrasound in the hands of our hospitalist subjects had poor diagnostic accuracy for valvular abnormalities. Absolute correct assessment rates (ie, percent true positives) were low (∼35%). Overall, the error rates were no better and sometimes worse than physical examination alone.

This study has several important limitations. First, we assessed only 1 level of hand-carried ultrasound training. Although the training regimen was based on our previous work,²² which suggested this level might be sufficient for physicians to acquire competency, our more recent study shows that skills achieved are more modest; hospitalists so trained do not match the ability of echocardiography technicians to acquire or interpret images.¹⁶

Second, training internists to perform a technically difficult assessment, which is performed better and at a lower cost by a technician, requires justification in terms of clinical benefit (eg, the immediacy of the information) and cost. In this article, we have not addressed the questions of cost-effectiveness or potential clinical impact.

Third, we did not measure the impact of hand-carried ultrasound on patient satisfaction, physician satisfaction with work, or the doctor–patient relationship. Although technology can in theory distance the doctor from the patient, because hand-carried ultrasound, if performed by a doctor, would require “hands-on” doctor–patient interaction for approximately 20 minutes, it is possible that hand-carried ultrasound could improve patient satisfaction with care.

Finally, it must be noted that our results might have been influenced by the variability inherent in a study of this type in which the physicians were not a group with uniform background and training and the examinations were performed on real patients. Although this can be seen as a limitation, we believe that the “real world” aspect of this study is one of its strengths. The prior background and training of the hospitalists in this study and any potential prior knowledge of the patients they examined are as likely to have influenced the yield of hand-carried ultrasound as to influence the yield of any diagnostic technique used by practicing physicians. Of note, a logistic regression analysis was performed to evaluate the degree to which variations in background and training of the hospitalists and in their prior knowledge of the patient could have influenced the results. This analysis adjusted for the hospitalists' time spent on additional echocardiography training (apart from what was required); their previous experience in this area (ie, the self-reported number of previous echocardiograms the hospitalists had performed); the degree to which hospitalists' assessments were influenced by additional sources of information (current conventional echocardiogram, other previous echocardiograms, previous familiarity with the patient, and medical history, all assessed by self-report); and the number of echocardiograms hospitalists performed as part of this study before the examination in question. This analysis showed that the strongest and virtually the only predictor of performance of hand-carried ultrasound by hospitalists was the number of echocardiograms that hospitalists performed as part of this study before the examination in question (data not shown).

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Conclusions 

This study shows that hand-carried ultrasound in the hands of internists adds information to that obtained from the physical examination for particular parts of the cardiac assessment: left ventricular function, cardiomegaly, and pericardial effusion. For valvular dysfunction, hand-carried ultrasound does not add information. Detecting left ventricular dysfunction is important because it is often asymptomatic and early diagnosis and treatment improve its associated morbidity and mortality.²³, ²⁴, ²⁵, ²⁶, ²⁷ Whether the clinical benefit achieved by improved immediacy of this information counterbalances the financial cost, the loss of physician time, and the effects of relatively high error rates (both false positives and false negatives) has not been determined. Until more definitive assessment of these issues is done, internist use of hand-carried ultrasound at the bedside should be limited to clinically focused situations for which there is a proven informational benefit, such as for left ventricular function and pericardial effusion when the timeliness of the information may be important.

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Acknowledgments 

The authors thank the hospitalists of Johns Hopkins Bayview Medical Center for participating in this study, and SonoSite Inc, for providing equipment used in this study.

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