Handheld ultrasound references

The below is a rough summary of publications discussing handheld ultrasound equipment – particularly with reference to cardiac scanning. It is designed to assist anybody who is currently researching handheld echo. 

 

Gianstefani et al. (2013)

“Pocket-size imaging device: effectiveness for ward-based transthoracic studies”

  • 92 patients
  • Patients were included where there was a focused clinical question: quantification of left ventricular function (LVF); presence of regional wall motion abnormalities (RWMA); evidence of pericardial effusion, exclusion of significant valve pathology.
  • In 83 patients [k=90% 95% CI, it was possible to answer the clinical question by PSID examination alone
  • There was agreement between the findings of PSID and TTE in 86 cases [79%;k = 47%, 95% CI]
  • When the clinical question was focused on LVF, the agreement was excellent [k= 96%,95% CI (95.3 – 97.9)], as was the agreement in the detection of RWMA [k= 94.57%, 95% CI (82.4 – 95.1)]. There was also good concordance in the detection of valve pathology and pericardial effusion. Using PSID, the reduction in the scanning and reporting time was 66%. The cost-effectiveness analysis produced very favourable results: with PSE, we obtained an overall cost saving per scan of 76%, compared with TTE.
  • Conclusion: This study demonstrates that PSID can provide a valuable alternative to TTE in the presence of focused clinical questions and can provide an efficient way of delivering a ward-based transthoracic echo service.

 

Fredreiksen et al. (2010).

“New pocket echocardiography device is interchangeable with high-end portable system when performed by experienced examiners.”

 

  • In group 1 (n=30), focus on image quality; in group 2 (n=31), focus on time taken.
  • Done 1 day post surgery.
  • Only did four echocardiographyic views (FATE protocol).
  • “Did not focus on the ability” to detect significant pathology.

 

“Undiagnosed cardiac disease is known to cause serious perioperative complications and to increase morbidity and mortality during and after surgery and anaesthesia” his references were:

Reich et al., (1999). Intraoperative hemodynamic predictors of mortality, stroke, and myocardial infarction after coronary artery bypass surgery. Anesth Analg 89: 814-22.

Reich et al. (2002). Intraoperative tachycardia and hypertension are independently associated with adverse outcome in noncardiac surgery of long duration. Anesth Analg 95: 273-7.

Slogoff & Keats (1985). Does perioperative myocardial ischemia lead to postoperative myocardial infarction? Anesthesology 62: 107-14.

 

Whilst no significance impact on morbidity has been found due to inability to have a control group, has been shown that changes are made to anaesthesia plan post-echo and also known that undiagnosed cardiac disease can increase morbidity and mortality in the perioperative setting (Frederiksen et al., 2010).

 

Cullen et al. (2014)

“Diagnostic capability of comprehensive handheld vs transthoracic Echocardiography” (unlike Fredreiksen’s which was not comprehensive)

 

  • Prompted to do this study as prior studies “have typically been small, have enrolled unselected patients, and have limited the scope of the handheld examination.”
  • Images obtained on TTE and HHE by sonographers, then independently interpreted by echocardiographers.
  • 190 patients.
  • K values ranging from 0.52 – 0.89
  • 27% had discordant findings, with tendency for HHE to underestimate (uh oh) the severity of abnormal findings. Most common discordant finding was presence v absence of regional wall abnormalities.
  • Conclusion: “In experienced hands, HHE shows moderate correlation with standard TTE, but discordant findings were present in 27% of patients. Even when performed and interpreted by experienced operators, HHE should not be used as a surrogate for standard TTE.”
  • “We defined the criteria for discordant findings on the basis of clinical classification for the parameters in the analysis. For example, we considered ventricular size and regurgitant valvular lesions to be discordant only when a difference of more than a full 1 level of severity existed between the HHE and TTE reports. We considered stenotic valvular lesions discrepant when 1 modality failed to identify them because of the implications that even mild undiagnosed mitral or aortic stenosis could have for long-term clinical surveillance. We have used similar criteria for ascending aortic enlargement and regional wall abnormalities. Any degree of aortic dilation implies the nee for additional surveillance. A single segment of wall motion abnormality can identify coronary artery disease.” So the discordant findings do have serious implications.

 

Hashim et al. (2014)

Can hospital rounds with pocket ultrasound by cardiologists reduce standard echocardiography?

 

  • 240 patients
  • Handheld images obtained by cardiology fellows with over 6 months of echocardiography training (level II), full sized obtained by ultrasonographer (level III). So not performed by the same level of person… but you could say this makes the study more applicable because if handheld were introduced for screening, surely the whole idea is that the echocardiographers would not have to do it?
  • Logistic regression was performed to assess the relationship between device agreement and age, sex and BMI.
  • TTE was more sensitive than handheld for wall motion abnormalities or aortic insufficiency, and the presence “of small, trivial pericardial effusions.”
  • Evaluation of IVC and LV end-diastolic dimension was diminished with pocket mobile echocardiography because of suboptimal visualisation. The diagnostic accuracy of pocket echo for LV function, wall motion abnormalities and valvular lesions has also been demonstrated to be a problem in the Prinz et al study.

 

Skjetne et al. (2011)

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

 

  • 119 randomly selected patients
  • Screening performed by expert consultant cardiologists on patients who wouldn’t otherwise have had an echo at all.
  • Corrected the primary diagnosis in 16% of patients
  • 10% of patients had an additional important diagnosis found

 

Cardim et al. (2010)

Usefulness of a new miniaturized echocardiographic system in outpatient cardiology consultations as an extension of physical examination

  • 189 patients
  • Performed no comparison with an echocardiographic gold standard
  • Device not designed to perform a complete study but to select patients who must be referred to echo labs.

 

Leibo et al. (2011)

Is pocket mobile echocardiography the next-generation stethoscope? A cross-sectional comparison of rapidly acquired images with standard transthoracic echocardiography.

 

  • Different interpreters to scanners
  • Scanners restricted in time allowed to spend
  • IVC imaging with handheld device was sub-optimal
  • Unskilled technicians showed less agreement than skilled operators

 

Voigt & Prinz (2011)

Anywhere, anytime?

  • “As with any other imaging technique, the diagnostic gain depends less on the machine rather than on the skills and expertise of the operator.”

 

Testuz et al. (2013)

Diagnostic accuracy of packet-size handheld echocardographs used by cardiologists in the acute care setting

 

  • 104 patients
  • Trained cardiologists
  • In the urgent echocardiography setting
  • High agreement between VScan and high end for LV systolic function (kappa 0.89) and pericardial effusion (kappa 0.81), good or moderate for aortic, mitral and tricuspid values and LV size (0.55 – 0.66)

 

Bhatia et al. (2012): Comparison of the 2007 and 2011 appropriate use criteria for transthoracic echocardiography in various clinical settings. J Am Soc Echocardiogr. = found that 22% of transthoracic echocardiography scans performed were unnecessary.

 

Further discussion of number of unnecessary studies: Douglas et al. (2007), appropriateness criteria for transthoracic and transesophageal echocardiography: a report of the American College of Cardiology…. Am Coll Cardiol 50:187-204

Kisslo (1995), Recommendations for continuous quality improvement in echocardiography. J Am Soc Echocardigr 8:51-28.

 

There are no published studies, however, that look at the effectiveness of the handheld scanner for preoperative screening in patients scheduled for non-cardiac surgery and its implications for reduced waiting times or even avoiding the possibility of undergoing surgery without having had any kind of echocardiographic assessment beforehand in instances where busy echocardiography departments may not have availability for the patient before the scheduled surgery time.

The ability to screen these patients before surgery to assess cardiac risk or at least quickly clear those without significant abnormality frees up resources and avoids unnecessary delay to the patients’ procedures which may cause morbidity or even mortality.

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