Name: quantitative autonomic testing
Uploaded: 2011-07-19T15:00:00
Duration: 11 min 40 s
Description: Watch this Scientific Journal Video about Quantitative Autonomic Testing at JoVE.com

Author thanks to Dr. Lan Qin and Shane Stanek for help with collection of data.

<ol>
	<li>Low, P. A., Denq, J. C., Opfer-Gehrking, T. L., Dyck, P. J., O'Brien, P. C., Slezak, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+age+and+gender+on+sudomotor+and+cardiovagal+function+and+blood+pressure+response+to+tilt+in+normal+subjects.">Effect of age and gender on sudomotor and cardiovagal function and blood pressure response to tilt in normal subjects.</a> Muscle Nerve. 20, 1561-1568 (1997).</li><li>Low, P. A., Denq, J. C., Opfer-Gehrking, T. L., Dyck, P. J., O'Brien, P. C., Slezak, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+age+and+gender+on+sudomotor+and+cardiovagal+function+and+blood+pressure+response+to+tilt+in+normal+subjects.">Effect of age and gender on sudomotor and cardiovagal function and blood pressure response to tilt in normal subjects.</a> Muscle Nerve. 20, 1561-1568 (1997).</li><li>Low, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Composite+autonomic+scoring+scale+for+laboratory+quantification+of+generalized+autonomic+failure.">Composite autonomic scoring scale for laboratory quantification of generalized autonomic failure.</a> Mayo Clin Proc. 68, 748-752 (1993).</li><li>Low, P. A., Low, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+evaluation+of+autonomic+function.">Laboratory evaluation of autonomic function.</a> Clinical Autonomic disorders. , 179-209 (1997).</li><li>Low, P. A., Low, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+evaluation+of+autonomic+failure.">Laboratory evaluation of autonomic failure.</a> Clinical Autonomic disorders. , 179-209 (2008).</li><li>Novak, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+sympathetic+index+from+Valsalva+maneuver.">Assessment of sympathetic index from Valsalva maneuver.</a> Neurology. , (2011).</li></ol>

No conflicts of interest declared.

Pitfalls 
Completing the autonomic testing is in most of patients straightforward and can be done within 1 hours. Particular pitfalls of each step of testing is discussed below.
Equipment, data acquisition and processing of autonomic signals. 
There are number of pitfalls related primarily to data quality. Inadequate cleaning of skin can lead to excessive noise in ECG signal that can render detection of R wave difficult. Improper placement of the blood pressure sensor my give false high or low values. Transcranial Doppler signal of high quality can be difficult to get in elderly patients due small bone window. Software for data processing may not be robust enough to distinguish artifacts at the blood pressure, for example in Parkinson patients with tremor.
Deep breathing
<ol>
 <li>Anxiety and abnormal respiratory pattern can affect the results of deep breathing. Subject should be well relaxed during the testing. A good marker of anxiety is the heart rate profile. If subject is anxious, the heart rate can be elevated. Before starting deep breathing test, make sure that the heart rate is not trending up or down, if this happened wait until the mean heart rate remains flat.
 The resting respiratory pattern should be normal, e.g there should be no hyperventilation (as measured by end tidal CO2) or tachypnea (respiratory rate is above 11 per minute).</li> 
 <li>The deep breathing test has limited usefulness in certain cardiac dysrythmia for example in atrial fibrillation or when the heart rate is controlled by pacemaker because the vagal nerve modulation of the heart will be override by either the heart-generated rhythm or by a pacemaker. Basic knowledge of cardiac rhythm abnormalities is recommended.</li>
 <li>Improper detection of R waves due artifacts will obviously cause errors in results. This can happened if the R waves are too small to be reliably detected, or if the ECG background is noisy for example due poor skin contact.</li> 
</ol>
Valsalva maneuver
Valsalva maneuver requires considerable cooperation from the subjects Many elderly or frail patients cannot perform the Valsalva maneuver correctly. Most common reason is weakness of the mouth muscles that results in air leak during the respiratory strain. In this case it is effective to gentle seal the air leak around the tube with fingers6. 
Evaluation of adrenergic functions cannot be done in a square-wave variant of Valsalva maneuver (Figure 10). This response is rare but can be seen in healthy subjects or in patients with congestive heart failure.
Tilt testing
Number of medication can affect the tilt test rendering interpretation of the test difficult. It is not always practical to discontinue medication before testing.
It may be difficult to obtain good quality recordings in movement disorders patients, for example in Parkinson patients with tremor.
Sudomotor testing (QSART)
<ol>
 <li>Incomplete removal of oily surface or too much skin irritation can affect sweat output.</li>
 <li>Leaks if the capsule is not watertight or pain due too much tight capsule </li>
 <li>Commonly used medication has anticholinergic effect that interferes with the sweat test. In many cases, is in impractical to discontinue these medications rendering interpretation of results difficult.</li>
</ol>
Grading of autonomic impairment using the Composite Autonomic Severity Score (CASS).
Generation of CASS score is quite cumbersome because it involves multiple comparisons in both absolute and percent values. Unfortunately, there is no commercial software that enables to calculate the score automatically. At UMASS, we use proprietary software that generates the CASS score automatically. Example of CASS scores is on the Table 8.

Table 9 Recommended equipment.
<table border="1">
	<tbody>
		<tr>
			<td>Name of the equipment</td>
			<td>Company</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Motorized tilt table</td>
			<td>WR Medical Electronic</td>
			<td>Any table with smooth movement reaching 70 degree within 5-10 seconds</td>
		</tr>
		<tr>
			<td>ECG monitor</td>
			<td>&nbsp;</td>
			<td>Any device with analog output</td>
		</tr>
		<tr>
			<td>Noninvasive beat-to-beat blood pressure monitor</td>
			<td>Finapres Medical Systems</td>
			<td>Several models are available, all are similar</td>
		</tr>
		<tr>
			<td>Q-Sweat</td>
			<td>WR Medical Electronic</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Transcranial Doppler</td>
			<td>&nbsp;</td>
			<td>Any device with analog output</td>
		</tr>
		<tr>
			<td><a href="http://www.adinstruments.com/products/hardware/research/Data*Acquisition*Systems/" target="_blank">Recording system</a></td>
			<td><a href="http://www.adinstruments.com/products/software/research/LabChart-Software/" target="_blank">LabChart</a>, <a href="http://www.adinstruments.com/" target="_blank">ADInstruments</a></td>
			<td>Simple programming</td>
		</tr>
		<tr>
			<td>Recording system</td>
			<td>Labview</td>
			<td>Complex programming</td>
		</tr>
		<tr>
			<td>Recording system</td>
			<td>Matlab</td>
			<td>Complex programming</td>
		</tr>
		<tr>
			<td>Recording system</td>
			<td>WR Medical</td>
			<td>Ready to use, but limited flexibility</td>
		</tr>
		<tr>
			<td>CO2 monitor</td>
			<td>&nbsp;</td>
			<td>Many models used for sleep studies</td>
		</tr>
		<tr>
			<td>Respiratory monitor</td>
			<td>&nbsp;</td>
			<td>Simple thermistor attached to a recording system</td>
		</tr>
	</tbody>
</table>

quantitative autonomic testing

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be invaluable tool for evaluation of these disorders, both in clinic and research. There are number of autonomic tests, however, only few were validated clinically or are quantitative. Here, fully quantitative and clinically validated protocol for testing of autonomic functions is presented. As a bare minimum the clinical autonomic laboratory should have a tilt table, ECG monitor, continuous noninvasive blood pressure monitor, respiratory monitor and a mean for evaluation of sudomotor domain. The software for recording and evaluation of autonomic tests is critical for correct evaluation of data. The presented protocol evaluates 3 major autonomic domains: cardiovagal, adrenergic and sudomotor. The tests include deep breathing, Valsalva maneuver, head-up tilt, and quantitative sudomotor axon test (QSART). The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores (CASS). Detailed protocol is provided highlighting essential aspects of testing with emphasis on proper data acquisition, obtaining the relevant parameters and unbiased evaluation of autonomic signals. The normative data and CASS algorithm for interpretation of results are provided as well.

Watch this Scientific Journal Video about Quantitative Autonomic Testing at JoVE.com

Quantitative Autonomic Testing

Standardized, comprehensive and fully quantitative testing of autonomic functions is described. The autonomic tests consist of evaluation of all three major autonomic domains including cardiovagal, adrenergic and sudomotor. The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores.

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be ...

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