Medical Image of the Week: PSG Sweat Artifact

Figure 1. A 30 second epoch suggestive of sweat artifact and incidentally noted snore artifact on the M1 channels.

Figure 2: Sweat artifact as seen in a 10 second epoch.

Figure 3.  30 second epoch after removal of the M1 channels.

A 61-year-old man, with a past medical history significant for hypertension, COPD and morbid obesity with a body mass index (BMI) of 45.81 is referred for an overnight sleep study for suspicion of obstructive sleep apnea. Artifact was noted on the polysomnogram recording as shown above (Figures 1-3).

Sweat artifact is characterized by slow undulating movement of the baseline recording in the affected channels due to perspiration altering the potential of the involved electrodes (1). Sweat artifact may mimic delta waves and scored as non-rapid eye movement (NREM) stage 3 sleep. Lowering the room temperature, using a fan on the scalp or replacing the conductive paste on the electrodes may help eliminate the artifact.

Safal Shetty, MD¹ and John Roehrs, MD²

¹Banner University Medical Center Tucson, AZ

²Southern Arizona VA Health Care System

Tucson, AZ

Reference

1. Siddiqui F, Osuna E, Walters AS, Chokroverty S. Sweat artifact and respiratory artifact occurring simultaneously in polysomnogram. Sleep Med. 2006;7(2):197-9. [CrossRef] [PubMed] 

Cite as: Shetty S, Roehrs J. Medical image of the week: PSG sweat artifact. Southwest J Pulm Crit Care. 2015;11(4):171-2. doi: http://dx.doi.org/10.13175/swjpcc097-15 PDF 

Medical Image of the Week: DBS Polysomnogram Artifact

Safal Shetty, MD

Kenneth S. Knox, MD 

Pulmonary, Allergy, Critical Care & Sleep Medicine

Banner University Medical Center

Tucson, AZ 

Figure 1. Thirty second epoch showing DBS artifact obscuring all recording channels except flow, efforts belts and the EKG channels. 

Figure 2. Ten second epoch showing the electrical artifact due to DBS.

A 79-year-old man with known Parkinson’s disease and status post deep brain stimulator (DBS) implantation underwent an overnight polysomnogram for clinical suspicion of obstructive sleep apnea. Artifact was seen on the polysomnogram recording (Figures 1 & 2).

Patient-related electrical artifacts may be seen from devices such as pacemakers, deep brain stimulators and vagal nerve simulators. Abrupt discontinuation of DBS is associated with a high likelihood of worsening of symptoms in patients with Parkinson’s disease (1). Patients with DBS are most commonly programmed in monopolar mode. Bipolar configuration, forms a short electrical dipole that affects a relatively smaller volume of tissue and generates far less artifact, suggesting that this may be an effective option in a Parkinsonian patient with indications for polysomnography (2).

References

1. Chou KL, Siderowf AD, Jaggi JL, Liang GS, Baltuch GH. Unilateral battery depletion in Parkinson's disease patients treated with bilateral subthalamic nucleus deep brain stimulation may require urgent surgical replacement. Stereotact Funct Neurosurg. 2004;82(4):153-5. [CrossRef] [PubMed]
2. Frysinger RC, Quigg M, Elias WJ. Bipolar deep brain stimulation permits routine EKG, EEG, and polysomnography. Neurology. 2006;66(2):268-70. [CrossRef] [PubMed]

Cite as: Shetty S, Knox KS. Medical image of the week: DBS polysomnogram artifact. Southwest J Pulm Crit Care. 2015;11(4):151-2. doi: http://dx.doi.org/10.13175/swjpcc096-15 PDF