The Ultimate Acoustic Stethoscope Review (page 2)
The Test Stethoscopes Dimensions:
The measured physical dimensions of the stethoscopes are listed below. The length is from the earpieces to the diaphragm. Some of the dual head scopes (DRG, Cardiology III) use a second smaller diaphragm in lieu of the bell. Those with a bell are indicated.
|Model||Length, inches (cm)||Weight ounces (gms)||Single or Dual Head, Bell|
|ADC Platinum Cardiology 615||30 (76.2)||5.5 (156)||Single|
|ADC Adscope Professional 603||30 (76.2)||5.7 (162)||Dual, Bell|
|AllHeart Cardiology||28 (71.1)||8.4 (238)||Dual, Bell|
|DRG Puretone Traditional PT3||28 (71.1)||5.7 (162)||Dual|
|Single Head Nursing Stethoscope||31 (78.7)||2.4 (68)||Single|
|Littmann Cardiology I||21.3 (54.1)||7.2 (204)||Dual, Bell|
|Littmann Cardiology III||27.3 (69.3)||6.1 (173)||Dual|
|Littmann Master Classic II||27.3 ((69.3)||5.7 (162)||Single|
|Littmann Classic II SE||28 (71.1)||4.7 (133)||Dual, Bell|
|Omron Sprague Rappaport||29 (73.7)||8.3 (236)||Dual, Bell|
|Prestige Sprague Rappaport Stealth||28.3 (71.9)||7.7 (219)||Dual, Bell|
|Welch Allyn Tycos Elite||24.5 (62.2)||7.2 (204)||Dual, Bell|
The main issue in the performance of an acoustic scope is acoustic coupling from the patient to the examiners ears. The entire diaphragm must make good contact with the patient’s skin. There also must not be any air leakage between the diaphragm and the examiners ears. An excellent scope can be rendered useless if the earpieces don’t fit the examiner’s external ear. Soft gel or rubber earpieces are not only more comfortable, but they insure good acoustic coupling between the scope and the examiners ears. All of the scopes tested had either soft gel or rubber earpieces with the exception of the Generic single head, and the Omron Sprague Rappaport.
We tested all of the scopes for internal air leakage using pressurized air. All screw connections were checked for tightness before performing this test. Only one stethoscope flunked the pressurized air test. The Allheart Cardiology Stethoscope had air leaks between the metal tubing and the earpieces. Both earpieces did not fit properly on the tubing. They were cross threaded. See the below photo. They had to be removed with a set of pliers. All of the spare earpieces that came with the Allheart scope were of the same incorrect size. This is a serious defect, and impairs performance. In order to see what the Allheart scope was capable of without the defect, we substituted proper fitting earpieces onto the Allheart scope (from the Prestige Brand scope) for all subsequent tests.
A manufacturing issue affected the DRG scope, but was easily resolved. There were injection molding stems on the surface of the DRG scope diaphragm. They interfered with acoustic coupling between the patient’s skin, and the diaphragm. The stems were easily removed with a set of nail clippers. See the photo below.
Otherwise the scopes tested were of good build quality. Scopes with excellent fit and finish were the Welch Allyn Scope, all of the Littmann scopes, the DRG scope, all of the ADC scopes, and the Prestige Sprague-Rappaport scope.