System for ECG monitoring with selective lead switching

Details System for ECG monitoring with selective lead switching System for ECG monitoring with selective lead switching

2001-03-09

2003-04-22

Schaetzle, Kennedy (Department: 3762)

Surgery

Diagnostic testing

Cardiovascular

C600S522000

Reexamination Certificate

active

06553250

ABSTRACT:

The present invention relates to a system as defined in the preamble of claim
1
.
In the prior art, a system for ECG monitoring as represented by the diagrams in
FIGS. 1 and 2
is known. In
FIG. 1
, the same patient P is diagrammatically represented by two pictures of the torso, where the lower picture shows a standard four-point placement of measuring electrodes R, F, L and N (so-called limb electrodes). For the sake of clarity, the upper picture separately shows a standard placement of ECG measuring electrodes, i.e. precordial electrodes V
1
, V
2
, V
3
, V
4
, V
5
, V
6
on the patient's thorax. Together the limb electrodes and precordial electrodes form a so-called 12-lead connection system. A so-called 5-lead connection system also used in ECG measurement consists of limb electrodes together with one of the precordial electrodes, e.g. R, F, L, N and V
1
.
A 12-lead connection system as presented in
FIGS. 1 and 2
comprises 1-10 signal leads, which are connected to corresponding measuring electrodes R, L, N, F; V
1
, V
2
, V
3
, V
4
, V
5
, V
6
as mentioned above, attached to the patient P according to standard electrode placement Each signal lead
1
-
10
is provided with a first connector element
11
. The system further comprises a collecting cable
12
with an adapter
24
at its end. The adapter
24
comprises a collecting connector
13
provided with second connector elements
14
for receiving the first connector elements
11
of the signal lead. At the other end of the cable
12
is a third connector element
15
The system further comprises an ECG apparatus
30
, which comprises an amplifier unit
16
.
The amplifier unit
16
is provided with a fourth connector element
17
, to which the third connector element
15
of the collecting cable
12
is connected.
ECG monitoring and diagnostic so-called 12-lead ECG have traditionally been performed using different sets of equipment. Monitoring was performed as a continuous process using 3-lead or 5-lead equipment and 12-lead monitoring was generally performed when necessary under the supervision of a cardiologist as a short separate operation. However, it is possible to build an apparatus using modern electronics which brings the price of 12-lead ECG to a reasonable level, thus making it sensible to use continuous 12-lead monitoring. However, 12-lead equipment is more complicated than 5-lead equipment as it needs ten measuring electrodes as Mentioned above: R, F, L, N,; V
1
, V
2
, V
3
, V
4
, V
5
, V
6
and therefore also ten patient cables, i.e. signal leads
1
-
10
from the amplifier to the patient's skin. The end of the shielded collecting cable
12
in the prior-art 12-lead system is overloaded with a collecting connector
13
, which is also presented in
FIG. 2
as a diagram showing it in an end view. It comprises twenty connector elements
14
in all. Placed in the upper row on the right are circular connector elements
14
for the connector elements.
11
of the signal leads
1
-
5
coming from the limb electrodes R, F, L, N, and one precordial electrode V
1
. Connected to the circular connector elements
14
1
in the left-hand part of the upper row are the connector elements
11
of the signal leads
6
-
10
coming from the precordial electrodes V
2
, V
3
, V
4
, V
5
and V
6
. The shield of each signal lead
1
-
10
is connected to one of the rectangular connectors in the lower row (connections consistent with the AAMI standard), which are connected to a floating ground G.
Grounding of the shields of the signal leads has an importance especially in ECG monitoring performed during anesthesia, because surgical operations are often performed using a so-called diathermic device, i.e. an electric surgical knife, whose high-frequency electric current would otherwise confuse the ECG monitoring process.
The figure also shows protective resistors
23
, whose function is to protect the amplifier electronics against the high-voltage pulse of a defibrillator. Two resistors are provided for each one of leads
1
-
5
because in most cases, in addition to ECG measurement, the patient's respiration also needs to be monitored, which is done using a parallel apparatus measuring thorax impedance.
The problem with the prior-art system is that, in a 12-lead system, the collecting adapter is a very wide, large and heavy component when traditional, standardized shielded signal leads are used, in which each conductor runs inside a separate shield. The large size and weight are a problem in respect of usability, because the aforesaid collecting adapter is usually placed near the patient and can easily be dropped to the floor, where the adapter and the leads connected to it may be damaged.
The object of the invention is to eliminate the problems referred to above.
A specific object of the invention is to disclose a system which can work both as a 5-lead system and as a 12-lead system and in which it is possible to combine a 5-lead and a 12-lead amplifier connector and signal leads, allowing the same amplifier unit to function alternatively in a 5-lead system with shielded leads or in a 12-lead system with unshielded leads.
A further object of the invention is to disclose a system in which a small and light-weight collecting adapter can be used.
As for the features characteristic of the invention, reference is made to the claims presented below.
According to the invention the system comprises measuring attached to a patient in accordance with a standard electrode placement; signal leads connected to corresponding measuring electrodes each of said signal leads being provided with a first connector element; a collecting connector containing second connector elements for receiving the first connector elements; an ECG apparatus comprising an amplifier unit to which the measurement signals are passed from the collecting connector; and change-over switches which are so implemented that, in a first connection position, they will conduct the measurement signals from the measuring electrodes attached to the patient to the ECG apparatus so that the corresponding signal leads are electrically connected to the patient, while in a second connection position they establish a shielding ground connection for at least some of said signal leads.
Shielding is not necessarily needed in all monitoring situations, so it is possible to use signal leads substantially without a shielding ground connection.
In an embodiment of the system, the collecting connector is placed in the amplifier unit, and the signal leads are connected directly from the patient to the amplifier unit.
In an embodiment of the system, the system comprises a collecting cable between the signal leads and the amplifier unit. In this case, the collecting connector is connected to the collecting cable.
In an embodiment of the system, the collecting connector comprises a number of second connector elements corresponding to the number of measuring electrodes defined in the 12-lead ECG standard.
In an embodiment of the system, the changeover switches in their second connection position establish a shielding ground connection for a first group of signal leads via the connector elements in the collecting connector intended for a second group of signal leads
In an embodiment of the system, the measuring electrodes are connected to the patient in accordance with the 12-lead ECG standard. In this case, in order to accomplish a 12-lead ECG measurement, the changeover switches are in the said first position to pass the measurement signals from all measuring electrodes to signal processing in the ECG apparatus the signal leads now being electrically connected to the patient.
In an embodiment of the system, the measuring electrodes are connected to the patient in accordance with the 5-lead ECG standard. In this case, to accomplish a 5-lead ECG measurement with grounded shielding, the change-over switches are in the said second position, the first group of signal leads now having a shielding ground connection to a floating ground.
In an embodiment of the system, the second connector e

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