Although cardiac monitors and ECG strips can be used to calculate heart rate, the calculated rate is merely an estimate of the number of times per minute the heart has been electrically excited. In the normal heart, each excitation should be followed by cardiac contraction. However, in some situations, electrical activity can occur without contraction,
resulting in a lack of perfusion. Therefore, the heart rate obtained from the cardiac monitor or ECG strip should never be substituted for the determination of heart rate by palpating the pulse.
Both the atrial and the ventricular rates can be estimated by examining the ECG. To determine the ventricular rate, count the number of QRS complexes in a 6-second strip and multiply by 10. To estimate the atrial rate, count the number of P waves in a 6-second strip and multiply by 10. In the normal patient, the atrial and the ventricular rates should be the same. This method of rate calculation provides an estimate of heart rate for regular and irregular rhythms.
Another method of rate calculation can be used if the rhythm is regular. The ventricular heart rate is estimated by dividing 300 by the number of large boxes on the ECG paper between two R waves (the RR interval). The atrial rate is calculated by dividing 300 by the number of large boxes on ECG paper between two P waves (the PP interval).
Another quick method for estimating rate involves the use of a series of numbers. To use this method for estimating ventricular rate, the nurse first finds a QRS complex that falls directly on a dark line of the ECG paper. This dark line is the reference point. The next six dark lines of the paper are labeled 300, 150, 100, 75, 60, and 50 (Fig. 17-20). Then, the nurse finds the next QRS complex immediately after the reference point and estimates the ventricular rate using the sequence of numbers. The same method can be used for estimating atrial rate by using the P waves.
resulting in a lack of perfusion. Therefore, the heart rate obtained from the cardiac monitor or ECG strip should never be substituted for the determination of heart rate by palpating the pulse.
Both the atrial and the ventricular rates can be estimated by examining the ECG. To determine the ventricular rate, count the number of QRS complexes in a 6-second strip and multiply by 10. To estimate the atrial rate, count the number of P waves in a 6-second strip and multiply by 10. In the normal patient, the atrial and the ventricular rates should be the same. This method of rate calculation provides an estimate of heart rate for regular and irregular rhythms.
Another method of rate calculation can be used if the rhythm is regular. The ventricular heart rate is estimated by dividing 300 by the number of large boxes on the ECG paper between two R waves (the RR interval). The atrial rate is calculated by dividing 300 by the number of large boxes on ECG paper between two P waves (the PP interval).
Another quick method for estimating rate involves the use of a series of numbers. To use this method for estimating ventricular rate, the nurse first finds a QRS complex that falls directly on a dark line of the ECG paper. This dark line is the reference point. The next six dark lines of the paper are labeled 300, 150, 100, 75, 60, and 50 (Fig. 17-20). Then, the nurse finds the next QRS complex immediately after the reference point and estimates the ventricular rate using the sequence of numbers. The same method can be used for estimating atrial rate by using the P waves.
Комментариев нет:
Отправить комментарий