There has been very little research evaluating the measurement of pulse rates. It is likely, that when heart rate is of concern, cardiac monitors are used to determine not only rate, but also rhythm. The role of the "pattern of the pulse", for example regular pulse versus irregular pulse or strong pulse versus weak pulse, have not been addressed in the context of vital signs or patient observations. On this basis, an important role of pulse rate monitoring will likely be to identify when more advanced monitoring is required.
Measurement of a person's pulse rate in the presence of atrial fibrillation was evaluated and results suggest that pulse rate, measured apically using a stethoscope for a 60 second count period, is likely to be the most accurate rate. This study noted that 86% of nurses underestimated the pulse rate, and that as the heart rate increased the magnitude of error also increased. Another study recommended a 30 second count period as the most accurate and efficient way of measuring pulse rate, noting that the 15 second count time was the least accurate. A third study found that there was no advantage in using the longer 60 seconds, over the 15 or 30 second count periods. These researchers suggest that counting an accurate pulse rate may be more difficult than commonly recognised.
A study assessing infants apical pulse rate using a stethoscope, suggested that length of time may not be the primary factor in errors, and that like respiratory rate, pulse rate also appears to be influenced by infant states in addition to illness.
While these studies have identified that the accuracy of pulse rate measurements is influenced by the number of seconds that the pulse is counted, the clinical significance of these findings is unclear. The contradictory findings of studies suggest that the count period used to determine pulse rate is of only limited significance.