Our study found a significant correlation between reduced pulmonary function and IP in subjects aged ≥ 65 using nationally representative data in Korea, this finding highlights the importance of careful assessment for IP, especially in subjects with reduced pulmonary function. Pulse palpation and then optional ECG for those with an IP could help identify the associated arrhythmia, especially AF, which is the most beneficial diagnosis for the early prevention of stroke in asymptomatic and undiagnosed elderly subjects.
COPD is usually diagnosed using PFT; FEV1/FVC < 70% confirms the presence of persistent airflow limitation and thus of COPD . The worldwide prevalence of COPD is estimated to be 3–11% . However, the prevalence of self-reported COPD in the present study was just 1–2%. Therefore, the prevalence as assessed by PFT was higher than that determined from the patient responses on the questionnaires. This suggests that many subjects in this study had undiagnosed COPD. Yoo et al. showed a similar trend, reporting that, despite the high prevalence of COPD in Korea, the disease is actually underdiagnosed, and most COPD patients are under-treated .
Reduced FEV1 and obstructive pulmonary disease are associated with the incidence of AF. The Atherosclerosis Risk in Communities (ARIC) study reported that impaired pulmonary function was correlated with higher AF incidence , while the Malmö Preventive Project found that impaired pulmonary function was an independent predictor of AF . Therefore, further evaluation of systematic AF screening is encouraged in at-risk populations . Because the diagnosis of AF requires rhythm documentation using an ECG, we suggest that measuring pulse palpation-guided ECG diagnostic testing may help to detect AF in this at-risk group. Pulse palpation is currently the evidence-based method of choice for screening for arrhythmia among individuals aged ≥ 65 . Kallmuzer et al. reported that pulse palpation at the radial artery is a simple, noninvasive, first-step screening tool to guide ECG diagnostics for cardiac arrhythmias like AF; moreover, its diagnostic accuracy is appropriate compared with continuous ECG . Therefore, pulse palpation is a powerful tool for identifying subjects who require confirmatory ECG to diagnose AF. Undiagnosed AF is common, and opportunistic screening for silent AF is likely to be cost-effective in the elderly [9, 25]. Screening of older populations yielded a prevalence of 2.3% for chronic forms of AF . In the present study, the prevalence of IP was only 2.6%. This finding is consistent with the low or underestimated prevalence of AF in the general population in Korea. In a healthy, asymptomatic rural Korean population, the prevalence of ECG-diagnosed AF was only 2.3% among 60- and 70-year-olds . Because subjects with paroxysmal AF may be classified as having an RP, pulse palpation may only be able to screen those with persistent or permanent AF.
Inpatient measurement of vital signs, such as pulse palpation, is usually performed by nurses. It is important that all nurses in primary or secondary care are aware of the significance of IP to detect new AF or prevent stroke in an early and timely manner. In particular, nurses working in pulmonology or cardiology departments should be well trained and cautioned not to miss IPs in patients with reduced pulmonary function and suspected AF. The present study showed that the lowest quartile of FVC or FEV1, predicted FVC < 80%, and a restrictive or obstructive pattern based upon spirometry interpretation were significant risk factors of IP. Therefore, clinical nurses should pay particular attention to patients with a more severely decreased FVC or FEV1 level or those already diagnosed with COPD or restrictive lung disease. In contrast to inpatients, who are carefully monitored by nurses, elderly community dwellers do not commonly have the opportunity for someone to check their pulse on a daily or even weekly basis. To confirm AF, outpatients should undergo further examination, such as ECG, in addition to pulse palpation. Fortunately, some authors have reported that a smartphone can be used to check for an IP at home without visiting a hospital [28–29]. This is particularly promising for elderly subjects because information technology applications will enable them to self-monitor for an IP at home without the aid of medical staff. Elderly people who are not accustomed to new technology, such as smartphones, could be assisted by family members. The appropriate application of such technology will enhance the timely detection of AF, even in elderly community members who are not hospitalized, especially those with reduced pulmonary function.
In this study, there were no statistically significant differences in the risk of IP when patients with restrictive or obstructive spirometry patterns were analyzed separately. However, when the restrictive and obstructive patterns were combined, abnormal spirometry was a significant risk factor for IP compared with a normal spirometry pattern. This finding may indicate the presence of overlap between restrictive and obstructive spirometry patterns on spirometry; 157 (36.5%) of 474 participants with FVCp < 80% were classified as having an obstructive pattern.
This study has a few limitations. We used a cross-sectional survey design, so our results may have been influenced by selection bias because we excluded ineligible subjects who lacked complete data. There were no available ECG data to verify specific arrhythmia diagnoses. Elderly subjects are susceptible to a wide range of different cardiac arrhythmias, many of which may be associated with radial pulse irregularities. In addition, there are no data about the period of discontinuation of smoking in ex-smokers or the exact prevalence of cardiomyopathy or thyroid disease, which might influence pulmonary function or the prevalence of arrhythmia, respectively. Lastly, COPD may be misdiagnosed using FEV1/FVC < 0.7 among subjects aged ≥ 65. However, a major strength of this study was that no previous study has described the association between pulmonary function and pulse palpation in the general population. Further studies with confirmatory ECG are needed.