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ORIGINAL ARTICLE
Year : 2017  |  Volume : 16  |  Issue : 1  |  Page : 1-5  

Impact of operator hearing threshold on manual blood pressure measurement


1 Department of Otolaryngology, Bayero University/Aminu Kano Teaching Hospital, Kano, Nigeria
2 National Ear Care Centre, Kaduna, Nigeria

Date of Web Publication14-Mar-2017

Correspondence Address:
Abubakar Danjuma Salisu
Department of Otolaryngology, Aminu Kano Teaching Hospital, Kano
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aam.aam_31_16

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   Abstract 


Introduction: Une déficience auditive non détectée chez le personnel de santé pourrait affecter leur capacité à obtenir une pression artérielle (PA) précise avec des conséquences négatives sur les soins aux patients. Le but de cet article était de déterminer l'impact de l'audition de l'opérateur sur la mesure manuelle de la pression artérielle. Méthodologie: Une étude transversale portant sur 25 patients et 60 personnel de santé composé de 25 médecins (groupe 1), 25 infirmières (groupe 2) et 10 10 personnes qualifiées sélectionnées ayant une audition normale formé (groupe 3). Personnel du groupe 3 on mesurée le PA de chaque patient, ce qui a été jugé exact. Après une formation préliminaire sur la technique de mesure de la PA, une personne Des groupes 1 et 2 ont mesuré la PA d'un patient en utilisant la technique d'auscultation manuelle et ont ensuite procédé à un dépistage du ton pur Audiométrie (PTA) avec le seuil de la meilleure oreille auditive enregistrée. Résultats: La majorité du personnel avait une audition normale (PTA ≤25 dB), 22% Avait un seuil d'audition> 25 dB au dépistage, avec une perte auditive débilitante notée chez une seule personne (2%). Il y avait un accord complet dans les mesures entre les participants ayant un seuil auditif ≤25 dB et le groupe témoin, mais chez les participants dont le seuil est> 25 dB, 100% Ont enregistré une PA diastolique inexacte et 64% ont enregistré une PA systolique inexacte avec tendance à sous-estimer la tension systolique et à surestimer la tension diastolique. Conclusion: La déficience auditive n'est pas rare chez le personnel de santé, ce qui entraîne des enregistrements inexacts de la PA. Les audiogrammes doivent être obtenu chaque fois que le personnel de santé remarque des différences fréquentes dans la mesure de la PA par rapport aux collègues. Formation sur la mesure de la PA a permis une mesure précise de la pression artérielle par tous les participants normaux de l'audition.
Résumé
Introduction: Undetected hearing impairment among health personnel could affect their ability to obtain accurate blood pressure (BP) measurements with consequent negative impact on patient care. The aim of this paper was to determine the impact of operator hearing threshold on manual BP measurement.
Methodology: A cross-sectional study involving 25 patients and 60 health personnel consisting of 25 doctors (Group 1), 25 nurses (Group 2), and 10 specially selected, normal hearing and trained control group (Group 3). Group 3 personnel measured BP of each patient and this was considered accurate. After preliminary training on BP measurement technique, one person each from Groups 1 and 2 measured BP of a patient using manual auscultation technique and then proceeded to have a screening pure tone audiogram (PTA) with threshold of the best hearing ear recorded.
Results: Majority of personnel had normal hearing (PTA ≤25 dB), 22% had hearing threshold >25 dB on screening, with debilitating hearing loss noted in one person (2%). There was a complete agreement in BP measurements between participants with hearing threshold ≤25 dB and the control group, but in participants with threshold >25 dB, 100% recorded inaccurate diastolic BP and 64% recorded inaccurate systolic BP with tendency to underestimate systolic and overestimate diastolic BP.
Conclusion: Hearing impairment is not uncommon among health personnel, resulting in inaccurate BP recordings. Audiograms should be obtained whenever health personnel notice frequent differences in measured BP compared to colleagues. Training on BP measurement technique resulted in accurate BP measurement by all normal hearing participants.

Keywords: Blood pressure measurement, health personnel, hearing


How to cite this article:
Salisu AD, Bakari A, Abdullahi H. Impact of operator hearing threshold on manual blood pressure measurement. Ann Afr Med 2017;16:1-5

How to cite this URL:
Salisu AD, Bakari A, Abdullahi H. Impact of operator hearing threshold on manual blood pressure measurement. Ann Afr Med [serial online] 2017 [cited 2017 Apr 29];16:1-5. Available from: http://www.annalsafrmed.org/text.asp?2017/16/1/1/202083




   Introduction Top


Undetected hearing impairment among health personnel could affect their ability to obtain accurate blood pressure (BP) measurements using the noninvasive manual auscultatory method with consequent negative impact on treatment outcome of patients.

This widely used BP measurement method may be affected by equipment used, knowledge of operator on BP measuring techniques, inter- and intra-observer errors.[1],[2],[3]

An important intraobserver error that may affect BP recording is the presence of hearing loss among health personnel.[4],[5]

The aim of this study was to determine the impact of operator hearing threshold on manual auscultation BP measurement.


   Methodology Top


This was a cross-sectional study involving 60 health personnel and 25 patients from 3 health institutions over a 6-week period. The health personnel consisted of 25 doctors (Group 1) and 25 nurses (Group 2) and 10 specially selected and trained “controls,” 5 male doctors, 5 female nurses (Group 3). Health personnel with previously diagnosed ear disease or previously obtained pure tone audiograms (PTA) were excluded from the study. Any patient unwell at the time of the study was excluded. None of the patients had been previously diagnosed hypertensive. All participants in Groups 1 and 2 and the patients were randomly selected. Group 3 participants were specially selected after an initial pilot study to act as controls for accurate BP measurement. Consent was sought from each participant/patient, and institutional review board approved the study.

All participants in the control group had normal hearing threshold, had adequate training on BP measurement technique, and accurately diagnosed BP on all tutorial video modules of British Hypertension Society.[6] BP measurement average by any two members of the control group in the study was regarded as accurate.

All participating doctors and nurses had questionnaire administered, then each participant was updated on techniques of BP measurement, this was followed by otoscopy and screening pure tone assessment using Welch Allyn TM 262 Auto Tympanometer/Audiometer, current calibration. Pure tone audiometry was carried out in a quiet environment (sound pressure level = 28–46 dB) with masking of nontest ear whenever appropriate.

BP measurements by participants were carried out between the hours of 09:00 a.m. and 12:00 noon daily following standard protocols for BP measurement of the British Hypertension Society.[6] Two participants of the “control” group determined the accurate BP recording of each patient. One participant from each of the two groups then took the BP of the patient twice and the average BP taken by each participant was recorded. At least 5 min elapsed between any two BP measurements.

The hearing threshold of each participant over 250–8000 Hz frequencies was determined and PTA of the best hearing ear was recorded, BP recordings obtained by the participant were recorded. In this study, any operator-participant with screening PTA threshold >25 dB in the best hearing ear was considered to have suspected hearing impairment and any BP measurement obtained, that is, beyond ±2 mmHg of the control group measurement was considered inaccurate.

Data obtained were input into MedCalc Statistical Software version 16.4.3 (MedCalc Software bvba, Ostend, Belgium; https://www.medcalc.org; 2016). Level of statistical significance was set at P < 0.05. The BP recordings between the three groups were compared and intergroup differences were sought. A correlation between the hearing threshold and BP recordings of participants was sought.

Limitations

The findings in this research may have been affected by other intraobserver errors such as momentary inattention, bias toward textbook “normal” BP, bias for even digits, and also interobserver errors such as “white coat hypertension” when BP is measured by doctors.


   Results Top


There were 60 participants, consisting of 10 personnel as control group (5 male doctors and 5 female nurses) and the test groups of 25 doctors and 25 participating nurses, all aged between 22 and 50 years with mean of 35.14 ± 7.96.

The test groups

Age range of doctors was 31–50 years with mean 39.15 ± 6.45. Age range of nurses was 22–48 years with mean 31.12 ± 7.35.

Duration of practice ranged from 3 to 25 years with mean 12.92 ± 8.52.

Twenty-nine of the participants were males, 21 were females.

Six participants (12%) had complaints of hearing impairment and/or tinnitus.

No participant admitted to having difficulty with auscultation of the Korotkoff sound. Forty-three (86%) could not confirm distinguishing all the five phases of the Korotkoff sounds.

Sixteen participants (32%) admitted their BP measurements frequently differ from others.

Pattern of hearing of participants

Six (12%) of the participants showed hearing impairment with one participant (2%) disabling as shown in [Table 1].
Table 1: Result of pure tone audiometry in best hearing ear of fifty participants

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Blood pressure measurement by participants compared with controls

Doctor participants with PTA ≤25 dB as a group (n = 20)

Mean BP measurement = 125.4 ± 20.5/84.8 ± 13.25. Corresponding controls mean BP measurement = 126.8 ± 21.52/84.7 ± 13.09. Difference of −1.4 mmHg and +0.1 mmHg for systolic and diastolic pressures, respectively, compared to controls. Three individual participants (15%) had systolic BP measurement significantly different from controls.

Nurse participants with PTA ≤25 dB as a group (n = 19)

Mean BP measurement = 126.4 ± 20.5/85.6 ± 12.2. Corresponding controls mean BP measurement = 128.0 ± 20.18/85.4 ± 12.01. Difference of −1.6 mmHg and +0.2 mmHg for systolic and diastolic pressures, respectively, compared to controls. Four participants (21%) recorded significantly different systolic BP compared to controls and one participant (5%) recorded diastolic BP significantly different from control.

Participants with PTA 25–30 dB as a group (n = 5)

Mean BP measurement = 122.4 ± 11.26/88.4 ± 5.2. Corresponding controls mean BP measurement = 124 ± 12.56/83.2 ± 5.4. Difference of −1.6 mmHg and +5.2 mmHg for systolic and diastolic pressures, respectively, compared to controls. Two participants (40%) recorded significantly different systolic BP compared with controls and all participants (100%) recorded significantly different diastolic BP compared with controls.

Participants with PTA > 30 dB as a group (n = 6)

Mean BP measurement = 117.3 ± 16.2/89.3 ± 11.29. Corresponding controls mean BP measurement = 122.6 ± 15.05/83.0 ± 11.29. Difference of −5.3 mmHg and +6.3 mmHg for systolic and diastolic pressures, respectively, compared to controls. Five participants (83%) recorded significantly different systolic pressure from corresponding controls and all participants (100%) recorded different diastolic BP compared with controls.

Agreement between blood pressure measurement by participants and controls

BP measurement by normal hearing personnel was in agreement with the controls, but differences in measurements from controls were noted, especially in diastolic readings of all hearing impaired personnel [Table 2].
Table 2: Inter-rater agreement between participants and controls

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Correlation between PTA and blood pressure

Correlation between PTA and systolic blood pressure [Figure 1]
Figure 1: Relationship between PTA and systolic blood pressure estimation

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Statistically significant correlation (r = −0.57, P < 0.0001, 95% confidence interval [CI]) was noted. As hearing threshold worsens, the tendency to underestimate systolic pressure increases.

Correlation between PTA and diastolic BP [Figure 2]
Figure 2: Relationship between PTA and diastolic blood pressure estimation

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Statistically significant correlation (r = 0.75, P < 0.0001, 95% CI) was noted. As hearing threshold worsens, the tendency to overestimate diastolic pressure increases.


   Discussion Top


In clinical practice, BP is routinely measured as part of physical examination. Indications for obtaining a BP measurement are many, but it is particularly indicated before any surgical operation and for screening and monitoring of hypertension.

Variations in BP measurement have been reported between and within observers.[7],[8],[9],[10] BP is also known to vary within same subject after such activities as exercise, intake of coffee, or other stimulants and smoking.[11],[12],[13] Variations of BP may also be related to timing within 24 h when measurements are taken, with lower BP recordings obtained at night during sleep.[14]

An important intraobserver error that may affect BP recording is the presence of hearing loss among health personnel.[4]

While 22% of the participants on hearing screening in this study were noted to have PTA >25 dB, only one person (2%), however, had disabling hearing impairment (PTA >40 dB). This suggests that hearing impairment may not be uncommon among health personnel and that 20% of staff may require further evaluation by diagnostic audiometry. These figures are likely to be lower if the personnel were to undergo diagnostic audiometry. These figures compare with 14.8% reported hearing loss prevalence among general practitioners but lower than the 30% hearing loss prevalence reported among dentist associated with occupational noise exposure.[15],[16]

Majority (83%) of those with suspected hearing impairment were found to be in the age bracket 40–50 years, which is higher than the mean of 31 years (nurses) and 39 years (physicians) noted among participants. Findings from this study agree with previous studies that suggest hearing loss is associated with increasing age. Other studies have similarly reported advancing age as a factor in hearing impairment.[17],[18],[19]

Commonly, health personnel assume their hearing is adequate for their clinical duties.[4] While 12% of participants (PTA >30 dB) complained of some difficulty with hearing, 10% of participants (PTA = 26–30 dB), however, reported no such difficulties describing their hearing as satisfactory. Although these participants may prove to have normal hearing on diagnostic audiometry, it is, however, noteworthy that Rabinowitz et al. reported that 46% of physicians with hearing loss actually described their hearing as good.[4] This lack of awareness of hearing impairment may have implications on clinical practice.

Definite perception of the five distinct phases of Korotkoff sound does not appear to be a universal experience among health personnel, but the inability to recognize all the five phases of Korotkoff sound does not appear to be a major factor in determining accuracy of BP reading as most operators appeared to focus on the “beginning” and “end” of the Korotkoff sounds to determine systolic and diastolic BP. In this study, though no participant admitted to having any difficulty with perception of the Korotkoff sound, majority (86%) however admitted they could not distinctly make out all the five phases of the Korotkoff sound. Although clear perception of all the phases of Korotkoff sound may improve with training, studies have, however, shown that Phases II and III sounds may be entirely absent in some cases.[20]

Adequate training on BP measurements resulted in overall accurate BP measurement by the normal hearing participants as a group in this study. This was also the experience of other researchers.[21],[22] Many studies have blamed lack of training and failure to adhere to standard BP measurement technique as being responsible for inaccurate BP reading.[23],[24],[25] In this study, however, all participants were exposed to adequate training on BP measurement, and Kappa statistics showed inter-rater agreement between participants and control to be almost perfect despite differences in background professional training (physicians versus nurses), age, gender, or years of experience. Agreement in BP measurements obtained between doctors and nurses was also very good. Other studies, however, noted BP measurement variations between doctors and nurses with doctors recording slightly higher systolic BP which has been tagged as “white coat hypertension.”[8],[9],[10]

In normal hearing participants, inaccurate BP recording was more frequently seen with systolic BP recording. This was noted in 18% of participants compared with 2.5% of participants which recorded inaccurate diastolic BP. The variations in BP measurement noted in normally hearing individuals in this study cut across professional calling. It was believed to result from factors other than training and these factors may have included momentary inattention, “white-coat hypertension,” end-digit preference among other inter- and intra-observer errors.[8],[26]

In contrast to normal hearing participants, participants with suspected hearing impairment generally recorded inaccurate systolic pressure (64%) and inaccurate diastolic BP (100%) when compared with controls. Kappa statistic showed agreement was weak between diastolic BP recorded by participants and that recorded by controls for all persons with PTA >25 dB. Agreement was only fairly good in systolic BP recordings for those with hearing threshold between 25 and 30 dB; however, agreement in both systolic and diastolic BP measurements became poor when hearing threshold of participant was beyond 30 dB. There was a statistically significant tendency to underestimate systolic BP and overestimate diastolic BP by health personnel with hearing threshold >30 dB. This has similarly been reported by other researchers.[5]

It appeared that diastolic BP measurement was more frequently affected when hearing impairment was present with as little as 5 dB loss resulting in inaccuracy in diastolic reading. All participants with suspected hearing impairment (100%) recorded diastolic BP inaccurately; the same participants fared better with systolic BP recording, with 83% recording systolic BP inaccurately. A multiplicity of factors may be responsible for this. Vision clearly plays a role in BP measurement.[27] During BP measurement, in addition to auscultation for Korotkoff sound, the operator visualizes the movement of mercury column after cuff deflation with almost certain visual identification of the systolic BP reading, the role of vision however in ascertaining diastolic BP may be less pronounced, forcing the operator to rely more heavily on auditory acuity. Second, the concept of sound frequency selectivity and discrimination, which refers to the ability of the hearer to reliably perceive that two sounds which differ in frequency are indeed different, may also play a role.[28],[29] A hearing-impaired individual with sound frequency discrimination challenges may have difficulties in determining transition of one phase of Korotkoff sound to another. A third factor may be the presence of background noise, which for practical purposes cannot be eliminated during BP measurement procedures, this may also be a factor in inaccurate BP measurement by hearing-impaired individuals. Background noise generally affects hearing of the hearing-impaired individual.[30]

Interestingly, all personnel with suspected hearing impairment in this study admitted that their BP measurements commonly differed from readings obtained by their colleagues. This was statistically significant when compared with normal hearing individuals with similar complaints. This appears to be a sensitive pointer to hearing impairment among health personnel. Admittedly, differences in BP measurements by two operators may be due to a variety of inter- and intra-observer errors, nevertheless frequent differences in recorded BP among colleagues should raise a suspicion of hearing impairment and audiograms of affected individuals should be obtained. On the other hand, self-reporting of hearing loss was not found to be a very sensitive pointer to hearing loss among health personnel as only about half of those suspected to have hearing loss actually complained of hearing difficulties; however, whenever hearing difficulty was reported by the individual, it was found to be consistent with audiometric hearing loss as similarly reported by Rabinowitz et al.[4]


   Conclusion Top


Hearing impairment is not uncommon among health personnel, the presence of which results in underestimation of systolic BP and overestimation of diastolic BP during BP measurement. Any health personnel reporting frequent differences in BP recordings when compared to BP recordings by other colleagues should have hearing assessment.

Training of personnel on BP measurement improves accuracy of measurement by all normal hearing personnel.

Regular auditory screening of health personnel involved in BP measurement is advised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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    Figures

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    Tables

  [Table 1], [Table 2]



 

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