Heart Rate Variability and Asthma Control Test
Heart Rate Variability and Asthma Control Test
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Date
2015-04-12
Authors
Faisal, Mohamed
Journal Title
Journal ISSN
Volume Title
Publisher
UOFK
Abstract
Background
HRV is widely accepted to have prognostic significance in patients with
cardiovascular diseases especially after acute myocardial infarction. However,
recently, interest has grown in relating some pathologies with abnormal autonomic
activity based on HRV studies. Although asthmatics are known to have enhanced
cholinergic activity, little HRV studies were done on asthma patients. Moreover, the
results of these studies are not reproducible, probably due to inter-individual
differences of autonomic balance in test group or inadequately designed methods.
Objectives
1. To develop an effective spirometric score that can faithfully reflect ventilatory
functions of the lungs and efficiently discriminating asthmatics from nonasthmatics
2. To detect reliability and validity of Asthma Control Test (ACT) and National
Asthma Education and Prevention Program (NAEPP) in the classification of
studied asthmatic patients based on above-mentioned spirometric score.
3. To correlate asthma control (using ACT and NAEPP) and ventilatory function
with parameters of autonomic balance.
4. To detect the pattern of autonomic balance in asthmatics using a parameter known
to be influenced by sympathetic and parasympathetic e.g. airways narrowing
indicated by spirometry, blood pressure and blood glucose concentration.
Methods
The study involved 56 apparently healthy subjects and gender and an age matched
group of 100 asthma patients classified into subgroups according to asthma severity
using ACT and NAEPP classifications. Blood pressure, anthropometric, spirometric,
HRV measurements together with drug therapy, blood level of glucose, hemoglobin
and electrolytes were assessed for every subject. All spirometric measurements were
condensed into one representative score (discrimination analysis score (DAS)) using
discrimination analysis. Sensitivity and specifity of DAS were tested using
conditional ratios and Receiver Operating Characteristic (ROC) curve. Screening of
studied variables for significant correlations and mean differences among different
groups with adjustment for possible confounding factors was performed using
appropriate statistical techniques.
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Results
Spirometry: Correlations between all spirometric measurements and DAS were
highly significant (P = 0.000 for all correlations). DAS when compared with FEV1%
(at the most accurate cutoff equal to 80%) as a predictive measurement for presence
of asthma, is proved to be more sensitive (81.00% for DAS and 71.00% for FEV1%),
specific (94.14% for DAS and 92.86% for FEV1%) and accurate (86.54% for DAS
and 78.85% for FEV1%). For further verification, accuracy of DAS was compared
with the remaining of spirometric measurements using ROC curves. DAS is proved to
be the most sensitive measure in diagnosing asthma (area under the curve = 0.933, P =
2.77E-19 and 95% confidence interval 0.897 - 0.971).
Of asymptomatic asthma patients, 34.0 % were labeled poorly controlled and 41.5%
were labeled uncontrolled. ACT score was higher while NAEPP class was lower in
symptoms free compared with symptomatic asthmatic patients (P = 0.000 and 0.005
respectively). DAS correlate significantly, but moderately, with ACT score and
NAEPP class (P = 0.000 for both, CC = 0.38 and -0.49 respectively).
Heart Rate Variability: Sympathetic tone (LF Norm) of mild asthmatics was
significantly lower while parasympathetic tone (HF Norm) was significantly higher
compared with apparently healthy subjects (P = 0.016 and 0.017 respectively). This
was also true when mild asthmatics are compared with severe asthma patients (P =
0.020 and 0.015 respectively). ACT state of asthmatics correlate significantly, but
weakly, with LF Norm (CC = 0.292, P = 0.003) and HF Norm (CC = 0.309, P =
0.002).
Blood Pressure and Blood Glucose Concentration: In contrast to systolic and mean
arterial blood pressures, diastolic blood pressure was significantly higher in
asthmatics compared with non-asthmatics (P = 0.002). Blood pressures correlate
positively with sympathetic and negatively with parasympathetic activity in nonasthmatics
(P < 0.05 for all). However, these correlations are lost in asthmatics.
Blood glucose concentrations in asthmatic patients were significantly higher as
compared with healthy subjects (P = 0.000). Blood glucose concentrations correlate
positively with parasympathetic and negatively with sympathetic in non-asthmatics (P
< 0.05 for all). Nevertheless, these correlations are lost in asthmatic patients.
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Conclusions
1. DAS is more sensitive, specific and accurate compared with other spirometric
measurements, but like other indicators it fails to reach 100% sensitivity and
specifity on asthma diagnosis.
2. Presence or absence of symptoms did not correlate with asthma control which
draws attention to asthma classification criteria.
3. The autonomic balance of mild asthma (showing high parasympathetic and low
sympathetic activities) is different compared to the severe form of the disease
(which showed normal parasympathetic and sympathetic activities).
4. Autonomic balance might influence symptomatology but not ventilatory function
5. Many signs of functional impairment (control of blood pressure and blood glucose
concentrations) of the autonomic nervous system are noted in asthmatic patients.
Description
Keywords
Heart, Rate, Variability, Asthma, Control, Test