Journal of Medicine and Medical Science Vol. 3(4) pp. 232-236, April 2012
Available online http://www.interesjournals.org/JMMS
Copyright © 2012 International Research Journals
Full Length Research Paper
Use of peak expiratory flow measurement for the
assessment of asthma in adults in the emergency
department
Rhys H. Clark1,2, Zoe V. Wake1,3, Hannah Forward1,2
1
Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Western Australia, 6009.
University of Notre Dame Australia, 13-19 Mouat St, Fremantle, Western Australia, 6160.
3
Princess Margaret Hospital, Roberts Rd, Subiaco, Western Australia, 6008.
2
Abstract
Asthma is a major cause of morbidity and mortality in emergency departments worldwide. New
guidelines recommend the measurement of Peak Expiratory Flow or Spirometry to assess
severity and monitor response to treatment. This is a retrospective review of asthma
presentations to an emergency department. The objective of this study is to determine the
proportion of adult patients (aged over 16 years) with mild to moderate asthma who have an
evaluation of Peak Expiratory flow measured and documented at their initial assessment in the
emergency department. 63 patients were included in this study with a median age of 50 years.
Peak expiratory flow was documented for 68.3% (43) of the 63 patients during their initial
assessment, and 86.0% (37) of these 43 patients had a follow-up PEF measurement subsequent
to the commencement of treatment. There was no difference in the proportion of patients who
had PEF documented when compared by severity of asthma. Emergency Departments should
take measures to increase access to spirometry and peak flow meters for clinicians and nursing
staff to more accurately assess patients and monitor response to treatment.
Keywords: Asthma, Asthma Severity, Peak Expiratory Flow, Spirometry, Emergency department triage.
INTRODUCTION
Asthma is a major cause of morbidity and mortality in
Australia, affecting approximately 2 million people
(Australian Centre for Asthma Monitoring [ACAM],
2007).
Acute asthma exacerbations account for
105,000 emergency department(ED) visits, 40,000
hospital admissions, and over 300 deaths every year in
Australia (Australian Centre for Asthma Monitoring
[ACAM], 2005). Unfortunately, despite national
initiatives to improve asthma care and more effective
medications, the mortality rate from asthma is on the
rise and a recent national health survey showed that the
management of asthma remains suboptimal (ACAM,
2007).
The Peak Expiratory Flow (PEF) rate provides a
simple, quantitative, and reproducible measure of the
*Corresponding Author E-mail: rhc306@me.com
degree of airflow limitation that is used with the patients
clinical
symptoms
to
risk
stratify
asthmatic
presentations. Several studies (Beasley et al., 1989;
Ignacio-Garciaand Gonzalez Santos, 1995) have found
that PEF monitoring used as a component of asthma
management optimises patient outcomes. The National
Asthma Council has published guidelines that
recommend PEF for determining severity and guiding
treatment decisions in the ED (National Asthma Council
[NAC], 2006).
There are no studies published that investigate the
outcomes of performing lung function tests in patients
with asthma in the emergency setting. However, a study
of emergency physicians’ ability to use clinical signs to
risk stratify asthmatics demonstrated that they
frequently underestimated the degree of airway
obstruction and that subsequent knowledge of lung
function results altered management in 20.4% of
patients (Emermanand and Cydulka, 1995). Objective
measurements of lung function are useful as there are
Clark et al. 233
Figure 1. Summary of national asthma council steps in management of acute asthma
Table 1. Initial assessment of acute asthma in adults, National Asthma Council Australia [NAC] (2006) Asthma
Management Handbook 2006, Melbourne, p39
Findings
Physical
exhaustion
Moderate
No
Talks in
Pulse rate
Pulsus paradoxus
Central cyanosis
Wheeze intensity
PEF
Sentences
< 100/min
Not palpable
Absent
Variable
More than 75% predicted (or
best if known)
Phrases
100-120/min
May be palpable
May be present
Moderate to loud
50-75% predicted
(or best if known)
FEV1
More
predicted
-
50-75% predicted
Oximetry
on
presentation
Arterial
blood
gases (assay)
Other
investigations
#
Mild
No
than
75%
Not necessary
Not required
Necessary if initial
response poor
May be required
Severe and life-threatening*
Yes
Paradoxical chest wall movement
may be present
Words
More than 120/min†
Palpable‡
Likely to be present
Often quiet
Less than 50% predicted (or best
if known) or less than 100 L per
min#
Less than 50% predicted or less
than 1 L
Less than 90% Cyanosis may be
present**
Necessary††
Check for hypokalaemia Chest Xray to exclude other pathology
(e.g. infection, pneumothorax)
Patient may be incapable of performing test.
often large disparities between symptoms and degree
of obstruction. This is particularly useful in patients who
are poor perceivers of their symptoms (NAC, 2006).
Once patients present to an ED with acute asthma,
the management algorithm relies solely on assessment
of the severity of their asthma as mild, moderate or
severe. These steps recommended by the NAC are
summarised here in Figure 1. Assessment is based on
clinical signs as well as Spirometry or PEF. Although
spirometry is the lung function test of choice for
assessing asthma severity it is more time consuming
and is not always available in the emergency
department. PEF meters are small, portable and more
widely used in initial asthma assessment.
This study was designed to audit the compliance with
national guidelines that recommend the documentation
of PEF to risk stratify patients. The objective is to
determine the proportion of adult patients (aged over 16
years) with mild to moderate asthma who have an
evaluation of Peak Expiratory flow measured and
documented at their initial assessment in the
emergency department. This was completed with the
aim of expanding the use of PEF as a tool to assess
severity and improve patient outcomes in the treatment
of asthma.
MATERIALS AND METHODS
The current Australia standard of care is the National
Asthma Council – Asthma Management Handbook
which has been endorsed by The Thoracic Society of
Australia and New Zealand, the Australasian College
for Emergency Medicine and the Royal Australian
College of General Practitioners (NAC, 2006). The
guidelines require health professionals to perform
spirometry and/or PEF measurement to gain an
objective measure of airflow limitation (NAC, 2006). All
patients with clinically diagnosed mild or moderate
asthma should have a documented PEF level in their
medical record within the time of their initial assessment
in ED. National Health and Medical Research Council
(NHMRC) level of evidence for this standard is
recommenced best practice based on clinical
experience and expert opinion.
234 J. Med. Med. Sci.
Figure 2. Severity of asthma presentation by age of participants
Study participants
Adult patients, aged over 16 years, who presented to
the emergency department of an outer metropolitan
hospital from 1 January 2008 – 30 April 2008 with the
diagnosis of mild to moderate asthma were included in
this study. Patients with severe asthmas were excluded
as they may not be able to perform PEF if lung function
was severely restricted.
the initial clinical assessment of the severity of asthma
as mild, moderate or severe. The notes were also
searched for documentation of findings that confirmed
this level of severity such as pulse rate, physical
exhaustion, cyanosis and wheeze. The findings
required to classify the severity of the presentation by
the NAC are included in full in Table 2. The level
documented (mild/mod/severe) was checked for
consistency with the findings recorded. Where no level
of severity was documented, the investigators used the
clinical findings to classify the presentation.
Data collection
Data was collected using the database Emergency
Department Information Systems (EDIS, version 10.0)
by searching for patients entered with a principal
diagnosis of asthma (ICD-10 code J46) for the period
01/01/2008 to 20/04/2008. Medical records were
searched by the investigators and data was entered in
to a Microsoft Office Excel 2007 spreadsheet for
storage and collation. Investigators cross-checked 20%
of medical records to ensure data was entered
correctly.
The data collected included demographic details of
patient age at presentation and gender and clinical
details of assessment of severity as mild, moderate,
severe, and whether or not PEF was documented pre
and/or post-treatment and the percentage of the
predicted or best PEF if documented. This data was
collected as it allowed the investigators to not only audit
the proportion of patients who had their PEF
documented in total but to also look for some possible
correlation between the asthma severity (mild or
moderate) and the proportion of patients with PEF
documented.
The emergency department notes written by the
assessing clinician were searched for documentation of
RESULTS
A total of 63 of the 70 patients initially identified met the
selection criteria for inclusion. Patients were excluded if
they were assessed has having severe asthma or had
inadequate documentation to determine severity. Ages
ranged from 18 to 67 years old with a median age of 50
years. Of the 63 patients, 42.9% (27) were male and
57.1% (36) were female. The clinical assessment of
asthma severity by the attending ED doctor was mild in
65.1% (41) of cases and moderate in 34.9% (22)
cases. Figure 2 represents the severity of asthma
presentations by age group.
Peak expiratory flow was documented for 68.3% (43)
of the 63 patients during their initial assessment, and
86.0% (37) of these 43 patients had a follow-up PEF
measurement subsequent to the commencement of
treatment.
Figure 3 represents the number of patients who had
PEF documented by asthma severity group
Of the patients who had an initial PEF documented,
90% (39) of patients had a response to treatment PEF
documented. The values of PEF documented ranged
from 130-530L/min and did not appear to have any
Clark et al. 235
Figure 3. Percentage of patients with mild and moderate asthma who
had initial Peak Expiratory Flow (PEF) documented in the Emergency
Department
correlation with clinical assessment of asthma severity.
DISCUSSION
The key finding of this audit is that 68.3% of patients
had PEF documented during their initial assessment
and 86.0% of these patients had a post-treatment PEF
documented. There were very similar percentages
across the different severity groups indicating that
asthma severity did not change documentation of PEF.
Reasons hypothesised that PEF was not documented
in 31.7% of cases included uncertainty about whose
role it was in the ED, lack of access to the PEF meter,
uncertainty about the new guidelines. Doctors within the
department also expressed doubt about the validity of
PEF and therefore routinely did not use it as a
measurement when spirometry was not available.
The measurement of PEF has significant limitations in
that it is dependent on patient effort and technique and
it not ideal as a one off reading but as a series of
readings (NAC, 2006; Miller et al., 1992; Sawyer et al.,
1998). As this is a retrospective review of medical
records, this study relies heavily on medical
documentation which is often inadequate and may have
resulted in patients who refused PEF not being
recorded appropriately. Finally, several of the ED
presentations coded as asthma may not have been
attributable to acute attacks of asthma. Several papers
discuss the use of the ED for routine primary care by
asthmatics (Ford et al., 2001; Hanania et al., 1997). In
these patients, documentation of PEF is not appropriate
as they may not be experiencing acute asthma but
requiring refills of prescription or medical certificates
and this may underestimate the actual proportion who
were managed according to the guidelines.
To increase measurement of PEF in the emergency
department education sessions were held with medical
and nursing staff and training was provided with the
PEF equipment.
Posters were displayed in the
assessment and triage area for early measurement of
PEF and equipment was stored in a more accessible
location. Instructions were taped to PEF storage
containers for ease of use.
The broader context of this study is that this data is
relevant to other emergency where the measurement of
PEF in asthma is inconsistent with the relatively new
clinical guidelines. There have been no other clinical
audits published on the use of PEF in the ED
internationally however both the United Kingdom and
United States have recently published new acute
asthma management guidelines that make the same
recommendation for early PEF measurement (British
Thoracic Society, 2008; US National institute of Health,
2007). Therefore the results of this study may be useful
for health professionals internationally to appreciate that
there has not been 100% realization of asthma the
guidelines.
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