Prevalence
Clinical
features
Differential
Diagnosis
Investigations
Therapy
Prevention
Prognosis
|  | | | Clinical
features |
Look for evidence of hypercapnia:
c
-
this is more likely with
-
a quiet chest
-
too dyspnoeic to talk
-
cyanosis
-
requiring supplemental oxygen
and less likely with
-
on beta-agonists
-
use of accessory muscles
-
no previous visit to emergency department within 2 weeks
Why?
Clinical signs can help rule hypercapnia in or out.
| Patient |
Target Disorder and
Reference Standard |
Diagnostic Test |
LR+
(95% CI)
|
Post-test Probability |
LR-
(95% CI)
|
Post-test Probability |
admitted with acute asthma
c
(pre-test probability: 27%)
|
hypercapnia
(arterial blood gas pCO
2
> 5 kPa)
|
quiet chest
|
13
(4.6 to
37)
|
83% |
0.71
(0.59 to
0.84)
|
20% |
|
|
|
too dyspnoeic to talk
|
6.0
(3.1 to
12)
|
69% |
0.65
(0.53 to
0.80)
|
19% |
|
|
|
cyanosis
|
5.1
(2.1 to
12)
|
65% |
0.82
(0.72 to
0.94)
|
23% |
|
|
|
requiring supplemental oxygen
|
5.1
(3.0 to
9.0)
|
65% |
0.59
(0.47 to
0.75)
|
18% |
|
|
|
on beta-agonists
|
1.2
(1.1 to
1.4)
|
31% |
0.32
(0.13 to
0.77)
|
10% |
|
|
|
use of accessory muscles
|
1.2
(1.1 to
1.3)
|
30% |
0.11
(0.015 to
0.76)
|
4% |
|
|
|
no previous visit to emergency department within 2 weeks
|
1.2
(1.1 to
1.3)
|
30% |
0.40
(0.15 to
0.90)
|
12% |
|
internal medicine