Relevance of the expression
“obs stable ” :
a retrospective study
Gregory Scott Academic clinical fellow
Roshan Vijayan Core surgical trainee
Pandora Male Medical student
Obs stable
Seriousne
ss
Quite silly
and not
important
 Christmas
BMJ
Serious
and
important
 BMJ
Importanc
Should we seriously worry
about what we write?
What’s wrong with “obs
stable”?
1.“Stable” might be interpreted
as “normal”
But
A patient with persistent
tachycardia has
“stable”
observations
2. “Obs stable” implies a lack
of rigour
What do we even mean by
“stable”?
Current obs within
“normal” range?
L
t
Variation in obs
within “normal”
limits (L) for a
given time period
(t)?
Study
• Objective: To ascertain whether use of the term
“obs stable” is so liberal as to render it
meaningless.
• Design: Retrospective study
• Setting: Three London hospitals
• Methods
– Searched notes for current admission of 46
randomly selected inpatients for “obs stable”
entries
– Reviewed the nursing observations recorded
during the 24 hours preceding each entry
– Calculated for these 24 hour periods:
• Frequency of any abnormalities
• Frequency of persistent abnormalities (occurring in
every observation)
• Range (max.-min.) of observation values if at least two
Results: “obs stable”
occurrences
– 1+ “obs stable” entry in 36 (78%)
notes
– 178 “obs stable” entries total (3.9
per patient)
– 1st “obs stable” entry on day 2
(median)
– 3.9 nursing observations charted in
Results: abnormalities in
the 24 hours preceding
“obs stable”
– 1+ abnormality in 113 (71%) of 159
cases
• Tachypnoea (55%), hypotension (21%),
tachycardia (13%), desaturation (16%)
– 1+ one persistent abnormality in
31 (19%) cases
– Abnormality occurred in the
observations immediately preceding
Definitions
an entry= SBP
in <100mmHg,
42%
Hypotension
Tachycardia = HR
>100/min
Pyrexia = temperature >38C, Tachypnoea = RR≥20/min
Oxygen desaturation = saturations <95%
Results: all “stable”
observations
Results: 24 hourly range
of “stable” observations
Discussion: findings
• Doctors regularly used the expression
“obs stable”
• “Obs stable” was often associated
with a 24 hour period which included
abnormal observations
• In two fifths of cases, an
abnormality occurred in the
observations immediately preceding an
“obs stable” entry
• The range of observations over a 24
hour period that were designated
“stable” occasionally exceeded normal
Discussion: limitations
• Small sample
• No comparison with non-“stable”
entries
• Arbitrary definition of
abnormalities
• Arbitrary choice of 24 hour period
• Difficult to define “normal”
diurnal variation
Discussion: why do we write
“obs stable”?
•
•
•
•
Lack of time given to documentation
Intended to be less committal
Observation chart design
The patient seems well
Conclusions
• The meaning of “obs stable” is
ambiguous and does not always
indicate normality.
• What could we write instead?
– Write the observations in full
– Qualify “obs stable” by adding
“for the last X hours” or
– “Last abnormal observation was X
[observation] at Y [time]”
• Perhaps obs stable has become
ubiquitous precisely because it of
its ambiguity.
Thank you