POSSUM in colorectal surgery
description
Transcript of POSSUM in colorectal surgery
POSSUMin
colorectal surgery
Dermot Burke
The General Infirmary at Leeds
APACHE
APACHE (1981) 34 physiological variables
APACHE II (1985) 12 physiological variables age and chronic health history.
APACHE III (2001) 17 physiologic variablesage and chronic health historyprior diagnosis
APACHE IITemperature - core
Mean arterial pressure
Heart rate
Respiratory rate
Oxygenation
FIO2
Arterial pH
Serum sodium
Serum potassium
Serum creatinine
Haematocrit
White blood cell count
APACHE II
Developed for use in intensive care setting
Takes no account of surgical insult
Jones HJ et al Value of a surgical high-dependency unit. Br J Surg. 1999 Dec; 86: 1578-1582
“The POSSUM score is the most appropriate of
the currently available scores for general
surgical practice……
in the estimation of risk of dying.”
What is POSSUM?
Physiological and Operative Severity
Score for the enUmeration of
Morbidity and Mortality
What is POSSUM?
A method of operative risk prediction
that allows for case-mix
What is POSSUM?
18 variables
12 physiological 6 operative
Physiological Operative
Age OperationCardiac status Number of proceduresECG Blood lossRespiratory status Peritoneal contaminationBP Extent of malignancyPulse Elective / emergency GCS HbWCCUreaSodiumPotassium
POSSUM mathsEach variable divided into 1, 2, 3, or 4 levels
weighting of 1, 2, 4 or 8 applied to that level
Amount (ml)
<100
101- 500
501 – 1000
>1000
Weighting
1
2
4
8
Level
1
2
3
4
e.g. blood loss
Physiology weighting numbers added togetherto give a physiology score
Operative weighting numbers added togetherto give an operative severity score
Scores put into equations
POSSUM maths
Original POSSUM equations
MorbidityIn [R/(1-R)] = -5.91 + (0.16*phys score) + ( 0.19*op sev score)
MortalityIn [R/(1-R)] = -7.04 + (0.13*phys score) + ( 0.16*op sev score)
Minimum risk of mortality = 0.40%
P-POSSUM
Minimum risk of mortality = 0.22%
In [R/(1-R)] = -9.06 + (0.169*phys score) + (0.155*op sev score)
Differences between Possum and P-Possum
The main difference is in the statistical method of analysis
Difference in minimum risk of morbidity
POSSUMs around the bodyLung surgery Brunelli et al Ann Thorac Surg. 1999; 67 :329-331
Bariatric surgery Cagigas et al Obes Surg. 1999; 9: 279-281
Ruptured AAA Lazarides et al Ann Vasc Surg. 1997; 11: 155-158
General vascular Midwinter et al Br J Surg. 1999; 86: 471-474
D2 gastrectomy Parikh et al Br J Surg. 1996; 83: 1595-1599
Colorectal Sagar et al Br J Surg. 1994 ; 81: 1492-1494
POSSUMsin Colorectal Surgery
Tekkis et al (GI) Dis Col Rect 2000, 43: 1528-1532
Tekkis et al Br J Surg 2003, 90: 340-345
Overpredicts young, fit, elective
Underpredicts elderly, emergency
CR-POSSUM
AgeCardiac statusBPPulseHbUrea
OperationPeritoneal contaminationExtent of malignancyEmergency / Elective
Physiological Operative
Minimum risk of mortality = 0.27%
Practicalities
Calculating POSSUMCalculate P-POSSUM and CR-POSSUM directly at http://www.riskprediction.org.uk
Downloading POSSUMDownload ACCESS 97 database from www.edu.rcsed.ac.uk/lectures/lt1.htm
Practicalities
Practicalities
Download POSSUM for use on Palm PDA and Pocket PC at www.gaspalm.co.uk/
How the NHS has used last year's performance indicators
Outcomes of Surgery********** City Hospital was prompted by last year's clinical indicator on 'deaths following surgery' to investigate this issue and develop initiatives to ensure risks of death following surgery are as low as possible.A key development in Nottingham City Hospital's general surgery directorate has been the introduction of a robust risk assessment system called POSSUM (Physiological and Operative Severity Score for enumeration for Mortality and Morbidity). This is designed to quantify each patient's vulnerability by taking into account factors of their condition and the procedure they are to undergo.This accurate assessment allows doctors and nurses to design care packages which best meet their individual needs - patients with high POSSUM scores are targeted for higher levels of support and patients with medium scores are monitored more closely to ensure they do not deteriorate.The plan is to 'roll out' the system to other surgical directorates and POSSUM is clearly expected to improve the outcomes for more and more patients following surgery at *********City Hospital.
How the NHS has used last year's performance indicators
clearly expectedto improve the outcomesfor more and more patientsPOSSUM
Government unveils hospital league tables
David BattyTuesday September 25, 2001 The Guardian
Man UtdNewcastleMan CityLiverpoolChelseaEvertonArsenalLeeds UtdAston VillaTottenhamSouth’tonLeicester Mid’broughBirm’hamWolvesBoltonBlackburnCharltonPortsmouthFulham
Leeds Utd
Man Utd
Bolton
Everton
LiverpoolMan City
P W D L F A W D L F A GD PTS Arsenal 28 11 2 0 26 9 10 5 0 29 9 37 70 Chelsea 28 8 2 3 22 10 11 2 2 28 11 29 61 Man Utd 28 9 3 2 30 13 9 1 4 22 16 23 58 Charlton 28 6 3 5 22 22 6 4 4 17 12 5 43 Newcastle 28 8 3 3 23 9 2 9 3 15 20 9 42 Birm’ham 28 7 4 4 19 16 4 5 4 11 14 0 42 Aston Villa 28 7 4 2 19 12 4 3 8 17 20 4 40 Liverpool 27 6 2 4 18 13 4 7 4 20 18 7 39 Fulham 28 8 3 4 24 16 3 3 7 17 22 3 39 Tottenham 28 8 2 5 29 23 3 2 8 11 20 -3 37 South’ton 28 7 4 4 18 11 2 5 6 11 16 2 36 Mid’brough 28 4 4 6 12 16 5 3 6 17 19 -6 34 Bolton 28 3 7 4 15 16 5 3 6 17 28 -12 34 Everton 28 7 4 4 22 15 1 4 8 12 24 –5 32 Man City 28 3 7 4 21 17 4 2 8 19 23 0 30 Blackburn 28 3 3 8 20 26 4 4 6 19 20 -7 28 Leicester 28 2 7 5 14 23 3 4 7 24 28 -13 26 Portsmouth 27 6 2 5 23 15 0 4 10 6 26 -12 24 Wolves 28 5 5 4 17 26 0 4 10 7 30 -32 24 Leeds Utd 28 3 5 6 15 22 2 2 10 11 33 -29 22