POSSUM

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PHYSIOLOGICAL SCORE
Age
<60 61-70 >71  
Cardiovascular
Normal Diuretic, digoxin, antianginal antiHTN Peripheral oedema, warfarin, borderline c'myopathy raised JVP, c'megaly
Respiratory
No dyspnoea Dyspnoea on exertion, mild COPD Limiting dyspnoea (1 flight), mod COPD Dyspnoea at rest, fibrosis or consolidation
ECG
Normal AF, rate 60-90 Any other abnormal rhythm, >4/min extopics, Q waves, ST/T changes  
Systolic blood pressure
110 - 130 100 - 109
or
131 - 170
>170
or
90-99
<99
Pulse rate
50 - 80 40 - 49
or
81 - 100
101 - 120 <40 or >120
Haemoglobin
130 - 160 115 - 129
or
161 - 170
100 - 114
or
171 - 180
<100 or >180
WBC
4 - 10 10.1 - 20
or
3.1 - 4
>20 or <3  
Urea
<7.6 7.6 - 10 10.1 - 15 >15
Sodium
>135 131 - 135 126 - 130 <126
Potassium
3.5 - 5 3.2 - 3.4
or
5.1 - 5.2
2.9 - 3.1
or
5.4 - 5.9
<2.9 or gt;5.9
GCS
15 12 - 14 9 - 11 <9
OPERATIVE SCORE
Operation type
Minor operation Moderate operation Major operation Complex major operation
Number of procedures
One Two >2  
Operative blood loss (ml)
<100 101-500 501-999 >1000
Peritoneal Contamination
No soiling Minor soiling Local pus Free bowel content, pus or blood
Malignancy Status
Not malignant Primary malignancy only Malignancy + nodal mets Malignancy + distant mets
CEPOD
Elective Urgent emergency Emergency (within 2 hours)  

About Possum

  • There is some variation in constants used. I have used:
    • Possum morbidity logit R = ln[R/(1-R)]=-5.92 + (0.16 x physiological) + (0.19 x operative)
    • Possum mortality logit R = ln[R/(1-R)]=-7.04 + (0.13 x physiological) + (0.16 x operative)
    • P-Possum mortality logit R = ln[R/(1-R)]=-9.065+ (0.1692 x physiological) + (0.155 x operative)
  • POSSUM (Copeland 1991) possibly over-predicts death in especially in low-risk patients (Whiteley et al 1998).
  • P-Possum (D.Prytherch) was supposed to be better, but subsequently found to be equivalent. It still over-predicts death.