Delirium

You are a young doctor working the night shift at the surgical ICU. A nurse calls you to a confused patient who is third day after hip replacement (male, age 70, 177 cm, 95 kg). He is not oriented to place, time, or situation. He talks to you as if you were his nephew, his answers don't make any sense. Recently he has been complaining about postoperative pain. What could the differential diagnosis be?
(Also consider monitor, examination and lab tests.)
70
years
177
cm
95
kg
man
RR
20 /min
HR
95 /min
SpO2
99 %
BP
121/88 (99) mmHg
temperature
37 °C
EKG
rythm: sinus
action: regular
frequency: 95 bpm
ST bez denivelace
Examination
CRP: day before was 150 mg/L
Glycaemia
Gly
4,7  mmol/L
Complete blood count
HGB
150  g/L
HTC
0,4
ERC
4,7  x1012/L
LEU
9,5  x109/L
PLT
400  x109/L
Biochemical analysis
Na
144  mmol/L
K
4,8  mmol/L
Cl
102  mmol/L
Inflammatory markers
CRP
85 mg/L
Glycaemia
Take a sample
Complete blood count
Take a sample
Biochemical analysis
Take a sample
Inflammatory markers
Take a sample