R1iv / 15B02: Describe the consequences of mild hypothermia in the early post
15B02: Exam Report
Describe the consequences of mild hypothermia in the early post-operative setting.
35% of candidates passed this question.
A well organised answer would provide details on domains of physiology, pharmacology and “other”, such as patient centred effects. Few answers mentioned pharmacology. Providing a definition of “mild” was often overlooked but doing so assisted a focused answer. Many answers spread beyond “mild” hypothermia or address the “causes” rather than the consequence – neither of which gained marks as they were not answering the question asked.
R1iv / 15B02: Describe the consequences of mild hypothermia in the early post-operative setting
Defintion: Mild Hypothermia = core body temp 32-25 C
Physiological
Pharmacological
NEURO
- ↑CBF & CMRO2 7% per 1°C
- Cerebral depression
- ↓MAC
A
- ↓absorption due to reduced gut motility
CVS
- SNS stimulation ↑circulating catecholamines = ↑afterL
- ↑HR
- ↑↓CO & MAP
- ↑workload can cause myocardial ischaemia
- ECG: prolonged PR, 1HB, J waves
D
- propofol has prolonged effect due to ↓intercompartmental clearance
RESP
- Increased MV
- Cold induced brochorrhoea
- Abnormal ciliary function
- Depressed cough reflex
M
- ↓hepatic drug clearance
- Impaired Hoffman degradation
GI
- ↓GI motility = Ileus
E
- ↓renal blood flow = ↓ drug elimination
RENAL
- Cold diuresis; peripheral VC → central hypervolaemia → ↓ADH secretion → diuresis
PD
- ↓drug-receptor interactions
- NMBD = ↓onset/offset
- Slow to wake
HAEM
- L) shift ODC → ↓O2 delivery
- ↓WCC, platelets 2 sequestration in spleen
- ↑bloods viscocity
- Coagulopathy at 34°C
METABOLIC
- ↓BMR 6% for ↓1°C
- ↓O2 consumption
- ↑BSL 2 insulin secretion
MSK
- Shivering
- ↑O2 consumption
IMMUNO
- Immune suppression
- ↓O2 delivery to tissues
- ↑wound infection and delayed wound healing
ACID/BASE
- ↑pH
- ↑gas solubility
- Author: Krisoula Zahariou