R1iv: Outline the physiological consequences of therapeutic hypothermia at 32C
Moderate Hypothermia = 30-32C
Severe Hypothermia = < 30C
Physiological
Pharmacological
NEURO
↓CBF & CMRO2 7% per 1°C
Cerebral depression → LOC
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
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