Shock
[[_oh_sections]]
"[[Overview of shock]]"
"[[Haemodynamic_monitoring]]
"[[Multi-organ dysfunction syndrome]]"
"[[Monitoring oxygenation]]"
"[[Hyperlactatemia in Critical Illness]]"
Shock - "Failure to maintain adequate oxygen supply to the tissues, with development of anaerobic cellular metabolism"
Shock / Circulatory Failure
- Cardiogenic
- Hypovolaemic
- Obstructive
- Anaphylactic
- Septic
- Neurogenic 1
Underlying Problems
You can divide these shocks into: 1
- Hypovolaemic, Cardiogenic, and Obstructive: Primary Failure of Cardiac Output, Causing a Circulation/Vasculature Failure secondarily 1
- Septic, Anaphylactic, Neurogenic: Primary Failure of Peripheral Circulation, which will cause failure of CO secondarily. 1
I think putting hypovolaemic into a cardiac output failure seems a bit tenuous
Cardiac Tamponade
In cardiac tamponade. RA and LA pressures are both increased due to external pressure. Cardiac output is reduced, as stroke volume is markedly reduced bilaterally, due to impaired filling and increased pressures to push against. Venous compliance is down, I think from a sympathetic activation sense. HR is up to attempt to cancel out the decreased cardiac output. Global O2 delivery is again markedly impaired.
Major Haemorrhage
In a haemorrhage state. Hypovolaemia results in reduced preload, and so also CO, and pulmonary and systemic MAPs. HR goes up, as does venous resistance. Stroke work goes down (again from a preload sense). Venous compliance goes down from an increased resistance sence. Arterial O2 content and global O2 delivery both go down. From a less blood and less cardiac output sense. That last bit's interesting in that MAP may only be down by ~10%, but global O2 delivery can still be halved.