ICU Flashcards
Right ventricle determines?
Flow
Left ventricle determines?
Pressure
Adaptive changes in chronic heart failure?
- Fluid retention
- Increased oxygen extraction
- Renin-Angiotensin up-regulation
Etiology of heart failure?
- Ischaemic cardiomyopathy (dilation)
- Aortic stenosis (Hypertrophy & dilation)
- Hypertension (Hypertrophy & dilation)
- AF & arrhythmias
Treatment for chronic heart failure?
- ACE inhibitors
- Diuretics
- Calcium channel blockers
- Beta-blockers
Etiology of Acute heart failure?
- ACS
- Post-op cardiac surgery
- Sepsis
- COPD/ARDS
- Chest trauma
Hypotension is ?
SBP < 90 mmHg or decrease in baseline > 30mmHg
Forresters classification of heart failure?
- Class 1 = < 18 (PCWP) > 2.2 (CI) - Normal
- Class 2 = > 18 (PCWP) > 2.2 (CI) - Pulmonary congestion
- Class 3 = < 18 (PCWP) < 2.2 (CI) - Cardiac failure
- Class 4 = > 18 (PCWP) < 2.2 (CI) - Cardiogenic shock
Mortality in forresters classification?
- Class 1 < 3%
- Class 2 9%
- Class 3 23%
- Class 4 51%
Pulmonary artery occlusion pressure AKA?
Pulmonary Capillary Wedge Pressure
Determinants of LV function?
- Contractility
- Preload (End-diastolic volume)
- Afterload (Wall stress)
- Heart rate
- Synchrony
Starling’s law?
Describes preload
Anrep effect ?
Describes contractility
Factors increasing contractiity ?
- Autonomic tone / Increase - Exercise, stress / Decrease - Diabetes
- Catecholamines/ Decreased n chronic HF
- Catecholamine receptors / Decrased in sepsis
- Coronary blood flow / Increases contractility
- Serum calcium / Decreased contractility with hypocalcaemia
Compliance of the heart?
Determined by the change in volume to pressure
Causes of decrease in LV compliance ?
Primary
- Ischaemia
- LV hypertrophy
- Stunned myocardium
Secondary
- RV dilation (Pulmonary HTN, Volume overload)
- Hyperinflation
- Tamponade
Laplace’s law? Determinant of afterload
- Wall stress
- Tension = P x r
Afterload reduction ? Functions?
- Decreases wall stress
Chronotropy?
Increasing HR with increased contractility
HR and LVH?
Increasing HR decreases contractility
Factors affecting preload? in LV impairment
- Hypovolaemia
- Diastolic dysfunction
Factors affecting contractility? in LV impairment
- Ishcaemia
- Septic cardiomyopathy
Factors affecting afterload? in LV impairment
- Aortic stenosis
- Malignant HTN
Factors affecting chronotropy? in LV impairment
Brady & tachyarrhythmias
Factors affecting dyssychrony? in LV impairment
Usually MI
BBB
Effect of MI on LV pressure-volume relationship?
- Depression of the curve with MI
- Increase in diastolic compliance curve
- Increased filling pressures - Pulmonary oedema
- Requires dobutamine for contractility
- Increased contractility willl improve filling pressures
- Nitroprusside for decreasing afterload
Management of Acute HF?
- Maintain coronary blood flow - Norad , Dopamine & balloon pump
- Augment contractility - Dobutamine (Acute), Chronic (Phosphodiesterase inhibitors - )
- Treat reversible causes - Ischaemia, Aortic stenosis
- Reverse arrhythmias
- Decrease LV afterload (Nitrates & CCBs)
- Maintain preload
- VAD - Ventricular assist devices
Function of intra-aortic balloon pump?
- Maintain coronary perfusion
- Decrease in afterload
Indications for mechanical assist devices?
Bi-ventricular assist device / LVAD
- Severe symptomatic HF - CI < 2, Ppao > 20 mmHg & inotrope dependent
- LV dysfunction with persistent arrhythmias
- Hepatic & renal failure
PAC wave form and pressures ?
XY - CV - A - Based on location
RA - 1 - 5 mmHg
RV - 15 - 30 mmHg (systolic) / 1 - 7mmHg (Diastolic)
PA - 15 - 30mmHg (Systolic)/ 4 - 12 mmHg (Diastolic) / 9 - 19 mmHg (mPAP)
PCWP - 4 - 12mmHg
Variables from PAC?
- Mixed venous oxygen saturations
- MAP
- RAP
- PAP/mPAP
- PCWP
- CO
Thermodilution measurement with PAC?
- Injectate to porximal port
Measurement Cardiac index?/
CI = CO (L/min) / BSA
Normal range - 2.5 - 4 L/min/m2
Calculation of stroke volume?
SV = CO / HR
Normal range - 0.06 - 0.1 L/beat
Calculation of stroke volume index?
SVI = SV / BSA
Normal range - 0.033 - 0.047
When calculating indexes?
The variable divided by BSA (m2)
Calculation of MAP?
MAP = 2 (DBP) + SBP / 3
Normal range - 70 - 110 mmHg
Calculation of SVR?
SVR (Dyne/sec/cm -5) = MAP - mRAP / CO x 80
Normal range - 800 - 1200 dyne/sec/cm-5
Calculation of SVRI?
SVRI (dyne/scec/cm-5 / m2) = MAP - mRAP / CI x 80
Normal range - 1970 - 2390 dyne-sec-cm-5/m2
Calculation of PVR?
PVR = mPAP - PCWP / CO x 80
Normal range - < 250 dyne-sec-cm-5
Calculation of PVRI?
PVRI = mPAP - PCWP / CI x80
Normal range - 255 - 285 dyne-sec-cm-5/m2
Calculation of DO2?
DO2 = CO [(Hb x SaO2 x 1.34) + (PaO2 x 0.0031)]
Normal range - 500-600ml/min
Normal VO2?
200 - 250 ml/min
Oxygen extraction ratio?
25 - 30%
Gold standard for CO measurement?
Pulmonary artery thermodilution
Indications for PAC
- Cardiothoracic surgery
- Pulmonary HTN
- Shock & Right ventricular failure
Pulse wave analysis components?
- Contractility
- SV
- Aortic compliance
- Afterload
- Vascular tone
Phases of ARDS?
- Exudative (1-7 days) - Acute inflammatory response of alveolar epithelium & endothelial damage
- Proliferative phase (1-3 weeks) - Proliferation of type II pneumocytes, fibroblasts & myofibroblasts leading to widening of alveolar septae
- Fibrotic phase (> 3 weeks) - Remodelling and fibrosis
Dead-space and fibrosis?
Fibrosis increase dead-space
What is driving pressure?
Plateau preassure - PEEP