Week 4-6 Flashcards
• Define each stage of the cardiac action potential
Phase 0 depolarisation
Phase 1 early rapid repolarisation - Na+ into cell
phase 2 - plateau phase where the cell membrane action potential is maintained near 0mV Ca+ into cell
stage 3 - final rapid repolarization phase.-K+ leave cell
Stage 4 - resting membrane phase Left K+ allows negativity to be present
• Describe the reasons for assessment and monitoring of critically ill patients
Critically ill patients cannot compensate as well as healthy individuals
• What are the key principles for cardiac assessment and monitoring
Heart rate and rhythm Continuous cardiac monitoring 4 or 5 lead 12 lead ECG Hemodynamic monitoring Non invasive, (TPR&BP, oximetry, UO). Invasive intra arterial pressure monitoring Invasive CVP Pulmonary artery pressure (PAP) Cardiac output (CO) thermodilution (measures temperature change). Non invasive = probe, BP cuff, Invasive = catheter Arterial pressure monitoring Cardiovascular monitoring Central venous pressure Mean arterial pressure Right ventricular pressure Pulmonary artery wedge pressure Left atrial pressure Left ventricular pressure Aortic pressure
FBC Red blood cells White blood cells Platelets Electrolytes Potasium and calcium can cause cardiovascular abnormalities – arrhythmias Cardiac enzymes Creatine Kinase CK Troponin T (Trop T/I) D-Dimer
• Describe the electrical activity of the heart in relation to contractility and cardiac output
P wave: the sequential activation (depolarization) of the right and left atria
QRS complex: right and left ventricular depolarization (normally the ventricles are activated simultaneously)
ST-T wave: ventricular repolarization
U wave: origin for this wave is not clear - but probably represents “afterdepolarizations” in the ventricles
PR interval: time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex) QRS duration: duration of ventricular muscle depolarization QT interval: duration of ventricular depolarization and repolarization RR interval: duration of ventricular cardiac cycle (an indicator of ventricular rate) PP interval: duration of atrial cycle (an indicator of atrial rate)
• What are the clinical features of AMI?
Pain: Chest Left arm Right arm Both arms Neck Jaw back
Skin: Pale Sweaty Clammy cyanosed
Respiratory:
Tachypnoea
Dyspnoeic
Pulmonary oedema
Physical signs:
Nausea
Vomiting
Psychological:
Anxiety
confusion
• Discuss the initial treatment of a patient with sudden onset of chest pain
Patient History Symptoms ECG Bloods? Reassure patient – rest Baseline observations Need for cardiac monitoring 12 lead ECG IV access Troponin (T & I) levels and cardiac enzymes (CK – creatine kinase) Contact Dr
Thrombolysis
PCI
what is preload?
Pressure or stretch exerted on the walls of the ventricle by the volume of blood filling the ventricles at the end of diastole; used as an indication of volume status
What is afterload?
Pressure required to open aortic valve
The resistance to ventricular contraction; pressure the ventricles have to overcome to eject blood into the circulation
what is contractility
The ability of a muscle to shorten when stimulated; in particular, the force of myocardial contraction
what is normal stroke volume SV
50 - 100ml / beat
what is normal cardiac output CO
4-8L / min
