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NURS3032 - NC5 Critical Care > Circulation > Flashcards

Circulation Flashcards

1
Q

Atherosclerosis

A

The build up of plaque (fats/cholesterol) in and on artery walls leading to atheroma (hardening) and stenosis (narrowing). Increases SVR leading to hypertension and contributes to PAD/PVD. Increases risk of thrombosis/occlusion leading to PE, MI or CVA.

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2
Q

Hypertensive Crisis

A

A sudden, severe and persistent increase in blood pressure involving damage to vessels, tissues and organs due to elevated pressures.
SBP = 180+ OR DBP = 110+

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3
Q

Cardiac Cycle

A

Atrial diastole (S to p wave)- heart muscles relax and valves closed; systemic blood returns to atria.
Atrial systole (p to R wave) - atrial contraction and AV valves open; blood flows to ventricles.
Ventricular systole (S to T wave) - ventricular contraction and semilunar valves open; blood passes to aorta/pulmonary arteries
Ventricular diastole (T to S wave) - heart muscles relax and valves closed.

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4
Q

Cardiac Conduction System

A

Network of specialised cardiac cells (myocytes) and nerves that transmit electrical impulses to initiate contraction of the heart muscle, thereby controlling the rate and rhythm of heartbeats.

SA node initiates depolarisation > atrial contraction > slow conduction of excitation signal through AV node (allow for atrial emptying) > rapid conduction through bundle of His to Purkinje fibres > ventricular contraction.

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5
Q

SA Node

A

Cluster of specialised cardiac cells located in upper R) atrium that generates electrical impulses to stimulate atrial contraction, thereby initiating and pacing heartbeats.
Controlled by autonomic nervous system (para/sympathetic) which releases hormones (nor/adrenaline) based on activity and stress.

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6
Q

AV Node

A

Cluster of specialised cardiac cells and nerves located in triangle of Koch. Delays the electrical signal from SA node by consistent amount of time before transmitting to Purkinje fibres.

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7
Q

Bundle of His (AV Bundle)

A

Branch of nerve fibres extending from AV node to L) and R) ventricles, located along inter-ventricular septum. Transmit electrical signal to Purkinje fibres.

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8
Q

Purkinje Fibres

A

Nerve fibres located on subendocardial surface of ventricle walls. Transmit rapid electrical signals to L) and R) ventricles to stimulate contraction.

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9
Q

Cardiac Output

A

The amount of blood the heart pumps through circulatory system in 60sec.
CO = HR X SV

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10
Q

Stroke Volume

A

The volume of blood ejected by the LV during each systolic contraction.
SV = EDV - ESV

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11
Q

Preload

A

The stretch of the ventricular myocardium (volume) BEFORE systole.
Preload = EDV

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12
Q

Afterload

A

The pressure the heart must work against to eject blood during ventricular systole.
Afterload <–> MAP

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13
Q

Contractility

A

The force of contraction of the heart muscle. Proportional to the initial length of the muscle fibre (i.e. greater stretch = greater contractility)
Increased contractility = increased SV and decreased ESV

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14
Q

Central Venous Pressure

A

The pressure of blood within the right side of the heart (vena cava and R) atria)

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15
Q

Ejection Fraction

A

The percentage of the total volume of blood in the heart that is pumped out with each contraction. Normal EF is 50+%.
EF = (SV/EDV) X 100

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16
Q

End Diastolic Volume

A

The volume of blood in the ventricles BEFORE systole.

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17
Q

Systemic Vascular Resistance

A

The opposition to systemic blood flow as a result of friction between blood cells/proteins and vessel walls.
SVR <–> MAP

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18
Q

End Systolic Volume

A

The volume of blood remaining in the ventricles AFTER systole.

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19
Q

MAP

A

Mean arterial pressure.
MAP = CO X SVR.

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20
Q

Vasopressors

A

Vasoconstriction > increased SVR > increased MAP > increased systemic perfusion.
Phenylephrine, norepinephrine, epinephrine, and vasopressin.
Dopamine is dose-dependent vasopressor/inotropic.

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21
Q

Percutaneous Coronary Intervention

A

Insertion of catheter and balloon into coronary arteries (via femoral/inguinal) to dilate vessels (compress) plaque and place stent to maintain patency.

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22
Q

Thrombolytic/Fibrinolytic Therapy

A

IV administration of thrombolytic agents to dissolve existing clots - e.g. alteplase, reteplase, tenecteplase.
Must be administered within 30min of arrival.

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23
Q

THROMBINS2

A

Initial management of patient with chest pain and suspected ACS (MI).

Thienopyridines - clopidogrel, prasugrel - antiplatelets.
Heparin/enoxaparin - anticoagulant.
Renin-angiotensin blockers (ACEIs/ARBs) - antihypertensive
Oxygen - titrated to SpO2 (avoid excess > incr. coronary resistance)
Morphine/fentanyl - PRN analgesia and anxiolysis
Beta-blockers - antihypertensive and reduce HR.
Invasive procedures - PCI.
Nitroglycerin (GTN) - vasodilation.
Statins
Salicylate (aspirin 300mg) - ROUTINE antiplatelet.

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24
Q

Transcutaneous Pacing

A

Temporary non-invasive method of cardiac pacing in conscious patients with symptomatic bradycardia or heart block. Delivers synchronised ventricular stimulation via transcutaneous patches.
Aim to stabilise haemodynamics until underlying problem can be treated.

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25
Pacemaker
Medical device composed of pulse generator and leads/electrodes implanted in the heart. Delivers controlled electrical stimuli to the heart muscle to regulate rhythm. May be temporary or permanent.
26
Cardioversion
Planned procedures to treat arrythmias (e.g. Afib, AFl). Electrical - delivery of controlled (100-300j) electrical shocks via electrodes placed on chest that are synchronised with QRS complex. Chemical - use of anti-arrhythmic medications
27
Defibrillation
Emergency procedure to treat life-threatening arrhythmias or pulseless cardiac arrest. Manual or automated delivery of unsynchronised powerful (200-300j) electrical shock via electrode pads to depolarise heart cells and disrupt the arrhythmia.
28
Catheter Ablation
Minimally-invasive procedure involving insertion of catheter into heart via blood vessels to destroy small areas of tissue using radiofrequency energy to prevent tachy-arrhythmias (e.g. SVT, VT).
29
CABG
Surgery to restore blood flow in coronary arteries. Attachment of healthy blood vessel (from chest/leg) below blockage to reroute blood flow to muscle.
30
Non-Invasive Haemodynamic Monitoring Definition Types
Haemodynamic monitoring that does NOT require insertion of any device into the body. 1. Non-invasive blood pressure (sphygmomanometer) 2. 12-lead Electrocardiogram (ECG) 3. Echocardiogram (ultrasound) 4. Pulse oximetry - SpO2, PR.
31
Haemodynamic Monitoring Definition Types
Study of movement and forces of blood within cardiovascular system. 1. Invasive vs non-invasive 2. Continuous vs intermittent
32
Invasive Haemodynamic Monitoring Definition Types
Haemodynamic monitoring requiring cannulation of vascular system to accurately measure pressure or flow in real time. 1. Arterial lines 2. Central venous catheters 3. Transoesophageal echocardiography 4. Pulmonary artery catheter
33
Arterial Lines Definition Pros/cons
Continuous monitoring of arterial blood pressure via catheter inserted into radial or femoral artery. Pros - continuous, sensitive, repeat ABGs. Cons - expensive, complex, risk of complications, requires expertise.
34
Arterial Lines Indications Complications
Indications: 1. Critical illness and/or unstable BP - e.g. trauma, high-risk surgery, shock. 2. IV vasoactive agents - e.g. vasopressors/inotropes. 3. Mechanical ventilation Complications - bleeding, infection, peripheral ischemia, embolism, aneurysm.
35
Arterial Lines Management
1. Infection control 2. Labelling 3. Aseptic dressing 4. Continuous monitoring - bleeding, distal perfusion, phlebitis/infection. 5. Ensure sufficient flush volume and pressure in system - >250ml saline, >300mmHg. 6. Levelling and zeroing- air-fluid interface levelled to mid-axillary line; re-zero transducer. 7. Waveform monitoring
36
Central Venous Catheters Definition Uses
Catheter inserted into internal jugular, femoral or subclavian veins and advanced into inferior/superior vena cava or right atrium. 1. Establish venous access during circulatory collapse 2. Administer prolonged IV therapy or irritating agents 3. Measure CVP 4. Perform haemodialysis
37
Pulmonary Artery Catheter Definition Uses
Catheter inserted through major vein and advanced through right heart into pulmonary artery and wedged in pulmonary vessel via balloon inflation. Used to monitor: 1. Central temperature 2. Pulmonary artery pressure 3. RA/RV pressure 4. Venous saturations 5. Left-sided diastolic filling
38
Transoesophageal Echocardiography Definition Uses
Flexible telescope with ultrasound scanner inserted via oeseophagus to provide images of the heart. Used to assess: 1. Regional wall motion and ischaemic changes 2. Ventricular function 3. Valvular function 4. Intra-cardiac air or masses
39
ECG Definition
Electrocardiograph using 12 leads and 10 electrodes to generate a 3D map of electrical activity in the heart.
40
ECG Electrode Placement
PRECORDIAL ELECTRODES: V1: 4th ICS RIGHT sternal margin V2: 4th ICS LEFT sternal margin V3: midway between V2-V4 V4: 5th ICS, mid-clavicular V5: 5th ICS, midway between V4-V6. V6: 5th ICS, mid-axillary line (same level as V4) LIMB ELECTRODES: RA - right arm LA - left arm RL - right leg LL - left leg
41
ECG Limb Leads
Lead I - RA to LA. Lead II - RA to LL. Lead III - LA to LL Lead aVR - LA to LL x RA. Lead aVL - RA to LL x LA Lead aVF - RA to LA x LL
42
Einthoven's Triangle
The 3D image of the heart created by the triangular cross-section of planes generated by the 6 limb leads - I, II, III, AVR, AVL and AVF.
43
ECG Lead Images
II, III, and aVF - inferior surface of the heart V1 to V4 - anterior surface I, aVL, V5, and V6 - lateral surface V1 and aVR - right atrium and cavity of left ventricle
44
p Wave
ATRIAL DEPOLARISATION (discharge of SA node) Atrial systole (contraction) occurs from peak of p-wave to R wave. Normal p-wave is < 0.12sec (3 small sq.)
45
Pathologic Q waves
Q waves that are: > 40 ms (1 mm) wide > 2 mm deep > 25% of depth of QRS complex Indicating current or prior MI.
46
ST elevation
Indicates infarction (OR pericarditis).
47
PR Interval
Atria to ventricular conduction time via His bundle. Normal PR interval is 0.12-0.2sec.
48
Prolonged PR interval
AV Block. 1st degree > 0.2sec 2nd degree (T1) - increasing PR interval. 2nd degree (T2) - constant prolonged PR interval. 3rd degree - p-waves and QRS dissociated.
49
ST depression
Indicates ischaemia.
50
QRS Complex
VENTRICULAR DEPOLARISATION. Ventricular systole (contraction) occurs from S to T wave. Normal QRS 0.08-0.12 sec (2-3 small sq.)
51
T Wave
VENTRICULAR REPOLARISATION. Ventricular diastole occurs from peak of T wave to S wave.
52
U Wave
Upright wave following T wave. Represents late-phase ventricular repolarisation. Indicates hypokalaemia.
53
Cardiac Arrythmia Definition Types
Group of conditions in which the heart beat is irregular and/or too fast or slow, due to dysfunction of the electrical conduction system. 1. Extra beats - e.g. PVC. 2. Supra-ventricular tachycardias - e.g. AFib, AFl. 3. Ventricular arrhythmias - e.g. VT, VFib. 4. Bradyarrhythmias
54
Troponin
Protein present only in cardiac muscle (NOT skeletal muscle). Damage to cardiac cells results in progressive release of troponin into bloodstream over 4-12 hours following symptoms. TnI - 0-0.04ng/ml (elevated within 4 hours) TnT - 0 -0.01 ng/ml (more-specific and detects smaller damage)
55
Antihypertensive Agents
Beta-blockers - e.g. atenolol, metoprolol. Calcium channel blockers - e.g. amlodipine, verapamil. ACEIs/ARBs - e.g. benazapril, enalapril. Diuretics - e.g. furosemide.
56
Anticoagulant Agents
Unfractionated Heparin DOACs (direct thrombin/factor Xa inhibitors) - e.g. dabigatran, apixaban, rivaroxaban. LMWH - e.g. enoxaparin Warfarin (vitamin K antagonist)
57
Anti-platelet Agents
Aspirin Clopidogrel Ticagrelor
58
Anti-arrhythmic Agents
Negative inotropes: 1. Rate-controllers (negative inotropes) - BBs/CCBs 2. Rhythm-controllers - sodium/potassium channel blockers - e.g. amiodarone, lidocaine. Other - atropine
59
Fibrinolytic Agents
Alteplase Streptokinase Tenecteplase
60
Perfusion
The process and adequacy of the delivery of oxygen via the circulatory system to organs/tissues to enable normal cellular/metabolic function.
61
Atrial Diastole
Atrial relaxation and passive filling with blood from vena cavae. AV valves closed. Approx. 0.7 sec
62
Atrial Systole
Atrial contraction and ejection of blood into ventricles. AV valves open. Aortic/pulmonic valves closed. Approx. 0.1 sec.
63
Ventricular Diastole
Commences before atrial systole. Ventricular relaxation and passive filling with blood from atria. AV valves open. Aortic/pulmonic valves closed. Approx 0.5 sec.
64
Ventricular Systole
Ventricular contraction and ejection of blood into pulmonary artery and aorta. AV valves closed. Aortic/Pulmonic valves open. Approx. 0.3sec
65
Positive Inotropes
Increased cardiac contractility > increased CO > maintains MAP > maintains systemic perfusion E.g. epinephrine, norepinephrine, dobutamine, digoxin and milrinone. Dopamine is dose-dependent vasopressor/inotropic.
66
Negative Inotropes
Decrease cardiac contractility and heart rate to treat hypertension and/or arrythmia. E.g. beta-blockers, calcium-channel blockers, amiodarone, lidocaine.
67
4 A's of Arrythmia
Atropine - bradyarrythmia Adenosine - SVT Adrenaline - asystole/PEA Amiodarone - VT, VF, AFib
68
ECG Interpretation
1. Is there any electrical activity? 2. What is the QRS rate (is this normal)? 3. What is the QRS interval? (0.08-0.1sec) 4. Is the QRS rate regular or irregular? 5. Is atrial activity present? (p-waves)? 6. What is the atrial rate (is this normal)? 7. What is the relationship between atrial and ventricle activity? * What is the PR interval? (<0.2sec). * How many p-waves for each QRS complex?
69
MET Criteria
Cardiac arrest PR = /=140bpm SBP = <90mmHg *Oliguria/Anuria
70
Full Blood Count (FBC) RBC WBC Platelets Hb
RBC - 4.0-5.9 (male) OR 3.8-5.2 (female) x 10(12)/L WBC - 4.5-11 x 10(9)/L Platelet - 150-450K/mcL Hb - 14-18 (male) OR 12-16 (female) g/dl
71
Urea/Electrolytes Sodium Calcium Phosphate Potassium Creatinine Urea
Sodium - 135-145 mEq/L Calcium - 2.2-2.7 mmol/L (8.5-10.5mg/dl) Phosphate - 1.12-1.45 mmol/L (3.4-4.5 mg/dl) Potassium - 3.5-5.5 mEq/L Creatinine 0.7-1.3 (male) OR 0.6-1.1 (female) mg/dl Urea - 1.8-7.1mmol/L (5-10 mg/dl)
72
Abnormal T waves High-voltage Low-voltage + U waves Low-voltage + ST depression Inverted
High-voltage - hyperkalemia. Low voltage + u waves - hypokalaemia. Low voltage + ST depression - heart disease. Inverted - coronary ischemia.
73
High-voltage p-waves
Atrial hypertrophy.
74

NURS3032 - NC5 Critical Care (6 decks)

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