Cardiovascular monitoring and support

Question 1

Indications for monitoring

Answer 1

Failure to restore normal homeostasis
Procedures that give rise to rapid or profound changes in preload or afterload
Treatment with vasoactive drugs that influence preload, after load or MF
Risk of developing low perfusion state from any cause

Monitor blood pressure
CVP
Cardiac output or cardiac index

Question 2

Arterial pressure

Answer 2

Connect cannula to transducer

Radial or DP used with 20G or 22G

Always do Allen’s prior

Contraindications - local coagulopathy, local sepsis

Complications - haematoma, thrombosis, distal ischaemia, intimal damage, false aneurysm formation, disconnection and injection of irritant drugs

Question 3

Technique for art line

Answer 3

Position and palpate
Insert at 45

Advance needle in linear fashion not wiggling

If miss restart

Let syringe fill and withdraw

Pressure haemostasis

Advance guidewire through needle

Railroad cannula over guidewire

Check back flow and secure cannula

Connect transducer and flushing set-up

Connected via rigid tubing to a three way tap, flush device and transducer

Always calibrate, make sure no air, and sitting at right anatomic level

Sharp peaked up swing and down swing with low dicrotic notch –> hypovolaemia (cannot draw conclusions unless system is adequately damped)

Question 4

CVP

Answer 4

Ability of right heart to accept and deliver circulating volume

Influenced by venous return, right heart compliance, intrathoracic pressure and patient position

Usually 0-8mmHg or 0-10cmH2O

Question 5

Central vein cannulation

Answer 5

Tilt patient 20 degree head down and head turned away

Skin nick and insert cannula 1-2cm below midpoint of the clavicle

Advance towards suprasternal notch do not wiggle

Venous aspirated freely –> remove syringe and insert guidewire

Railroad catheter without losing wire!!!

Make sure tip lies in distal SVC

USS
Vein is medial border of SCM at level of the thyroid cartilage and anterolateral to the carotid artery

Displace the artery medially

Advance at 30 degrees to skin parallel to artery but lateral –> often towards ipsilateral nipple

Contraindications
Local sepsis, coagulopathy, abnormal anatomy, operative site and previous vein usage

Internal jugular difficult to do but less risk than subclavian which can cause pneumothorax and haemothorax

Question 6

CVP waves

Answer 6

A atrial contraction
C wave is bulging of tricuspid 
X descent is atrial relaxation
V wave rise in atrial pressure prior to the tricuspid valve opening
Y descent atrial emptying

Question 7

Indications for CVP measurement

Answer 7

Administration of fluid replacement for hypovolaemia
Central vein cannulation not for primary route of access because risk of complications and low flow rates achievable
To measure effect of vasoactive drugs on venous capacitance - particularly vasodilators
Aid diagnosis of RVF
Administration of potent drugs
Administration of TPN - needs it’s own clean lumen

DOES NOT equal IV volume

Pitfalls
Poor calibration, inaccurate placement, TR/incompetence, AV dissociation and nodal rhythms
Variations in IV volume, sympathetic tone, CO and IT pressure (PEEP) –> may falsely elevate it
ALWAYS get a flush, check pressure fluctuation and confirm position with X-ray

Question 8

Complications of CVC

Answer 8

Damage to veins or other structures, rupture of vessel and haemorrhage with local haeamtoma or haemothorax, TP, air embolism, extravascular catheter placement, knotting of catheters, catheter breakage, catheter misplacement, neuropraxia, arterial puncture, lymphatic puncture, trachobronchial puncture, sepsis

SEPSIS!!!!

Question 9

Measurements

Answer 9

SVR - if too high systemic hypo perfusion, if too low maintenance of BP will be difficult

SV, SI - major determinant of CO and governable by preload

LVSWI - function of the systemic side of heart

DO2 - index of O2 delivered

VO2 - index of oxygen consumption

Question 10

TOD

Answer 10

Preload, stroke volume and after load

Area under triangular curve represents the stroke volume flowing through the descending aorta and applying a factor determined from age, heigh and weight allows SV to be calculate

FTc corrected flow time

Low in hypovolaemia and may be used to derive SVR

CANNOT BE USED in coarctation of aorta or people with intra-aortic balloon pumps

OR risk to oesophagus / varies / oral surgery patients

Question 11

Inotropic agents

Answer 11

SEE Photo