Factors influencing CVP

Factors influencing CVP

· the venous return or volume of blood returned to the heart (preload of right ventricle)

· the pumping ability of the right heart

· the intra-thoracic pressure (peep, auto peep)

This latter effect can be seen during ventilation. During spontaneous ventilation, there is a 1-2 cmH20 fall on inspiration, and rise during expiration. During IPPV or positive pressure ventilation the reverse occurs. The effect is more pronounced if hypovolaemia coexists.

A low CVP indicates that the patient has a low blood volume and a high value suggests failure of the pumping ability of the heart, relative fluid overload or obstruction in the pulmonary circulation e.g. ® pulmonary embolus.

CVP trace (bottom)

Peripheral intravenous access

Indications

· intravenous fluid administration

· intravenous medication Administration

Complications

· infection

· thrombosis

· extravasation in tissues

Pulmonary artery catheter indications

· evaluation of volume status

· evaluation of cardiac and pulmonary pressures

· evaluation of cardiac function

· haemodynamic monitoring (following MI, heart failure, sepsis, labile blood pressure, pulmonary congestion, vaso-active pharmacological support)

· diagnosis and evaluation of specific conditions (ARDS, cardiogenic shock, cardiac tamponade, pulmonary hypertension, valvular dysfunction, hypovolaemia, and sepsis)

Pulmonary artery catheter

Pulmonary artery catheter insertion

Common sites for PA catheterisation

· subclavian

· jugular

· femoral veins

Insertion

Equipment Procedure trolley, sterile gown and gloves, persist plus, dressing pack, drape (with hole), drape, blue sheet, syringe 10mls x 2, blue needle, orange needle heparinised saline 10mls, 1% lignocaine, introducer, PA Catheter, Fenwell pressure cuff, 500 ml N/Saline and 500 units heparin, Transducer kit and cardiac output set, cartridge and cable, interlink bungs x 3, 2/0 straight needle

Procedure

· erase previous patient data and explain the procedure to the patient if conscious

·

Set up

prepare monitor

a. press on monitor, select BP label, enter PAP.

b. enter height and weight of patient

c. ensure correct Co-efficient (.607 room temperature injection 23-25^o, .582 cold room temperature injection 19-22^o) and 10ml volume appropriately entered

d. prepare flush solution and transducer equipment if not insitu, zero transducer – place transducer level with patient’s right atrium (mid axilla – 4^th intercostal space )

· Assist medical officer to

a. prepare site of insertion with persist plus swabs and dressing pack

b. medical officer to gown and glove appropriately

c. draw up and administer local anaesthetic if required

d. apply sterile drapes

e. open and prime introducer kit with heparinized saline

· Medical officer inserts the introducer by
venipuncturing the vessel with supplied syringe and needle
introducing the guide wire
remove the syringe and needle
inserting the introducer

· Insertion of pulmonary catheter
open and prime PAC kit with Heparinized saline and apply bungs to
unused lumens
attach distal lumen transducer and pressure tube to distal lumen
check monitor to ensure appropriate transducer.
ensure protective sheath applied over PAC catheter

check integrity of balloon

· Thread PAC via introducer (transducer connected to the distal lumen and monitored on oscilloscope)
monitor oscilloscope for characteristic RA trace waveform changes, and the
ECG for ectopics
inflate balloon when RA trace visualized
record pressures as catheter passes RA, RV, PA, and PCWP
deflate balloon once PA wedge has been obtained and note the return of
characteristic PA waveform

· suture catheter and apply tegaderm

· note insertion distance

· obtain chest x-ray to confirm catheter placement

· connect cardiac output and temperature cables as well as cardiac output kit with 250ml 5% dextrose to proximal lumen with three-way tap and CVP transducer lumen and pressure tube.

Complications of insertion

· cardiac arrhythmia due to myocardial irritation

· pulmonary artery rupture due to distal migration of catheter, abnormal balloon inflation, perforation of wall with catheter tip or excessive pressure from balloon on vessel wall

· pulmonary infarction as the result of catheter migration into the wedged position, the balloon being left inflated or a thrombus formation around the catheter

· infection due to poor aseptic technique, migration of non-sterile portion of catheter, prolonged insertion time

· catheter kinking or knotting as the result of excessive length of insertion

· air embolism as the result of balloon rupture, excessive inflation volume, prolonged placement (> 48 hrs), during placement of introducer or insertion of catheter (through introducer) and during catheter removal

· pneumothorax or haemothorax on insertion

Management

· observe insertion site for signs of inflammation

· the catheter should be secured, and dressed with tegaderm

· maintain transducer level with patient’s right atrium (mid axilla, 4^th intercostal space)

· maintain continuous heparinized saline flush, utilizing the Fenwell pressure bag at 300mmHg

· maintain the system free of air bubbles or blood

· zero transducer at start of each shift

· continuously monitor the pulmonary artery waveform (distal lumen) to detect spontaneous wedging of the pulmonary catheter

· record PA pressures hourly

· ensure balloon deflates promptly following PCWP reading (do not actively withdraw air from wedge syringe - allow to passively recoil)

· cardiac output measurements performed as required

· if a spontaneous wedge trace occurs

· check that there is adequate volume of flush solution, and that the Fenwell pressure bag has remained inflated at 300mmHg

· the distal lumen should be checked that it is not occluded via three-way tap or syringe

· check that the PA catheter has not migrated

· do not flush the distal lumen

· apply 10ml syringe onto distal lumen and aspirate, if blood returns then it is safe to flush lumen

· if blood does not return, retract catheter 2cm and re-attempt to aspirate blood back from distal lumen

· continue this process until blood can be aspirated, which indicates that it is safe to flush the lumen

· if blood cannot be aspirated, or wedge trace continues, retract PA catheter to RA and notify medical officer immediately

do not advance PA Catheter in any circumstances