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Pulmonary Artery Catheterization

93

 

Rajesh Chawla, Vishakh Varma, and Atul Kulkarni

 

A 65-year-old male patient, a known case of chronic obstructive pulmonary disease with cor pulmonale, hypertension, and coronary artery disease with chronic congestive heart failure, was admitted to the ICU with right lower lobe pneumonia. He was in respiratory failure and in shock. On the second day, he developed renal failure and azotemia. A pulmonary arterial catheter (PAC) was inserted.

The pulmonary artery catheterization (PAC) provides direct pressure measurements from the right atrium, right ventricle, pulmonary artery, and pulmonary artery occlusion pressure. It is also a mean of measuring cardiac output and mixed venous oxygen saturation. Routine use of this should be avoided, but it has still a role in expert hands in cardiac surgery, difficult to treat heart failure, congenital heart disease, and complex fluid management situations.

Step 1: Assess the need for PAC—indications

PAC is used in situations where right-sided pressures (i.e., central venous pressure [CVP]) may not reflect the changes in pressures in the left side of the heart. Right-sided filling pressures are disproportionately elevated compared to the left-sided filling pressures.

R. Chawla, M.D., F.C.C.M. (*) • V. Varma, M.D.

Department of Respiratory, Critical Care & Sleep Medicine, Indraprastha Apollo Hospitals, New Delhi, India

e-mail: drchawla@hotmail.com

A. Kulkarni, M.D.

Department of Anaesthesia, Critical Care and Pain, Tata Memorial Hospital,

Mumbai, India

R. Chawla and S. Todi (eds.), ICU Protocols: A stepwise approach,

743

DOI 10.1007/978-81-322-0535-7_93, © Springer India 2012

 

744

R. Chawla et al.

 

 

PAC should be used in centers with nursing expertise in the management of catheters and sufficient physician experience in the interpretation of data in the following conditions:

For management of heart failure

Patients with refractory shock not responding to noninvasive management

Patients with significant azotemia on diuretic therapy and are clinically volume overloaded

As part of workup or bridge to cardiac transplant or the left ventricular assist device

Complex fluid management (shock, burns, acute renal failure, major surgery) in patients with poor left or right ventricular function

Cardiac surgery patients on cardiopulmonary bypass or patients with complex cardiac lesions

High-risk obstetric cases such as severe preeclampsia and abruptio placentae

Surgical procedures such as liver transplant and aortic cross clamping

Step 2: Check for the contraindications

Relative contraindications are as follows:

Complete left bundle branch block may convert to complete heart block.

Wolff–Parkinson–White syndrome and Ebstein’s malformation because of possible tachyarrhythmias. A catheter with pacing capability is preferred in these situations.

Coagulopathy.

Severe pulmonary hypertension.

It should not be used in centers that do not have experience and expertise in its use.

Step 3: Know the PAC

Circumference should be 7–9 Fr.

Length is 110 cm, marked at 10 cm intervals.

The distal port (yellow colored) at the catheter tip is used for monitoring of pulmonary artery pressure.

The second port (blue colored) is 30 cm proximal from the tip and is used for monitoring of CVP and injecting fluid bolus for computing cardiac output with bolus technique.

The third lumen (red colored) leads to a balloon near the tip, with a locking port.

The fourth lumen houses wires for a temperature thermistor, the end of which lies just proximal to the balloon. This attaches to the interface cable from the cardiac output monitor.

The continuous cardiac output PAC has a copper thermal filament embedded in the catheter at 30 cm. Once inserted and connected to the monitor, this filament heats up every few seconds, warms blood around it, and thermistor in the pulmonary artery detects the change in temperature and calculates cardiac output.

93 Pulmonary Artery Catheterization

745

 

 

The PAC set also contains the following:

Large-bore introducer sheath with a one-way valve at its outer end and a side arm extension for intravenous access. (The PAC is introduced through the one-way valve. Some sets may not contain this sheath, but is also available separately.)

Stiff dilator

Plastic sheath to cover the catheter

A 1.5-mL syringe for balloon inflation

Guidewire

Puncture needles and syringes

Three ways and connectors

A disposable knife

Step 4: Obtain informed consent

This has been explained in detail in Chap. 91.

Step 5: Select the appropriate PAC for insertion

Select the PAC which is appropriate for that patient.

Catheters are available, which can perform the following additional functions:

An extra venous infusion port.

Pacing capability.

Continuous mixed venous oximetry: Special fiber-optic PACs can be used to

monitor mixed venous oxygen saturation (SvO2) continuously, initially developed as a surrogate for continuous cardiac output.

An ejection fraction catheter has a faster thermistor response time so that it can calculate RV ejection fraction in addition to the cardiac output.

Continuous cardiac output.

Step 6: Prerequisites

Establish monitoring of ECG, noninvasive blood pressure, and pulse oximetry.

Keep ready all emergency medication and transcutaneous pacing equipment.

Provide sedation in a conscious patient.

Supply oxygen through the nasal cannula.

Secure a peripheral venous access.

Assemble the pressure transducer and flush it.

An assistant is needed who can prepare the set and closely monitor the patient.

The patient should be in supine position with the head slightly down and turned toward the opposite side.

Make use of maximum sterile barrier precautions, described Chap. 91.

Step 7: Choose the site of insertion

Generally the right internal jugular vein or left subclavian is selected.

Alternatively any other site used for central venous cannulation can be selected keeping in mind the distance from the puncture site to the right atrium.

An extra distance of 5–10 cm from the left internal jugular, 15 cm from the femoral veins, and 30–35 cm from the antecubital veins is required. But accurate placement rates are lower from these sites.

746

R. Chawla et al.

 

 

Step 8: Prepare the cannulation set

With maximum sterile precautions do the following:

Pass the catheter through the sterile sheet.

Flush the catheter with heparinized saline.

Inflate the balloon with 1.5 mL air and check for its shape and any leakage.

Zero and level the transducer and connect to the saline-filled catheter.

Place the tip of the catheter at the heart level; pressure on the monitor should read zero.

Next, raise the catheter tip to 30 cm height; the monitor should show a pressure of 22 mmHg (equivalent to 30 cm H2O).

Step 9: Insertion of PAC through internal jugular vein

Use maximum sterile barrier precautions.

Apply generous local anesthesia.

Locate the internal jugular vein.

Puncture the vein with the puncture needle preferably under ultrasound guidance.

Pass the guidewire through the needle and remove the needle.

Dilate the skin and subcutaneous tissue with the dilator. This is generally done with the dilator loaded inside the introducer sheath. A small incision is often needed.

Pass the large-bore sheath using Seldinger technique.

Confirm placement by aspirating blood, flush it, and secure it with stitches.

Introduce the prepared catheter through the introducer up to a distance of 20 cm with the balloon deflated. Note the waveform on the monitor—CVP tracing should be seen.

Rotate the catheter so that curvature is at 11 o’clock position from patient’s head end.

Inflate the balloon gently with 1.5 cc of air and lock it. During pulmonary artery occlusion pressure (PAOP) measurement if the balloon is left inflated, you may cause a pulmonary infarct.

Advance slowly and keep looking at the monitor for RV waveform with systolic peaks of 25–35 mmHg. Note that the diastolic pressure is close to zero. This is reached at around 30–35 cm length.

If the RV or PA is difficult to enter:

Have the patient take deep breath.

Raise the head end of the bed or tilt the table to left or right.

Flush the PA port with 1–2 mL cold sterile saline so that the catheter becomes stiff.

Keep inserting further; PA is reached at 40–45 cm. At PA, there is an increase in the diastolic pressure (Fig. 93.1).

Now advance another 5–10 cm or so very gradually keeping an eye on the monitor to look for wedging. When it is wedged, the waveform becomes similar to that of CVP tracing at a pressure near to the PA diastolic pressure. This is the pulmonary artery occlusion pressure PAOP, and it is always lower than the pulmonary artery diastolic pressure (Fig. 93.1).

93 Pulmonary Artery Catheterization

 

747

 

 

 

1 sec

30

R

R

R

R

 

 

a c

a c v

 

 

 

 

 

0

 

 

 

Right atrium

Right ventricle

Pulmonary artery

Wedge

Fig. 93.1 Pressure tracings recorded from the right atrium, right ventricle, pulmonary catheter, and on pulmonary artery occlusion

Do not advance any further; deflate the balloon.

Now inflate the balloon with 0.5 cc increments and look for wedging. If it wedges before 1.5 cc, pull the catheter back 3–4 cm. Do not pull with the inflated balloon.

Fix the catheter at that length. Note the length of the catheter that led to a good PAOP tracing in the case chart.

Never keep the PAC wedged continuously; deflate the balloon after taking the readings.

Measured and derived hemodynamic indices values are mentioned in Tables 93.2 and 93.3.

Step 10: Manage complications

Minor complications are seen in up to 50% of patients, but major complications are seen in only 0.1–0.5% of patients.

Besides all the complications of insertion and maintenance of central venous

lines, there are a few unique complications of the use of the PAC (Table 93.1).

Step 11: Interpretation of data obtained (Tables 93.2, 93.3 and 93.4)

Measuring Cardiac Output

Enter the catheter constant into the monitor; this is generally written on the pack of the set or the insert.

10 mL of cold or room temperature saline is smoothly injected from the proximal (blue) port in the right atrium. In small children or patients with volume overload, smaller volumes (2 and 5 mL) may be used.

A cable from the cardiac output monitor is dipped into the same bottle saline from which the injectant volume was aspirated.

The temperature of the blood mixed and cooled with the cold saline is measured at the end of the catheter by a thermistor.

This produces a thermodilution curve, from which the cardiac output is calculated by the monitor. Usually three measurements are made.

These measurements may have a variability of up to 10%.

There are various factors that influence the accuracy that include intracardiac shunts, tricuspid regurgitation, pulmonary valve regurgitation, respiratory cycle influences, and rapid injection of saline.

Table 93.1 Complications of the PAC

 

 

Complication

Description

Treatment

I. Catheterization

 

 

a. Arrhythmias, ventricular

Self-limited arrhythmias extremely common during passage

3.1% of patients require treatment, mostly withdrawal

fibrillation

 

of catheter or guidewire

b. Right bundle branch block,

Transient during passage in 5%

May need transcutaneous or transvenous pacing

complete heart block

Permanent in 0.9%

 

 

Should rule out ischemia

 

II. Catheter resistance

 

 

a. Mechanical, catheter knots

Suspect if the catheter is blocked or difficulty in withdrawing

Radiological maneuver

 

Confirm on a chest X-ray

Surgery

b. Thromboembolism

Clots seen within hours

The heparin-coated catheter reduces risk

 

Thromboembolism rare

 

c. Pulmonary infarction

Opacity on a chest X-ray

Removal of the catheter

d. Infection, endocarditis

Significant risk after 72 h especially in septic patients

Should be removed as soon as feasible

e. Endocardial damage, cardiac

53% in autopsy series, but clinically significant regurgitation

Removal of the catheter

valve injury

does not occur

 

f. Pulmonary artery rupture

0.02–0.2% of patients

One-lung ventilation to isolate normal lung

 

Mortality is 50%

Positive end-expiratory pressure to the affected lung

 

Cause:

Reverse anticoagulation

 

Excessive insertion depth

May try to reinflate to cause tamponade

 

Persistent wedging

May need surgical intervention

 

Frequent manipulations

 

 

Inflation with liquid

 

 

Presents as hemoptysis and desaturation

 

g. Pulmonary artery

Sequelae of PA rupture

Surgery may be needed

pseudoaneurysm

May cause secondary hemorrhage

 

III. Misinterpretation of data

 

May be widespread

 

 

Use requires expertise and experience

IV. Misuse of equipment

 

 

93 Pulmonary Artery Catheterization

 

749

 

 

Table 93.2 Normal cardiovascular pressures

 

 

Pressure

 

 

Average (mmHg)

Range (mmHg)

Right ventricle

 

 

Peak systolic

25

15–30

End-diastolic

6

1–7

Pulmonary artery

 

 

Peak systolic

25

15–30

End-diastolic

9

4–12

Mean

15

9–19

Pulmonary artery wedge

 

 

Mean

9

4–12

Left ventricle

 

 

Peak systolic

130

90–140

End-diastolic

8

5–12

Central aorta

 

 

Peak systolic

130

90–140

End-diastolic

70

60–90

Mean

90

70–105

Continuous Thermodilution Cardiac Output

Near-continuous cardiac output can be measured by a specially designed pulmonary artery catheter.

The RV portion of the catheter has a thermal filament that releases a small amount of heat in a pulsatile manner.

This temperature variation is measured at the tip of the catheter. It has a measurement delay of 5–15 min, but the measurement is quite reliable.

Acute changes in cardiac output are detected more slowly, but it has the advantage of ease of operation, minimal handling, and reduced risk of fluid overload.

Pulmonary Capillary Wedge Pressure

Imagine that the vessel in which the pulmonary artery catheter lies is like a tube connected to the left atrium.

When there is no flow of blood through the tube, the pressure at the tip of the tube will be the same as the pressure at the left atrium. So, we stop the blood flow by inflating the balloon and measure the pressure at the tip of the pulmonary artery catheter and call it the pulmonary capillary wedge pressure (PCWP), but technically the correct term is pulmonary artery occlusion pressure (PAOP) as PCWP is actually lower than PAOP.

Pulmonary artery diastolic pressure can be used as an alternative to PCWP to measure left ventricular filling pressure, which we assume predicts left ventricular volume.

750

Table 93.3 Derived hemodynamic indices

 

 

 

Parameter

Physiologic significance

Formula

Normal value

Systemic vascular resistance

Reflects impedance of the systemic vasculature

80

× (MAP−CVP)/CO

700–1,600 dyne·s·cm−5

Pulmonary vacular resistance

Reflects impedance of pulmonary circuit

80

× (PAM−PCWP)/CO

20–130 dynes·cm−5

Cardiac index

Allows for meaningful comparison between patients

CO/BSA

2.5–4.2 L·min−1·m−2

Stroke volume index

Reflects fluid status and ventricular performance

CI/HR × 1,000

40–60 mL·beat−1·m−2

Left ventricular stroke work index

Estimates work of the left ventricle, reflects contractile state

(MAP − PCWP) × SVI × 0.0136

45–60 gm·m−2

Right ventricular stroke work

Estimates work done by the right entricle and RV

(PAM − CVP) × SVI × 0.0136

5–10 gm·m−2

index

performance

 

 

 

CI cardiac index, CO cardiac output, CVP central venous pressure, HR heart rate, MAP mean arterial pressure, PAM pulmonary artery mean pressure, PCWP pulmonary capillary wedge pressure, SVI stroke volume index

.al et Chawla .R

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