Vascular Access & Cannulation

Dr Osama BawazirAssistant Professor , Consultant Pediatric surgeon

FRCSI, FRCS(Ed), FRCS (glas), FRCSC,FAAP,FACS.

• ECMO is a supportive measure, which can be instituted as an urgent, semi elective or elective procedure

• Time in relation to the event is the limiting factor when going through the assessment cascade in order to accomplish a successful result

• PRE-ECMO ASSESSMENT

• CANNULATION

• INITIATION AND MAINTENANCE OF ECMO

• EVALUATION

Introduction

CANNULATIONCANNULATION

The establishment and maintenance of

adequate vascular access is essential

for ECMO

CANNULATIONCANNULATION- Patient age and size- Underlying disease &

condition- Cause of the cardiorespiratory

compromise- Type of support:

– Veno-venous (VV) ECMO – Veno-arterial (VA) ECMO

- Time of the event in relation to the peri-operative period

- Location

CANNULATIONCANNULATION For each modality, there are

different kinds and sizes of cannulae that can be used

Target activated clotting time (ACT) should be accomplished first before ECMO (heparin 100 units/kg) 3 minutes before cannulation.

Consent GA

Guidelines for Cannula size Guidelines for Cannula size

Weight (Kg)Venous cannula arterial cannula

2-4 8-14 8-10

5-15 15-19 12-15

16-20 19-21 15-17

21-35 21-23 17-19

35-60 23 19-21

>60 23 21

Poiseuille’s LawPoiseuille’s Law

• Poiseuille's law: In an artificial system, flow through a cylindrical tube or any segment of a tube is directly proportional to ΔP, the driving pressure along the tube, and the fourth power of the radius, r. Flow is inversely proportional to L the length of the segment and to η, the viscosity of the liquid. The proportionality constant is π/8.

Cannula ConsiderationCannula Consideration

• Venous cannula should be with the largest lumen and shortest length possible (gravity).

• Venous cannula should have side holes.

• M-number

• Resist kinking

• The smallest double lumen cannula is size 12 F ( for V V ecmo in neonate)

CANNULATIONCANNULATION• Veno-Venous (V-V) ECMO

- Mainly used for respiratory support (ARDS & Congenital Diaphragmatic Hernia)

- V-V ECMO provides adequate oxygenation and CO2 removal

- The venous access can be established by using the system in one site, or two different sites

CANNULATIONCANNULATION

• Veno-Arterial (VA) ECMO

provides cardiac as well as respiratory

support and is mainly used for post op

cardiac case

(V-V) ECMO Advantage offer (V-A) ECMO

• Eliminate the potential for arterial embolization and ischemia

• Arterial ligation or repair is unnecessary

• Improve the blood flow and oxygenation to pulmonary circulation.

• No hemodynamic effects

CANNULATION TECHNIQUE

• Open

• Semi-open

• Percutaneous

CANNULATIONCANNULATIONInternal jugular vein

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Subclavian vein & Right atrium

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Femoral vein

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One site

- A double lumen cannula is inserted into the internal jugular vein

- Only one site for venous access

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Two different sites

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• Veno-Arterial (VA) ECMO

provides cardiac as well as respiratory support and is

mainly used for post op cardiac case

CANNULATIONCANNULATION

Internal jugular vein and the common

carotid artery

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Right atrium and ascending aorta

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Femoral vein and artery

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A Left atrial pressure line can be utilized to

monitor the LA pressure

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In situations where ECMO support is anticipated

- Chest will be left open and covered by a Silastic patch

- Purse-string sutures will be left snared in place

- Standby preprimed pump will be kept in ICU

CANNULATIONCANNULATION PROBLEMS PROBLEMS

• Threading the venous catheter

• Vein division

• Proximal vein lost in mediastinum

• Lack of venous return

• Intrathoracic vein perforation

ComplicationComplication

• Vascular injury( tear, intimal dissection, perforation).

• Obstruction (kinking, positional).

• Misplacement( AI, afterload LV failure).

• Bleeding.• Recirculation.

Thank You