Breathing systems and the anaesthetic machine

Zsolt Molnár

SZTE, AITI

• Irish anaesthetist (1888-1986)– Endotracheal tube, anaesthesia (The Magill endotracheal tube, oral & nasal

designs)– An anaesthetic breathing system (Magill circuit and expiratory valve)– Intubating Forceps– Laryngoscope a straight bladed version– Catheter mount (endotracheal tube-to-circuit connector)– Endotracheal tube connectors, oral & nasal versions– Magill tracheal spray (glottis anaesthetic)– Single-lung anaesthesia– Endobronchial tubes and bronchial blockers– Bobbin flowmeters

Sir Ivan Whiteside Magill

• British anaesthetist

• Cardiff 1952– Mapleson WW. The elimination of rebreathing in various semi-closed

anaesthetic systems. Br J Anaesth 1954; 26: 323–32

– Mapleson WW, Mushin WW. Relaxant action in man: an experimental study. Anaesthesia 1955; 10: 265–78, 379–90

Mapleson WW. Br J Anaesth 2004; 93: 319-321.

WW Mapleson

• „Auld” definitions• Open-, semi open-• Semi-closed, closed-systems

• „New”: Mapleson systems 1954• Rebreathing• Non-rebreathing

Introduction

• VT• 4-7 ml/kg

• VD• 2-3 ml/kg

• Peak inspiratory flow (PIF)• At rest: 20-30 l/min

• Breathing cycle• Inspiration – expiration – expiratory pause

Physiolgy refreshment course

• Parts• FG inlet• Rezervoire balloon• Pop-off valve

• Efficacy• FGF – to prevent CO2 rebreathing

Mapleson systems

• Parts• Disc• Sharp edge • Spring

• Safety opening P• 60-70 cmH2O

Pressure relieving valve

• „Magill attachment”• >110 cm• FGF = 1 x VA (70ml/kg/m)• VA = ?• PIF = ?• Monitoring: capnograph

Mapleson A – spont. breathing

• A: normal

• B: rebreathing

• C: diaphragm movements

• D: cardiac oscillation

• E: sampling error

• F: bronchospasm

Molnár ‘99

A B

C D

E F

pCO2

Capnography

History

• Birth of: intensive therapy, blood gas machine, and the use of Mapleson C

• 1952 Coppenhagen: polio-epidemic

• 31 patients – 21 dead within 72 hrs

• Bjorn Ibsen (1915-2007)• Waters: To-and-fro

Lassen HCA. 1956. Management of poliomyelitis. In HCA Lassen Management of life threatening poliomyelitis. Copenhagen, 1952-1956; E.S. Livingstone Ltd, London

SZEGEDI INTENZÍVES TALÁLKOZÓ 2010

SZINT

Water’s circuit

Molnár ‘99

Mask, ET-tube

O2

Valve

Rezervoire baloon

• E: Ayre’s T-piece• Spont: FGF = 1.5 x VA

• IPPV: FGF = 3 x VA

• F: Jackson-Rees• Monitoring• PEEP

Mapleson E and F

T-piece

Molnár ‘99

T-piece

Inlet

Outlet

A happy chapy on T-piece

Molnár ‘99

The anaesthetic machine

• Cylinders (O2, N2O, Air)• Rotameters• Vaporizers• Breathing circuit• CO2 absorber• Safety:

• FiO2 + alarm• O2 bypass• Pressure relieving valve

Rebreathing system (circuit)

CO2 absorber

• CaOH2, NaOH, sylicate

• CO2 + 2NaOH Na2CO3 + H2O + heat• Na2CO3 + CaOH2 2NaOH + CaCO3

Rotameters

Rotameters

10

4

8

πpp

l

RI

• Gas specific• Safety features:

• Min FiO2 = 0.3• FiO2 alarm

Vaporisers ages ago…

• Inside the circuit• Small vaporizing surface• Quick cooling

…and today

• Outside the circiut• Well insulated containers

…and today

• Outside the circiut• Well insulated containers• Agent safe

…and today

• Outside the circiut• Well insulated containers• Agent safe• Heat compensation

• Mapleson systems: advantages• Simple, cheap, safe• Low resistance• Good for practice

• Mapleson systems: disadvantages• Non-economic• Not environment friendly• High heat and humid loss

Summary

Get to know your equipment!