Functional Residual Capacity

70 Pages·2010·1.55 MB·English

by  Cecilia Olegård

Functional Residual Capacity

Development of new monitoring techniques
for critically ill patients

Cecilia Olegård

Department of Anaesthesiology and Intensive Care
Institute of Clinical Sciences at Sahlgrenska Academy
University of Gothenburg
Gothenburg, Sweden
2010
© Cecilia Olegård
ISBN 978-91-628-8122-1
http://hdl.handle.net/2077/22292

Printed by Intellecta Infolog AB
Gothenburg, Sweden 2010

ii
To Magnus

Rickard ,Fredrik and Henrik

iii
iv
Functional Residual Capacity
Development of new monitoring techniques for critically ill patients

Cecilia Olegård

Institute of Surgical Sciences,
Department of Anaesthesiology and Intensive Care.
Sahlgrenska University Hospital, Gothenburg University, Sweden.

Abstract

Functional residual capacity (FRC) and end-expiratory lung volume (EELV) are important para-
meters for respiratory monitoring in critically ill adult and paediatric patients. Until now we have
lacked clinically useful methods to measure these lung volumes. In this thesis two methods for
bedside measurements of FRC in mechanically ventilated patients have been developed and eva-
luated. The first method (FRC ) is based on quantification of metabolic gas fluxes of O and CO
flux 2 2
during a short apnoea. The second method is a modified nitrogen wash-out/wash-in technique
(FRC ) based on standard monitoring equipment. The possibility to combine measurements of
N2
EELV with a tool to assess lung mechanics by measuring volume dependent compliance (VDC)
was also assessed.

Methods: Baseline exchange of oxygen and carbon dioxide was measured using indirect calorime-
try for both the FRC and the FRC method. End-tidal (~alveolar) O and CO concentrations
flux N2 2 2
were obtained before and after a few seconds of apnoea, and FRC was calculated according to
flux
standard wash-out/wash-in formulae taking into account the increased solubility of CO in blood
2
when tension is increased during apnea. The FRC was calculated using changes in inspiratory
N2
and end-tidal gas concentrations breath-by-breath after a small step-change for inspiratory oxygen
(FO). These methods were validated both in mechanically ventilated patients and in lung models.
I 2
The FRC technique was also tested in small children and infants both perioperatively, using a
N2
Mapleson -D system, and in the ICU. A lung injury animal model was used to investigate the
effects on FRC and VDC by lung lavage and after three different lung recruitment manoeuvres
N2
(RMs).

Results: The FRC measurement methods showed good precision and reproducibility. Experimen-
tal acute lung injury caused by lung lavage resulted in large decreases in EELV and VDC. There
were differences in the response to RMs in individual animals demonstrated by combined meas-
urements of changes in EELV and volume-dependent compliance.

Conclusions: New methods have been developed for measurements of lung volumes using stan-
dard monitoring equipment only. The FRC method makes it possible to measure lung volumes in
N2
realtime at the bedside in combination with volume-dependent compliance. Combined measure-
ments of changes in lung volume and compliance could be helpful to define responders and non-
responders to lung recruitment manoeuvres, and to increases in positive end-expiratory pressure
(PEEP). These new monitoring tools may help clinicians to tailor ventilation to the individual
patient and hopefully attenuate the risk for ventilator induced lung injury.

Keywords: FRC, functional residual capacity, EELV, end expiratory lung volume, volume depen-
dent compliance, VDC, acute respiratory failure, recruitment manouvre, PEEP
ISBN 978-91-628-8122-1 http://hdl.handle.net/2077/22292
v
CONTENTS

ABBREVIATIONS AND EXPLANATIONS .......................................................................ix
LIST OF PUBLICATIONS .................................................................................................viii
INTRODUCION ...................................................................................................................... 1
Mechanical ventilation in adult ARF/ALI and ARDS .................................................... 1
Mechanical ventilation in children and infants with acute respiratory failure ............ 2
Stress and strain ................................................................................................................ 3
Functional residual capacity (FRC) and end expiratory lung volume (EELV) ............ 3
Methods for FRC/EELV measurements ......................................................................... 4
Dilution techniques ....................................................................................................... 4
Closed-circuit method ............................................................................................. 4
Helium dilution ....................................................................................................... 4
Open multiple breath procedures ............................................................................ 5
Sulfur hexafluoride (SF ) ....................................................................................... 5
6
Direct measurements of N washout by N analysis in adults ................................. 5
2 2
Direct N washout measurements of FRC in children and infants .......................... 6
2
Indirect measurements of N washout by O and CO analysis ............................... 7
2 2 2
Computed Tomography Scan, CT scan ......................................................................... 8
Body plethysmography ................................................................................................. 8
Assessment of lung recruitment in acute lung injury ..................................................... 9
The clinical problem ........................................................................................................ 10
AIM OF THIS THESIS ........................................................................................................ 11
METHODS ........................................................................................................................ 12
Ethical issues .................................................................................................................... 12
Patients and animals ....................................................................................................... 12
Patients (I,II,III) .......................................................................................................... 12
Animals (IV) ............................................................................................................... 13
Experimental models ....................................................................................................... 14
Mechanical lung models (I,II,III) ................................................................................ 14
Lung injury model (IV) ............................................................................................... 15
Measurements and calculations ..................................................................................... 15
Paper I ........................................................................................................................ 15
Paper II,III ................................................................................................................... 19
Paper IV ...................................................................................................................... 23
Airway gas analysis ......................................................................................................... 23
Experimental procedures ................................................................................................ 24
Paper I ........................................................................................................................ 24
Lung model ................................................................................................................. 24
Patients ........................................................................................................................ 24
Paper II ........................................................................................................................ 25
Lung model ................................................................................................................. 25
Patients ........................................................................................................................ 25
Paper III ........................................................................................................................ 26
Lung model ................................................................................................................. 26
Patients ........................................................................................................................ 26
Paper IV ........................................................................................................................ 27
Animals ....................................................................................................................... 27
vi
Statistics ........................................................................................................................ 28
RESULTS ........................................................................................................................ 29
Paper I ........................................................................................................................ 29
Lung model ................................................................................................................. 29
Patients ........................................................................................................................ 29
Paper II ........................................................................................................................ 30
Lung model ................................................................................................................. 30
Patients ........................................................................................................................ 31
Paper III ........................................................................................................................ 32
Lung model ................................................................................................................. 32
Pediatric perioperative and intensive care FRC measurements ................................... 33
Paper IV ........................................................................................................................ 34
DISCUSSION ........................................................................................................................ 37
Methodological considerations ....................................................................................... 37
O2 and CO2 dissociation curves and fluxes of gases .................................................... 38
In search of a reference method for measuring FRC/EELV ....................................... 38
Breath-to-breath gas analysis (Papers II, III) ............................................................... 39
Indirect calorimetry and high FIO2 (Papers II,III) ..................................................... 40
N2 solubility (Papers II,III) ............................................................................................ 40
Nitrogen wash-out/wash-in technique in small children and infants .......................... 41
The Brody formula for oxygen consumption in paediatric measurements................. 42
The “first breath” conundrum ....................................................................................... 43
Clinical perspective ......................................................................................................... 44
Bedside measurements of FRC/EELV ........................................................................... 44
Ventilator induced lung injury ....................................................................................... 45
The baby lung .................................................................................................................. 45
Stress and strain .............................................................................................................. 46
Monitoring alveolar recruitment ................................................................................... 47
CONCLUSIONS .................................................................................................................... 49
ACKNOWLEDGEMENTS .................................................................................................. 50
REFERENCES ...................................................................................................................... 51
POPULÄRVETENSKAPLIG SAMMANFATTNING ...................................................... 58
PAPERS I-IV

vii
LIST OF PUBLICATIONS

This thesis is based on the following papers, which will be referred to in the text
by their Roman numerals I-IV.

I. Stenqvist O, Olegård C, Söndergaard S, Odenstedt H, Karason K,
Lundin S. Monitoring functional residual capacity (FRC) by
quantifying oxygen/carbon dioxide fluxes during a short apnea.
Acta Anaesthesiol Scand 2002; 46:732-739

II. Olegård C, Söndergaard S, Houltz E, Lundin S, Stenqvist O.
Estimation of functional residual capacity at the bedside using
standard monitoring equipment: A modified nitrogen
Wash-out/wash-in technique requiring a small change of the
inspired oxygen fraction.
Anesth Analg 2005; 101:206-12

III. Olegård C, Söndergaard S, Pålsson J, Lundin S, Stenqvist O.
Validation and clinical feasibility of nitrogen wash-in/wash-out
functional residual capacity measurements in children.
Acta Anaesthesiol Scand 2009; Oct 15 [Epub ahead of print]

IV. Olegård C, Söndergaard S, Odenstedt H, Lindgren S, Lundin S,
Stenqvist O.
Volume-dependent compliance and resistance during three
different recruitment maneuvers.
In manuscript 2010.

viii
ABBREVIATIONS AND EXPLANATIONS

ALI acute lung injury F O end-tidal oxygen fraction before
ET 2pre
ARDS acute respiratory distress syn- apnoea
drome FN inspiratory N fraction
I 2 2
ARF acute respiratory failure FN inspiratory N fraction at end of
I 2end 2
BV baseline ventilation washout
Cfin compliance at final part of tidal FN inspiratory N fraction at start of
I 2ini 2
volume washout
Cini compliance at initial part of tidal FO the inspiratory fraction of oxy-
I 2
volume gen
Cmid compliance at middle part of FRC functional residual capacity
tidal volume FRC alveolar functional recidual
alv
CO carbon dioxide capacity
2
CT computed tomography FRC FRC measured by O /CO
flux 2 2
ΔEtCO end-tidal CO change fluxes
2 2
ΔFRC functional recidual capacity FRC FRC measured by nitrogen
N2
change wash-out/wash-in
EELV end-expiratory lung volume He Helium
F fraction I:E inspiratory to expiratory ratio
ICU intensive care unit
FECO2 mixed expiratory fraction of CO2
kPa kilo Pascal
FEO2 mixed expiratory fraction of O2 LCBCO2 carbon dioxide in lung capillary
FETCO2 alveolar/end-tidal fraction of blood caused by apnoea
carbon dioxide MBNW multiple breath nitrogen wash-
F CO end-tidal carbon dioxide fraction out
ET 2post
after apnoea N2 nitrogen
FETCO2pre end-tidal carbon dioxide fraction O2 oxygen
before apnoea P pressure
FETN2 end-tidal N2 fraction Palv alveolar pressure
F O end-tidal O fraction PCRM pressure control recruitment
ET 2 2
F O end-tidal oxygen fraction after manoeuvre
ET 2post
apnoea PCV pressure controlled ventilation
P dynostatic alveolar pressure
dyn
ix
PEEP positive end expiratory pressure VCV volume controlled ventilation
P expiratory pressure V physiological deadspace,
exp D
P inspiratory pressure VDC volume-dependent compliance
insp
PSVC Pressure Regulated Volume VDR volume dependent resistance
Control ventilation
V expiratory minute ventilation
E
RDS respiratory distress syndrome
V expiratory volume
Rfin resistance at final part of tidal exp
volume middle VI inspiratory minute ventilation
Rini resistance at initial part of tidal V inspiratory volume
insp
volume middle VILI ventilator induced lung injury
RM recruitment manoeuvre ViCM vital capacity recruitment ma-
Rmid resistance at middle part of tidal noeuvre
volume middle VN volumes of nitrogen
2
RQ respiratory quotient VO volume of O
2 2
SD standard deviation
VO oxygen consumption
2
SF sulfur hexafluoride
6
SLRM slow, low-pressure recruitment VCO carbon dioxide production
2
manoeuvre
VO amount of O taken up from the
2apnea 2
t apnoea time
apne alveoli during apnea
TV expiratory alveolar tidal volume
AE VO volume of O in the FRC before
2pre 2
TV inspiratory alveolar tidal volume
AI the apnea
V volume
V CO breath-by-breath CO exchange
T 2 2
V flow V tidal volume
T
VAE expiratory alveolar minute VTO2 breath-by-breath O2 exchange
V N breath-by-breath N exchange
T 2 2
ventilation
ZEEP zero end-expiratory pressure
VA inspiratory alveolar minute
I
ventilation
VCO carbon dioxide production
2
VCO amount of CO which was
2apnea 2
excreted into the alveoli during
apnea
VCO volume of CO in the FRC
2pre 2
before the apnea
x