changes in the respiratory pattern during induction of general

CHANGES IN THE RESPIRATORY PATTERN DURING INDUCTION OF GENERAL
ANESTHESIA: OUR EXPERIENCE IN DEVELOPING A SOFTWARE FOR THE
MATHEMATICAL ANALYSIS OF THE CAPNOGRAM
L.Floris*, L.Pistidda*, G.Sales*, C.Liperi*, L.Pulina°, L.Brazzi*
*Dipartimento di Scienze Chirurgiche, Microchirurgiche e Mediche, Università degli Studi di Sassari;
°Dipartimento di Scienze Politiche,Scienze della Comunicazione e Ingegneria dell’Informazione, Università
degli Studi di Sassari
Background
Morphological changes of the capnographic waveform provide information about the patient's
breathing pattern earlier than SpO2 and EtCO2.
Computer analysis of the morphological variations of the capnogram would permit a greater
accuracy providing an additional tool for the anesthesiologist.
Objectives
To develop an analysis software aimed to evaluate the curves of the capnogram not only from a
“morphological” but also from a mathematical point of view.
Methods
We acquired in continuous basal clinical parameters and
expired CO2 values, provided by a monitor
(Capnostream20, Oridian Medical), of twenty patients
(ASA I -II, aged >18) undergoing elective head and neck
surgery with general anaesthesia; data were analyzed
with Excel.
From CO2 values we obtained the caphnografic curves;
waveform were analyzed with a software we developed
for their mathematical study (pic.1)
Pic.1
Results
The software analyzed the slope variations of the phases of capnogram and the angles between
them.
Pic.2 shows a progressive increase of the
angles2 (alpha) and 3 (beta), with a higher
slope of the plateau.
Angle4 is progressively reduced with a
decreased slope and an extension of the
inspiratory phase.
Angle1 remains virtually unchanged.
Pic.2
Conclusions
The study demonstrates that a mathematic analysis of the curves through a software permits,
compared to the simple morphological analysis, a greater accuracy in detecting the changes in the
patient’s breathing pattern.
This grants an additional warning tool for the anesthesiologist during his activities in the operating
room and in NORA.