A study to investigate central feedback control in breathing pattern of weaning

A Study to Investigate Central Feedback Control in Breathing Pattern of Weaning

,

Meng-Lun Hsueh',

Jen-Chien

Chien, Fok-Ching Chong,Huey-Dong Wu'

'Institute of Electrical Engineering, National Taiwan University. Taiwan, R.0.C 'National Taiwan University Hospital

Abrrran- Weaning the discontinuation of mechanical ventilator, outcome. An elevated respiratory frequency is often the sign it can be regarded as a stress processll]. It will trigger central of impending respiratory failure. T a c h y p e a is common neural feedback response to maintain the balance of our bods index of intubation for resniratorv failure and index ~~~ ~~~~~ of .. and environments. This phenomenon is ususlly easily observed weaning failure [4],

Additional information on respiratory center function can in breathing pattern. Weaning will caused B rhythmic change in

breathing panern. We collect data before and after weaning,

he obtained by an alternative approach to breathing pattern weaning success and weaning failure in clinical environment.

Statistics1 analysis metbodr are used to investigate this rhythm analysis. The Of ventilation can be svstem. In this DaDer. we showed that there is obviouslv component whereas tidal volume can he participated into change. it also provides valunble information about rerpiratoT panitioned into respiratory frequency and tidal \ d u m e

. .

.

diflerence in normalized standard deviation of after weaning data minus belore weaning data between weaning success and weaning failure groups. The success groups also have lower

flow and inspiration time. Respiratory flow rate,-especially the mean inspiratory flow rate, is employed as a measure resDiratow drive.

value @ellow to zero) in after minus before weaning d a h than failure groups. This central feedback control phenomenon in breathing pattern may be used in good weaning index to predict weaning success and failure.

'ne

ciassic methods for analyzine breathing pattern all focused on sing,e or mean ,,slue,

For

example, in rapid shallow index value above I05 is considered to h e potential

Kavn,d,v merhsniral ventilator. rhvthmic reaninp. weaning failwe and in tidal volulne \*slue less than 300 mi

breathing pattern

I INTRODUCTION

~ - ~ , ~~~~~~ -,

suggests an unsuccessful weaning outcome. Little attention is given to rhythm change. Series data may give more

Recently, mechanical ventilation is widely used in Intensive Care Unit and plays an important role in lifesaving. However, it may he associated with numerous complications. It should be discontinued as soon as possible. Many weaning indices have been developed to predict the successful discontinuation of mechanical ventilator. However, determination of the optional time to discontinue ventilator support can he very difficult. The existing weaning indexes include breathing panern, arterial blood gas and lung mechanisms. With the help for these weaning indexes, the reintubation rate (weaning failure) still range form 7 to 19%

and patients of weaning failure also have high mortality [2]. Analyzing breathing pattern can provide valuable information about respiratory system. In a patient with intact respiratory center (preserved brain stem function), which is as usual in most patients, respiratory center output is most closely associated to patients stress and physiologic condition. Many weaning parameters, such as frequency, tidal volume, rapid shallow breathing index, are related to respiratory center output.

Attention has been focused on the pattern of breathing as a guide to weaning outcome, i.e. respiratory frequency, tidal volunie and rib cage-abdominal motion. It is suggested that respiratory muscle fatigue might he a primary course of failure to weaning [2]. Patients who failed a weaning trail had considerable breath-to-breath variation in relative contribution of the rib cage and abdomen to tidal volume [3]. Many methods have been used to analyze breathing pattern and respiratory central output. The most famous one is the rapid shallow index that can predict better weaning

information than spot data. A time-series, breath-by breath plot of respiratory frequency and tidal volume in a patients who failure a weaning trial showed a rapid and fluctuated respiratory frequency.

Without exfernal stimulation. breathing panern is relative stable hut not clockwise regdarity. The regularity of breathing panern is not studied. From clinic observation, the breathing pattern is rhythmic change in normal or lightly stressed patients, but it is more fluctuate in impending respiratoly failure patients. There are few studies concerned about breathing pattern changing after weaning. In this paper, we use signal process methods (spectral analysis) to study the breathing pattern (rhythm) change before and after weaning. Then after quantification, we try to find out the difference between success and failure weaning group. 11. METHOEOLOGY

Our experiment is bellow: 1)Patients Selection

W e select twenty-nine patients, who is mechanically ventilated for more than 24 hours in Intensive Care Unit and prepared for weaning. The timing of weaning is according to the general weaning guideline and decided by the primary care physician who does not involve in this study.

?)Weaning Protocol and Data Collection

For each patient, general care and sputum suction, a fixed orifice flow sensor is connected into endotracheal tube orifice. The signals of flow are collected by Ventra!& respiratory monitor with sample rate of 100 Hz. The patient breaths form T-tube with F i 0 2 5% higher than the ventilator setting, which supply by an all-purpose nebulizer. The signal

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will he collected at least

5 min

after 30

minutes

of T-tube

TABLE

I lndependcni t- FCai"rC tesi Extr,,tio"- t Narmnlizcd C Standard Deviation

trial, No therapy or physical interniption is allowed in this .Peak Pu~~crRrliooiln.plnlonTimc bc1sii.n hulurEmddi...~rninC

period. The patient's basic information includin_e sex, age,

n F T ; " " " I

causes

of

respiratory failure, ventilator day and weaning

outcome will be recorded. The failure of weaning is defined Success Group Failure Group & n o r w ~ ~ n i " r # mi",,< mn1r,ra

lnrpiiarory Time Expiratory Timc Respiratory Timc Breathing Pattcrn Variability

,...

".

I_._.

_. Weaning Training hours of weaning. The usage of noninvasive ventilator is not

3)Signal Process 0.00ea

as intubation or reuse of mechanical ventilator within 48 regarded as weaning failure.

The VentrakO raw data is shown as fig 1.We process the data as shown in fie2. First. we use a filter to eliminate error

(0.083) (0.127)

-0.039 0.004e

-

and noise. Then, the inspiratory time, expiratory time, cycle time and breathing pattern variability. four physiology parameters, will be identified by zero-crossing method. 4)Statistical Analysis Method

Breath-by-breath base variables will be calculated. These include mean and standard deviation. Normalized standard deviation (standard deviatiodmean) is used to investigate neural control of weaning stress.

Mean: Standard Deviation: I " ((0.071) Breathinq Pattern 1-0 043 r " " ' " " " " i r a t o w

1;::~;;

1;;;;1

10-oo8j

TimeICycle Time) Breathing Pahem variability IExsDiralon 10.039) 10.1 17'1

However there is obviously difference in the difference value of'after minus before weanine normalized standard drviatton 111 four paramcierr bemeen' u ' c a n ~ r p s u x e s s and

roups In \\emin&! suicesj groit tnr norm~lizcd %~r$dcviaiion I S Iniwr than \\canine h I u e proins. and

_-

- .

the values are all below zero.

IV. DISCUSSION .3 CONCLUSIONS

Accordin to the results, \ye consider that weaning trainine mav%elo to tneser oatlent's automatlc breathme. The

central'

neuial feedbkk 'control will make breathitg pattern highly identicall It also means that lhe disturbance will be drasticallv smalzr. Thus. w e can consider hreathine

pattern as a good-weanine index.

-

In this oaver. we iiwestieate hreathine oanem usine

normalized.ita'ndard deviation a f after minus~b<fore weanini data to distinguish success and failure yeanirig groups. This can orovide some information of resoiratory svstem to the

_{. .}

medical persons.

REFERENCES

[ l ] Cohen CA. Zagelbaum G. Gros:; D. Roussos C. Macklem

PT. Clinical manifestations of inspiratory muscle fatigue.

American Journal qfA4edicine. 73(3):308-16, 1982 Sep.

83019736

[2] Estehan A. Alia I. Tobin MI. Gil A. Gordo F. Vallverdu

I. Blanch L. Bonet A. Vazquez A. de Pablo R. Torres A. de La Cal MA. Macias S. Effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation. Spanish Lung Failure Collaborahm Group.

American Journal of Remiraton' 6: Critical Care Medicine.

...- 159(2):5 12-8, 199<Feb.&99126673

[3] Tobin MI. Perez W. Guenther SM. Semmes BJ. Mador MJ. Allen SJ. Lodato R F Dant.zker DR. The pattern of

A,,,erican R ~ + , , , of

111. KESULTS

In our analysis, no matter inspiratory time, expiratory sigificant difference is found for normalized standard time, cycle time, and breathing panem variability, no deviation before and after weaning. this also in weaning

breathing during successful

ResDiro,orvDiseme. 134(6):1

1.8,

1986 D ~ ! ~ , 8,074370

unsucce:ssful trials of

from mechanical

, ,

success and failure groups. _{[4]'Tobin MJ, Perez W, Guenther SM et al. The pattern of} breathing during successful and unsuccessful trials of waning

from mechanical ventilation. A m Rev R':spi Dis 1986; 134:llll-1118.