Positive Pressure Ventilation by: dr.behzad barekatain Assistant professor of pediatrics neonatalogist Isfahan university of medical science.

Positive Pressure Ventilation by:

dr.behzad barekatain

Assistant professor of pediatrics

neonatalogist

Isfahan university of medical science

PPV via

1.ambobag 2.ventilator(mechanical ventilation)

Definition & Importance most common approach for treatment of

res.failure in both term &pre-term neonate

Classification Volume-controlled ventilator Pressure-preset ventilator

VOLUME vs PRESSURE VENTILATOR

Pressure ventilator is preferable because of: 1.greater simplicity of design & compact design 2.lower cost 3.simple to operate 4.same pressure in each breathe 5.type of pul.dis in neonate & better responsive

to pressure ven.

CONTROL (fixed)VARIABLE Volume: in volume-controlled ventilator Pressure:in pressure-preset ventilator PHASE (changeable)VARIABLE Triggeringاغازگر :شروع دم را کنترل میکند *

.time triggering>>>>>in IMV mode (ALS,IVH) .patient triggering>>>>in SIMV OR A/C

mode(sensor) Limitting* محدود کننده فاکتورهای تنفسی یا حداکثر مجاز :وقتی ونتیالتور به حداکثر

.مجاز آن متغییر برسد دریچه های تخلیه را باز میکند Cycling*پایان دم را کنترل میکند

.Volume-cycled .Time-cycled .Pressure-cycled

IMPORTANT ISSUSES IN SUCCESSFULLY RES.CARE

1.operation by device(hardware)>>>5% 2.principles of physiology(software)>>>95% 3.other pripheral issues .infection control .nutritional support .fluid & electrolyte management .comfort & pain relief .assessment of circulation .tempreture

Procedure for initiating M.V 1.electrical connection 2.O2 & air gas source to provide adequate

prssure(50 psi) 3.all connection must fit securely 4.tube & circuit shoud be specific for ventilator 5.humidification system Low>>>necrotizing tracheobronchitis High>>>overhydration & increase resistant 6.temperature 35 to 36 (+,- 2) Low>>>bronchospasm High>>>airway inflamation

VENTILATOR CONTROLS .fio2 .pip .peep .rate .flow .Ti ,Te,I/E ratio .assist sensitivity .termination sensitivity .alarm setting .graphic monitoring .map .other(psv,manual breath,hf mode,demand flow)_

FIO2 O2 is the Most commonly used DRUGin nicu Inadequate O2 >>>hypoxemia & neurologic

injury Exessive VARIATION in O2 adm>>>ROP High level of O2>>>BPD Depended on disease(eg;MAS or PH) or

associated condition(eg;duct depended heart disease)

SO Accurate measurment of O2 (via puls

oximetry or ABG is mandatory in NICU care

Major factor in determining tidal volume(PIP_EDP) in pressure preset vent

Starting level depend on:GA,W,type & severity of disease,lung compl,Resistance,time constant,mode of ventilator,...

Check before & after attachment to patient(2-3 cmh2o)

Appropriate PIP can be judged on examination(chest expantion) and ABG analysis

The lowest PIP that adequately ventilated neonate is optimal

PEEP stabilizes & recruits lung volume PEEP improves compliance PEEP improves V/Q matching PEEP is selected by physician but maybe

altered by other variable .increase rate>>>auto PEEP .decreaseTe>>>increase PEEP .increase airway resistant>>>increase PEEP SO Add to the selected level>>>air traping &

ALS Elevation of PEEP maybe beneficial in pulm

hemorrage

TIME CONSTANT:RESISTANT.COMPLIANCE

IN RDS:>>>compliance decrease>>>T.C decrease

IN MAS:>>>resistant increase>>>T.C increase

Minute ventilation=rate . Vt>>>↑ Rate >>> ↑ alveolar ventilation >>> ↓PCO2

Controlled by directly selecting in time-cycled ventilator

↑ ↑ rate short TE incomplete expiration gas trapping decresed compliance, intrinsic PEEP ↓VT ↑PCO2

Optimal rate:40-60 with Ti:0/3_0/4 sec because of low TC in most pul.disease such as RDS

High rate in PH & low rate in weaning

NORMAL:1/3 – 1/1 The major effect on oxygenation ↑ ratio or even reversed I/E (Ti longer than

Te) ↑ PO2 but its effect is less than change in PIP and PEEP.

CO2 elimination is usually not altered by changes in I/E ratio .

Reversed I/E ratio may lead to increase in the incidence of pneumothorax,co2 retention,decrease co,increase PVR,

Reversed I/E ratio maybe used in CLD because of long TC.

I/E<1/3 maybe used in weaning or MAS

The speed of flow to reach PIP. Min : at least 2 times the minute volume(./2-

1 l/min) .Most pressure ventilators operate at flows of 4-10 L/min.

Low flow (./5-3)>>sine wave>>↓ risk of barotrauma but dead space ven>> co2 retention

High flow >>square wave>> ↑risk of alveolar rupture

Very high flow >>decrease Vt secondry to increased turbulance in high resistant,small diameter ET tube>>Reintubated with bigger ET tube.

Wave Forms Sine wave:more closely to normal

spontaneous breathing

Square wave:provide a higher map than do sine waveform if identical PIP used because the PIP is reached more rapidly with square waves.

MAP:

(PIP_PEEP).(Ti/Ti+Te)+PEEP

Definition of Res.failure Two or more criteria from the following clinical &

laboratory categories:.clinical:1.Retraction(intercostal,supraclavi,suprasternal)2.Grunting3.rate>604.Central cyanosis5.Intractable Apnea6.Decrease activity & movment.laboratory:1.Paco2>60 mmhg2.Po2<50 mmhg or O2sat<80%(Fio2=1.0)3.PH<7.25

An aggressive (but gentle)early approach often is preferable in neonates,regardless of their disease.

RDS SCORE: 1.rate(<60:0,60-80:1,>80:2) 2.cyanosis(no in room air:0,no under hood:1,yes

under hood:2) 3.intercostal retraction(no:0,mod:1,severe:2) 4.air exchange(good:0,decreased:1,no:2) 5.grunting(no:0,with stethos:1,without stethos:2)<3:O2+follow up4-6:NICU care + supportive management6-8:cpap>8:intubation+MV

One should think about weaning every day. Do not increase ventilator days

unnecessory First decrease PIP & Fio2 on A/C mode and

when reach to 12 &40% switch back to SIMV mode and then reduce the RATE.

After infant stable for 4-8h & ABG suggest decreasing vetilatory needs.

Before initiation of weaning obtain CXR. Graphic monitoring & PFT and diuresis is

usefull in gauging the capacity for weaning. Appropriate caloric balance

If at any point : FiO2 increased to >60%, ↑spontaneous breathing or distressed with accessory muscle use, agitation or lethargic, hypercarbia weaning should be paused and the support level increased .

Fio2<40%,RATE:10,PIP:10-12 NPO for 4 hrs before extubation. CXR before & 2 and 24 h after ext. The procedure is carried out by 2 nurses. Give prolonged sigh of 15-20cmh2Owhile the

ET tube is extracted. Aspiration of NG tube before extubation ETT & oropharyngeal suctioning to remove

secretion and good gag reflex Prepare emergency equipments (O2, suction,

airway, humidifier, emergency intubation equipments)

NPO for 4-6 h after extubation OR until the infant can make an audible cry.

In <1500gr use CPAP after extubation for 2-3 day.in >1500gr placed under oxyhood or nasal o2 with an O2 5% greater.

Watch for several minute after ext.

Increasing hoarseness Respiratory stridor Decrease in saturation(optimal:92-96%) Increase work of breathing Increase respiratory rate if yes:reintubated infant and retry 2 day if 2 attempts failed: flexible fibreoptic

bronchoscopy if negative:dexamethazon (./5mg/kg/day divided

in 2dose 48 h before continuing 24 after ext.(methylxanthines?)

if several attempts failed:consider laryngotracheomalasia,maybe needs tracheostomy

DOPE D : Displacement O : Obstruction P : Pneumothorax E : Equipment failure