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PPV. P ositive P ressure V entilation by: dr.behzad barekatain Assistant professor of pediatrics neonatalogist Isfahan university of medical science. PPV via 1.ambobag - PowerPoint PPT PresentationTRANSCRIPT
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.
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