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

 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

 Minute ventilation=rate. Vt>>> ↑ Rate >>> ↑ alveolar ventilation >>> ↓ PCO 2  Controlled by directly selecting in time- cycled ventilator  ↑ ↑ rate  short T E  incomplete expiration  gas trapping  decresed compliance, intrinsic PEEP  ↓ V T  ↑ PCO 2  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.

 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 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