One Lung Ventilation: Difference between revisions

* <u>Introduction</u>   - Pediatric thoracic anesthesia is more challenging than Adults

* <u>Important measurements</u>[[File:Measurements.png|left|thumb]]

* <u>Pediatric Airway Diameters</u>Average neonatal trachea has an AP diameter of about 4.3 mm for both males & females Trachea grows uniformly in males and females to about 14 mm at the age of 15 yrs old  At this time, female trachea stops growing, but male trachea continues to grow to 16–18 mm by age of 19.  trachea is elliptical in shape, with the transverse diameter being larger than AP diameter  Sizing of airway devices should be based on the smaller (anteroposterior) diameter.  

* <u>Devices & Approaches</u>1- Single-Lumen Tracheal Tube Simplest option, can be used at any age but mostly used for the very young patients < 6 m.o.s  Placing SLT in the right mainstem bronchus is easier than the left due to the less acute angle that it takes off from the trachea  '''Pros:''' Simple/ Quick  '''Cons:''' potential for inadequate collapse of operative lung / inability to suction the operative lung / inability to deliver (CPAP) to operative lung / Missing the RUL when doing right mainstem intubation  <br />2- Bronchial Blockers  Many types, include vascular balloon catheters, the Uniblocker (Fuji Systems), and Arndt endobronchial blocker, Cohen, EZ blocker  Catheters may be placed either within (Coaxial) or external to the TT (Extra-axial)  Use of Bronchoscope is imperative during placement of BB  Deflation of the operative lung occurs by absorption atelectasis and requires a considerably longer period of time  <br />Vascular Devices:  Fogarty arterial embolectomy catheter, and Miller atrio-septostomy catheter  No central channel for deflation or CPAP to the operative lung  Both has angled tip which allows the user to direct the catheter to the desired bronchus.  Ballon cuffs are high pressure, low volume and should be only inflated and positioned under FOB to avoid damaging bronchial mucosa  <br />Arndt blockers:  Has four-way adapter, and comes with swivel connector that allows ventilation during placement  The blocker has a 2 ml cuff and lower inflation pressures.  Has an inner lumen that contains a flexible nylon wire that extends along the length of the catheter and terminates as a flexible loop  This loop slides over the bronchoscope and aids in positioning.  Once the nylon guide is removed, it cannot be reattached, which may make repositioning attempts difficult should the blocker fall out of place.  Once the nylon wire is removed, the central lumen may be used for suctioning and CPAP  <br />Sizing of BB and FOB for SLTs  Same sizing principles apply when using BB and FOB together as to when sizing FOB alone  Typically in pediatrics, two sizes of bronchial blockers are used—5 and 7 Fr  BB sized by Fr, divide by 3 to know the size in mm  <br />When using the coaxial technique, the Arndt bronchial blocker works well.  However, when using the parallel technique, a bronchial blocker with a stiffer shaft and angled tip should be used.  This can be accomplished with the 5 Fr Fuji Uniblocker, or a vascular device such as a 5 Fr Fogarty embolectomy catheter, or a 5 Fr Miller atrio-septostomy catheter  <br />3- Univent Tubes  TT that has a bronchial blocker within a separate lumen.  If double-lung ventilation is required again, the bronchial blocker may be deflated and withdrawn into the tracheal lumen again  Available Univent pediatric sizes: 3.5 and 4.5 mm ID  Size of a Univent TT refers to the ID, where the OD will be much larger than the equivalent sized SLT  Main disadvantage is that cross-sectional diameter of the ventilation lumen is smaller in order to accommodate the blocker lumen.  This increases airway resistance and also limits the size of fiberoptic bronchoscope used to facilitate positioning  Narrow age range where this method is the preferred: 6–8 yrs  <br />4- Double Lumen Tubes Considered Gold standard in ages > 8 yrs  The equation of Size =Age×1.5+14  can help to estimate the sizing needed  Smallest DLT size is a 26 Fr, which is generally suitable for children 8–10 yrs of age

* <u>Recommended method for each age group</u>