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      <P align="center"><B><font color="#0c2d83" size="+2">Literature Reviews</font></B> 

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      <P><FONT COLOR="#0c2d83"><b>The sitting position for neurosurgery in children: 
        a review of 16 years experience.</b></FONT> <br>
        <I>Br J Anaesth 88 (1): 12-17 (2002)</I> 
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<P><B>Summary:</B> Prior studies in children undergoing sitting craniotomy have revealed an incidence of 
venous air embolism (VAE) of 29-69%.  The authors performed a retrospective analysis of all 
sittings craniotomies done at the Great Ormond Street Hospital for Children, London, from 1982-1998.  
VAE was defined as a fall in end-tidal 
Pco<SUB>2</SUB> of  &gt; 0.4 kPa (3 torr).  Hypotension was defined as a fall 
of systolic blood pressure &gt; 10% of baseline.  Ninety percent of all children had the same 
anesthesiologist and 99% of operations were performed by the same neurosurgeon.  Besides routine monitors, 
arterial lines were placed, and a capnography monitor was set to alarm when 
Pco<SUB>2</SUB> became 0.5 kPa below baseline.  Preoperative screening echocardiography, central lines, precordial dopplers, and PEEP 
were not utilized.
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<P>A total of 407 procedures were reviewed (376 posterior fossa masses, 15 pineal surgeries, 16 
foramen magnum decompressions).  The mean age was 5 years.  There were a total of 43 episodes of VAE in 
38 patients (9%).  No episodes of VAE were noted in infants younger than 1 year.  VAE was 
accompanied by hypotension in 9/43 episodes (21% of VAE episodes, 2% of all cases).  The time of occurrence 
of VAE was usually during opening or closing of the dura. There was no increase in 
post-operative morbidity in patients diagnosed with intraop VAE.  Management of VAE included immediate 
bilateral jugular venous compression, covering the surgical field with saline-soaked swabs, IV fluids, 
and ventilation with 100% O<SUB>2</SUB>.
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<P><B>Comment:</B> This study shows that in skilled hands, use of the sitting craniotomy position for children 
is safe.  The authors suggest the incidence of VAE is probably lower in children than adults and that 
this may be related to higher dural sinus pressures in children.  It is difficult to compare studies on 
this subject because of differences in the sensitivity of the techniques used to detect VAE (TEE &gt; Doppler 
&gt; Etco<SUB>2</SUB>).  Despite its relative insensitivity, this study demonstrates the clinical utility of closely 
monitoring Etco<SUB>2</SUB> during sitting craniotomy.  Although I will not abandon the use of a pre-cordial Doppler, 
the authors make a good case for not routinely placing central catheters.  This study implies that the 
<P><U>response</U> to likely VAE may be of critical importance, and good communication between surgeon 
and anesthesiologist is part of optimizing that response.
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<P><B>Reviewed by </B>Samuel Golden, MD


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