Comparison of inferior venacava collapsibility index with internal jugular vein collapsibility index for predicting post induction hypotension in general anaesthesia

Background

More than  300 million1 surgeries are performed  every  year and arterial  hypotension  is a common occurrence in  patients  undergoing  surgery  under general  anaesthesia  which  is  associated  with  unfavourable  patient outcome .An  arterial  blood  pressure  below  the  lower  limit  of  autoregulation  can  lead  to ischemia2  of  vital  organs  ie  heart , brain  and  kidney  leading  to  myocardial  infarction or injury, stroke  and  acute  kidney  injury. These  can  lead  to prolonged  hospital  stay with  increased  cost  and  can  lead to  mortality. Post induction  hypotension(PIH) is  defined  as hypotension which occurs  after  induction  of  anaesthesia  or  from  induction  till  beginning of  surgical  incision3 . The incidence of PIH  has  a   range   from  10.3%  to  66.3% which may be because of the differencecs in criteria used to define hypotension. This   post  induction   hypotension (PIH)    is   a  modifiable  factor  which has an impact on  the clinical   outcome   of  the  patient   and  so  it  is  important  that   we  prevent  it   at  all  cost. This  may  become  possible  if  we  are  able  to  correctly  predict  it  before  its occurrence.  Factors  which   influence  the  occurrence  of  PIH  are  the  volume  status  of  the  patient , the  drug  and   dose  of   the  anaesthetic  drug  used  for  induction, administration  of  GA  in  combination  with  neuraxial  block,  lower  SBP  at  the  time  of  induction , elderly  patient  ,emergency surgery preoperatively volume depleted and  diabetes mellitus.

IVC collapsibility index (CI)   by ultrasound  provides  a  dynamic  non invasive  point  of  care  estimate  of   relative  intravascular  volume.  It has been  shown  to  be  a  safe  and  non invasive  technique  to  measure  fluid  responsiveness  in  ICU 4.  IVC CI is  predictive  of  volume  responsiveness    with  a  pooled  sensitivity  of  75%  and   specificity  of  82%  in  mechanically  ventilated  patients   and   a  pooled  sensitivity  of  71%  and  specificity  of  81%  in  spontaneously  breathing patient 5 IVC CI  is  calculated  by  the   formula [maximum diameter  on  expiration-(minimum   diameter  on  inspiration/ maximum  diameter  on  expiration].

There  are  a  few  studies  which  have  been  done  to look  at  IJV diameter , cross sectional  area   and  their  collapsibility  index  by  ultrasonography  as  an  indirect  means  of  CVP.  Killu et al  showed  that  IJV  CI    of   > 39%  had  a  sensitivity  of 87.5%   and   specificity  of  100%  in  identifying  hypovolemia  in  ICU  patients.

Purpose

To check if the IVCCI or the IJVCI can predict hypotension before it occurs in patients undergoing surgeries under GA