This study is a retrospective work involving the review of patients who were scheduled for VP or LP shunt in Siriraj Hospital, Mahidol University, Thailand. The sample size calculation was based on the rule of thumbs of the logistic regression comprising 18 risk factors. The incidence of post-induction hypotension according to our institution's pilot study November 2019-January 2020) was 47%. With 10% addition for missing data and other possible reasons, the sample size was 426. The primary objective of the study is to report the factors associated with post-induction hypotension in iNPH patients undergoing VP or LP shunt procedures. Our secondary objective is to determine the incidence of post-induction hypotension in these patients.

Inclusion Criteria:

• Elective cases of iNPH scheduled for VP and LP shunt
• Patients aged > 18 years old

Exclusion Criteria:

• Emergency cases

- Elective cases of iNPH scheduled for VP and LP shunt whose medical records were acquired from the hospital's central database.