The purpose of this study is to find out which of the variables related to fluid responsiveness (e. g., perfusion index [PI], pleth variability index [PVI], pulse oximetry plethysmographic variance [ΔPOP]) can best predict hypotension during induction of anesthesia.

Propofol is a widely used intravenous agent for induction of anesthesia in children aged 3 years and more. A well-known adverse effect of propofol is hypotension, which can be properly dealt with hydration and/or administration of inotropics and vasopressors. However, severe hypotension during anesthetic induction may not be immediately cured if anesthesiologist should concentrate on ventilation of the patient. Since pediatric patients have smaller reservoir for oxygen supply and perfusion to various organs of the body, delayed handling of severe hypotension may result in irreversible damage to the vital organs.

Hypotension during anesthesia is caused, though not entirely, by dehydration. There are a variety of non-invasive variables that are related to the severity of dehydration, but which of the variables can best predict anesthesia-induced hypotension in pediatric patients. In this study, we will measure the preoperative values of non-invasive variables related to fluid status, and find out which of them are most closely related to the occurrence of hypotension during anesthesia induction.

Inclusion Criteria:

• Children aged 3-6 years
• Scheduled to undergo elective surgery under general anesthesia

Exclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status classification III or more

• Contraindication of laryngeal mask airway (LMA) insertion:

  (1) Esophagitis, gastritis, peptic ulcer, pyloric or intestinal stenosis, history of upper gastrointestinal tract surgery, body mass index [BMI] > 30, expected anesthesia time > 2 hours)

• Arrhythmia

• Left ventricular failure (ejection fraction < 40%)

• Congenital syndromes which are known to affect cardiopulmonary function

• Use of inotropics/vasopressors before anesthesia

• History of allergic reaction to drugs used in general anesthesia

Children aged 3-6 years