Hypercapnic Spontaneous Hyperpnoea and Recovery From Sevoflurane Anesthesia

University Health Network, Toronto44 enrolled

Overview

The rate of elimination of inhalation agent is directly proportional to the degree of alveolar ventilation. Using Isocapnic Hyperpnoea (IH) device, it is possible to maintain constant end-tidal CO2 with increased minute ventilation. This is achieved by passively adding a flow of CO2 to the inspirate in proportion to increases in ventilation above the baseline. In animal and human studies IH shortens the time of awakening from isoflurane and sevoflurane anesthesia when manual positive pressure ventilation is applied. IH device could be used for spontaneous hyperpnoea as well. The investigators want to compare recovery times from sevoflurane anesthesia in patients with application of hypercapnic spontaneous hyperpnoea (HSH) versus the standard anesthesia protocol (controls). 44 patients ill be randomized to either HSH facilitated recovery, or conventional recovery (controls).The time intervals from the end of anesthesia (turning off the vaporizer) until recovery milestones will be recorded.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Enrollment

Conditions

Anesthesia Surgery

Interventions

Standard Anesthesia management for post surgical patientsOTHER

The O2 flow on the anesthetic machine will be set at 15 L/min. Ventilatory assistance will be performed to maintain O2 saturation \>97% and end tidal CO2 at 35-45mmHg.

Hypercarbic Spontaneous HyperpnoeaDEVICE

Patient will be disconnected from the anesthetic circuit and connected to the resuscitation bag attached to the IH system. With O2 flow of 2 L/min patient will be gently ventilated until recovery of the spontaneous ventilation. After starting spontaneous ventilation basal O2 flow will be adjusted to keep ETCO2 in range of 50-60 mm Hg or minute ventilation of 15-17 L/min, whichever occurs first.

Eligibility

Sex: FEMALEMin age: 18 YearsMax age: 80 Years

Medical Language ↔ Plain English

Inclusion Criteria: * elective gynecological surgery * age 18-80 * ASA I-III * informed consent Exclusion Criteria: * ASA IV-V, * contra-indications to sevoflurane anesthesia or other anesthetics included in the protocol * history of cardiac or respiratory disease * intracranial pathology * alcohol or drug abuse * psychiatric illness and/or medications

Outcomes

Primary Outcomes

Time from the end of anesthesia to the readiness for post-anesthesia care unit (PACU) discharge.

Time frame: End of anesthesia (turning off the vaporizer) until readiness for PACU discharge, approximately 30 minutes to 2 hours

Secondary Outcomes

Comparison of pain and sedation scores

Time frame: End of anesthesia (turning off the vaporizer) to PACU discharge, approximately 30 minutes to 2 hours