Bariatric Electrical Impedance Tomography

Insel Gruppe AG, University Hospital Bern30 enrolled

Overview

This study investigates under controlled conditions the variation of poorly ventilated lung units (silent spaces) in obese patients scheduled for laparoscopic bariatric surgery in the perioperative phase.

Eligible patients with written informed consent, scheduled for laparoscopic bariatric surgery. As for standard of care no premedication will be given for bariatric patients. Patients will be monitored according the local standard. Thoracic electrical impedance tomography measurements (each measurement will last 1 min) will be performed at the following time points: before induction of the anaesthesia; before the surgical procedure when the induction is terminated and recruitment manoeuvers have been performed; after the termination of the surgical procedure; before transport to the Post anaesthesia Care Unit (PACU); before the discharge from the PACU after 2 hours of monitoring. An additional thoracic electrical impedance tomography measurement (duration 1 min) will be performed before discharge at home. For this, resulting potential differences are measured, and impedance distribution sampled at 30 Hz will be calculated by an automated linearized Newton-Raphson reconstruction algorithm. Relative change in poorly ventilated lung regions (silent spaces) and end-expiratory lung impedance (EELI) and measures of ventilation inhomogeneity such as the global inhomogeneity index will be calculated.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Anesthesia

Interventions

Electrical impedance tomography during anesthesiaOTHER

Thoracic electrical impedance tomography measurements ( min each) will be performed at the following time points: before induction of the anaesthesia; before the surgical procedure when the induction is terminated and recruitment manoeuvers have been performed; after the termination of the surgical procedure; before transport to the Post anaesthesia Care Unit (PACU); before the discharge from the PACU after 2 hours of monitoring. An additional thoracic EIT-measurement will be performed before discharge at home. For this, resulting potential differences are measured, and impedance distribution sampled at 30 Hz will be calculated. Relative change in poorly ventilated lung regions (silent spaces) and end-expiratory lung impedance (EELI) and measures of ventilation inhomogeneity will be calculated using customised code (Matlab R2021a, The MathWorks, Nattick, Massachusetts, USA).

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * BMI \>40 * ASA physical status 1 to 4 * Over 18 years of age providing written informed consent Exclusion Criteria: * BMI \<40 * Known severe pulmonary hypertension, * Need of home oxygen therapy * Known heart failure * Suspected, or known recent pulmonal infections

Locations (1)

University Hospital Bern

Bern, Switzerland

Outcomes

Primary Outcomes

Proportion of poorly ventilated lung areas (silent spaces)

Proportion of poorly ventilated lung areas (silent spaces) by using electrical impedance tomography (EIT) before the discharge from PACU (two hours after admission to PACU).

Time frame: 2 hours