Influence of HFNO on Spontaneous Ventilation in Patients of Different ASA Risk During Analgo-sedation for Vitrectomy

Summary

Pars plana vitrectomy is minimally invasive endoscopic procedure which is usually performed in moderate analgo-sedation given by anesthesiologist combined with topical anesthesia and retrobulbar or Subtenon block performed by surgeon. Intravenously applied anesthetics can often lead to slower breathing rate or cessation of breathing which introduces risk of low blood oxygen level despite careful adjustment of anesthetics' dose and application of standard low-flow nasal oxygenation (LFNO). Respiratory instability is often accompanied by circulatory instability manifested by disturbances of heart rate and blood pressure. LFNO provides maximally 40% inspired fraction of oxygen and can cause discomfort of a patient due to coldness and dryness of inspired gas.

On the other hand, high-flow nasal oxygenation (HFNO) can bring up to 100% of inspired oxygen fraction to patient, providing noninvasive pressure support of 3-7 cmH2O in patients' upper airway which ensures better oxygenation especially in higher anesthesia risk patients. Because of carrying warmed and humidified air/oxygen mixture via soft nasal cannula, HFNO is better tolerated by patients.

In this trial investigators will compare effect of HFNO to LFNO during intravenously applied standardized analgo-sedation given for vitrectomy in normal weight patients of low and high anesthesia risk.

Investigators hypothesize that normal weight patients of low and high anesthesia risk, whose breathing pattern is preserved, receiving HFNO vs. LFNO during standardized analgo-sedation for vitrectomy will be more respiratory and circulatory stable, preserving normal blood O2 and CO2 level, breathing pattern, heart rate and blood pressure.

Conditions

• Noninvasive Ventilation
• Respiratory Insufficiency
• Moderate Sedation
• Hypoxia
• Airway Management
• Vitrectomy

Interventions

DEVICE

Low-flow nasal oxygenation (LFNO) ASA I

Active comparator LFNO: O2 flow 5 L/min, FiO2 40%

DEVICE

Low-flow nasal oxygenation (LFNO) ASA II

Active comparator LFNO: O2 flow 5 L/min, FiO2 40%

DEVICE

Low-flow nasal oxygenation (LFNO) ASA III

Active comparator LFNO: O2 flow 5 L/min, FiO2 40%

DEVICE

High-flow nasal oxygenation (HFNO) ASA I

Experimental HFNO: O2 flow 40 L/min, FiO2 40%

DEVICE

High-flow nasal oxygenation (HFNO) ASAII

Experimental HFNO: O2 flow 40 L/min, FiO2 40%

DEVICE

High-flow nasal oxygenation (HFNO) ASA III

Experimental HFNO: O2 flow 40 L/min, FiO2 40%

Sponsors & Collaborators

• Clinical Hospital Centre Zagreb

  collaborator OTHER

• University of Split, School of Medicine

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2019-08-01

Primary Completion

2020-02-01

Completion

2020-08-01

Countries

• Croatia

Study Locations