Physiology of Lung Collapse Under One-Lung Ventilation: Underlying Mechanisms (PLC-OLV)

May 11, 2020 updated by: Jean Bussières, Laval University
Lung isolation technique and one-lung ventilation (OLV) are the mainstays of thoracic anesthesia. Two principal lung isolation techniques are mainly use by clinicians, the double lumen tubes (DLT) and the bronchial blockers (BB). The physiology of lung collapse during OLV is not well described in the literature. Few publications characterized scant aspects of lung collapse, only with the use of DLT and sometime in experimental animals. Two phases of lung collapse have been described. The first phase is a quick and partial secondary to the intrinsic recoil of the lung. The second phase is the reabsorption of gas contained in the alveoli by the capillary bed. The investigators plan to describe the physiology of the second phase of lung deflation using of DLT or BB, in a human clinical context.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Lung isolation and one-lung ventilation (OLV) have been used for more than 60 years, principally via double lumen endotracheal tubes (DLT). Since the beginning of the 21st century, modernisation of bronchial blockers (BB) has favoured their more frequent use. Meanwhile, video assisted thoracoscopic surgery (VATS) has increased, becoming the standard for the majority of intra-thoracic pulmonary surgeries.

Lung collapse during OLV undergoes two distinct phases. The first phase occurs at the opening of the pleural cavity and corresponds to a quick but partial collapse of the lung due to its intrinsic recoil. This phase probably ends when small airways are closed. Thereafter, the second phase, a slower one, corresponds to the reabsorption, by the capillary bed, of gas contained into the alveoli. The speed of this reabsorption depends on the solubility of the gas contained in the alveoli.

Intriguingly, the physiology of lung collapse under OLV remains poorly understood, especially with the use of BB. Theoretically, many aspects of lung isolation may influence lung collapse, including the ventilation strategy before OLV, the timing and the lung isolation devices being used. While oxygen at 100% is widely used for ventilation before OLV, the timing of initiation of lung isolation varies from centers to centers. Indeed, the most conservative will begin the lung isolation just before the opening of the pleural space, whereas others begin the lung isolation following the appropriate positioning of the patient and confirmation that the lung isolation device is properly positioned by fiberoptic bronchoscopy (FOB) examination. Therefore, the period between initiation of lung isolation and pleural opening may vary from a few minutes to >30 minutes. The mechanic of lung isolation differs between DLT and BB and consequently the physiology of lung deflation may be different. When using DLT, the lumen that corresponds to the collapsed lung is disconnected from the ventilator and is continuously in communication with the ambient air. When using BB a bronchial cuff is inflated within the main bronchus following a 30 seconds apnea period, allowing the initial lung deflation to be mediated by elastic lung recoil. After this initial phase, the only communication with ambient air is through the small (2 mm) and long internal (67 mm) channel, which is completely different from the larger lumen of the DLT.

Rapid and complete lung collapse is essential during lung isolation for VATS otherwise; there is no alternative available for the surgeon to get proper view of the pulmonary hilum. Previous studies suggested that BB allow a less effective lung collapse than the one obtained with DLT. However, the authors recently documented that the use of BB with its internal channel occluded creates a statistically significant shorter time to complete lung collapse during VATS compared to DLT (36.6 ± 29.1 vs 7.5 ± 3.8 min; p<0.001). In contrast to the previous studies, the authors used off-line review videos recorded during the surgery to obtain a more objective evaluation of the complete lung collapse time which probably reflected the second phase of lung deflation. Although, our definition of lung collapse was very strict, meaning complete collapse of all the lung areas, graded using a standardized visual scale and chart. However, authors do not have any data to explain why this internal channel occlusion may have some positive impact. The authors hypothesized that their results could be explained by the optimisation of the reabsorption phases following enhanced atelectasis by gas reabsorption (phase 2) after bronchial blockade. This latter hypothesis is supported by a pilot observation that ambient air (FiO2 at 0.21) was "sucked up" within the collapsing lung when using DLT to a greater extent than with the use of BB (unpublished data). The presence of ambient air (21%) in the alveolar space may likely slowing subsequent gas reabsorption compared to intra-alveolar 100% O2 . However, these hypotheses remain to be confirmed.

The investigators proposed this study to update the knowledge about lung collapse with the actual lung isolation devices: DLT and BB. This protocol will describe the lung collapse physiology and allows getting data for the elaboration of further studies.

Thus the present hypothesis is that during the second phase of lung collapse, the inflow of air through the lumen of the non-ventilated lung of the DLT is greater than through the internal channel of the BB, in the course of lung isolation for OLV.

The main objective of this study is the gas volume quantification (GVQ) coming from ambient air towards the alveoli space of the non-ventilated lung during OLV with the use of DLT and BB. These measurements will be performed from the beginning of OLV until 60 minutes after, meaning approximatively 45 minutes after the opening of the pleura by the surgeon. The secondary objective is the intra-pulmonary pressure measurement (IPM) in the non-ventilated lung with the use of DLT and BB during the same period.

Study Type

Interventional

Enrollment (Actual)

40

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
      • Québec, Canada
        • Institut Universitaire de Cardiologie et de Pneumologie de Quebec

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • elective unilateral lung resection (anatomical segmentectomy, lobectomy or pneumonectomy) for lung cancer

Exclusion Criteria:

  • anticipated difficult mask ventilation or intubation
  • pleural pathology
  • previous thoracic surgery
  • previous sternotomy
  • previous chemotherapy or chest radiotherapy
  • severe COPD or asthma (FEV1 ≤ 50%)
  • active or chronic pulmonary infection
  • endobronchial mass
  • tracheostomy

Post randomisation exclusion criteria :

  • severe desaturation before or during the observation period
  • any clinical situation precluding the use of one of the lung isolation device
  • air leak at the level of bronchial isolation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Intra-pulmonary pressure determination
A pressure tubing catheter will be connected to the luerlock adaptor of the bronchial blocker (BB) or to the adaptor located on the side of the occluding system mounted at the extremity of the double lumen tube (DLT). The catheter will then be connected to a differential pressure transducer (AD Instruments, Colorado Springs, CO, USA), allowing direct visualisation of the bronchial pressures. Along with intra-bronchial pressure, esophageal pressure will also be measured to eliminate the pressure generated by the positive pressure of the ventilated lung (Adult esophageal balloon catheter, Cooper Surgical, Trumbull, CT, USA). Intra-bronchial pressures will be measured at end-inspiration and end-expiration.
Device: Double lumen tube
Either gaseous volume quantification or intrapulmonary pressure measurements will be done in patients randomized in the L-DLT group.
Other Names:
  • Left-sided double lumen tube (BronchoCath, Mallinkrodt)
Device: Bronchial blocker
Either gaseous volume quantification or intrapulmonary pressure measurements will be done in patients randomized in the BB group.
Other Names:
  • Bronchial blocker (Fuji Uniblocker, Fuji Systems)
Other: Volume determination
A one-liter bag (Roxon, Etobicoke, ON, Canada) will be filled precisely with 300 mL of air with the use of a calibrated syringe of 3 liters (Hans Rudolph inc, Shawnee, Kansas, United States), through a three-way valve (Hans Rudolph inc, Shawnee, Kansas, United States). Following the filling of the bag, it will be connected to the non-ventilated lumen of the double lumen tube (DLT) or to the bronchial blocker (BB) through the three-way connector. At the end of the observation period, the collector bag will be connected to the calibrated syringe and will emptied from its residual volume.
Device: Double lumen tube
Either gaseous volume quantification or intrapulmonary pressure measurements will be done in patients randomized in the L-DLT group.
Other Names:
  • Left-sided double lumen tube (BronchoCath, Mallinkrodt)
Device: Bronchial blocker
Either gaseous volume quantification or intrapulmonary pressure measurements will be done in patients randomized in the BB group.
Other Names:
  • Bronchial blocker (Fuji Uniblocker, Fuji Systems)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Quantification of Gas Volume Coming From Ambient Air Towards the Alveoli Space of the Non-ventilated Lung During OLV With the Use of DLT and BB.
Time Frame: From the beginning of OLV until 60 minutes
From the beginning of OLV until 60 minutes

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Measurement of Intra-pulmonary Pressure in the Non-ventilated Lung With the Use of DLT and BB
Time Frame: From the beginning until 10 minutes of OLV
Intra-pulmonary pressure measured from initiation of OLV to pleural opening were similarly analyzed using a two-way ANOVA. Two experimental factors, one associated to the comparison between two groups (DLT versus BB), factor fixed and one associated to the comparison among results from the time periods (0 to 10 minutes), factor fixed with interaction terms between the fixed factors were defined. The data was analyzed using a repeated mixed model. An autoregressive covariance structure was used to consider the dependency among repeated measurements.
From the beginning until 10 minutes of OLV

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Laval University

Investigators

  • Principal Investigator: Olivier Moreault, MD, Laval University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 1, 2016

Primary Completion (Actual)

December 1, 2016

Study Completion (Actual)

December 1, 2016

Study Registration Dates

First Submitted

September 28, 2016

First Submitted That Met QC Criteria

September 28, 2016

First Posted (Estimate)

September 29, 2016

Study Record Updates

Last Update Posted (Actual)

May 26, 2020

Last Update Submitted That Met QC Criteria

May 11, 2020

Last Verified

May 1, 2020

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IUCPQ 21299

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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