Pulmonary Function by Litter Position

April 6, 2026 updated by: University of California, San Francisco
A litter is often needed to extract a person from an austere environment like the wilderness or from confined, urban spaces. A horizontal litter is generally assumed to be better for patient care, but often makes for a more difficult, if not impossible, evacuation from some settings such as confined space rescue, cave rescue, or wilderness rescue when the litter must be moved up or down a cliff with an undercut edge. A litter in a vertical orientation is easier to move in these situations, which may expedite movement towards definitive care. In some wilderness rescue circles, the mantra is that movement IS definitive care. It is already known that lying flat on the ground negatively affects pulmonary function compared to a sitting baseline.1 It is possible that a vertically oriented litter is better for a subset of patients with respiratory issues than a horizontal litter. The investigators hypothesize that pulmonary function measured by FEV1, FVC, and FEV1/FVC, is better in simulated patients in a vertically oriented litter compared to a horizontally oriented one.

Study Overview

Status

Enrolling by invitation

Intervention / Treatment

Detailed Description

Objective To quantify changes in pulmonary function tests (PFTs) based on litter position.

Hypotheses:

  • Compared to sitting baseline, all PFTs in the litter will have decreased forced vital capacity (FVC) and 1 second forced expiratory volume (FEV1).
  • Compared to lying down, persons straight upright and pitched forward will have better forced vital capacity (FVC) and 1 second forced expiratory volume (FEV1).
  • We do not hypothesize any changes in FEV1/FVC.

Study Design This randomized crossover study will use twelve healthy volunteers. All subjects will do baseline sitting pulmonary testing. Experimental order is balanced to avoid any training effects. Choice of sequence will be by random selection of envelope.

Methods Once consented, included subjects will do baseline sitting measurement of FEV1 and FVC which will give FEV1/FVC. Each subject will then be secured in a Ferno-Washington Model 71 litter wearing their own type 2 or 3 harness, or in a UL tested CMC ATOM Global Harness (California Mountain Corporation, Santa Barbara, CA) meeting ANSI Z359.11-2014 and NFPA 1983-2017 standards, if they don't have their own. The person will be secured with double Vs from the litter sides to the harness and footloops supporting them so their weight is on their feet and only minimally on the harness (if vertical). This process is consistent with industry standards for securing a patient in the litter and follows the specific model of the National Cave Rescue Commission.3 See figure 1 Prior to being secured in the litter the patient will do sitting baseline FEV1 and FVC with an NDDD spirograph. Once there is baseline data the subject will be secured in the litter. The investigators will then repeat spirometry, pulse, and blood pressure in a horizontal position (see figure 2), in a vertical position (see figure 3), and pitched slightly forward in a position that results from a Pike and Pivot rigging for raising up past a difficult cliff edge (see figure 4). The subject will get a rest period in their preferred position until pulse returns to within 5 beats of baseline.

Litter suspension will be with a four-legged litter spider when horizontal, with a high bridle tied directly to the litter head for the full vertical position, and from a low bridle in Pike-and-Pivot formation when pitched forward. The litter will be lifted into position with a 3:1 mechanical advantage system tied to an anchor. No matter the position, the lowest point of the litter will be no more than 6 inches off of the ground. The system will be configured for immediate lower for any expressed concern. The PI (RM) is a technical rescue instructor for the National Cave Rescue Commission and Assistant Training Officer-Technical Rescue for Fresno County search and rescue. The Co-PIs (SS and SD) are on the rope team of Fresno County search and rescue. Each is well versed in rope systems, anchor selection, and patient packaging.

Study Type

Interventional

Enrollment (Estimated)

12

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

    • California
      • Fresno, California, United States, 93701
        • UCSF Fresno

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • 130-310 pounds

Exclusion Criteria:

  • Significant cardiac or pulmonary diseae

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: Supportive Care
  • Allocation: Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Flat
Secured in a flat litter
Testing basic pulmonary function in three positions in a rescue litter, compared to sitting baseline
Active Comparator: Vertical
Secured in a vertical litter
Testing basic pulmonary function in three positions in a rescue litter, compared to sitting baseline
Active Comparator: Pitched forward
Secured in a litter leaning forward
Testing basic pulmonary function in three positions in a rescue litter, compared to sitting baseline
Placebo Comparator: Baseline
Sitting baseline pulmonary function
Testing basic pulmonary function in three positions in a rescue litter, compared to sitting baseline

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Forced Vital Capacity
Time Frame: Immediately
Measurable lung volume on expiration
Immediately

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
FEV1
Time Frame: Immediately
Air volume exhaled in 1 second
Immediately

Collaborators and Investigators

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

Investigators

  • Principal Investigator: Roger B Mortimer, MD, UCSF - Fresno

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)

February 15, 2026

Primary Completion (Estimated)

April 1, 2026

Study Completion (Estimated)

April 1, 2026

Study Registration Dates

First Submitted

September 19, 2025

First Submitted That Met QC Criteria

October 17, 2025

First Posted (Actual)

October 21, 2025

Study Record Updates

Last Update Posted (Actual)

April 8, 2026

Last Update Submitted That Met QC Criteria

April 6, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

  • 25-45106

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Deidentified data will be submitted to a statistician

IPD Sharing Time Frame

1/1/26 to 6/1/26

IPD Sharing Access Criteria

Roger Mortimer, MD Sarah Davis, DO Sue Spano, MD Amanda Mortimer, PhD

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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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