Respiratory, Limb Muscle Properties, and Physical Performance in Adult Lung Transplant Recipients

The goal of this observational study is to evaluate respiratory and limb muscle properties in adults awaiting lung transplantation and determine how these measures relate to physical performance, symptoms, and recovery after transplantation. Respiratory and limb muscle weakness may contribute to impaired mobility, frailty, and delayed postoperative recovery, but their specific role in lung transplant candidates is not well understood. Participants will undergo muscle ultrasound imaging at weekly basis, respiratory and limb strength testing, physical performance assessments, and symptom questionnaires once before and after transplantation. Researchers will also collect information from medical records regarding intensive care unit stay, hospital length of stay, rehabilitation participation, and postoperative recovery outcomes.

Study Overview

• Status: Recruiting
• Conditions: Lung Transplantation; End Stage Lung Disease
• Intervention / Treatment: Diagnostic test: Respiratory and Limb Muscle Assessment

Detailed Description

Respiratory and peripheral muscle dysfunction are common in individuals with advanced lung disease awaiting lung transplantation. Muscle weakness, atrophy, and impaired contractile function may contribute to reduced physical performance, frailty, symptom burden, and delayed recovery after transplantation. Although physical function tests provide an overall assessment of performance, they provide limited information regarding specifics of respiratory and limb muscle impairments. Ultrasound imaging is a noninvasive and reliable method to evaluate muscle structure, quality, and contractile function and has been associated with clinical outcomes in several critically ill populations, including prolonged mechanical ventilation, longer intensive care unit (ICU) and hospital stays, and increased morbidity.

The purpose of this study is to characterize respiratory and limb muscle properties before and after lung transplantation and determine how these measures relate to physical performance, patient-reported outcomes, and postoperative recovery. Respiratory muscle function will be assessed using maximal respiratory pressure testing and ultrasound evaluation of the diaphragm and abdominal muscles. Limb muscle function will be assessed using ultrasound imaging and strength testing of the quadriceps muscles. Physical performance, frailty, dyspnea, pain, fatigue, anxiety, and ICU/hospital-related outcomes will also be evaluated.

The central hypothesis of this study is that respiratory and limb muscle weakness, atrophy, and impaired contractile function are associated with poorer physical performance, greater symptom burden, and delayed postoperative recovery after lung transplantation. To test this hypothesis, a prospective observational study of adult lung transplant candidates will be conducted from their hospital admission to their post-operative day 14. Participants will undergo serial ultrasound imaging assessments before transplantation and during the early postoperative period along with symptom questionnaires; while respiratory and limb strength testing, functional assessments, symptom questionnaires will be collected on the first and last day of research visit. Collection of ICU and hospital outcomes will occur from the electronic medical record. The central hypothesis will be evaluated through the following aims:

Aim 1: Evaluate relationships between respiratory strength and ultrasound measurements of contractile dysfunction in candidates awaiting lung transplant.

Aim 2: Characterize the associations between respiratory and limb muscle properties (atrophy, strength), physical performance, and patient-centered outcomes (dyspnea, frailty, pain, fatigue, and anxiety) in pre-lung transplant candidates.

Aim 3: Identify the influence of preoperative respiratory and quadriceps contractile function on the early postoperative mobility progression in lung transplant recipients Aim 4: Determine relationships between postoperative diaphragm dysfunction and functional status at hospital discharge

• Study Type: Observational
• Enrollment (Estimated): 36

Contacts and Locations

• Study Contact: Name: Barbara K Smith, PhD, PT; Phone Number: 352-294-5315; Email: bksmith@ufl.edu
• Study Contact Backup: Name: Wagner Souza Leite, PT; Phone Number: (352) 273-6085; Email: wagnersouzaleite@ufl.edu

Study Locations

• United States
  • Florida
    • Gainesville, Florida, United States, 32608
      • Recruiting
      • UF Health Shands Medical Center
      • Contact: Mindaugas Rackauskas, MD, PhD; Phone Number: (352) 265-5470; Email: mindaugas.Rackauskas@surgery.ufl.edu
      • Contact: Mohammad A. Aladaileh, MBBS, MRCSI, EBCTS, FRCSIC-Th; Phone Number: (352) 265-5470; Email: maladaileh@ufl.edu
      • Principal Investigator: Barbara K Smith, PhD
      • Sub-Investigator: Wagner Souza Leite, PT
      • Sub-Investigator: Sandra Morgan, RN, PhD
      • Sub-Investigator: Jessica Cornman, PT
      • Sub-Investigator: May Smith-Hublou, PhD, CCC-SLP
      • Sub-Investigator: Ushna Khan, MD
      • Sub-Investigator: Amir M Emtiazjoo, MD, MSc
      • Sub-Investigator: Marc O Maybauer, MD, PhD, EDIC, FCCP, FACC, FAS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Adult lung transplant candidates receiving care at UF Shands hospital. Participants are individuals with advanced lung disease undergoing evaluation and treatment while awaiting lung transplantation in the hospital. The study population includes adults who are able to complete study assessments of respiratory and limb muscle function before transplantation and during the early postoperative recovery period.

Description

Inclusion Criteria:

• 18 years or older.
• Hospitalized as potential candidates for single- or bilateral-lung transplant surgery.
• Hemodynamically stable for out-of-bed mobilization

Exclusion Criteria:

• Baseline cognitive impairment
• History of previous solid organ transplantation or thoracic surgery
• Existing phrenic nerve lesion
• Lower limb amputation or fracture
• External fixators or open wounds of the lower extremities
• Diagnosed neuromuscular disorder.
• Morbid obesity (body mass index >45 kg/m²).
• Any other medical condition that, in the opinion of the investigators, would make participation unsuitable.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Adult Lung Transplant Candidates; adults enrolled for in-hospital evaluation for lung transplant and listed for surgery who undergo serial assessments of respiratory and limb muscle properties before transplantation and during the early postoperative period. Assessments include ultrasound imaging, respiratory and limb strength testing, physical performance measures, patient-reported outcomes, and collection of clinical outcomes from the medical record.

Diagnostic test: Respiratory and Limb Muscle Assessment; Participants undergo serial assessments of respiratory and limb muscle structure and function before and after lung transplantation. Assessments include ultrasound imaging of the diaphragm, rectus abdominis, and quadriceps muscles; respiratory muscle strength testing; handgrip strength testing; knee extension strength testing; physical performance measures; and patient-reported outcome questionnaires.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Diaphragm structure	Diaphragm thickness (unit of measure: mm) assessed by ultrasonography	Weekly from baseline through postoperative day 14 (±2 days)
Respiratory Muscle Strength	Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) obtained during maximal respiratory efforts against a one-way valve.	Baseline and at postoperative day 14 (±2 days)
Abdominal muscle structure	Rectus abdominis muscle thickness (measurement unit: mm) assessed by ultrasonography.	Baseline through postoperative day 14 (±2 days)
Limb muscle strength	Handgrip force and knee extension force measured using dynamometry.	At the first baseline visit and postoperative day 14 (±2 days)
Rectus femoris thickness	Rectus femoris muscle thickness (unit of measurement: mm) assessed by ultrasonography.	Baseline through postoperative day 14 (±2 days)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Five-Repetition Sit-to-Stand Test	Time required to complete five sit-to-stand repetitions as a measure of physical performance. Retrieved from the medical record.	Baseline and hospital discharge
Frailty Status	Frailty assessed using the Clinical Frailty Scale (CFS), a 9-point scale ranging from 1 to 9, where 1 = Very Fit and 9 = Terminally Ill. Higher scores indicate greater frailty and a worse clinical status.	Baseline and at postoperative day 14 (±2 days)
patient-reported symptoms	Dyspnea, physical fatigue, and pain assessed using an 11-point numeric rating scale ranging from 0 to 10, where 0 indicates no symptom and 10 indicates the worst symptom severity ever experienced. Higher scores indicate worse symptom burden.	Baseline and at postoperative day 14 (±2 days)
Six-Minute Walk Distance	Distance walked during the Six-Minute Walk Test (6MWT), retrieved from the medical record.	Baseline and at hospital discharge, an average of 3 weeks after surgery.
Anxiety	Anxiety assessed using the State-Trait Anxiety Inventory (STAI). The STAI score ranges from 20 to 80, with higher scores indicating greater anxiety and a worse outcome. Data will be retrieved from the medical record.	Baseline and at hospital discharge, up to an average of 3 weeks after surgery.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Duration of Mechanical Ventilation	Total duration of postoperative invasive mechanical ventilation, measured in days.	From surgery through hospital discharge, up to an average of 3 weeks after surgery.
Intensive Care Unit Length of Stay	Number of days from intensive care unit (ICU) admission to ICU discharge.	From ICU admission through ICU discharge, up to an average of two weeks after surgery.
Hospital Length of Stay	Number of days from ICU admission to hospital discharge	From ICU admission through hospital discharge, up to an average of 3 weeks after surgery.

Collaborators and Investigators

• Sponsor: University of Florida

Publications and helpful links

General Publications

• Parry SM, El-Ansary D, Cartwright MS, Sarwal A, Berney S, Koopman R, Annoni R, Puthucheary Z, Gordon IR, Morris PE, Denehy L. Ultrasonography in the intensive care setting can be used to detect changes in the quality and quantity of muscle and is related to muscle strength and function. J Crit Care. 2015 Oct;30(5):1151.e9-14. doi: 10.1016/j.jcrc.2015.05.024. Epub 2015 Jun 3.
• Maury G, Langer D, Verleden G, Dupont L, Gosselink R, Decramer M, Troosters T. Skeletal muscle force and functional exercise tolerance before and after lung transplantation: a cohort study. Am J Transplant. 2008 Jun;8(6):1275-81. doi: 10.1111/j.1600-6143.2008.02209.x. Epub 2008 Apr 29.
• Kelm DJ, Bonnes SL, Jensen MD, Eiken PW, Hathcock MA, Kremers WK, Kennedy CC. Pre-transplant wasting (as measured by muscle index) is a novel prognostic indicator in lung transplantation. Clin Transplant. 2016 Mar;30(3):247-55. doi: 10.1111/ctr.12683. Epub 2016 Feb 11.
• Huh S, Cho WH, Kim D, Son BS, Yeo HJ. Clinical impact of preoperative diaphragm dysfunction on early outcomes and ventilation function in lung transplant: a single-center retrospective study. J Intensive Care. 2022 May 15;10(1):23. doi: 10.1186/s40560-022-00614-7.
• LoMauro A, Righi I, Privitera E, Vergari M, Nigro M, Aliverti A, Frykholm P, Tarsia P, Morlacchi L, Nosotti M, Palleschi A. The impaired diaphragmatic function after bilateral lung transplantation: A multifactorial longitudinal study. J Heart Lung Transplant. 2020 Aug;39(8):795-804. doi: 10.1016/j.healun.2020.04.010. Epub 2020 Apr 21.
• Rozenberg D, Wickerson L, Singer LG, Mathur S. Sarcopenia in lung transplantation: a systematic review. J Heart Lung Transplant. 2014 Dec;33(12):1203-12. doi: 10.1016/j.healun.2014.06.003. Epub 2014 Jun 9.

Study record dates

Study Major Dates

• Study Start (Actual): February 5, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: July 27, 2026
• First Submitted That Met QC Criteria: July 30, 2026
• First Posted (Actual): August 5, 2026

Study Record Updates

• Last Update Posted (Actual): August 5, 2026
• Last Update Submitted That Met QC Criteria: July 30, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: rehabilitation; respiratory muscles; diaphragm ultrasound; lung transplant candidates; limb muscles ultrasound; quadriceps muscles
• Additional Relevant MeSH Terms: Diagnostic Techniques and Procedures; Diagnosis; Circulatory and Respiratory Physiological Phenomena; Respiration; Respiratory Physiological Phenomena; Physical Examination; Vital Signs; Respiratory Rate
• Other Study ID Numbers: IRB202501059

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Participant data that underlie the results reported in this article after deidentification.
• IPD Sharing Time Frame: 9 months and ending 36 months following article publication.
• IPD Sharing Access Criteria: Investigators whose proposed use of the data has been approved by an independent review committee.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No