title: Ultrasound assessment of diaphragmatic function in patients with amyotrophic lateral sclerosis.
abstract: OBJECTIVE
  Evaluation of diaphragm function in Amyotrophic Lateral Sclerosis (ALS) is critical in determining when to commence non-invasive mechanical ventilation (NIV). Currently, forced vital capacity (FVC) and sniff nasal inspiratory pressure (SNIP) are volitional measures for this evaluation, but require collaboration and are poorly specific. The primary aim of this study was to assess whether diaphragmatic thickness measured by ultrasound (US) correlates with lung function impairment in ALS patients. The secondary aim was then to compare US diaphragm thickness index (ΔTdi) with a new parameter (ΔTmax index).
  
  
  METHODS
  41 patients with ALS and 30 healthy subjects were enrolled in the study. All subjects underwent spirometry, SNIP and diaphragm US evaluation, while arterial blood gases were measured in some patients only. US assessed diaphragm thickness (Tdi) at tidal volume (Vt) or total lung capacity (TLC), and their ratio (ΔTmax) were recorded. Changes (Δ) in Tdi indices during tidal volume (ΔTdiVt) and maximal inspiration (ΔTdiTLC) were also assessed.
  
  
  RESULTS
  ΔTdiTLC (p <0.001) and ΔTmax (p = 0.007), but not ΔTdiVt, differed between patients and controls. Significant correlation (p < 0.05) was found between ΔTdiTLC, ΔTmax and FVC. The ROC curve analysis for comparison of individual testing showed better accuracy with Δtmax than with ΔtdiTLC for FVC (AUC 0.76 and 0.27) and SNIP (AUC 0.71 and 0.25).
  
  
  CONCLUSIONS
  Diaphragm thickness assessed by ultrasound significantly correlates with global respiratory alterations in patients with ALS. ΔTmax represents a new US index of early diaphragmatic dysfunction, better related with the routinely performed lung function tests.
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Fantini
authors.affiliation: Department of Neuroscience, St Agostino-Estense Hospital, University of Modena and Reggio Emilia.
authors.forename: Jessica
authors.initials: J
authors.lastname: Mandrioli
authors.affiliation: Infectious Diseases Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Stefano
authors.initials: S
authors.lastname: Zona
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Federico
authors.initials: F
authors.lastname: Antenora
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Andrea
authors.initials: A
authors.lastname: Iattoni
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Marco
authors.initials: M
authors.lastname: Monelli
authors.affiliation: Department of Neuroscience, St Agostino-Estense Hospital, University of Modena and Reggio Emilia.
authors.forename: Nicola
authors.initials: N
authors.lastname: Fini
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tonelli
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Enrico
authors.initials: E
authors.lastname: Clini
authors.affiliation: Respiratory Disease Clinic, Policlinico Modena, University of Modena and Reggio Emilia.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Marchioni
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D003964:Diaphragm / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation / Q000379:methods; D012372:ROC Curve; D012129:Respiratory Function Tests / Q000379:methods; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D013990:Tidal Volume; D061665:Time-to-Treatment; D014463:Ultrasonography / Q000379:methods*; D014797:Vital Capacity
keywords: Amyotrophic lateral sclerosis; diaphragm ultrasound; lung function; noninvasive mechanical ventilation; respiratory failure