title: Effects of diaphragmatic control on the assessment of sniff nasal inspiratory pressure and maximum relaxation rate.
abstract: OBJECTIVE
  To assess the influence of diaphragmatic activation control (diaphC) on Sniff Nasal-Inspiratory Pressure (SNIP) and Maximum Relaxation Rate of inspiratory muscles (MRR) in healthy subjects.
  
  
  METHODS
  Twenty subjects (9 male; age: 23 (SD=2.9) years; BMI: 23.8 (SD=3) kg/m²; FEV1/FVC: 0.9 (SD=0.1)] performed 5 sniff maneuvers in two different moments: with or without instruction on diaphC. Before the first maneuver, a brief explanation was given to the subjects on how to perform the sniff test. For sniff test with diaphC, subjects were instructed to perform intense diaphragm activation. The best SNIP and MRR values were used for analysis. MRR was calculated as the ratio of first derivative of pressure over time (dP/dtmax) and were normalized by dividing it by peak pressure (SNIP) from the same maneuver.
  
  
  RESULTS
  SNIP values were significantly different in maneuvers with and without diaphC [without diaphC: -100 (SD=27.1) cmH2O/ with diaphC: -72.8 (SD=22.3) cmH2O; p<0.0001], normalized MRR values were not statistically different [without diaphC: -9.7 (SD=2.6); with diaphC: -8.9 (SD=1.5); p=0.19]. Without diaphC, 40% of the sample did not reach the appropriate sniff criteria found in the literature.
  
  
  CONCLUSIONS
  Diaphragmatic control performed during SNIP test influences obtained inspiratory pressure, being lower when diaphC is performed. However, there was no influence on normalized MRR.
authors.affiliation: Departamento de Fisioterapia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
authors.forename: Kadja
authors.initials: K
authors.lastname: Benício
authors.affiliation: Departamento de Fisiologia, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Fernando A L
authors.initials: FA
authors.lastname: Dias
authors.affiliation: Departamento de Fisioterapia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
authors.forename: Lucien P
authors.initials: LP
authors.lastname: Gualdi
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico Di Milano, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Aliverti
authors.affiliation: Departamento de Fisioterapia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
authors.forename: Vanessa R
authors.initials: VR
authors.lastname: Resqueti
authors.affiliation: Departamento de Fisioterapia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
authors.forename: Guilherme A F
authors.initials: GA
authors.lastname: Fregonezi
mesh_terms: D003964:Diaphragm / Q000502:physiology*; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D007320:Inspiratory Capacity / Q000502:physiology*; D009666:Nose / Q000502:physiology; D011312:Pressure; D012132:Respiratory Muscles / Q000502:physiology*