title: Comparison between respiratory pulse oximetry plethysmographic waveform amplitude and arterial pulse pressure variations among patients with and without norepinephrine use.
abstract: OBJECTIVE
  Arterial pulse pressure respiratory variation is a good predictor of fluid response in ventilated patients. Recently, it was shown that respiratory variation in arterial pulse pressure correlates with variation in pulse oximetry plethysmographic waveform amplitude. We wanted to evaluate the correlation between respiratory variation in arterial pulse pressure and respiratory variation in pulse oximetry plethysmographic waveform amplitude, and to determine whether this correlation was influenced by norepinephrine administration.
  
  
  METHODS
  Prospective study of sixty patients with normal sinus rhythm on mechanical ventilation, profoundly sedated and with stable hemodynamics. Oxygenation index and invasive arterial pressure were monitored. Respiratory variation in arterial pulse pressure and respiratory variation in pulse oximetry plethysmographic waveform amplitude were recorded simultaneously in a beat-to-beat evaluation, and were compared using the Pearson coefficient of agreement and linear regression.
  
  
  RESULTS
  Thirty patients (50%) required norepinephrine. There was a significant correlation (K = 0.66; p < 0.001) between respiratory variation in arterial pulse pressure and respiratory variation in pulse oximetry plethysmographic waveform amplitude. Area under the ROC curve was 0.88 (range, 0.79 - 0.97), with a best cutoff value of 14% to predict a respiratory variation in arterial pulse pressure of 13. The use of norepinephrine did not influence the correlation (K = 0.63, p = 0.001, respectively).
  
  
  CONCLUSIONS
  Respiratory variation in arterial pulse pressure above 13% can be accurately predicted by a respiratory variation in pulse oximetry plethysmographic waveform amplitude of 14%. The use of norepinephrine does not alter this relationship.
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Guilherme Loures de Araújo
authors.initials: GL
authors.lastname: Penna
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Paula Araujo
authors.initials: PA
authors.lastname: Rosa
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Pedro Martins Pereira
authors.initials: PM
authors.lastname: Kurtz
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Fabricio
authors.initials: F
authors.lastname: Braga
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Gustavo Ferreira
authors.initials: GF
authors.lastname: Almeida
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Marcia
authors.initials: M
authors.lastname: Freitas
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Luis Eduardo
authors.initials: LE
authors.lastname: Drumond
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Ronaldo Vegni E
authors.initials: RV
authors.lastname: Souza
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Michel Schatkin
authors.initials: MS
authors.lastname: Cukier
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: André
authors.initials: A
authors.lastname: Salgado
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Clóvis
authors.initials: C
authors.lastname: Faria
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: José
authors.initials: J
authors.lastname: Kezen
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: André Miguel
authors.initials: AM
authors.lastname: Japiassú
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Kalichsztein
authors.affiliation: Serviço de Terapia Intensiva, Casa de Saúde São José, Rio de Janeiro, RJ, Brasil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Nobre