Pressure loss caused by pediatric endotracheal tubes during high-frequency-oscillation-ventilation

In a physical model of a pediatric respiratory system we measured the pressure drop across ETTs of 3 and 4mm inner diameter (ID) when we varied frequency, mean airway pressure and pressure amplitude of high-frequency-oscillation-ventilation (HFOV). Depending on ventilator settings the relative loss of mean pressure amplitude caused by the ETT ranged from 3.3% to 24.7% for ETT 4mm ID, respectively, from 23.8% to 51.8% for 3mm ID. In addition to the well-described flow dependency, ventilation frequency affected ETT resistance. Due to this frequency dependence, calculation of the pressure drop across the ETT using Rohrer's or Blasius-Itos' approach underestimated the true pressure drop significantly (p<0.001). Based on the experimental results, nomograms for graphical determination of the pressure drop across the ETT during HFOV were developed. We conclude that the pressure drop across the ETT during HFOV is dependent on ETT size, pressure amplitude and ventilation frequency. Calculation of this pressure drop with conventional methods is inaccurate. The high-frequency-resistance of the ETT might protect the lungs from excessive pressure amplitudes during HFOV.

[1]  V. Arrington,et al.  High frequency oscillatory ventilation. , 1994, Virginia medical quarterly : VMQ.

[2]  A. Vanderkelen,et al.  High frequency percussive ventilation and conventional ventilation after smoke inhalation: a randomised study. , 2002, Burns : journal of the International Society for Burn Injuries.

[3]  G. Redding,et al.  Partial obstruction of endotracheal tubes in children: incidence, etiology, significance. , 1979, Critical care medicine.

[4]  Z. Hantos,et al.  Monitoring of lung volume recruitment and derecruitment using oscillatory mechanics during high-frequency oscillatory ventilation in the preterm lamb , 2004, Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.

[5]  M. Banner,et al.  Intratracheal pressure: A more accurate reflection of pulmonary airway pressure in pediatric patients with respiratory failure , 2005, Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.

[6]  M. Lattuada,et al.  Good short-term agreement between measured and calculated tracheal pressure. , 2003, British journal of anaesthesia.

[7]  S. Derdak.  High-frequency oscillatory ventilation for adult acute respiratory distress syndrome: a decade of progress. , 2005, Critical care medicine.

[8]  S. Derdak.  High-frequency oscillatory ventilation for acute respiratory distress syndrome in adult patients. , 2003, Critical care medicine.

[9]  T. Stewart,et al.  Clinical use of high-frequency oscillatory ventilation in adult patients with acute respiratory distress syndrome , 2005, Critical care medicine.

[10]  F. Bowen,et al.  Postnatal Changes in Pulmonary Mechanics and Energetics of Infants with Respiratory Distress Syndrome following Surfactant Treatment , 2005, Neonatology.

[11]  A. Harf,et al.  Detection of positional airway obstruction in neonates by acoustic reflection. , 2000, American journal of respiratory and critical care medicine.

[12]  U. Sjöstrand.  In what respect does high frequency positive pressure ventilation differ from conventional ventilation? , 1989, Acta anaesthesiologica Scandinavica. Supplementum.

[13]  Fritz Rohrer,et al.  Der Strömungswiderstand in den menschlichen Atemwegen und der Einfluss der unregelmässigen Verzweigung des Bronchialsystems auf den Atmungsverlauf in verschiedenen Lungenbezirken , 1915, Pflüger's Archiv für die gesamte Physiologie des Menschen und der Tiere.

[14]  A. Stark.  High-frequency oscillatory ventilation to prevent bronchopulmonary dysplasia--are we there yet? , 2002, The New England journal of medicine.

[15]  J. Guttmann,et al.  Polymorphous Ventilation: A New Ventilation Concept for Distributed Time Constants , 1992 .

[16]  R. Clark,et al.  Prospective randomized comparison of high-frequency oscillatory and conventional ventilation in respiratory distress syndrome. , 1992, Pediatrics.

[17]  N. Weiler,et al.  High-frequency oscillatory ventilation in adult acute respiratory distress syndrome , 2003, Intensive Care Medicine.

[18]  M. Keszler,et al.  NEONATAL HIGH-FREQUENCY VENTILATION: Past, Present, and Future , 2001 .

[19]  B Louis,et al.  Estimation of inspiratory pressure drop in neonatal and pediatric endotracheal tubes. , 1999, Journal of applied physiology.

[20]  H. K. Chang.  Mechanisms of gas transport during ventilation by high-frequency oscillation. , 1984 .

[21]  Josef Guttmann,et al.  Continuous Calculation of Intratracheal Pressure in Tracheally Intubated Patients , 1993, Anesthesiology.

[22]  Michael Pasquale,et al.  High-frequency percussive ventilation: an alternative mode of ventilation for head-injured patients with adult respiratory distress syndrome. , 2004, The Journal of trauma.

[23]  B Louis,et al.  Use of the Blasius resistance formula to estimate the effective diameter of endotracheal tubes. , 1992, The American review of respiratory disease.

[24]  N. Marlow,et al.  High-frequency oscillatory ventilation for the prevention of chronic lung disease of prematurity. , 2002, The New England journal of medicine.

[25]  J. Bates,et al.  Dependence of Intrapulmonary Pressure Amplitudes on Respiratory Mechanics during High-Frequency Oscillatory Ventilation in Preterm Lambs , 2002, Pediatric Research.

[26]  J. Bates,et al.  Correcting for the Bernoulli effect in lateral pressure measurements , 1992, Pediatric pulmonology.

[27]  Ali Salim,et al.  High-frequency percussive ventilation , 2005, Critical care medicine.

[28]  R. Clark,et al.  High-frequency ventilation: issues of strategy. , 1991, Clinics in perinatology.

[29]  S. Mehta,et al.  High-Frequency Oscillatory Ventilation for Adult Patients With ARDS , 2007, Chest.

[30]  July 1999 This official conference report was cosponsored by.  International consensus conferences in intensive care medicine , 1999 .

[31]  J. Guttmann,et al.  Detection of endotracheal tube obstruction by analysis of the expiratory flow signal , 1998, Intensive Care Medicine.

[32]  Josef Guttmann,et al.  Continuous calculation of intratracheal pressure in the presence of pediatric endotracheal tubes , 2000, Critical care medicine.

[33]  J. Guttmann,et al.  Detection of partial endotracheal tube obstruction by forced pressure oscillations , 2007, Respiratory Physiology & Neurobiology.

[34]  T. Stewart,et al.  The use of high-frequency oscillatory ventilation in adults with acute lung injury. , 2001, Respiratory care clinics of North America.

[35]  Sangeeta Mehta,et al.  High-frequency oscillatory ventilation for acute respiratory distress syndrome in adults: a randomized, controlled trial. , 2002, American journal of respiratory and critical care medicine.

[36]  Arthur S Slutsky,et al.  High-frequency oscillatory ventilation and ventilator-induced lung injury , 2005, Critical care medicine.

[37]  J. Nielsen,et al.  Different ventilatory approaches to keep the lung open , 1995, Intensive Care Medicine.

[38]  J. Fredberg,et al.  Respiratory system impedance from 4 to 40 Hz in paralyzed intubated infants with respiratory disease. , 1983, The Journal of clinical investigation.