TGIF: Tracheal Gas Insufflation

per second. The National Television Systems Committee video format used in the United States allows 30 frames per second to be studied. With digital techniques, each frame identifies sharp, clear images of the vocal fold edge and fine details of laryngeal activity, including mucosal abnormalities and opening and closing patterns. Shape, movement, vibratory patterns, time relationships between opening and closing of vocal folds, and maximum opening and closure of vocal folds are observed. Routine use of videotape recording is required for documentation of changes resulting from treatment; enhancement of teaching to patients, families, professionals, and students; archival record keeping; a means for more than one specialist to view the procedure at the same time; a means for repeated observation of the same event repeatedly and definitively; quantitative and qualitative visual explanations of the data and disorders; and a means for visual feedback training. FEES without videotape recording relies on subjective interpretation and documentation, thereby diminishing the validity and reliability of conclusions. All sports fans know that the instant replay has revolutionized the way that we watch sports and the way in which they are judged. Should anything less precise be offered to our patients? Within the next year or two, inclusion of videotape recording for FEES, FEESST and strobovideolaryngoscopy procedures will be mandated by the Center for Medicare and Medicaid Services. ACKNOWLEDGMENT: The author thanks Laurie H. Dagesse for assistance with manuscript preparation and Helen K. Gallivan, RN for assistance in research and editing.

Gregory J. Gallivan, MD, FCCP Springfield, MA Dr. Gallivan is Assistant Professor of Clinical Surgery, The University of Massachusetts Medical School, and Thoracic, Airway and Voice Surgeon, Mercy Medical Center. Correspondence to: Gregory J. Gallivan, MD, FCCP, 299 Carew St, Suite 404, Springfield, MA 01104-2361; e-mail: singingsurgeon@ attbi.com

References 1 Gallivan GJ, Dawson JA, Robbins LD. Videolaryngoscopy after endotracheal intubation: implications for voice. J Voice 1989; 3:76 – 80 2 Gallivan GJ, Dawson JA, Opfell AP. Videolaryngoscopy after endotracheal intubation: Part II. A critical care perspective of lesions affecting voice. J Voice 1990; 4:159 –164 3 Langmore SE, Schatz K, Olsen N. Fiberoptic endoscopic examination of swallowing safety: a new procedure. Dysphagia 1988; 2:216 –219 4 Langmore SE, Schatz K, Olson N. Endoscopic and videofluoroscopic evaluations of swallowing and aspiration. Ann Otol Rhinol Laryngol 1991; 100:678 – 681 5 Langmore SE. FEES: fiberoptic endoscopic evaluation of swallowing and management of the adult with dysphagia in www.chestjournal.org

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the acute care setting. Presented at: Topics in Dysphagia Conference, New England Medical Center Hospitals, Boston, MA, October 1, 1992 Langmore SE. FEES: fiberoptic endoscopic evaluation of swallowing. Presented at: Current Issues in Anatomic and Physiologic Aspects of Dysphagia, Kessler Conference Center, West Orange, NJ, June 19, 1993 American Speech-Language-Hearing Association. Instrumental diagnostic procedures for swallowing. ASHA Suppl 1992; 34(Suppl 7):25–33 Kidder TM, Langmore SE, Martin BJW. Indications and techniques of endoscopy in evaluation of cervical dysphagia: comparison with radiographic techniques. Dysphagia 1994; 9:256 –261 Langmore SE, Hicks DM. Presented at: Symposium on Endoscopy as a Tool for Clinical Evaluation of Swallowing and Voice Disorders, Orlando, FL, March 3– 4, 1995 Aviv JE, Kim T, Sacco RL, et al. FEESST: a new bedside endoscopic test of the motor and sensory components of swallowing. Ann Otol Rhinol Laryngol 1998; 107:378 –387 Aviv JE. Prospective, randomized outcome study of endoscopy vs modified barium swallow in patients with dysphagia. Laryngoscope 2000; 110:563–574 Aviv JE, Sataloff RT, Cohen M, et al. Cost-effectiveness of two types of dysphagia care in head and neck cancer: a preliminary report. Ear Nose Throat J 2001; 80:553–558 Aviv JE, Spitzer J, Cohen M, et al. Laryngeal adductor reflex and pharyngeal squeeze as predictors of laryngeal penetration and aspiration. Laryngoscope 2002; 112:338 –341

TGIF: Tracheal Gas Insufflation For Whom? administration of fresh gas or oxygen into D irect the trachea has been employed in several set-

tings. In outpatients in stable condition with severe COPD or pulmonary fibrosis, transtracheal oxygen (TTO) improves exercise tolerance, reduces inspired minute ventilation (without increasing Paco2), decreases dyspnea, and lessens the work of breathing.1–3 With this technique, oxygen flow continues during expiration, allowing the trachea to serve as an effective oxygen reservoir. This results in oxygen conservation as lower flow rates are required to maintain a given level of oxygenation. In addition to these physiologic benefits, TTO systems may result in improved comfort and a more favorable cosmetic effect when compared to nasal cannulae. In the setting of acute on chronic respiratory failure, TTO administered via a percutaneously inserted minitracheostomy maintained improvements in oxygen for 1 week and was ultimately successful (survival) in 65% of the patients.4 In critically ill patients receiving mechanical ventilation, tracheal gas insufflation (TGI) has been under investigation for several decades. Pioneering work by Slutsky et al5,6 showed that TGI of oxygen to CHEST / 122 / 5 / NOVEMBER, 2002

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paralyzed dogs maintained oxygen and a stable level of hypercapnia. Ultimately, investigators began to study TGI as an adjunct to mechanical ventilation, principally in patients with acute lung injury. More recently, TGI has been examined as an aid to weaning from mechanical ventilation and as a standalone mode of full ventilatory support. TGI can be delivered by a thin catheter placed through the endotracheal tube (terminating within 1 to 2 cm of the main carina) or via a modified endotracheal tube with channels embedded in the walls of the tube. TGI flow can be forward (toward the alveoli) or reversed in direction toward the proximal end of the endotracheal tube. During expiration, TGI reduces dead space by washing carbon dioxide out of the trachea, bronchi, and the endotracheal tube so that with the next breath less carbon dioxide is rebreathed. Continuous forward-flow TGI may also decrease Paco2 by enhancing distal gas mixing. During volume-cycled ventilation, continuous TGI augments tidal volume and will increase alveolar distending pressure and the risk for volutrauma in ARDS. The effect can be diminished by using pressure control ventilation, by downward adjusting machine-delivered tidal volume during volume-cycled ventilation, or by using TGI timed to occur only during expiration (expiratory TGI). Even when using the latter strategy, TGI can impede expiration, resulting in the development of intrinsic positive end-expiratory pressure. Using reverse flow or end-expiratory (rather than pan-expiratory) TGI, or the addition of tracheal gas exsufflation, may help alleviate this problem. A number of additional safety issues with TGI have been raised including concerns about ensuring adequate humidification, increased risk of airway mucosal injury, and adverse effects on secretion clearance (especially if desiccation occurs).7 The importance of these complications, especially with long-term use of TGI, remains to be defined. A large number of animal investigations with experimental lung injury8 and clinical studies in patients with ARDS managed with a strategy of permissive hypercapnia9 –13 demonstrate that TGI can be used as an adjunct to either volume- or pressure-cycled ventilation. In this context, TGI can allow for a reduction in tidal volume and alveolar distending pressure without further rise in Paco2. Alternatively, if tidal volume is held constant, TGI can result in a reduction in Paco2, a potentially important maneuver in a patient with ARDS and intracranial hypertension14 or severe metabolic acidosis. A pattern of rapid, shallow breathing and inefficient carbon dioxide clearance characterizes patients with COPD who cannot be weaned from mechanical 1516

ventilation.15 Therefore, TGI could facilitate liberation from ventilatory support by enhancing carbon dioxide clearance. In a sheep model of lung injury, Cereda et al16 combined TGI with continuous positive airway pressure during spontaneous breathing and demonstrated a reduction in the inspiratory work of breathing. In a flow-dependent manner, TGI decreased tidal volume, minute ventilation, dead space, and Paco2 in 12 patients with COPD undergoing weaning trials.10 Yet, in a bench lung model, Hoyt et al17 found that TGI may increase the work needed to open the demand valve and trigger the ventilator, a problem that may be surmounted by a system that stops TGI flow prior to the end of expiration. Intratracheal pulmonary ventilation (ITPV) is an adaptation of continuous TGI that allows for complete ventilatory support without the concomitant use of conventional ventilation. In this mode, a small catheter is placed through the endotracheal tube and positioned close to the carina. Inspiration and expiration occur as an expiratory valve is closed and opened, respectively. Expiration is further aided by a reverse-thrust catheter that entrains gas from the distal airways. In a sheep model using pressure control for comparison, ITPV reduced tidal volume, peak airway pressure, and dead space, at a constant Paco2.18 In this issue of CHEST (see page 1742), Tagaito and colleagues extend these applications by examining TGI, with and without periodic tracheal occlusions (PTOs), in a chronic tracheostomized dog model. As with previous studies, increasing TGI flow rates decreased minute ventilation without increasing Paco2 (dead space is decreased). The addition of PTOs led to increased minute ventilation and a fall in Paco2, demonstrating that this technique can be used to fully support spontaneous breathing. The degree of ventilatory support was determined by the number and duration of tracheal occlusions and the TGI flow rate. Although these physiologic changes are impressive, it is important to ask whether this “minimally invasive” technique offers tangible therapeutic advantages over currently available modes of invasive and noninvasive ventilation. At this point, there is no definitive evidence that TGI-PTO improves patient-ventilator interaction, facilitates weaning from mechanical ventilation, or otherwise provides advantages over currently available ventilatory support systems. Importantly, patient-ventilator synchrony using currently available modes and machines can be improved by setting the ventilator properly, by reducing trigger sensitivity to 0.5 to 1.0 cm H2O or using flow triggering, by providing adequate tidal volume and minute ventilation, and by matching inspiratory flow rates to patient ventilatory demand.19 Editorials

Similarly, the advantages of avoiding invasive airways and using mask interfaces (noninvasive ventilation) have been increasingly documented. As an example, when compared to invasive mechanical ventilation, noninvasive ventilation is associated with a lower risk for nosocomial infections, especially ventilatorassociated pneumonia.20 In addition, noninvasive ventilation can be used, in select patients, to facilitate liberation from mechanical ventilation and improve overall outcome.21 In conclusion, TGI is a modality with the potential to improve important pathophysiologic manifestations of acute respiratory failure. Newer applications, such as the addition of PTOs to provide complete ventilatory support, are of great clinical interest. However, at present, approved TGI systems are not commercially available. Even when this occurs, high-quality randomized controlled trials demonstrating the efficacy of this approach are required before widespread application of TGI can be recommended. Scott K. Epstein, MD, FCCP Boston, MA Dr. Epstein is Director, Medical Intensive Care Unit, Division of Pulmonary, Critical Care, and Sleep Medicine, Tufts-New England Medical Center, and Associate Professor of Medicine, Tufts University School of Medicine. Correspondence to: Scott K. Epstein, MD, FCCP, Division of Pulmonary, Critical Care, and Sleep Medicine, Box 369, New England Medical Center, 750 Washington St, Boston, MA 02111; e-mail: [email protected]

References 1 Benditt J, Pollock M, Roa J, et al. Transtracheal delivery of gas decreases the oxygen cost of breathing. Am Rev Respir Dis 1993; 147:1207–1210 2 Bergofsky EH, Hurewitz AN. Airway insufflation: physiologic effects on acute and chronic gas exchange in humans. Am Rev Respir Dis 1989; 140:885– 890 3 Couser JI, Make BJ. Transtracheal oxygen decreases inspired minute ventilation. Am Rev Respir Dis 1989; 139:627– 631 4 Andrivet P, Richard G, Viau F, et al. Treatment of respiratory failure using minitracheotomy and intratracheal oxygenation in selected patients with chronic lung disease. Intensive Care Med 1996; 22:1323–1327 5 Slutsky AS, Watson J, Leith DE, et al. Tracheal insufflation of O2 (TRIO) at low flow rates sustains life for several hours. Anesthesiology 1985; 63:278 –286

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6 Slutsky AS, Menon AS. Catheter position and blood gases during constant-flow ventilation. J Appl Physiol 1987; 62:513– 519 7 Kacmarek RM. Complications of tracheal gas insufflation. Respir Care 2001; 46:167–176 8 Nahum A. Animal and lung model studies of tracheal gas insufflation. Respir Care 2001; 46:149 –157 9 Ravenscraft SA, Burke WC, Nahum A, et al. Tracheal gas insufflation augments CO2 clearance during mechanical ventilation. Am Rev Respir Dis 1993; 148:345–351 10 Nakos G, Lachana A, Prekates A, et al. Respiratory effects of tracheal gas insufflation in spontaneously breathing COPD patients. Intensive Care Med 1995; 21:904 –912 11 Kalfon P, Rao GS, Gallart L, et al. Permissive hypercapnia with and without expiratory washout in patients with severe acute respiratory distress syndrome. Anesthesiology 1997; 87:6 –17 12 Kuo PH, Wu HD, Yu CJ, et al. Efficacy of tracheal gas insufflation in acute respiratory distress syndrome with permissive hypercapnia. Am J Respir Crit Care Med 1996; 154:612– 616 13 Richecoeur J, Lu Q, Vieira SR, et al. Expiratory washout vs optimization of mechanical ventilation during permissive hypercapnia in patients with severe acute respiratory distress syndrome. Am J Respir Crit Care Med 1999; 160:77– 85 14 Levy B, Bollaert PE, Nace L, et al. Intracranial hypertension and adult respiratory distress syndrome: usefulness of tracheal gas insufflation. J Trauma 1995; 39:799 – 801 15 Jubran A, Tobin MJ. Pathophysiologic basis of acute respiratory distress in patients who fail a trial of weaning from mechanical ventilation. Am J Respir Crit Care Med 1997; 155:906 –915 16 Cereda MF, Sparacino ME, Frank AR, et al. Efficacy of tracheal gas insufflation in spontaneously breathing sheep with lung injury. Am J Respir Crit Care Med 1999; 159:845– 850 17 Hoyt JD, Marini JJ, Nahum A. Effect of tracheal gas insufflation on demand valve triggering and total work during continuous positive airway pressure ventilation. Chest 1996; 110:775–783 18 Kolobow T, Powers T, Mandava S, et al. Intratracheal pulmonary ventilation (ITPV): control of positive end-expiratory pressure at the level of the carina through the use of a novel ITPV catheter design. Anesth Analg 1994; 78:455– 461 19 Epstein S. Optimizing patient-ventilator synchrony. Semin Respir Crit Care Med 2001; 22:137–152 20 Girou E, Schortgen F, Delclaux C, et al. Association of noninvasive ventilation with nosocomial infections and survival in critically ill patients. JAMA 2000; 284:2361–2367 21 Nava S, Ambrosino N, Clini E. Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease: a randomized, controlled trial. Ann Intern Med 1998; 128:721–728

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