Continuous Monitoring of Dynamic PulmonaryCompliance Enables Detection of EndobronchialIntubation in Infants and ChildrenAman Mahajan, MD, PhDNir Hoftman, MDAngela Hsu, MDRobert Schroeder, MDSamuel Wald, MDBACKGROUND: Auscultation of breath sounds is used routinely to confirm trachealplacement of endotracheal tubes (ETT). In infants and children, this method islimited by the conduction of breath sounds bilaterally, despite endobronchial intuba-tion. Although several methods of detecting endobronchial intubation have beendescribed, none is both simple and reliable. In this investigation, we determinedwhether changes in pulmonary compliance and airway pressures, measured usingcontinuous side stream spirometry, can reliably detect endobronchial intubation inpediatric patients.METHODS: Forty patients aged 1 month to 6 years were included. After endotrachealintubation the ETT was incrementally advanced as two observers monitored breathsounds and spirometry (Pressure–Volume Loops). Changes in pulmonary compli-ance, peak inspiratory pressure, or auscultation were reported, at which point ETTposition was confirmed by fiberoptic bronchoscopy.RESULTS: Endobronchial intubation decreased measured pulmonary compliance by45 ⫾ 11% (mean ⫾ sd; P ⬍ 0.001, Range 26%– 66%) and increased peak airwaypressures by 26 ⫾ 17% (mean ⫾ sd; P ⬍ 0.001, Range 0 –87). Changes in peakairway pressures were smaller and more variable when compared to changes incompliance. Breath-sound auscultation failed to detect endobronchial intubation in7.5% of cases.CONCLUSIONS: Pulmonary compliance changes are a sensitive and an accurateindicator of endobronchial intubation in infants and children. Both increased peakairway pressures and changes in breath sounds are less sensitive indicators ofendobronchial intubation.(Anesth Analg 2007;105:51–6)Unrecognized endobronchial intubation in childrenis common in clinical practice, and leads to preventablehypoxemia and atelectasis (1,2). Major pulmonary mor-bidity requiring intensive care unit (ICU) admission,although rare, has also been described (3,4). Despite theadvances in monitoring, clinicians still lack a simple,reliable, and inexpensive method or device for detectionof inadvertent endobronchial intubation. Chest radiog-raphy, the current “gold standard,” incurs radiationexposure and consumes valuable operating room (OR)time. Fiberoptic bronchoscopy, a reasonable alternativeto radiography, requires advanced expertise and train-ing in pediatrics and relies on costly equipment that isoften not readily available. Neither provides continuouspatient monitoring for endobronchial intubation.Clinical trials have evaluated the utility of morepractical methods for detecting endobronchial intuba-tion, including breath sound auscultation, pulseoximetry, visual chest rise, capnography, and peakinspiratory pressure (5–8). Novel devices utilizingacoustics and even magnetism have also been used(9–11). However, a simple and reliable method fordetecting endobronchial intubation remains elusive.Small children and infants are especially vulnerable toaccidental endobronchial intubation since minimalchanges in head position can lead to endobronchialmigration of the endotracheal tube (ETT) (12). Publisheddata in pediatric patients have demonstrated that byfocusing attention to the problem and increasing aware-ness, practitioners could reduce the endobronchial intu-bation rate from 20% to 7%, but not eliminate it (13).Continuous intraoperative spirometry using theD-Lite威 all-in-one flow sensor (Datex Ohmeda, Madi-son WI) can immediately detect endotracheal tubekinking, air leaks, and even malposition (14–16). Withthis small, lightweight, and inexpensive sensor, onecan accurately and reliably measure pulmonary com-pliance and airway pressures (17).From the Department of Anesthesiology, David Geffen School ofMedicine at UCLA, Los Angeles, California.Accepted for publication March 21, 2007.Supported by grants from NIH/NHLBI P01 HL078931 (Dr.Mahajan).Conflict of interest: None.Address correspondence and reprint requests to Aman Mahajan,MD, PhD, Associate Professor, Department of Anesthesiology,David Geffen School of Medicine at UCLA, Box 951778, LosAngeles, CA 90095. Address e-mail to [email protected] © 2007 International Anesthesia Research SocietyDOI: 10.1213/01.ane.0000268119.55909.b4Vol. 105, No. 1, July 2007 51This study sought to define the changes in 1)dynamic pulmonary compliance, 2) peak inspiratorypressure, and 3) auscultated breath sounds that occurduring endobronchial intubation. We hypothesize thatdecrease in dynamic pulmonary compliance usingcontinuous spirometry accurately detects endobron-chial intubation in pediatric patients, and that changein compliance is a more reliable monitor of endobron-chial intubation compared to change in peak pressureor auscultated breath sounds.METHODSAfter obtaining IRB approval and parental informedconsent, we prospectively enrolled 40 ASA I–III pediatricpatients into the study. This study group includedchildren scheduled to undergo general, orthopedic, neu-rological, urologic, head and neck, and vascular surgery.Patients with known pulmonary, major abdominal, neu-romuscular disease, chest wall deformities, obesity, orabnormal body habitus were excluded from enrollment.After a standard IV or inhaled general anesthetic induc-tion and institution of adequate neuromuscular blockade(train-of-four monitoring), an uncuffed ETT without aMurphy eye, was orotracheally inserted just beyond thevocal cords. After audibly confirming an ETT gas leak atⱖ16 cm H2O, the pediatric D-Lite威 sensor was connectedbetween the ETT and the Y-piece of the breathing systemwhile the Datex Capnomac Ultima gas monitor (DatexOhmeda) was programmed to display pressure–volumeloops (Fig. 1A). The D-Lite sensor consists of a combina-tion of small pitot tube-type pressure sensing ports,which allow continuous measurement of pressure andflow during a respiratory cycle (For details, see Ref. 17).The Datex Capnomac calculates the compliance (C,units ⫽ mL/cm H2O) of the respiratory system using thefollowing equation: C ⫽ (Tidal volumeexpiratory) (Pres-sureEnd inspiratory⫺ PressureEnd expiratory)⫺1.Mechanical volume-controlled ventilation with atidal volume of 10 mL/kg was then initiated, leavingrespiratory rate adjustment based upon the age of thechild and to achieve an end tidal CO2⬃36 mm Hg. Allpatients’ lungs were