how much air to inflate endotracheal tube cuff how much air to inflate endotracheal tube cuff

The poster can be accessed by following the link: https://pdfs.semanticscholar.org/c12e/50b557dd519bbf80bd9fc60fb9fa2474ce27.pdf. Measuring actual cuff pressure thus appears preferable to injecting a given volume of air. This result suggests that clinicians are now making reasonable efforts to avoid grossly excessive cuff inflation. Seegobin RD, van Hasselt GL: Endotracheal cuff pressure and tracheal mucosal blood flow: endoscopic study of effects of four large volume cuffs. V. Foroughi and R. Sripada, Sensitivity of tactile examination of endotracheal tube intra-cuff pressure, Anesthesiology, vol. In our study, 66.3% of ETT cuff pressures estimated by the LOR syringe method were in the optimal range. We did not collect data on the readjustment by the providers after intubation during this hour. We recorded endotracheal tube size and morphometric characteristics including age, sex, height, and weight. 2003, 38: 59-61. Underinflation increases the risk of air leakage and aspiration of gastric and oral pharyngeal secretions [4, 5]. C. Stein, G. Berkowitz, and E. Kramer, Assessment of safe endotracheal tube cuff pressures in emergency care - time for change? South African Medical Journal, vol. Hahnel J, Treiber H, Konrad F, Eifert B, Hahn R, Maier B, Georgieff M: [A comparison of different endotracheal tubes. Distractions in the Operating Room: An Anesthesia Professionals Liability? In addition, most patients were below 50 years (76.4%). 2, p. 5, 2003. The mean volume of inflated air required to achieve an intracuff pressure of 25 cmH2O was 7.1 ml. We intentionally avoided this approach since our purpose was to evaluate cuff pressures and associated volumes in three routine clinical settings. However, less serious complications like dysphagia, hoarseness, and sore throat are more prevalent [911]. 31. A syringe is inserted into the valve and depressed until a suitable intracuff pressure is reached. In the later years, however, they can administer anesthesia either independently or under remote supervision. The manual method used a pressure manometer to adjust pressure at cruising altitude and after landing. 10.1055/s-2003-36557. T. M. Cook, N. Woodall, and C. Frerk, Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Adequacy is generally checked by palpation of the pilot balloon and sometimes readjusted by the intubator by inflating just enough to stop an audible leak. However, a major air leak persisted. M. H. Bennett, P. R. Isert, and R. G. Cumming, Postoperative sore throat and hoarseness following tracheal intubation using air or saline to inflate the cuffa randomized controlled trial, Anesthesia and Analgesia, vol. This method is cheap and reproducible and is likely to estimate cuff pressures around the normal range. All authors have read and approved the manuscript. 1). 106, no. Support breathing in certain illnesses, such . R. D. Seegobin and G. L. van Hasselt, Endotracheal cuff pressure and tracheal mucosal blood flow: endoscopic study of effects of four large volume cuffs, British Medical Journal, vol. Retrieved from. The cookie is a session cookies and is deleted when all the browser windows are closed. In addition, over 90% of anesthesia care at this hospital was provided by anesthetic officers and anesthesia residents during the study period. Alternative, cheaper methods like the minimum leak test that require no special equipment have produced inconsistent results. An intention-to-treat analysis method was used, and the main outcome of interest was the proportion of cuff pressures in the range 2030cmH2O in each group. A newer method, the passive release technique, although with limitations, has been shown to estimate cuff pressures better [2124]. laryngeal mask airway [LMA], i-Gel), How to insert a nasopharyngeal airway (NPA), Common hypertensive emergencyexam questions for medical finals, OSCEs and MRCP PACES, Guedel Airway Insertion Initial Assessment of a Trauma Patient, Haemoptysis case study with questions and answers, A fexible plastic tube with cuff on end which sits inside the trachea (fully secures airway the gold standard of airway management), Ventilation during anaesthetic for surgery (if muscle relaxant is required, long case, abdominal surgery, or head positing may be required), Patient cant protect their airway (e.g. (Cuffed) endotracheal tubes seal the lower airway of at the cuff location in the trachea. It would thus be helpful for clinicians to know how much air must be injected into the cuff to produce the minimum adequate pressure. Every patient was wheeled into the operating theater and transferred to the operating table. Pediatr Pathol Lab Med. Outcomes were compared by tube size, provider, and hospital with either an ANOVA (if the values were normally distributed) or the Kruskal-Wallis statistic (if the values were skewed). Using a laryngoscope, tracheal intubation was performed, ETT position confirmed, and secured with tape within 2min. Smooth Murphy Eye. Summary Aeromedical transport of mechanically ventilated critically ill patients is now a frequent occurrence. Google Scholar. Issue PDF, We are writing to call attention to the often under-appreciated importance of checking the endotracheal tube (ETT) prior to the start of the procedure. This method has been achieved with a modified epidural pulsator syringe [13, 18], a 20ml disposable syringe, and more recently, a loss of resistance (LOR) syringe [21, 23, 24]. Nitrous oxide and medical air were not used as these agents are unavailable at this hospital. Endotracheal tube system and method . Data are presented as means (SD) or medians [interquartile ranges] unless otherwise noted; P < 0.05 was considered statistically significant. This point was observed by the research assistant and witnessed by the anesthesia care provider. Cuff pressure adjustment: in both arms, very high and very low pressures were adjusted as per the recommendation by the ethics committee. LOR group (experimental): in this group, the research assistant attached a 7ml plastic, luer slip loss of resistance syringe (BD Epilor, USA) containing air onto the pilot balloon. Patients with emergency intubations, difficult intubations, or intubation performed by non-anesthesiology staff; pregnant women; patients with higher risk for aspiration (e.g., full stomach, history of reflux, etc. Cuff pressure adjustment: in both arms, very high and very low pressures were adjusted as per the recommendation by the ethics committee. It is however possible that these results have a clinical significance. Bernhard WN, Yost L, Joynes D, Cothalis S, Turndorf H: Intracuff pressures in endotracheal and tracheostomy tubes. The cuff was considered empty when no more air could be removed on aspiration with a syringe. 1995, 44: 186-188. 1993, 76: 1083-1090. With approval of the University of Louisville Human Studies Committee and informed consent, we recruited 93 patients (42 men and 51 women) undergoing elective surgery with general endotracheal anesthesia from three hospitals in Louisville, Kentucky: 41 patients from University Hospital (an academic centre), 32 from Jewish Hospital (a private hospital), and 20 from Norton Hospital (also a private hospital). But interestingly, the volume required to inflate the cuff to a particular pressure was much smaller when the cuff was inflated inside an artificial trachea; furthermore, the difference among tube sizes was minimal under those conditions. Seegobin and Hasselt reached similar conclusions in an in vitro study and recommended cuff inflation pressure not exceed 30 cm H2O [20]. 4, pp. 307311, 1995. distance from the tip of the tube to the end of the cuff, which varies with tube size. . By using this website, you agree to our Am J Emerg Med . The groups were not equal for the three different types of practitioners; however, determining differences of practice between different anesthesia providers was not the primary purpose of our study. 1993, 104: 639-640. Lien TC, Wang JH: [Incidence of pulmonary aspiration with different kinds of artificial airways]. Document Type and Number: United States Patent 11583168 . J. R. Bouvier, Measuring tracheal tube cuff pressurestool and technique, Heart and Lung, vol. The cookie is created when the JavaScript library executes and there are no existing __utma cookies. Lomholt et al. American Society of Anesthesiology, Committee of Origin: Committee on Quality Management and Departmental Administration (QMDA). BMC Anesthesiol 4, 8 (2004). The Data Safety Management Board (DSMB) comprised an anesthesiologist, a statistician, and a member of the SOMREC IRB who would be informed of any adverse event. The air leak resolved with the new ETT in place and the cuff inflated. 5, pp. In most emergency situations, it is placed through the mouth. Acta Otorhinolaryngol Belg. Routine checks of the ETT integrity and functionality before insertion used to be the standard of care, but the practice is becoming less common, although it is still recommended in current ASA guidelines.1. We conducted a single-blinded randomized control study to evaluate the LOR syringe method in accordance with the CONSORT guideline (CONSORT checklist provided as Supplementary Materials available here). The chamber is set to an altitude of 25,000 feet, which gives a time of useful consciousness of around three to five minutes. Methods. stroke. Cuff pressure in tube sizes 7.0 to 8.5 mm was evaluated 60 min after induction of general anesthesia using a manometer connected to the cuff pilot balloon. Endotracheal tube cuff pressure: a randomized control study comparing loss of resistance syringe to pilot balloon palpation. Circulation 122,210 Volume 31, No. 48, no. APSF President Robert K. Stoelting, MD: A Tribute to 19 Years of Steadfast Leadership, Immediate Past Presidents Report Highlights Accomplishments of 2016, Save the Date! [21] found that the volume of air required to inflate the endotracheal tube cuff varies as a function of tube size and type. This study was not powered to evaluate associated factors, but there are suggestions that the levels of anesthesia providers with varying skill set and technique at direct laryngoscopy may be associated with a high incidence of complications. 2, pp. Cuff pressure in . A pressure manometer is a hand hand held device used to measure tracheostomy tube cuff pressures. The cookie is set by Google Analytics. This study shows that the LOR syringe method is better at estimating cuff pressures in the optimal range when compared with the PBP method but still falls short in comparison to the cuff manometer. This was statistically significant. Measured cuff volume averaged 4.4 1.8 ml. 3, pp. The cookie is updated every time data is sent to Google Analytics. Up to ten pilots at a time sit in the . 111115, 1996. At the time of the intervention, the study investigator retrieved the next available envelope, which indicated the intervention group, from the next available block envelope and handed it to the research assistant. This method provides a viable option to cuff inflation. The cookie is set by CloudFare. However, there was considerable variability in the amount of air required. In contrast, newer ultra-thin cuff membranes made from polyurethane effectively prevent liquid flow around cuffs inflated only to 15 cm H2O [2]. Taking another approach to the same question, we also determined compliance of the cuff-trachea system in vivo by plotting measured cuff pressure against cuff volume. Standard cuff pressure is 25mmH20 measured with a manometer. (States: would deflate the cuff, pull tube back slightly -1 cm, re-inflate the cuff, and auscultate for bilateral air entry). There are data regarding the use of the LOR syringe method for administering ETT cuff pressures [21, 23, 24], but studies on a perioperative population are scanty. Anesthesia was maintained with a volatile aesthetic in a combination of air and oxygen; nitrous oxide was not used during the study period. The pressure reading of the VBM was recorded by the research assistant. 2001, 55: 273-278. Related cuff physical characteristics, Chest, vol. Liu H, Chen JC, Holinger LD, Gonzalez-Crussi F: Histopathologic fundamentals of acquired laryngeal stenosis. The study would be discontinued if 5% of study subjects in one study group experienced an adverse event associated with the study interventions as determined by the DSMB, or if a value of <0.001 was obtained on an interim analysis performed halfway through patient accrual. With air providing the seal in the cuff the mean rise in cuff pressure was 23 cmH2O . The incidence of postextubation airway complaints after 24 hours was lower in patients with a cuff pressure adjusted to the 2030cmH2O range, 57.1% (56/98), compared with those whose cuff pressure was adjusted to the 3040cmH2O range, 71.3% (57/80). When considering this primary outcome, the LOR syringe method had a significantly higher proportion compared to the PBP method. Although we were unable to identify any statistically significant or clinically important differences among the sites or providers, our results apply only to the specific sites and providers we evaluated. Generally, the proportion of ETT cuffs inflated to the recommended pressure was less in the PBP group at 22.5% (20/89) compared with the LOR group at 66.3% (59/89) with a statistically significant positive mean difference of 0.47 with value<0.01 (0.3430.602). Precaution was taken to avoid premature detachment of the loss of resistance syringe in this study. With IRB approval, we studied 93 patients under general anesthesia with an ET tube in place in one teaching and two private hospitals. 1, p. 8, 2004. Comparison of distance traveled by dye instilled into cuff. CAS Advertisement cookies help us provide our visitors with relevant ads and marketing campaigns. CRNAs (n = 72), anesthesia residents (n = 15), and anesthesia faculty (n = 6) performed the intubations. Correspondence to Sao Paulo Med J. At the University of Louisville Hospital, at least 10 patients were evaluated with each endotracheal tube size (7, 7.5, 8, or 8.5 mm inner diameter [Intermediate Hi-Lo Tracheal Tube, Mallinckrodt, St. Louis, MO]); at Jewish Hospital, at least 10 patients each were evaluated with size 7, 7.5, and 8 mm Mallinckrodt Intermediate Hi-Lo Tracheal Tubes; and at Norton Hospital, 10 patients each were evaluated with size 7 and 8-mm Mallinckrodt Intermediate Hi-Lo Tracheal Tubes. The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2253/4/8/prepub. 109117, 2011. 1, pp. Google Scholar. Zhonghua Yi Xue Za Zhi (Taipei). Anaesthesist. However, they have potential complications [13]. ETT cuff pressure estimation by the PBP and LOR methods. We recognize that people other than the anesthesia provider who actually conducted the case often inflated the cuffs. If an air leak is present, add just enough air to seal the airway and measure cuff pressure again. We observed a linear relationship between the measured cuff pressure and the volume of air retrieved from the cuff. It is thus essential to maintain cuff pressures in the range of 2030 cm of H2O. 14231426, 1990. Note correct technique: While securing the ET tube with one hand, inflate the cuff with 5-10 cc's of air. The hospital has a bed capacity of 1500 inpatient beds, 16 operating rooms, and a mean daily output of 90 surgical operations. Anesthetists were blinded to study purpose. What is the device measurements acceptable range? 2023 BioMed Central Ltd unless otherwise stated. Anesthetic officers provide over 80% of anesthetics in Uganda. Bunegin L, Albin MS, Smith RB: Canine tracheal blood flow after endotracheal tube cuff inflation during normotension and hypotension. H. B. Ghafoui, H. Saeeidi, M. Yasinzadeh, S. Famouri, and E. Modirian, Excessive endotracheal tube cuff pressure: is there any difference between emergency physicians and anesthesiologists? Signa Vitae, vol. Male patients were intubated with an 8 or 8.5 mm internal diameter endotracheal tube, and female patients were intubated with a 7 or 7.5 mm internal diameter endotracheal tube. If more than 5 ml of air is necessary to inflate the cuff, this is an . Cuff Pressure Measurement Check the cuff pressure after re-inflating the cuff and if there are any concerns for a leak. Inflate the cuff with 5-10 mL of air. It has been demonstrated that, beyond 50cmH2O, there is total obstruction to blood flow to the tracheal tissues. 139143, 2006. This cookie is set by Google Analytics and is used to distinguish users and sessions. They were only informed about the second purpose of the study: determining the relationship between cuff volume and pressure. L. Zuccherelli, Postoperative upper airway problems, Southern African Journal of Anaesthesia and Analgesia, vol. Mandoe H, Nikolajsen L, Lintrup U, Jepsen D, Molgaard J: Sore throat after endotracheal intubation. We similarly found that the volume of air required to inflate the cuffs to 20 cmH2O did not differ significantly as a function of endotracheal tube size. Air leaks are a common yet critical problem that require quick diagnosis. Most manometers are calibrated in? 4, pp. Continuous data are presented as the mean with standard deviation and were compared between the groups using the t-test to detect any significant statistical differences. 1984, 24: 907-909. The cookies store information anonymously and assign a randomly generated number to identify unique visitors. If the tracheal lumen is in the appropriate position (i.e., it has not been placed too deeply), bilateral breath sounds will. 1984, 288: 965-968. This cookie is used to a profile based on user's interest and display personalized ads to the users. However you may visit Cookie Settings to provide a controlled consent. Endotracheal tube cuff pressure in three hospitals, and the volume required to produce an appropriate cuff pressure. In our case, had the endotracheal tube been checked prior to the start of the case, the defect could have been easily identified which would have obviated the need for tube exchange. El-Orbany M, Salem MR. Endotracheal tube cuff leaks: causes, consequences, and management. It is however difficult to extrapolate these results to the human population since the risk of aspiration of gastric contents is zero while working with models when compared with patients. Categorical data are presented in tabular, graphical, and text forms and categorized into PBP and LOR groups. Consequences of micro-aspiration of oropharyngeal secretions include nosocomial pulmonary infections [1]. The study was approved by Makerere University College of Health Sciences, School of Medicine Research Ethics Committee (SOMREC), The Secretariat Makerere University College of Health Sciences, Clinical Research Building, Research Co-ordination Office, P.O. 720725, 1985. adequately inflate cuff . Basic routine monitors were attached as per hospital standards. 10.1007/s001010050146. D) Pressure gauge attached to pilot balloon of defective cuff with reading of 30 mmHg with cuff not appropriately inflated. This cookie is used by the WPForms WordPress plugin. This cookie is set by Youtube and registers a unique ID for tracking users based on their geographical location. J. Liu, X. Zhang, W. Gong et al., Correlations between controlled endotracheal tube cuff pressure and postprocedural complications: a multicenter study, Anesthesia and Analgesia, vol. All tubes had high-volume, low-pressure cuffs. if GCS <8, high aspiration risk or given muscle relaxation), Potential airway obstruction (airway burns, epiglottitis, neck haematoma), Inadequate ventilation/oxygenation (e.g. California Privacy Statement, 2003, 29: 1849-1853. 10, no. This is the routine practice in all three hospitals. There was no correlation between the measured cuff pressure and the age, sex, height, or weight of the patients. These data suggest that management of cuff pressure was similar in these two disparate settings. P. Biro, B. Seifert, and T. Pasch, Complaints of sore throat after tracheal intubation: a prospective evaluation, European Journal of Anaesthesiology, vol. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. 769775, 2012. "Aire" indicates cuff to be filled with air. At this point the anesthesiology team decided to proceed with exchanging the ETT, which was successful. 70, no. These data suggest that tube size is not an important determinant of appropriate cuff inflation volume. Supported by NIH Grant GM 61655 (Bethesda, MD), the Gheens Foundation (Louisville, KY), the Joseph Drown Foundation (Los Angeles, CA), and the Commonwealth of Kentucky Research Challenge Trust Fund (Louisville, KY). After screening, participants were allocated to either the PBP or the LOR group using block randomization, achieving a 1:1 allocation ratio. CAS 2003, 13: 271-289. The author(s) declare that they have no competing interests. PubMed studied the relationship between cuff pressure and capillary perfusion of the rabbit tracheal mucosa and recommended that cuff pressure be kept below 27 cm H2O (20 mmHg) [19]. Martinez-Taboada F. The effect of user experience and inflation technique on endotracheal tube cuff pressure using a feline airway simulator. recommended selecting a cuff pressure of 25 cmH2O as a safe minimum cuff pressure to prevent aspiration and leaks past the cuff [17]; Bernhard et al. 8, pp. PBP group (active comparator): in this group, the anesthesia care provider was asked to reduce or increase the pressure in the ETT cuff by inflating with air or deflating the pilot balloon using a 10ml syringe (BD Discardit II) while simultaneously palpating the pilot balloon until a point he or she felt was appropriate for the patient. This cookie is native to PHP applications. R. J. Hoffman, V. Parwani, and I. H. Hahn, Experienced emergency medicine physicians cannot safely inflate or estimate endotracheal tube cuff pressure using standard techniques, American Journal of Emergency Medicine, vol. 2017;44 Tracheal Tube Cuff. The patient was the only person blinded to the intervention group. Symptoms of a severe air embolism might include: difficulty breathing or respiratory failure. Below are the links to the authors original submitted files for images. At the hypobaric chamber at the RAAF base in Edinburgh several hundred air force pilots each year get to check out their reactions to depressurization and the effects of hypoxia. Kim and coworkers, who evaluated this method in the emergency department, found an even higher percentage of cuff pressures in the normal range (2232cmH2O) in their study. Adequacy of cuff inflation is conventionally determined by palpation of the external balloon. 2016 National Geriatric Surgical Initiatives, 2017 EC Pierce Lecture: Safety Beyond Our Borders, The Anesthesia Professionals Role in Patient Safety During TAVR (Transcatheter Aortic Valve Replacement). Vet Anaesth Analg. There were no statistically significant differences in measured cuff pressures among these three practitioner groups (P = 0.847). Airway 'protection' refers to preventing the lower airway, i.e. protects the lung from contamination from gastric contents and nasopharyngeal matter such as blood. The primary outcome of the study was to determine the proportion of cuff pressures in the optimal range from either group. 10, pp. 1: anesthesia resident; 2: anesthesia officer; 3: anesthesia officer student; 4: anesthesiologist. Braz JR, Navarro LH, Takata IH, Nascimento Junior P: Endotracheal tube cuff pressure: need for precise measurement. Our secondary objective was to determine the incidence of postextubation airway complaints in patients who had cuff pressures adjusted to 2030cmH2O range or 3140cmH2O range. The distribution of cuff pressures (unadjusted) achieved by the different care providers is shown in Figure 2. Error in Inhaled Nitric Oxide Setup Results in No Delivery of iNO. To achieve the optimal ETT cuff pressure of 2030cmH2O [3, 8, 1214], ETT cuffs should be inflated with a cuff manometer [15, 16]. How do you measure cuff pressure? ismanagement of endotracheal (ET) tube cuff pressure (CP), defined as a CP that falls outside the recommended range of 20 to 30 cm H 2 O, is a frequent occur-rence during general anesthetics, with study findings ranging from 55% to 80%.1-4 Endotra-cheal tube cuffs are typically filled with air to a safe and adequate pressure of 20 to 30 cm H 2 In addition, acquired laryngeal stenosis may be caused by mechanical abrasion or pressure necrosis of the laryngeal mucosa secondary to high cuff pressure [13, 14]. mental status changes, such as confusion . Does that cuff on the trach tube get inflated with air or water? DIS contributed to study design, data analysis, and manuscript preparation. non-fasted patients, Size: 8mm diameter for men, 7mm diameter for women, Laryngoscope (check size the blade should reach between the lips and larynx size 3 for most patients), turn on light, Monitoring: end-tidal CO2 monitor, pulse oximeter, cardiac monitor, blood pressure, Medications in awake patient: hypnotic, analgesia, short-acting muscle relaxant (to aid intubation), Pre-oxygenate patient with high concentration oxygen for 3-5mins, Neck flexed to 15, head extended on neck (i.e. The allocation sequence was concealed from the investigator by inserting it into opaque envelopes (according to the clocks) until the time of the intervention. SP oversaw day-to-day study mechanics, collected data on many of the patients, and wrote an initial draft of manuscript. In case of a very low pressure reading (below 20cmH, https://pdfs.semanticscholar.org/c12e/50b557dd519bbf80bd9fc60fb9fa2474ce27.pdf. An endotracheal tube : provides a passage for gases to flow between a patients lungs and an anaesthesia breathing system . B) Dye instilled into the defective endotracheal tube stops at the entrance of the pilot balloon tubing into the main tubing (arrow in Figure 2A and 2B). The tube is kept in place by a small cuff of air that inflates around the tube after it is inserted. None of the authors have conflicts of interest relating to the publication of this paper. Conclusion. However, a full hour was plenty of time for the provider to have checked and adjusted cuff pressure to a suitable level. Nor did measured cuff pressure differ as a function of endotracheal tube size. Methods With IRB approval, we studied 93 patients under general anesthesia with an ET tube in place in one teaching and two private hospitals. ETT exchange could pose significant risk to patients especially in the case of the patient with a difficult airway. The amount of air necessary will vary depending on the diameter of the tracheostomy tube and the patient's trachea. Springer Nature. Manage cookies/Do not sell my data we use in the preference centre. 56, no. February 2017 175183, 2010. 66.3% (59/89) of patients in the loss of resistance group had cuff pressures in the recommended range compared with 22.5% (20/89) from the pilot balloon palpation method. Fernandez et al. These were adopted from a review on postoperative airway problems [26] and were defined as follows: sore throat, continuous throat pain (which could be mild, moderate, or severe), dysphagia, uncoordinated swallowing or inability to swallow or eat, dysphonia, hoarseness or voice changes, and cough (identified by a discomforting, dry irritation in the upper airway leading to a cough). While it is likely that these results are fairly representative, it is obvious that results would not be identical elsewhere because of regional practice differences. 1982, 154: 648-652. 965968, 1984. Also, at the end of the pressure measurement in both groups, the manometer was detached, breathing circuit was attached to the ETT, and ventilation was started. 32. Inflation of the cuff of . Dullenkopf A, Gerber A, Weiss M: Fluid leakage past tracheal tube cuffs: evaluation of the new Microcuff endotracheal tube. The integrity of the entire breathing circuit and correct positioning of the ETT between the vocal cords with direct laryngoscopy were confirmed. J Trauma. Laura F. Cavallone, MD, Associate Professor, Department of Anesthesiology, Washington University in St. Louis, MO.