Airway Evaluation and Management: Recent advances Disclosures No financial, consulting, contractual relationships Sachin Kheterpal MD MBA Assistant Professor Department of Anesthesiology University of Michigan Overview Difficult Airway Mgmt The Difficult Airway Mask ventilation I An outcome driven airway exam The wrong mask? New airway algorithms We have focused on Difficult Intubation Historically But, isn t mask ventilation what saves lives? 1
Difficult Airway Mgmt Walking the talk The ability to mask ventilate changes everything Inconsistency between clinical practice and research Difficult airway algorithm emphasizes mask ventilation Practitioners teach mask ventilation with priority We use mask ventilation as a rescue technique Paucity of mask ventilation literature No articles focused on mask ventilation prior to 2000 No definition for difficult mask ventilation Minimal pathophysiology research Mask ventilation I What is difficult? Published in Anesthesiology in 2000 Prospective observational study of adults undergoing Ortho, urology, abdominal, gynecologic, and neurosurgery All mask attempts performed by an attending Primary outcome = difficult mask ventilation clinically relevant and could have lead to potential problems if mask ventilation had to maintained for a longer time Objective measures Two-hand mask seal required SpO2 < 92% important gas flow leak Change of operator required Three categories essentially Easy Difficult (DMV) Impossible (IMV) Gas flow > 15 L/min No chest rise 2
Results 1,502 patients recruited, 75 DMV (5%), 1 IMV Predicting DMV Five Independent preoperative predictors of DMV What about intubation? Difficult intubation 4 X likely if DMV Impossible intubation 12 X likely if DMV What next? Univ of Michigan Scale Editorial accompanying Langeron s article Need for a mask ventilation scale What about DMV + DI? Letters to the editor What about jaw-protrusion test What about neuromuscular blockade What about experience of the provider 3
Grading of Mask Ventilation Data collection Phase II Mask Ventilation II Airway Trouble Published in 2006 Included all cases Ventilation by many providers Residents CRNAs Faculty 4
Compared to Langeron Real Airway Trouble Much lower incidence of DMV Offering a oral airway / adjuvant is key distinction Only 1.4% incidence of DMV Confirmed predictors Obesity Advanced age Beard Snoring Absent Edentulous dentition New predictors Jaw protrusion test Mallampati III or IV 77 cases of IMV 0.15% or 1 in 690 cases What do you do? Changing practice using data?? Paralyze or not to paralyze? 75% intubated without difficulty Six cases used an LMA as a temporizing measure Only 4 patients woken up 65 receive sux intubated 8 received non-depol 1 crico 3 received nothing woken 1 received nothing intubated 5
Outcome focused airway mgmt DMV + DI Difficult Mask Difficult Intubation How do you define it? How often does it occur? What predicts it? How do you handle it? Difficult Mask AND Intubation DMV + DI: Version 1 First analysis 22,260 patients 84 cases (0.37%) 1 in 270 patients Predictors of DMV + DI DMV + DI: Big n Second analysis 46,819 patients 176 cases (0.38%) 1 in 266 patients Predictors of DMV + DI 6
Maybe we were wrong all along It seems to make sense Prospective trial of nasal only vs classic mask ventilation Measured PIP, Tidal volume, Exhaled carbon dioxide Hypothesized that oral positive pressure CAUSES obstruction Classic nasal-oral positive pressure It seems to make sense The data were clear Nasal only positive pressure 7
Limitations Effectiveness of Glidescope Not a standard face mask Two separate masks: oral and nasal Patient position not optimized No jaw thrust No neck extension Only 17 patients No oral airway placed But it does make you wonder. How often does it work? When does it fail? Results Another (modern) algorithm High success rates: 97% Specific risk factors for failure Abnormal oropharyngeal / neck anatomy Reduced thyromental distance Cervical motion limitation Institution (mine) Specific Glidescope rescue DL Fiberoptic Other (LMA, Wake up, Trach, Blind) Incorporate new devices into the algorithm Train staff on the devices Focused group: 15 faculty anesthesiologists 8
Results So what should I do differently 1. Perform the jaw-protrusion or upper-lip-bite test 2. Shave beards for patients with mutiple risk factors for DMV or DI 3. Educate your procedural colleagues about Beards Jaw protrusion test 4. Consider a new diff airway algorithm 9