Epiglottoscopy, Positioning, The Neglected Orifice, & Passive Oxygenation

Transcription

1 Epiglottoscopy, Positioning, The Neglected Orifice, & Passive Oxygenation Richard M. Levitan, MD Jefferson Medical College Philadelphia PA

2 EPIGLOTTIS: The Anatomic Center of the Airway Start to Finish Tongue to Cords Right / Left midline

3 Mechanical Center of the Airway Epiglottis Tongue Tracheal axis Epiglottis positioned at intersection of two critical curves. Atlanto-occipital extension pivots tongue backward - not opening airway. Head elevation improves jaw mechanics, jaw distraction lifts tongue and jaw upward, opening the space between the blue and yellow curves.

4 Atlanto-occipital extension (tilting head backward) does NOT open the airway Courtesy of George Kovacs, MD Dalhousie NS Emergency Medicine

5 Imaging with Glidescope video system (Verathon) Epiglottis rests on the posterior pharyngeal wall when starting

6 Keys to Epiglottoscopy Proceed slowly, methodically down tongue Distract tongue and jaw forward, and lift epiglottis edge off the posterior pharynx If epiglottis is not seen, march down the tongue midline and then control the tongue Beware of epiglottis camouflage! fluids, blood, saliva pool in hypopharynx use suction tip if needed to clear hypopharynx and see epiglottis edge epiglottis: - reliable anterior landmark - able to be lifted out of fluids - top of laryngeal inlet

7 By the way, have been meaning to get this story to you... on my LAST SHIFT OF RESIDENCY at Jefferson I had the best airway story of my career... a poor young guy in his 20's comes in with a single GSW from his submental area extending through his face and out his forehead. Awake. Alert. Oxygenating, but blood gushing out of the remnants of his face and mouth... Trauma level 1's was called, so the whole ER and trauma/anesthesia service is surrounding me. I suction, push drugs...i take a look, see epiglottis edge and posterior cartilages, angle the blade so it lifts the epiglottis out of view, suction the pooling blood again, and get first pass success. Take a look at the 3D recon... with the tube in place.

8 Effect of different head positions on upper airway dimensions and mechanics of jaw opening Atlanto-occipital Extension Neutral Head forward positioning

9 Jaw mechanics: Mouth opening: widest with head brought forward relative to chest Thyromental distance: space tongue gets pushed into during laryngoscopy, enlarges with head forward

10 sniffing Kitamura Y, et al. Dynamic interaction of craniofacial structures during head positioning and direct laryngoscopy... Anesth 2007, 107; DL w lift Caudal and upward movements of the mandible and tongue base increase the distance between anterior and posterior obstacles...an increase of the submandibular space may be essential for caudal movements of anterior obstacles, allowing vertical arrangement of the anterior obstacles and larynx. Lifting the head lengthens the submandibular space (from M L), allowing the anterior structures to be distracted forward and upward. Note how axis of view steepens between positions.

11 Elevate the head until the ear is at the sternal notch Universal intubating and ventilation position Independent of age and size

12 Bimanual Laryngoscopy & Head Elevation

13 Cricoid Pressure > > Airway Collapse The effect of cricoid pressure on the cricoid cartilage and vocal cords: an endoscopic study. Palmer JHM. Anaesthesia, 2000: 55; % Cricoid Deformation 20 Newtons: 51-99% 100% 30 Newtons: 51-99% 100% 44 Newtons: 51-99% 100% Male (n=15) 1 (7%) 0 1 (7%) 2 (13%) 1 (7%) 4 (27%) Female (n=15) 2 (13%) 7 (47%) 0 11 (73%) 1 (7%) 11 (79%) Vocal Cord Closure 20 Newtons 30 Newtons 44 Newtons Difficult Ventilation 20 Newtons 30 Newtons 44 Newtons Male (n=15) 6 (43%) 8 (57%) 11 (78%) Male (n=15) 6 (43%) 10 (71%) 12 (86%) Female (n=15) 6 (50%) 7 (58%) 7 (58%) Female (n=15) 9 (75%) 12 (100%) 12 (100%) Cricoid deformation, vocal cord closure and difficult ventilation all increase with increasing force of CP % of patients have difficult ventilation at 44N

14 Boyce JR et al., Obes Surg Feb;13(1):4-9. A preliminary study of the optimal anesthesia positioning for the morbidly obese patient. 26 patients, BMI ~56! Reverse Trendelenburg (RT, 30 degrees tilt), Flat, Back Up Fowlers Time SaO2 to drop 100% to 92%: Safe Apnea Period (SAP)

15 3 min pre-oxygenation, safe apnea period (SaO2 drop from 100% to 95%) 386 seconds to fall to 95% in head up group 282 seconds to fall to 95% in supine group 100 sec EXTRA safe apnea with head elevation A Prospective, Randomized Controlled Trial Comparing the Efficacy of Pre-Oxygenation in the 20 Head-Up vs Supine Position Lane S, et. al. Anaesthesia 2005; 60:

16 Pre-oxygenation in the obese patient: effects of position on tolerance to apnoea Aldermatt FR, et. al. BJA 2005; 95: obese patients (BMI >35); Group 1 (sitting, n=20) or Group 2 (supine, n=20). - RSI in decubitus position, trachea intubated, pt left apneic and disconnected. - Time desaturation to 90% from end of induction of anaesthesia was recorded. - O2 and CO2 similar between groups, baseline and after pre-oxygenation. - Mean time to desaturation to 90% was significantly longer in the sitting group compared with the supine group [mean (SD): 214 (28) vs 162 (38) s, P<0.05]. - Pre-oxygenation in sitting position significantly extends the tolerance to apnoea in obese patients.

17 Pre-oxygenation: How it works Optimizing preoxygenation in adults Issam Tanoubi, et al. Can J Anesth/J Can Anesth (2009)) 56: Oxygen reserves in a normal healthy adult when breathing room air (left), after breathing 100% oxygen (right), at onset of apnea, and when reaching an oxygen saturation (SpO2) of 90%. In this example, a subject with an oxygen consumption of 250 ml per min could sustain a period of apnea of 228/250 =0.9 min after breathing air and 2267/250 = 9 min after breathing oxygen Oxygen Reserves (ml) Lungs Hemoglobin Plasma Air SpO2 = 90% Gas absorption continues with apnea Oxygen SpO2 = 90%

18 With pulse ox saturation in 90's, how close are you to the edge? Small changes in SaO2 can correlate with major changes in PaO2

19

20 Pre-oxygenation...get up onto on ledge No-oxygenation...jump! What if it was not the cessation of ventilation that causes hypoxemia...but the REMOVAL of oxygen? Post-oxygenation...landing

21 NO DESAT - Case Example: EtOH intoxication, level 560! Video Laryngoscopy Flat positioning, no O2, sonorous respiration - 70% Flat positioning, no O2, nasal trumpet - 70% Flat positioning, face mask, nasal trumpet - 73% Head up, trumpet, face mask 15 lpm, NC 15 lpm - 90% Head up, trumpet, bag mask, NC 15 lpm - 94% Head up, trumpet, apnea during VL*, NC 15 lpm - 98% *Video laryngoscopy with Glidescope x 4 (two operators, lots of secretions)

22 How apneic diffusion oxygenation works - Pre-oxygenation with 100% O2 followed by O2 insufflation - During the apnoeic period, O2 is extracted from the FRC into the blood at a rate of 250 ml/min to maintain metabolic O2 consumption. - Due to greater solubility of CO2 in blood (90% stays in tissue) CO2 is added to the alveolar space at a rate of only 10 ml/min - Net gas flow from the alveoli to the blood of 240 ml/min - A subatmospheric pressure is established in the alveoli, and the ambient oxygen is drawn en masse into the lungs and maintains oxygenation. Pulmonary uptake of oxygen, acid-base metabolism and circulation during prolonged apnea. Apneic diffusion oxygenation. Holmdahl M. Acta Chirurgica Scandinavica 1956; 212 Supplement (Suppl.):

23 Apneic Oxygenation in Man Frumin MJ, Epstein RM, Cohen G. Anesthesiology, Nov-Dec 1959, pp minutes without any ventilation Saturation O2 98%-100% Gas absorption CONTINUES without ventilation!

24 Apneic Oxygenation in Man Heller ML, Watson R, Imredy DS Anesthesiology, Jan-Feb 1964, pp When man becomes apneic after preliminary oxygenation, there is a marked difference in the rate of arterial deoxygenation on whether the airway is open to room air or attached to an oxygen reservoir. Polarographic arterial studies PO2 studies show a rapid fall in PaO2 when atmospheric air (containing 80% nitrogen) moves down the airway. In the case of pure oxygen reaching the alveolar space, high PO2 values greater than 400mm of mercury were observed even after 5 minutes of apnea. On the other hand, air with high nitrogen content dilutes alveolar oxygen... Oxygen uptake is inhibited as alveolar oxygen tension falls.

25 Pulmonary and Cardiac Effects of Apneic Oxygenation in Man Fraioli RL, Sheffer LA Anesthesiology, Dec 1973, pp

26 Pulmonary and Cardiac Effects of Apneic Oxygenation in Man Fraioli RL, Sheffer LA Anesthesiology, Dec 1973, pp Group II Obese, FRC 1/2 of Group 1

27 Pharyngeal Insufflation of Oxygen Prevents Arterial Desaturation During Apnea Teller LE, et al. Anesthesiology 1988; 69: n=20, nasal airway s/p induction (36 Fr) 8 Fr Catheter inserted just beyond nasal trumpet, 3 liters per minute Sux, sedation, apnea until pulse ox 92% or, 10 minutes had elapsed Each patient served as their own control (with and w/o 3 lpm)

28 Nasopharyngeal oxygen insufflation following pre-oxygenation using the four deep breath technique. Taha SK, et al., Anaesthesia, 2006, 61, pages Preoxygenation 4 deep breath technique within 30 s, 30 ASA I or II patients - Study group (n = 15), pre-oxygenation and insufflation O2 5 liter per min via a nasopharyngeal catheter commenced at the onset of apnoea. - In the control group, pre-oxygenation was not followed by nasopharyngeal oxygen insufflation (n = 15). - In the control group, SpO2 fell to 95% within a mean (SD) apnoea time of 3.65 (1.15) min, - in the study group, SpO2 was maintained in all patients at 100% throughout the 6 min of apnoea - Nasopharyngeal oxygen insufflation following pre-oxygenation using the four deep breath technique can delay the onset of haemoglobin desaturation for a significant period of time during the subsequent apnoea.

29 Apneic oxygenation during prolonged laryngoscopy in obese Richard patients: Levitan, MD a randomized, controlled trial of nasal oxygen administration. Ramachandran SK, et al. J Clin Anesth May;22(3): n = 30, BMI ~31 5 lpm via NC, 25 degree head up 8 deep breaths pre-oxygenation Onas (n=15) NOnas (n=15) Pre-induction ETO2 (mmhg) 88.3 (1.9) 88.7 (2.6) Pre-induction FIO2 (%) 97.4 (1.7) 97.6 (1.9) Initial ETCO (4.6) 43.8 (3.9) Lowest SpO2 (%) 94.3 (4.4) 87.7 (9.3)* SpO2 95% time (min) 5.29 (1.02) 3.49 (1.33)* Resaturation time (min) 0.69 (0.4) 1.57 (1.49) Results means (SD). Onas=nasal O2 NOnas= no nasal O2, ETO2=end-tidal O2, FIO2=inspired O2 concentration, ETCO2=end-tidal CO2, SpO2=oxygen saturation as measured by pulse oximetery. Resaturation time=time to regain SpO2 100% after tracheal intubation. Statistically significant difference.

30 HIGH FLOW NASAL VS HIGH FLOW MASK OXYGEN DELIVERY: TRACHEAL GAS CONCENTRATIONS THROUGH A HEAD EXTENSION AIRWAY MODEL 2002 Open Forum Abstracts, Am Assoc Resp Care (OF ) Tiep B, et. al. - Ultrasonic flow studies recorded on digital video - Mask O2 remains outside the nose and mouth until the subject inhales - Nasal O2 is stored in upper airways during exhalation - High flow nasal cannula delivery is more efficacious than the non-rebreather mask at equivalent flows, due to O2 storage in the upper airways during exhalation poised for delivery upon the next inhalation in addition to the continuous supply flow.

31 DELIVERY OF HIGH FIO2 John W. Earl RRT, BS. Abstracts Am Assoc Resp Care 2003 Flow rates 10, 15, 30, 45, 60 lpm comparing a non-rebreather mask (NRB) vs. simple face mask (SM) and simple mask with side ports taped. Healthy subjects, breaths per minute, TV Each test 5 minutes, nitrogen washout 3 minutes Results: Expired PO2 measured in pharynx: 10 LM SM-51% NRB-50% 15 LM SM-51% NRB-56% 30 LM SM-55% NRB-77% 45 LM SM-73% NRB-78% 60 LM SM 86% NRB-89% SM taped-93% "Current thinking that a NRB mask running at 15 L/m is an acceptable way to deliver high FIO2 is not valid and should be revised."

32 Flat, mask only > poor pulmonary function, flow doesn't meet requirements

33 Upright, mask only > better pulmonary function, flow insufficent

34 Ear-to-sternal notch > promotes upper airway patency Positioning improves pulmonary function Mask and NC combined flow approach appropriate needs 30 liters/minute

35 Improved positioning for oxygenation, ventilation, intubation, and reduced risk of regurgitation in trauma / C-spine immobilized

36 NO DESAT! NO DESAT! Mouth opened by oral device High FiO2 in pharynx O2 drawn passively into trachea APNEIC oxygenation via nasal cannula during oral intubation NO DESAT: Nasal Oxygen During Efforts Securing A Tube

37 Passive Apneic Oxygenation During Laryngoscopy

38 Oxygenation and Ventilation Strategy Based on Pulse Oximetry Weingart S, Levitan RM Preoxygenation and Weingart Prevention S, Levitan of Desaturation RM. During Emergency Text Airway Ann Emerg Management, Med Ann Mar;59(3): Emerg Med, in press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

39 CONCLUSIONS Safety hinges on oxygenation throughout procedure Positioning is easy, very important, under appreciated Pre-oxygenation: patent airway, max FiO2 > nasal O2 Passive oxygenation via nose during intubation efforts NO DESAT! Redundancy throughout: 2 ways to oxygenate 2 ways to intubate 2 ways to ventilate thanks! Cannot intubate >>> Passively oxygenate, then ventilate?