Supraglottic Airway Use in the Adult Obese Population

advertisement
Supraglottic Airway Use in the Adult Obese Population
BY
Chris Burford, RN, BSN
Faculty Mentor: Debra Maloy, EdD, CRNA, Associate Professor
Graduate Programs of Nurse Anesthesia
Texas Wesleyan University
Fort Worth, Texas
May, 2018
With 36% of Americans being obese (BMI > 30 kg/m2) anesthesia practitioners increasingly care
for patients in this population.1 Supraglottic airway (SGA) devices are considered safe
alternatives to endotracheal tubes with their use expanding into more complicated procedures
and their inclusion in difficult airway algorythms.2,3 SGA used as a stand-alone device in the
obese population requires more research to demonstrate clinical safety. However, is it possible
they can play a crucial role in this populations airway management?4,5 This case report will
investigate the current recommendations for SGA use in the obese population.
Case Report
An 83-year-old, 104.5 kg, 1.55 m (body mass index 43 kg/m2) morbidly obese female presented
for sentinel node biopsy of left breast. Medical history was significant for gastroesophageal
reflux disease (GERD), active breast cancer, asthma, mild aortic stenosis, mild mitral valve
regurgitation, mild tricuspid valve regurgitation, ejection fraction of 65%, hypertension,
hyperlipidemia, diverticulitis, hypothyroidism, type 2 diabetes mellitus, and stage III kidney
disease. Surgical history included hysterectomy, knee arthroscopy and previous bilateral breast
biopsies. The patient’s medication regimen included atorvastatin, montelukast, fenofibrate, ASA,
gabapentin, losartan, carvedilol, levothyroxine, albuterol HFA, esomeprazole, triamterene,
HCTZ and regular insulin. The patient had allergies to penicillin, amoxicillin, metoclopramide
and propoxyphene. Laboratory results were unremarkable. ECG revealed sinus bradycardia, left
ventricular hypertrophy, ST deviation and moderate T-wave abnormality.
Preoperative airway exam revealed a Mallampati 2 classification, thyromental distance greater
than 3 fingerbreadths, full range of motion of the neck, and an incisor distance of greater than 3
cm. The patient was taken to the operating room and placed in the supine position. Noninvasive
monitoring was initiated and initial vital signs were heart rate (HR) 61/min, blood pressure (BP)
155/80 mm Hg, SpO2 92% on room air, respiratory rate (RR) 12/min, and temperature 36.5 oC.
Oxygen was administered via facemask at 10 L/min until expired oxygen concentration was
greater than 85%. General anesthesia was induced with lidocaine 80 mg and propofol 180 mg.
After loss of lid reflex a supraglottic airway was inserted and the patient was placed on pressure
control ventilation until spontaneous respirations returned.
Anesthesia was maintained with sevoflurane 0.8-2.5% expired concentration in a mixture of
oxygen 1 L/min and air 1 L/min. Analgesia was accomplished with fentanyl 25 mcg and
augmented by surgeons injecting local after induction. A total of lactated ringers 250 ml was
used for maintenance IV fluid. Vital signs were stable throughout with the exception of a 5-7
minute period of post induction hypotension and bradycardia treated with ephedrine 15 mg and
glycopyrrolate 0.4 mg respectively.
During emergence the anesthetic gas and air were turned off and oxygen flows were increased to
10 L/min. The laryngeal airway was removed when the patient was following commands with
adequate regular spontaneous ventilations. The patient was then transferred to the recovery room
in stable condition.
Discussion
Dr. Larry Brain, the inventor of the Laryngeal Mask Airway (LMA, Teleflex Medical Europe
Ltd., Athlone, Ireland), accomplished the first airway rescue with the LMA in a morbidly obese
patient. The patient consequently underwent a successful three-hour abdominal procedure with
respirations controlled by a mechanical ventilator through the relatively new device without
anesthesia complications.6 Since then there have been many iterations of that original LMA.
Each device can typically be defined by where they seal; base of the tongue or peri-laryngeal,
how they seal; cuffed or non-cuffed, the incorporation of a gastric access tube to facilitate
aspiration protection and whether or not they allow intubation thru the ventilation tube. They are
more broadly referred to in the literature as supraglottic airways (SGA), extraglottic airway
devices or supralaryngeal airways. The equipment used on this patient for the duration of the
case was a cuffed, intubating, peri-laryngeal SGA without a gastric access tube.7 There is
currently no uniform classification system for these devices so for this case study SGA will be
used generically.
Expanding SGA use in more complicated procedures was explored in an observational study of
200 non-obese patients undergoing off-pump coronary artery bypass grafting (CABG)
comparing the endotracheal tube (ETT) to a cuffed SGA with a gastric tube. The investigation
evaluated adverse effects such as hypoxemia, bronchospasm, secretion, airway trauma and
soreness throughout the case. The authors concluded the SGA performed better than the ETT
with lower hemodynamic responses, lower use of muscle relaxation and fewer adverse events
relating to hypoxemia, bronchospasm and upper respiratory tract trauma ultimately declaring it a
safe alternative to endotracheal tubes.2 Coincident with the expansion of SGA use are
reservations about their limitations. A recent meta-analysis of 10 randomized controlled trials
including 996 patients suggested that using certain types of SGAs in patients at high risk of
aspiration could not be recommended. They also concluded problems could be encountered
using SGAs in morbidly obese patients.8 However, the researchers in this meta-analysis reported
the incidence of aspiration to be similar between the ETT and the SGA group and the sample
size was too small to draw any definitive conclusions.
The CABG study supported the use of SGAs as a safe alternative to the ETT but excluded
patients who were obese.2 The meta-analysis did not exclude obese patients and did take a
position discouraging SGA use in morbidly obese patients even though this position was not
explicitly tied to the research.8 These positions only marginally inform decisions on using SGAs
in the morbidly obese population.
Morbidly obese patients often present with a variety of airway management complications
resulting in hypoxemia and low oxygen saturation much more quickly than in the non-obese
population. Interventions to improve airway management in the obese community are; the use of
positive end-expiratory pressure (PEEP), twenty-five degrees head up ramp positioning and
continuous positive airway pressures (CPAP) during preoxygenation and emergence.1,5
The patient, in this case report, was a morbidly obese insulin dependent diabetic with GERD, all
of which place her at an increased risk for aspiration. Current studies do not support the use of
an SGA as a sole ventilation device with this type of patient because the sample sizes are too
small to rule out the increased risks and more importantly the studies each focus on specific
types of SGAs and these specific results cannot be generalized to all SGAs.1,8 However, SGA
use is being studied as an adjunct in the anesthetic management of obese patients with some
success. Specifically, incorporating the SGA into the preoxygenation phase of induction reduced
the duration of hypoxemia in the obese patient.5 This information supports the use of SGAs in
maintaining adequate oxygenation in the obese patient and is discussed below.
One objective measure used to evaluate adequate preoxygenation is the concept of the safe apnea
period (SAP). One study defined the SAP as the time lapse between cessation of a 5 minute
period of ventilation with a fraction of inspired oxygen (FiO2) of 100% to the point the apneic
patient reaches a SpO2 of 92%. In this study, 100 patients with BMI > 35 kg/m2 were
preoxygenated with 100% oxygen for 5 minutes and then induced with midazolam, fentanyl,
propofol and atracurium. Mechanical ventilation via face mask with oropharyngeal airway or
SGA was instituted with volume control ventilation settings of: tidal volume of 8 ml/kg, RR of
12/minute, FiO2 of 1.0 and PEEP of 5 cm H2O. Ventilation ended at the end of 5 minutes and
measurements were taken. These investigations revealed that the use of an SGA was superior to
the traditional approach of mask ventilation with an oropharyngeal airway. Specifically, the
mean SAP in the SGA group was 337 seconds compared to 205 seconds for the face mask
group.5 Utilizing this approach allowed an additional 2 minutes with adequate oxygenation to
establish a definitive airway. This study confirms superior SAP times with SGA devices and
supports the use of the SGA in the morbidly obese population as a bridge to intubation.
Research does support the SGA to manage a difficult airway and as a bridge to a more definitive
airway.3,5 However, a sufficient body of research is needed to established evidence-based
guidelines for SGA use in this population as a replacement for the ETT. Currently, the sample
sizes are too small to develop credible conclusions.8 Additionally, many studies focus on specific
types of SGAs, and this data does not apply to the many different designs of SGAs available.1
The case considered in this report did not result in any adverse outcomes as a result of the use of
an SGA. However, a current review of evidence did not support the use of an SGA as the sole
ventilation device for the duration of the case.
References
1. Nguyen-Mason J, Rodriguez R. Laryngeal mask airway use in morbidly obese patients
undergoing general anesthesia. AANA Journal . Apr2017, Vol. 85 Issue 2, p130-135. 6p.
2. Shah K. ProSeal laryngeal mask airway as an alternative to standard endotracheal tube in
securing upper airway in the patients undergoing beating-heart coronary artery bypass grafting.
Ann Card Anaesth. 2017;20(1):61-66.
3. Apfelbaum J, Hagberg C, Caplan R, et al. American Society of Anesthesiologists Task Force
on Management of the Difficult Airway. Practice guidelines for management of the difficult
airway: an updated report by the American Society of Anesthesiologists Task Force on
Management of the Difficult Airway. Anesthesiology. 2013;118(2):251-270.
4. Nicholson A, Cook TM, Smith AF, Lewis SR, Reed SS. Supraglottic airway devices versus
tracheal intubation for airway management during general anaesthesia in obese patients.
Cochrane Database Syst Rev. 2013;(9):CD010105.
5. Sinha A, Jayaraman L, Punhani D. ProSeal LMA increases safe apnea period in morbidly
obese patients undergoing surgery under general anesthesia. Obes Surg. 2013;23(4):580-4.
6. Van Zundert TC, Brimacombe JR, Ferson DZ, Bacon DR, Wilkinson DJ. Archie Brain:
celebrating 30 years of development in laryngeal mask airways. Anaesthesia. 2012;67(12):137585.
7. Michálek P, Miller D. Airway management evolution - in a search for an ideal extraglottic
airway device. Prague Med Rep. 2014;115(3-4):87-103.
8. Xu R, Lian Y, Li WX. Airway Complications during and after General Anesthesia: A
Comparison, Systematic Review and Meta-Analysis of Using Flexible Laryngeal Mask Airways
and Endotracheal Tubes. PLoS ONE. 2016;11(7):e0158137.
Mentor: Debra Maloy, EdD, CRNA, Associate Professor, Graduate Programs of Nurse
Anesthesia
dmaloy@txwes.edu
Smart Learning Objectives:
1. At the conclusion of a careful reading of this case study, every phase II nurse anesthesia
student will be able to identify 3 interventions to overcome airway complications commonly
found in the obese population.
2. At the conclusion of a careful reading of this case study, every phase II nurse anesthesia
student will be able to elucidate the results of the study involving the measurement of the safe
apnea period in obese patients.
3. At the conclusion of a careful reading of this case study, every phase II nurse anesthesia
student will be able to understand the significance of the results of the safe apnea study as it
relates to the induction phase of anesthesia.
Continuing Education Questions:
1. A patient with a body mass index of >40 kg/m2 falls into what American Society of
Anesthesiologist classification?
2. Who invented the laryngeal mask airway?
3. What percentage of Americans have a body mass index > 30 kg/m2?
4. Is there a current codified classification system for supraglottic airway devices?
5. How does PEEP improve oxygen reserves?
6. What physiologic principle does a 25 degree head up ramp position for pre-oxygenation and
induction of anesthesia address in the obese population?
7. How is functional residual capacity impacted in the obese population in the supine position?
8. How can insulin dependency place a patient at higher risk for aspiration?
10. How can the use of a SGA device in the pre-oxygenation phase of induction impact oxygen
reserves in obese patients?
Download