TY - JOUR
T1 - Laryngoscope force and cervical spine motion during intubation in cadavers-cadavers versus patients, the effect of repeated intubations, and the effect of type II odontoid fracture on C1-C2 motion
AU - Hindman, Bradley J.
AU - From, Robert P.
AU - Fontes, Ricardo B.
AU - Traynelis, Vincent C.
AU - Todd, Michael M.
AU - Zimmerman, M. Bridget
AU - Puttlitz, Christian M.
AU - Santoni, Brandon G.
N1 - Publisher Copyright:
Copyright © 2015, the American Society of Anesthesiologists, Inc.
PY - 2015
Y1 - 2015
N2 - Background: The aims of this study are to characterize (1) the cadaver intubation biomechanics, including the effect of repeated intubations, and (2) the relation between intubation force and the motion of an injured cervical segment. Methods: Fourteen cadavers were serially intubated using force-sensing Macintosh and Airtraq laryngoscopes in random order, with simultaneous cervical spine motion recorded with lateral fluoroscopy. Motion of the C1-C2 segment was measured in the intact and injured state (type II odontoid fracture). Injured C1-C2 motion was proportionately corrected for changes in intubation forces that occurred with repeated intubations. Results: Cadaver intubation biomechanics were comparable with those of patients in all parameters other than C2-C5 extension. In cadavers, intubation force (set 2/set 1 force ratio = 0.61; 95% CI, 0.46 to 0.81; P = 0.002) and Oc-C5 extension (set 2-set 1 difference =-6.1 degrees; 95% CI,-11.4 to-0.9; P = 0.025) decreased with repeated intubations. In cadavers, C1-C2 extension did not differ (1) between intact and injured states; or (2) in the injured state, between laryngoscopes (with and without force correction). With force correction, in the injured state, C1-C2 subluxation was greater with the Airtraq (mean difference 2.8 mm; 95% CI, 0.7 to 4.9 mm; P = 0.004). Conclusions: With limitations, cadavers may be clinically relevant models of intubation biomechanics and cervical spine motion. In the setting of a type II odontoid fracture, C1-C2 motion during intubation with either the Macintosh or the Airtraq does not appear to greatly exceed physiologic values or to have a high likelihood of hyperextension or direct cord compression.
AB - Background: The aims of this study are to characterize (1) the cadaver intubation biomechanics, including the effect of repeated intubations, and (2) the relation between intubation force and the motion of an injured cervical segment. Methods: Fourteen cadavers were serially intubated using force-sensing Macintosh and Airtraq laryngoscopes in random order, with simultaneous cervical spine motion recorded with lateral fluoroscopy. Motion of the C1-C2 segment was measured in the intact and injured state (type II odontoid fracture). Injured C1-C2 motion was proportionately corrected for changes in intubation forces that occurred with repeated intubations. Results: Cadaver intubation biomechanics were comparable with those of patients in all parameters other than C2-C5 extension. In cadavers, intubation force (set 2/set 1 force ratio = 0.61; 95% CI, 0.46 to 0.81; P = 0.002) and Oc-C5 extension (set 2-set 1 difference =-6.1 degrees; 95% CI,-11.4 to-0.9; P = 0.025) decreased with repeated intubations. In cadavers, C1-C2 extension did not differ (1) between intact and injured states; or (2) in the injured state, between laryngoscopes (with and without force correction). With force correction, in the injured state, C1-C2 subluxation was greater with the Airtraq (mean difference 2.8 mm; 95% CI, 0.7 to 4.9 mm; P = 0.004). Conclusions: With limitations, cadavers may be clinically relevant models of intubation biomechanics and cervical spine motion. In the setting of a type II odontoid fracture, C1-C2 motion during intubation with either the Macintosh or the Airtraq does not appear to greatly exceed physiologic values or to have a high likelihood of hyperextension or direct cord compression.
UR - http://www.scopus.com/inward/record.url?scp=84945314084&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84945314084&partnerID=8YFLogxK
U2 - 10.1097/aln.0000000000000830
DO - 10.1097/aln.0000000000000830
M3 - Article
C2 - 26288267
AN - SCOPUS:84945314084
SN - 0003-3022
VL - 123
SP - 1042
EP - 1058
JO - Anesthesiology
JF - Anesthesiology
IS - 5
ER -