Does Chest Wall Rigidity After Narcotic Administration Cause Difficult Ventilation? A Pilot Study
Yan Li, M.D., David G. Bjoraker, M.D.
Department of Anesthesiology, University of Florida,
Gainesville, FL
Original Science
Introduction: Difficult or impossible ventilation after narcotic
administration during induction of general anesthesia has been
reported in numerous studies and has generally been attributed
to muscular rigidity of the chest wall. However, Bennett et al.
concluded that the major cause was closure of the vocal cords
induced by the narcotic injection. By studying patients who have
either a post-laryngectomy stoma or a tracheotomy associated
with previous surgery, we examined whether chest wall rigidity
occurs after remifentanil infusion and is associated with
difficult ventilation.
Methods: After IRB approval and informed consent, patients who
met our study criteria were enrolled. These criteria included
age 18-75 years, presence of stoma or tracheotomy, and absence
of pulmonary disease (e.g., COPD). No medication was given
preoperatively. Standard ASA intraoperative monitors and a BIS
monitor were applied in the operating room. An endotracheal tube
was placed into the stoma or tracheotomy site and 100% 02 was
administered. Remifentanil (Remi), 15 µg/kg, was infused over 2
min; followed by succinylcholine (Remi + Sux), 1.5 mg/kg bolus
after a 1 min interval. When apnea occurred, mechanical
ventilation was initiated (tidal volume (TV), 12 ml/kg;
respiratory rate, 10 breaths/min; I/E ratio, 1:2). Recorded
endpoints included pressure-volume loops (Datex, Ohmeda Madison,
WI) to determine PIP, compliance, TV, and end-tidal CO2 at times
0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 min with time 0 min being the
start of the remifentanil infusion. In addition, SpO2, BIS
score, HR, and BP were noted. Data were analyzed using paired
t-test or one-way repeated measures ANOVA with pairwise Tukey
comparisons when appropriate. P< 0.05 was considered
statistically significant.
Results: BIS values and ventilatory parameters after
remifentanil without or with succinylcholine in 5 patients.
Intervention |
PIP (mm Hg) |
Compliance (ml/mm Hg) |
TV (ml) |
EtCO2 (mm Hg) |
BIS value |
|
Control |
- |
41.6± 12.6 |
835±239 |
36± 5 |
97.4± 0.55 |
|
Remi |
22.2± 6.3 |
32.0± 15.5 |
851± 142 |
35± 7 |
50.4± 14 |
|
Remi + Sux |
18.4± 2.7 |
53.0± 9.5 |
881± 68 |
35± 6 |
31.4± 7.6 |
P ValuesControl vs. Remi Control vs. Remi + Sux Remi vs. Remi + Sux |
-
-
0.282 |
0.059
0.031
0.004 |
0.112
0.270
0.457 |
0.746
0.724
0.848 |
0.0023
0.0004
0.1066 |
There was not a significant difference in PIP, TV, or end-tidal
CO2 between remifentanil and remifentanil plus succinylcholine;
however, compliance did significantly improve with muscular
relaxation. The magnitude of the remifentanil values however did
not cause overt chest wall rigidity. All patients could be
ventilated without difficulty. With this large induction dose of
remifentanil, hemodynamics remained stable during induction
while the BIS values indicated unconsciousness.
Conclusions: In this pilot study, we were unable to demonstrate
serious narcotic-induced chest wall rigidity causing difficult
ventilation even with a very high dose of remifentanil although
Jhaveri et al. reported an 80% incidence with this dose in 20
patients. The improvement in compliance during remifentanil
anesthesia by the administration of succinylcholine was
consistent with loss of remaining muscle tone in the chest wall.
While narcotic-induced rigidity leading to difficult ventilation
may be due to a combination of multiple factors, our preliminary
observations when the larynx is absent or bypassed are
consistent with the conclusion of Bennett et al. that closure of
the larynx is the major contributing cause.
