2006 OPEN FORUM Abstracts
EFFICACY OF VENTILATION VIA THE NASAL ROUTE VS. THE ORAL ROUTE IN PATIENTS UNDER GENERAL ANESTHESIA
YAFEN LIANG, MD; MOHAMED HELMY, MD; WILLIAM R.
KIMBALL, MD; I. DAVID TODRES, MD; WARREN M. ZAPOL, MD; YANDONG JIANG, MD, PhD;
ROBERT M. KACMAREK, PhD, RRT. Massachusetts General Hospital and Harvard Medical School, Boston,
Massachusetts
Background: Mouth to mouth breathing has been used in CPR for
over half a century. However, recent studies demonstrate that mouth-to-mouth
breathing plus chest compression during CPR does not produce better outcome for
patients receiving CPR than chest compression alone. We hypothesized that
mouth-to-mouth breathing adversely affects upper airway obstruction and does
not provide adequate ventilation. We questioned if nasal route ventilation is
more effective than oral route ventilation in non-paralyzed adult patients
under general anesthesia.
Methods: 7 adult ASA I-II patients requiring general
anesthesia were studied using separate oral and nasal masks. Ventilation was
provided via both masks together then randomly by each mask separately.
Airway flow, airway pressure, tidal volume and other respiratory parameters
during positive pressure ventilation was recorded with 2 NICO monitors (Respironics Corp).
Results: As shown in the following table, patients had
significantly higher peak inspiratory pressure (PIP)
during oral ventilation and higher peak inspiratroy
flow/PIP (PIF/PIP) during nasal ventilation. Furthermore, during
combined nasal and oral ventilation, 6 patients had higher PIF via
the nasal route than oral route at the same PIP. During separate nasal and
oral ventilation, all patients had higher PIP during oral ventilation
than during nasal ventilation. Five patients had higher exhaled tidal
volumes via the nasal route than the oral route.
Combined
Nasal
Oral ANOVA
ventilation ventilation ventilation
Peak (i)
Flow(L/min) 33.34±14.88
29.81±4.96 27.07±8.17 NS
Exhaled tidal vol (mL)
149.20±195.31 155.88±80.09
99.86±247.79 NS
PIP (cm H2O)
1.80±4.80
16.04±4.50
30.73±6.48
P=0.001*
PIF/PIP(L/(min·cmH2O))
1.56±0.59
2.05±0.83 0.93±0.44
P=0.01*
Conclusions: Nasal ventilation provides better ventilation with
lower airway pressure than oral ventilation or combined oral/nasal ventilation
in non-paralyzed patients under general anesthesia. Nasal ventilation may
prevent or reduce upper airway obstruction by forcing the tongue and soft
palate forward and establishing an open airway.