A Comparison of the Oral-nasal and Oral Mask Ventilation After Nasal Surgery.
American Society of Anesthesiologists (ASA) physical class I or II, adult patients ageing
19-45 yr, scheduled for nasal surgery will be recruited.
Patient characteristics will be recorded; age, gender ASA physical status, height, weight.
Simple randomization will be accomplished with a computer-generated sequence of numbers and
sealed envelopes will be used to allocate patients into 2 groups; oral mask ventilation
followed by oral-nasal mask ventilation or the opposite.
Patients will be premedicated with midazolam. Ringer's lactate infusion at 15 mL•kg-1•h-1
will be initiated. Standart monitors will be established including neuromuscular
monitorsation and the Bispectral index monitor (BIS).
The patients head will be placed in the neutral position on a positioning pillow Anesthesia
will be induced with propofol 2 ml kg and fentanyl 50 mcg. Anesthesia will be maintained
with oxygen in nitrous oxide and sevoflurane. The patient was ventilated trough an
oral-nasal face mask (Rusch………..). The appropriate size mask with the best fit will be
selected and the mask size noted. Gas flow will be 4 L min. Muscle relaxation and entubation
will be facilitated with rocuronium 0.6 mg kg. At the end of surgery trachea will be
extubated when TOF 0.9 is obtained. Volatile anesthesia will be continued and BIS was
maintained in the range of 60-70. An oropharengeal airway was inserted and spontaneous
ventilation will be assisted with mask ventilation.
The oral-nasal mask will be applied with the one handed EC-clamp technique. The mask will be
placed over the bridge of the nose and mouth and a chin-lift, head tilt maneuver will be
used. The oral mask; size 1 or 2 (Rüsch) child's mask will be placed only over the mouth and
the one handed EC-clamp technique with the chin-lift, head tilt maneuver will be used again.
The masks will be changed/switched after five consecutive measurements for each mask
technique and the crossover time will be extremely brief.
The respiratory parameters will be measured with the monitor contained in the Drager Primus
anaesthesia machine. The observer providing mask ventilation is experienced in mask
ventilation and blinded to the monitor display. All patients will be ventilated by the same
observer. Data will be recorded by independent residents. The mask ventilation
classification will be recorded. mean airway pressure (Pmean), maximum airway pressure
(Ppeak) , tidal volume (TV), expired tidal volume (TVe) and minute volume (MV) will be
recorded during spontaneous ventilation, while the patient is deep anesthetized defined by
BIS 60-70. Sufficient chest movement, mask leak, gastric insufflation will be assessed.
Indicators for difficult mask ventilation are defined as; TV< 4 ml kg, inadequate chest
movements, two handed mask ventilation, increased gas flow, gastric insufflation. The
primary end point is the mask ventilation classification. Secondary end points were Pmean,
Ppeak, TV, MV and TVleak.
Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator)
Mask ventilation class of the patients as Grade 0 Grade 1 Grade 2 Grade 3 Grade 4
assesement will be done after extubation, when the spontaneous respiratory rate is 10 breaths /min
5 min after extubation
Murat Sayın, Ass Prof
Ankara Diskapi Yildirim Beyazit Teaching and Research Hospital, Turkey.
Turkey: Ministry of Health