Nasal mask ventilation is better than face mask ventilation in edentulous patients

Abstract

Background and Aims: Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated.
Material and Methods: Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed.
Results: A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant.
Conclusion: Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients.

Full text

314 © 2016 Journal of Anaesthesiology Clinical Pharmacology | Published by Wolters Kluwer - Medknow
Nasal mask ventilation is better than face mask ventilation
in edentulous patients
Mukul Chandra Kapoor, Sandeep Rana, Arvind Kumar Singh, Vindhya Vishal, Indranil Sikdar
Department of Anaesthesiology, Command Hospital (CC), Lucknow, Uttar Pradesh, India
Introduction
Anticipation of the difficult airway is vital for safe and efficient
of airway management. Difficult airway generally includes
difficult laryngoscopy, difficult intubation, and difficult mask
ventilation (DMV). Mask ventilation provides the anesthesia
care provider with a rescue technique after unsuccessful
attempts at intubation.[1] The value of DMV seems to have
taken a back seat to the more glamorous problem of difficult
intubation.[2] DMV may result in inability to achieve adequate
ventilation with potential serious adverse outcomes.[3]
Face mask ventilation of the edentulous patient is often difficult
as ineffective seating of the standard mask to the face prevents
attainment of an adequate air seal.[4] In edentulous patients,
air leaks due to reduced contact between the mask and the
cheeks.[5] It is common practice for one person to hold the
mask with both hands over the patient’s face while a second
person ventilates the lungs by squeezing the bag.
Liang et al. recently demonstrated the efficacy of nasal ventilation
in reducing airway obstruction vis-à-vis oral-nasal ventilation.[1]
Nasal positive-pressure ventilation has been suggested as an
effective mode of ventilation in edentulous patients;[6] however
to our knowledge, it has never been investigated. Nasal positive
Address for correspondence: Dr. Mukul Chandra Kapoor,
6, Dayanand Vihar, New Delhi ‑ 110 092, India.
E‑mail: mukulanjali@rediffmail.com
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DOI:
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Original Article
Background and Aims: Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard
mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been
cited in case reports but has never been investigated.
Material and Methods: Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal
intubation, during a 17‑month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular
blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia
ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best‑fit.
Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best‑
fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best‑fit
with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed.
Results: A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of
the two masks at best‑fit was statistically significant (P = 0.0017). Despite the best‑fit mask placement, adequacy of ventilation
could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and
the difference was statistically significant.
Conclusion: Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients.
Key words: Difficult mask ventilation, edentulous, face mask leak, nasal mask ventilation
Abstract
How to cite this article: Kapoor MC, Rana S, Singh AK, Vishal V, Sikdar I.
Nasal mask ventilation is better than face mask ventilation in edentulous
patients. J Anaesthesiol Clin Pharmacol 2016;32:314-8.
This is an open access article distributed under the terms of the
Creative Commons Attribution-NonCommercial-ShareAlike 3.0
License, which allows others to remix, tweak, and build upon the
work non-commercially, as long as the author is credited and the
new creations are licensed under the identical terms.
For reprints contact: reprints@medknow.com
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Kapoor,
et al
.: Nasal mask ventilation is better in edentulous patients
Journal of Anaesthesiology Clinical Pharmacology | July-September 2016 | Vol 32 | Issue 3 315
pressure ventilation may be used in edentulous patients as the
mask contact is only on the maxillary plane.[1] We hypothesized
that, in edentulous patients requiring general anesthesia, the
nasal mask placement would be more effective in reducing air
leaks than the standard face mask placement.
Material and Methods
The study was performed at a tertiar y care hospital after
approval of the Institutional Ethics Committee of Command
Hospital (CC), Lucknow. Informed consent was obtained
from all patients. All consecutive edentulous adult patients
scheduled for surgery under general anesthesia with
endotracheal intubation, during a 17-month period, were
prospectively evaluated for inclusion in this study. A pilot study
was conducted on five patients to determine the minimum
number of patients required for the main study, as no similar
study on edentulous patients was available in contemporary
literature. Based on the pilot study, a minimum number
of 62 patients were required for 80% power (α = 0.05,
β= 0.2) and 83 patients for 90% power (α = 0.05,
β=0.1).Thetimeperiodwasdecidedbasedonpredicted
recruitment of 5-6 edentulous patients per month. The
exclusion criteria were contraindication to mask ventilation
(emergency cases requiring a rapid sequence induction,
planned awake intubation), prognathia or retrognathia, history
of snoring, sleep apnea, obesity, and patients with beards.
Dentures of all edentulous patients were removed before they
were taken to the operating room, as per standard practice of
the institution. All patients were routinely monitored using
electrocardiography, noninvasive blood pressure measurement
and peripheral oxygen saturation (SpO2) before induction
of general anesthesia. After preoxygenation, anesthesia was
inducedwithasequenceoffentanyl,2mcg/kg,intravenousanda
sleepdoseofthiopentone,3-5mg/kg,injectedintravenousover
60s.Afterlossofconsciousnessandpreliminaryverification
ofabilitytomaintainair way,vecuronium,0.8-1mg/kg,was
administered to achieve neuromuscular blockade. Lungs
were ventilated with positive-pressure ventilation holding a
single use anatomical face mask (EcoMask II, Intersurgical,
Berkshire, UK), with the left hand, using the ventilator circle
system,andcompressingthereservoirbagmanuallyfor1min.
A face mask of appropriate size (small adult, medium adult or
large adult) was chosen to achieve the best-fit for each patient.
After 2 min, on partial onset of neuromuscular block ade,
an ascending bellow anesthesia machine ventilator (AV-S
Ventilator, Penlon Limited, Abingdon, UK) replaced the
manual reservoir bag as the ventilation drive. The fresh gas
flowwaspresetat6-8l/minofoxygenwith2%sevoflurane,
and the ventilator set on volume-controlled mode with a tidal
volume of 10 ml/kg (delivered volume), respiratory rate
12breaths/minandI:Eratio1:2.
Standard face mask ventilation was performed by placing the
thumb and index finger on the body of the mask, whereas
the other fingers moved the mandible toward the upper teeth
and maintained the head in extended position (primary
positioning). Delivered and Expired tidal volumes were
measured with two spirometry sensors (Integrated in AV-S
Ventilator, Penlon Limited, Abingdon, UK), placed in the
delivery and expired ends of the anesthesia breathing system.
In case of inadequate ventilation for five consecutive breaths
(definedasadifferenceof>25%betweenthesetdelivered
and the expired tidal volume/fall in bellows of the ventilator/
inadequate capnograph trace/inadequate visual rising of the
chest wall), the mask position was adjusted by repositioning
the inferior end of the mask above the mandible, with the head
in extension position (best-fit positioning). The cephalad
end of the mask remained on the bridge of the nose for both
positions. The readings of the expired tidal volumes and
adequacy of capnograph trace were noted in the 3rd min after
stabilization in the best-fit position. The SpO2, peak airway
pressure, and fall in the bellows, in case any, were recorded.
In case of inability to achieve adequate ventilation, despite
above positioning, the mask was held with both hands as a
rescue measure. In case this too failed, a Guedel’s airway
was introduced and help of a second person taken to achieve
the face mask seal.
After 3 min, the face mask was changed to an infant size
transparent anatomical face mask (EcoMask II, Intersurgical,
Berkshire, UK) so placed that it covered only the nose. The
inferior end of the mask was seated on the upper lip. In case
the mask was small for the nose, it was changed to a pediatric
size mask with the inferior part of the mask seated on the upper
lip. The mask was held with the left hand by placing the thumb
and index finger on the body of the mask, whereas the middle,
ring, and little fingers moved the mandible toward the maxilla.
The mouth closed as a result of the upward pressure of the
threefingers[Figure1].Theheadwasplacedintheneutral
position and not extended. In case of inadequate ventilation
for five consecutive breaths (as defined above), the mask
position was adjusted by repositioning the inferior end of the
mask above the upper lip and ensuring that the mouth was
closed, while maintaining the head in neutral position (best-fit
positioning). No change in the delivered volume or ventilator
settings was made. After achieving best-fit positioning and
allowing a minute to pass, the readings of the expired tidal
volumes and adequacy of capnograph trace were noted. The
ventilation strategy flowchart followed in the study is shown
inTable1.TheSpO2, peak airway pressure, and fall in the
bellows, in case any, were recorded. In case of inability to
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Kapoor,
et al
.: Nasal mask ventilation is better in edentulous patients
316 Journal of Anaesthesiology Clinical Pharmacology | July-September 2016 | Vol 32 | Issue 3
achieve adequate ventilation, despite above positioning, other
airway adjuncts were used as rescue airway. The holding
of the mask was done in all cases by a resident with at least
2yearsexperienceinanesthesiology,undersupervisionofthe
principal investigator, and the tidal volume recordings were
noted by a junior resident blinded to the study.
Upon completion of the study, the subject’s airway was secured
in a normal manner by tracheal placement of an endotracheal
tube or using an airway adjunct in case of failure to intubate
the trachea. Anesthesia was maintained in a routine manner
as per the requirements of the case.
Statistical analysis
One-tailed paired Student’s t-test was used to compare expired
tidal volumes and maximum airway pressure at best-fit in the
standard face mask and nasal mask placements. The results are
expressed as mean ± standard deviation (SD). McNemar test
was used to compare the number of patients in whom inadequate
mask fit was not achieved despite best-fit mask placement using
the two techniques. All analysis was performed using Minitab
Statisticalsoftwareversion11(MinitabInc.,StateCollege,PA,
USA). P<0.05wasconsideredstatisticallysignificant.One-
tailed significance testing was done because our hypothesis stated
that the nasal mask ventilation placement would be more effective
in reducing air leaks than the standard face mask placement in
edentulous patients.
Results
Seventy-nine edentulous patients were recruited for the study
duringJanuary2010toMay2011.Thepatientcharacteristics
are shown in Table 2. Twenty-two patients underwent
oncosurgical, 18 gastrointestinal endoscopic, 13 cardiac-
surgical,9gynecological,9urological,and8reconstructive
surgical procedures. Five patients had limited flexion/extension
oftheneck,and2hadahistoryofneckradiationtherapy.
The differences in airway dynamic parameters and inadequacy
of ventilation after best-fit positioning with the use of face
mask and with the use of nasal mask are shown in Table 3.
The results are expressed as mean ± SD. The difference in
expiratory tidal volumes with the use of the two masks at best-fit
was statistically significant (P=0.0017).Despitethebest-
fit mask placement, adequate ventilation could not achieved
in19(24.1%)patientsduringfacemaskventilationand10
(12.7%)patientsduringnasalmaskventilation(P<0.05,
McNemar'stestwithYate'scorrection).Deliveryof<50%
ofthesettidalvolumewasachievedin7patients(8.9%)with
standardfacemaskandin2patients(2.5%)withnasalmask.
Rescue airway was needed in these patients.
Despite the best-fit positioning and use of airway adjuncts,
lungs of three patients were impossible to ventilate with the
standard face mask; however they could be ventilated with
a nasal mask, though with inadequate tidal volume. The
ventilator bellows could not be kept filled in these patients
and repeated use of oxygen flush was needed. No patient,
however, experienced SpO2 below 95% during the study
period.
Table 1: The ventilation protocol flowchart followed in
the study
Standard face mask ventilation after induction
↓
Preliminary check of ability to maintain airway
↓
Administration of neuromuscular blocking agent
↓
Manual supportive ventilation for 2 min
↓
Mechanical ventilation on volume control mode using standard face
mask after 2 min
↓
Mechanical ventilation on volume control mode after changing over
to a nasal mask after 3 min
Table 2: Patient demographics
Age (years) 64.9±8.8 (48‑83)
Sex (M/F) 45/29
Weight (kg) 59.4±9.3 (40‑78)
Height (cm) 163.7±10.7 (136‑180)
Body Mass Index (kg/m2) 22.1±2.2 (17.4‑27.0)
American Society of
Anesthesiologists class
Class 1=7, Class 2=46, Class 3=26
Mallampati score Class 1=31, Class 2=35, Class 3=13
Values given as Mean ± SD (Range)
Figure 1: Patient with nasal mask placement. The mask is held with the left
hand by placing the thumb and index finger on the body of the mask, while the
middle, ring, and little fingers move the mandible toward the maxilla to ensure
closure of the mouth
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Kapoor,
et al
.: Nasal mask ventilation is better in edentulous patients
Journal of Anaesthesiology Clinical Pharmacology | July-September 2016 | Vol 32 | Issue 3 317
Four patients had difficult tracheal intubation, requiring the
use of airway adjuncts. Two of these patients had associated
impossible face mask ventilation. Higher airway pressures
were achieved with the use of nasal mask. The difference in
airway pressures with the use of the two masks was statistically
significant.
Discussion
Difficult mask ventilation has been defined as the inability of
an unassisted anesthesiologist to prevent or reverse signs of
inadequate ventilation during positive pressure mask ventilation.[7]
Bodymassindex>26kg/m2,age >55 years, male gender,
higher Mallampati airway grading, history of habitual snoring,
macroglossia, lack of teeth, lower thyromental distance, neck
radiation changes, and presence of beard have been defined
as risk factors for DMV[5,7,8] with the presence of two of them
indicating high likelihood of DMV.[8] DMV has an incidence of
1.5-7.8%inthegeneralpopulation[7-9]and16%inedentulous
patients.[10] It results in inadequate ventilation characterized by
no/reduced perceptible chest movement, oxygen desaturation by
pulse oximetry, perception of severe gas flow leak around the
mask and an inadequate end tidal carbon dioxide.[8,11,12]
The edentulous patient has less friction between the upper
and lower jaw to maintain joint stability, contributing to air
leakage around the face mask.[8] Various mechanisms and
approaches to overcome this air leak in edentulous patients
have been proposed. Nonremoval of dentures at induction
of anesthesia helps maintain proper facial support, thus
permitting better face mask fit.[8] However, the dentures may
accidently be aspirated or swallowed.[10] Our institutional
protocol requires removal of the dentures before the patient
is sent to the operation theater. Other approaches suggested
to achieve a good seal are placement of the caudal end of the
mask between the inferior lip and the alveolar ridge; and lower
lip face mask placement with two hands grip.[10,13]
In a sedated person in supine position, the soft palate
and tongue fall backward due to gravity, and obstruct the
pharyngeal airway. Neuromuscular blockade worsens this
obstruction. The triple airway maneuver is performed to
maintain patency of the upper airway and permit face mask
ventilation. Liang et al. in their landmark study demonstrated
that nasal mask ventilation could be performed maintaining
the head in neutral position, without resorting to the triple
airway maneuver.[1] They hypothesized that the obstruction
of the oropharynx by the tongue facilitates nasal ventilation
by reducing the oral leak. In a recent study, the same group of
investigators has demonstrated that mouth-to-nose breathing is
more effective than mouth-to-mouth breathing in anesthetized,
apneic adult subjects without chemical paralysis.[14] We also
maintained the head in neutral position to minimize the oral
leak without displacing the tongue. We demonstrated higher
airway pressures with better air delivery and reduction of leaks
with the use of nasal mask in neutral position.
Mask ventilation is often ineffective in edentulous patients, and
in some cases almost impossible, because of the lack of facial
support. The placement of the inferior end of nasal mask over
the upper lip results in the contact of the mask with tissues
with maxillary support, which are not deficient in edentulous
patients. Mask ventilation is also affected by a number of other
variables such as amount of facial adipose tissue, contour of
the facial skeleton, and bone resorption in edentulous patients.
The lips are approximated by the upward force applied by
the fingers, preventing leakage of the breathing gases from
the oral cavity.
We found a statistically significant rise in the expired tidal
volume and peak airway pressure on changing over to nasal
mask ventilation. We also managed to reduce the number of
patientswithinadequatemaskventilationbyaround50%by
using nasal mask ventilation.
During our study volume controlled mechanical ventilation was
used to achieve a constant, predetermined tidal volume delivery
so that loss due to leak could be quantified. We considered
thefallinventilatorbellowsanda>25%differencebetween
the delivered and the expired tidal volume as indicators of
Table 3: Delivered/expired tidal volume and peak airway pressure recorded with use of face mask and nasal mask
ventilation
Parameter Face mask
ventilation (
n
= 79)
Nasal mask
ventilation (
n
= 79)
P
Delivered tidal volume ± SD (mL) 594±93.4 594±93.4
Expired tidal volume ± SD (mL) at best‑fit 498.7±150.7 532.3±118.3 0.0017
Percent difference in delivered and expired tidal volumes at best‑fit ± SD (%) 83.1±19.8 89.8±14.4 0.0018
Peak airway pressure at best‑fit ± SD (cm H2O) 9.2±3.9 11.8±3.4 <0.001
Number of patients with inadequate ventilation after best‑fit 19 10
Number of patients with >50% difference in delivered and expired tidal
volumes after best‑fit
7 2
SD = Standard deviation
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Kapoor,
et al
.: Nasal mask ventilation is better in edentulous patients
318 Journal of Anaesthesiology Clinical Pharmacology | July-September 2016 | Vol 32 | Issue 3
inadequate ventilation. Others have quantified inadequate
ventilationasadifferenceofatleast33%betweeninspired
and expired tidal volumes. The value was selected arbitrarily
as per their clinical experience that air leaks of lower magnitude
are not usually clinically relevant.[10]
We encountered a higher incidence of inadequate ventilation
delivery in edentulous patients with use of face mask, than
that reported earlier by Langeron et al.,[8] possibly because we
used two-hand face mask grip as a rescue method while they
used it as a primary method of mask holding. We also used a
stricter, quantifiable and a more objective criterion to define
inadequate ventilation. Racine et al. were able to reduce the
incidenceofDMVto16%withlowerlipplacementoftheface
mask.[10] However, with the use of nasal mask, we were able
to reduce it further. While using face mask, we encountered
impossible mask ventilation in 3 patients, but only one was
impossible to ventilate when nasal mask was used. We were
able to deliver reasonable ventilation in all cases and no patient
had oxyhemoglobin desaturation.
The limitations of our study were the inability to achieve
adequate blinding of the observer, and that the order of
treatments was not randomized. The recordings were made
morethan2minafterinitiationofmechanicalventilationas
per the recommendations of the manufacturer, to stabilize the
spirometer sensor function. By this time, the neuromuscular
blockade onset should have ensured a near constant upper
airway anatomy.
In summary, we found nasal mask ventilation in the neutral
position to be more efficient than standard face mask
ventilation in edentulous patients. The air leak was lower
due to a better contact between the facial tissue and the
mask. It is recommended that nasal mask ventilation should
be the primary mode of ventilation in edentulous patients.
Financial support and sponsorship
Nil.
Conflict of interest
There are no conflicts of interest.
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