Mask Ventilation Research Articles

Predictive factors for difficult mask ventilation in the obese surgical population

Background Difficult Mask Ventilation (DMV), is a situation in which it is impossible for an unassisted anesthesiologist to maintain oxygen saturation >90% using 100% oxygen and positive pressure ventilation to prevent or reverse signs of inadequate ventilation during mask ventilation. The incidence varies from 0.08 – 15%. Patient-related anatomical features are by far the most significant cause. We analyzed data from an obese surgical population (BMI> 30 kg/m 2) to identify specific risk and predictive factors for DMV. Methods Five hundred and fifty seven obese patients were identified from a database of 1399 cases associated with preoperative airway examinations where mask ventilation was attempted. Assessment of mask ventilation in this group was stratified by a severity score (0-3), and a step-wise selection method was used to identify independent predictors. The area under the curve of the receiver-operating-characteristic was then used to evaluate the model’s predictive value. Adjusted odds ratios and their 95% confidence intervals were also calculated. Results DMV was observed in 80/557 (14%) patients. Three independent predictive factors for DMV in obese patients were identified: age 49 years, short neck, and neck circumference 43 cm. In the current study th sensitivity for one factor is 0.90 with a specificity 0.35. However, the specificity increased to 0.80 with inclusion of more than one factor. Conclusion According to the current investigation, the three predictive factors are strongly associated with DMV in obese patients. Each independent risk factor alone provides a good screening for DMV and two factors substantially improve specificity. Based on our analysis, we speculate that the absence of at least 2 of the factors we identified might have a significant negative predictive value and can reasonably exclude DMV, with a negative likelihood ratio 0.81.

Predictive factors for difficult mask ventilation in the obese surgical population.

Background Difficult Mask Ventilation (DMV), is a situation in which it is impossible for an unassisted anesthesiologist to maintain oxygen saturation >90% using 100% oxygen and positive pressure ventilation to prevent or reverse signs of inadequate ventilation during mask ventilation. The incidence varies from 0.08 - 15%. Patient-related anatomical features are by far the most significant cause. We analyzed data from an obese surgical population (BMI> 30 kg/m (2)) to identify specific risk and predictive factors for DMV. Methods Five hundred and fifty seven obese patients were identified from a database of 1399 cases associated with preoperative airway examinations where mask ventilation was attempted. Assessment of mask ventilation in this group was stratified by a severity score (0-3), and a step-wise selection method was used to identify independent predictors. The area under the curve of the receiver-operating-characteristic was then used to evaluate the model's predictive value. Adjusted odds ratios and their 95% confidence intervals were also calculated. Results DMV was observed in 80/557 (14%) patients. Three independent predictive factors for DMV in obese patients were identified: age 49 years, short neck, and neck circumference 43 cm. In the current study th sensitivity for one factor is 0.90 with a specificity 0.35. However, the specificity increased to 0.80 with inclusion of more than one factor. Conclusion According to the current investigation, the three predictive factors are strongly associated with DMV in obese patients. Each independent risk factor alone provides a good screening for DMV and two factors substantially improve specificity. Based on our analysis, we speculate that the absence of at least 2 of the factors we identified might have a significant negative predictive value and can reasonably exclude DMV, with a negative likelihood ratio 0.81.

Two-minute training for improving neonatal bag and mask ventilation.

ObjectivesTo test effectivity of a two-minute training consisting of a few key-points in ventilation using the self-inflating bag (SIB).Study DesignExperienced and inexperienced caregivers were asked to mask ventilate a leak free manikin using the SIB before and after the training. Mask leak and pressures were measured using respiratory function monitoring. Pressures above 35 cm H2O were considered excessive. Parameters were compared using a Wilcoxon non-parametric test.ResultsBefore and after the short training, experienced caregivers had minimal median (IQR) mask leak (14 (3-75) vs. 3 (0-53)%; p<0.01). Inexperienced users had large leak which reduced from 51 (7-91)% before to 11 (2-71)% after training (p<0.01). Pressures above 35 cm H2O hardly occurred in experienced caregivers (0 (0-5) vs. 0 (0-0)%; ns). In inexperienced caregivers this frequently occurred but decreased considerably after training (94 (46-100) vs. 2 (0-70)%; p<0.01).ConclusionA two-minute training of bag and mask ventilation was effective. This training could be incorporated into any training program.

PS-224 Video Education To Improve Bag Mask Ventilation During Simulated Newborn Resuscitation

<h3>Aim</h3> To evaluate if video based education could improve quality of positive pressure ventilation (PPV) performed by novice health care providers during neonatal resuscitation. <h3>Methods</h3> Twenty-eight 4th year medical students were randomly paired and instructed to give PPV to a modified manikin as single-person resuscitators, then as two-person paired resuscitators using either an anatomical shaped neonatal face mask with an air cushion rim (IS) or a Laerdal round face mask (LM). After watching a video-tutorial they randomly repeated each mask ventilation performance. Airway pressure, gas flow, tidal volume, and mask leak were recorded. PPV performance quality was analysed using video recording. <h3>Results</h3> Mask leak was lower during one-person ventilation when using IS (56 ± 16%) compared to LM (71 ± 19%). LM mask leak during one-person ventilation was significantly lower when using the two point top hold in contrast to the ok rim hold (before training: 63 ± 22% vs. 72 ± 18%, after training: 57 ± 17% vs. 77 ± 12%, respectively). Watching a video-tutorial improved correct head position (score: 1.4 ± 0.7 vs. 3.8 ± 0.4) and chin lift manoeuvre (score: 2.3 ± 0.2 vs. 3.5 ± 0.2) during PPV, however mask leak was not significantly reduced. <h3>Conclusion</h3> A self-instructional educational video on adequate bag mask ventilation significantly improves performance quality scores in novice health care providers.

O-069 Mask Ventilation With Two Different Facemasks During Positive Pressure Ventilation In The Delivery Room: A Randomised Controlled Trial

Background and aims If infants fail to initiate spontaneous breathing after birth, international guidelines recommend positive pressure ventilation (PPV). However, mask PPV remains challenging with leakage occurring commonly. Despite a variety of available facemasks, none has been systemically studied in newborn infants. We aimed to determine if using a Fisher and Paykel (FP) round facemask would reduce mask leak compared to using a Laerdal round facemask during mask PPV in preterm infants. Methods From April to September 2013, at the Royal Alexandra Hospital, newborn infants. Results Fifty-eight preterm infants (n = 29 in each group) were enrolled; mean±SD gestation 28 ± 3 weeks; birth weight 1210 ± 448 g, 30(52%) male, 39(67%) born by caesarean section. Apgar scores at 1 and 5 min were 5 ± 3 and 7 ± 2, respectively. Infants randomised to the FP facemask and Laerdal facemask had similar mask leak (37 ± 17% vs. 33 ± 12%, respectively, p = 0.30) and tidal volume (7.3 ± 3.0 mL/kg vs. 6.9 ± 2.7 mL/kg, p = 0.73) during PPV. There were no significant differences in ventilation rate, inflation time or airway pressures between groups. Conclusions The use of either facemask during PPV in the delivery room yields similar mask leak.

English

Dear Editor, Sir, Adenotonsillectomy is one of the commonly done day care surgical procedures in paediatric patients. Airway obstruction following adenotonsillectomy requiring intubation in paediatric patients is one of the potential complications, and has been reported only in two cases in the literature (1, 2). In neither of the two cases was ventilation reported to be difficult. The inability to can be catastrophic. We present the first reported case of airway obstruction and inability to due to swollen uvula following adenotonsillectomy. A three-year old girl, weighing 15 kg, with recurrent attacks of tonsillitis was scheduled for elective adeno-tonsillectomy. She also had features of obstructive sleep apnoea (OSA). Apart from being allergic to penicillin, the preoperative assessment was unremarkable. The child was induced with propofol (30 mg), fentanyl (30 μg) and cisatracurium (2 mg). Following uneventful mask ventilation, orotracheal intubation was achieved on first attempt with 5 mm uncuffed tracheal tube. The patient was positioned with neck extension and mouth opened with Davis Boyle mouth gag. Adenoids were removed using a curette. Both tonsils were dissected and removed by applying a tonsillectomy snare to the lower poles. Haemostasis was achieved with packing and diathermy of bleeding vessels. In this child, the dissection of tonsils was technically difficult, resulting in longer operative time. Hence, laryngoscopy was done prior to extubation and a moderate uvular swelling was noted (Figure). Dexamethasone 4 mg and ranitidine 15 mg were administered intravenously. Neuromuscular blockade was reversed and extubation was performed when the child was awake in the post-tonsillectomy position. Figure Direct laryngoscopy immediately following surgery showing swollen uvula. T: tongue, U: uvula. Following extubation, the child was initially breathing normally but progressively developed obstructed breathing which was thought to be due to the observed uvular swelling. Over the next three minutes, SpO2 started to fall below 90% and she became bradycardic. Attempts to perform mask ventilation with oral airway were unsuccessful. She was thus administered glycopyrrolate IV, followed by suxamethonium (0.5 mg/kg). Mask ventilation was still not possible, suggesting supraglottic swelling only. Urgent laryngoscopy was done and the trachea was intubated with a 5.0 mm uncuffed tube. Following intubation, oxygen saturation and heart rate returned to normal. Nasal endoscopy confirmed worsening swelling of the uvula with no further abnormal findings. The patient's sedation, dexamethasone and ventilation were con-tinued for 24 hours. The patient's intensive care unit course remained uneventful and after 24 hours, direct laryngoscopy showed that uvular swelling had subsided significantly. The child was extubated uneventfully and was discharged home on the third postoperative day. Compared with adults, children have a two-fold higher incidence of fatal respiratory events in the postoperative period following adenotonsillectomy (3). One of the rare causes of airway obstruction following adenotonsillectomy is uvular swelling (4). In this patient, the technical difficulty in performing adenotonsillectomy would have resulted in uvular swelling leading to airway obstruction. The patient had OSA which can cause vascular engorgement of the uvula and compound the problem (5). It is possible that the negative pressure generated in the airway at the onset of spontaneous breathing gradually drew the swollen uvula toward the glottis, resulting in worsening uvular swelling and leading to complete airway obstruction. Hence, bag mask ventilation, even with oral airway, was unsuccessful. Failure to even after suxamethonium administration rules out laryngospasm. No other causes of airway obstruction were apparent on direct laryngoscopy. In retrospect, having noticed moderate uvular swelling before extubation, elective ventilation until the swelling subsided could have been a better option. In conclusion, uvular oedema should be recognized as one of the potential causes of airway obstruction following adenotonsillectomy. The obstruction could lead to potentially dangerous cannot ventilate situation. In difficult oropharyngial surgeries, direct laryngoscopy preceding extubation and a high degree of suspicion can avoid catastrophic complication.

Intubation difficile : il faut suivre les recommandations

Intubation and ventilation impossible mask is a dramatic situation with potentially serious consequences. We report the case of a patient of 43 years, followed for a goiter, which was scheduled for a total thyroidectomy under general anesthesia. Preoperative evaluation is not noted signs of compression or tracheal deviation, and there were no criteria predictive of intubation or difficult mask ventilation. The induction of anesthesia was standard. Mask ventilation was effective allowing paralysis. The standard laryngoscopy showed a score of Cormack and Lehane grade IV. Several attempts at intubation were made leading to a situation of intubation and ventilation impossible mask with deep desaturation. A tracheostomy was done urgently. The patient was operated on, six months later, with a fiber optic intubation. Through this case, the authors draw attention to the difficulty of achieving an emergency tracheotomy in the presence of goiter and emphasize the need for integration of different modes of learning and retention of management skills of the upper airway.

Volutrauma and Regional Ventilation Revisited

Volutrauma and Regional Ventilation Revisited

Incidence, Predictors, and Outcome of Difficult Mask Ventilation Combined with Difficult Laryngoscopy

Research regarding difficult mask ventilation (DMV) combined with difficult laryngoscopy (DL) is extremely limited even though each technique serves as a rescue for one another. Four tertiary care centers participating in the Multicenter Perioperative Outcomes Group used a consistent structured patient history and airway examination and airway outcome definition. DMV was defined as grade 3 or 4 mask ventilation, and DL was defined as grade 3 or 4 laryngoscopic view or four or more intubation attempts. The primary outcome was DMV combined with DL. Patients with the primary outcome were compared to those without the primary outcome to identify predictors of DMV combined with DL using a non-parsimonious logistic regression. Of 492,239 cases performed at four institutions among adult patients, 176,679 included a documented face mask ventilation and laryngoscopy attempt. Six hundred ninety-eight patients experienced the primary outcome, an overall incidence of 0.40%. One patient required an emergent cricothyrotomy, 177 were intubated using direct laryngoscopy, 284 using direct laryngoscopy with bougie introducer, 163 using videolaryngoscopy, and 73 using other techniques. Independent predictors of the primary outcome included age 46 yr or more, body mass index 30 or more, male sex, Mallampati III or IV, neck mass or radiation, limited thyromental distance, sleep apnea, presence of teeth, beard, thick neck, limited cervical spine mobility, and limited jaw protrusion (c-statistic 0.84 [95% CI, 0.82-0.87]). DMV combined with DL is an infrequent but not rare phenomenon. Most patients can be managed with the use of direct or videolaryngoscopy. An easy to use unweighted risk scale has robust discriminating capacity.

Influence of the Hand Squeeze and Mask Distensibility on Tidal Volume Measurements during Neonatal Mask Ventilation

Background: During mask ventilation, the mask volume can vary as it is pressurized or when it is squeezed. The change in volume of the mask may affect tidal volumes delivered and difference in inspired (V_ti) and expired tidal volumes (V_te). Objectives: To investigate whether hand squeeze and distensibility of the mask during ventilation influences tidal volume measurements. Methods: For both experiments, we ventilated a leak-free mask ventilation model using pressures of 25/5 cm H₂O through a t-piece. V_ti and V_te were measured. (A) Two consultants performed mask ventilation with (1) consistent hand squeeze, (2) release during inflation and squeeze during expiration, (3) squeeze during inflation, release during expiration, and (4) gentle squeeze. Results: (B) Thirty caregivers performed mask ventilation. Experiment A: V_ti was different during consistent hold (1) 8.1 ml (0.4) and loose grip (4) 8.2 ml (0.3), compared to squeezing during inflation (2) 18.9 ml (1.9), or expiration (3) 6.4 ml (3.5). Variance in difference between V_ti and V_te occurred only when the mask was squeezed during inflation (-47.4% (101.5)). Experiment B: volumes measured were consistent (intraindividual CV 3-5%, interindividual CV 9-10%). When comparing gas flow rate of 6-10 l/min, volumes increased by approximately 8%, differences in V_ti and V_te were small with both flow settings (-0.9% (-3.9-1.4) and -0.6% (-3.3-1.8); n.s.). Conclusion: Variation in mask hold during mask ventilation can influence volume measurement, but this hardly occurs when testing caregivers.

Mask Versus Nasal Tube for Stabilization of Preterm Infants at Birth: A Randomized Controlled Trial

Positive-pressure ventilation (PPV) using a manual ventilation device and a face mask is recommended for compromised newborn infants in the delivery room (DR). Mask ventilation is associated with airway obstruction and leak. A nasal tube is an alternative interface, but its safety and efficacy have not been tested in extremely preterm infants. An unblinded randomized controlled trial was conducted in Australia, and the Netherlands. Infants were stratified by gestational age (24-25/26-29 weeks) and center. Immediately before birth infants were randomly assigned to receive PPV and/or continuous positive airway pressure with either a nasal tube or a size 00 soft, round silicone mask. Resuscitation protocols were standardized; respiratory support was provided using a T-piece device commencing in room air. Criteria for intubation included need for cardiac compressions, apnea, continuous positive airway pressure >7 cm H2O, and fraction of inspired oxygen >0.4. Primary outcome was endotracheal intubation in the first 24 hours from birth. Three hundred sixty-three infants were randomly assigned; the study terminated early on the grounds of futility. Baseline variables were similar between groups. Intubation rates in the first 24 hours were 54% and 55% in the nasal tube and face mask groups, respectively (odds ratio: 0.97; 95% confidence interval: 0.63-1.50). There were no important differences in any of the secondary outcomes within the whole cohort or between the 2 gestational age subgroups. In infants at <30 weeks' gestation receiving PPV in the DR, there were no differences in short-term outcomes using the nasal tube compared with the face mask.

Sugammadex to rescue a ‘can't ventilate’ scenario in an anticipated difficult intubation: is it the answer?

Sugammadex to rescue a ‘can't ventilate’ scenario in an anticipated difficult intubation: is it the answer?

Difficult Mask Ventilation and Muscle Paralysis

To the Editor:We read with great interest the study by Ikeda et al.1 and the accompanying editorial.2 It is now increasingly recognized that muscle relaxants are beneficial in overcoming difficult mask ventilation in adults.2–4 However, both current papers are lacking a sufficient discussion of the reasons why muscle relaxation improves difficult mask ventilation. This can primarily be deduced from recent pediatric evidence where functional airway obstructions are the main reason for difficult mask ventilation.Difficult mask ventilation in otherwise normal children is exceptionally rare and usually caused by anatomical/mechanical or functional airway obstructions.5 Functional airway obstructions (laryngospasm, insufficient depth of anesthesia, opioid-induced muscle rigidity with glottic closure, and bronchospasm) are common in children;6 result in significant morbidity;7 and require clear concepts and algorithms.8 Early muscle relaxation or even “pre-ventilation” muscle paralysis will overcome all functional airway problems with the exception of severe bronchospasm for which systemic epinephrine should be immediately available.9 This approach will also allow early and less traumatic direct laryngoscopy and tracheal intubation, if required urgently, without provoking coughing and straining or regurgitation and vomiting.Amazingly, although muscle paralysis has been shown to improve mask ventilation in adults and is increasingly becoming a key role in the difficult mask ventilation in children with normal airways,9 none of current difficult airway algorithms in adults consider functional airway obstructions. However, this view is shifting in adults too, as the recently published NAP4 report recommends muscle paralysis prior to proceeding with an invasive (surgical) airway in the “cannot intubate - cannot ventilate” scenario or when waking the patient up is not an option.10†Difficult mask ventilation due to functional airway obstruction with increasing hypoxemia requires muscle paralysis. “Cross the Rubicon fast” in patients with a normal airway.

Mask Ventilation and Dispersion of Exhaled Air

Mask Ventilation and Dispersion of Exhaled Air

Bag Valve Mask Ventilation Versus Controlled Ventilation for Minor Pediatric Surgery.

Introduction: Paediatric anaesthesia deals with Examination under anaesthesia to complicated surgical interventions. Most of the minor surgeries can be performed with Bag Valve Mask Ventilation which avoids complications of endotracheal intubation. Methods: A retrospective randomized control study was undertaken in 654 paediatric surgeries performed at Shree Birendra Hospital, Chhauni (April 2005-March 2010). The children underwent minor general, Ear nose throat and orthopaedic surgery to compare spontaneous Bag Valve Mask ventilation in 503 patients (BVM Group) and controlled ventilation in 151 patients (CV Group). The BVM group was done under spontaneous mask ventilation and CV group under endotracheal intubation. Anaesthesia was induced and maintained with oxygen and halothane, using a Mapleson F system with spontaneous ventilation and a Rendell-Baker face mask. The duration of anaesthesia was less than one hour. Results: In this study we noted the complications like trauma to face and lips, dental trauma, laryngospasm, perforation of tracheaor esophagus, pulmonary aspiration of gastric contents or foreign bodies and post extubation complications. Conclusions: It is concluded that the need of controlled ventilation with endotracheal tube is limited to only a few procedures and many of the paediatric surgeries can be performed with spontaneous mask ventilation. Therefore anaesthesia with oxygen and halothane with spontaneous mask ventilation is a satisfactory method for minor procedures in children. Medical Journal of Shree Birendra Hospital; Jan-June 2012/vol.11/Issue1/17-20 DOI: http://dx.doi.org/10.3126/mjsbh.v11i1.7761

Airway management in a patient with Morquio–Brailsford syndrome

Airway management in a patient with Morquio–Brailsford syndrome

Mask ventilation of preterm infants in the delivery room

ObjectiveTo measure tidal volumes (VT) and describe the interactions between spontaneous breaths and positive pressure ventilation (PPV) inflations during stabilisation of preterm infants in the delivery room (DR). We used...

Effects of Muscle Relaxants on Mask Ventilation in Anesthetized Persons With Normal Upper Airway Anatomy

Background Recent studies suggest advantages of muscle relaxants for facemask ventilation. However, direct effects of muscle relaxants on mask ventilation remain unclear because these studies did not control mechanical factors influencing ventilation. We tested a hypothesis that muscle relaxants, either rocuronium or succinylcholine, improve mask ventilation. Methods In anesthetized adult persons with normal upper airway anatomy, tidal volumes during facemask ventilation were measured while maintaining the neutral head and mandible positions and the airway pressures of a ventilator before and during muscle paralysis induced by either rocuronium (n=14) or succinylcholine (n=17). Tidal volumes of oral and nasal airway routes were separately measured with a custom-made oronasal portioning full facemask. Behavior of the oral airway was observed by an endoscope in six additional subjects receiving succinylcholine. Results Total, oral, and nasal tidal volumes did not significantly change at complete muscle paralysis with rocuronium. In contrast, succinylcholine significantly increased total tidal volumes at 60 s after its administration (mean±SD; 4.2±2.1 vs. 5.4±2.6 ml/kg, P=0.02) because of increases of ventilation through both airway routes. Abrupt tidal volume increase occurred more through oral airway route than nasal route. Dilation of the space at the isthmus of the fauces was endoscopically observed during pharyngeal fasciculation in all six subjects. Conclusions Rocuronium did not deteriorate facemask ventilation, and it was improved after succinylcholine administration in association with airway dilation during pharyngeal fasciculation. This effect continued to a lesser degree after resolution of the fasciculation.

Difficult airway management in a case with lingual tonsil hypertrophy and temporo-mandibular joint partial ankylosis

Difficult airway management in a case with lingual tonsil hypertrophy and temporo-mandibular joint partial ankylosis

Undiagnosed light chain systemic amyloidosis: does it matter to anesthesiologists? -a case report-

Light chain systemic amyloidosis is rare but may accompany laryngeal or pulmonary involvement, which may increase the risk in airway management. We present a case of a patient planned for resection of cervical epidural mass. The patient had face and neck ecchymoses and purpuras with an unknown cause. Mask ventilation and intubation were successful, but the operation was cancelled to evaluate bleeding from facial skin lesions. A diagnosis of light chain systemic amyloidosis prompted evaluation of involvement of other organs and treatment. This case shows the importance of preoperative evaluation and careful airway management in patients with systemic amyloidosis.