A Two-handed Jaw-thrust Technique Is Superior to the One-handed "EC-clamp" Technique for Mask Ventilation in the Apneic Unconscious Person
Pulmonary, Allergy and Critical Care, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA. Anesthesiology
(Impact Factor: 5.88).
10/2010; 113(4):873-9. DOI: 10.1097/ALN.0b013e3181ec6414
Mask ventilation is considered a "basic" skill for airway management. A one-handed "EC-clamp" technique is most often used after induction of anesthesia with a two-handed jaw-thrust technique reserved for difficult cases. Our aim was to directly compare both techniques with the primary outcome of air exchange in the lungs.
Forty-two elective surgical patients were mask-ventilated after induction of anesthesia by using a one-handed "EC-clamp" technique and a two-handed jaw-thrust technique during pressure-control ventilation in randomized, crossover fashion. When unresponsive to a jaw thrust, expired tidal volumes were recorded from the expiratory limb of the anesthesia machine each for five consecutive breaths. Inadequate mask ventilation and dead-space ventilation were defined as an average tidal volume less than 4 ml/kg predicted body weight or less than 150 ml/breath, respectively. Differences in minute ventilation and tidal volume between techniques were assessed with the use of a mixed-effects model.
Patients were (mean ± SD) 56 ± 18 yr old with a body mass index of 30 ± 7.1 kg/m. Minute ventilation was 6.32 ± 3.24 l/min with one hand and 7.95 ± 2.70 l/min with two hands. The tidal volume was 6.80 ± 3.10 ml/kg predicted body weight with one hand and 8.60 ± 2.31 ml/kg predicted body weight with two hands. Improvement with two hands was independent of the order used. Inadequate or dead-space ventilation occurred more frequently during use of the one-handed compared with the two-handed technique (14 vs. 5%; P = 0.013).
A two-handed jaw-thrust mask technique improves upper airway patency as measured by greater tidal volumes during pressure-controlled ventilation than a one-handed "EC-clamp" technique in the unconscious apneic person.
Available from: Sassan Sabouri
- "Because we aimed to simulate a scenario in which airway management was not optimized when emergency ventilation was needed or difficult mask ventilation occurred, the subject’s head was placed on a pillow and elevated about 10 cm from the operating room table, but no backward head tilt, jaw thrust, or mouth closing was performed. Airway patency was indirectly assessed by measuring expired tidal volume (Vte) by using the plethysmograph at a given peak inspiratory pressure over PEEP (PIP/PEEP) . "
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ABSTRACT: Upper airway obstruction (UAO) is a major problem in unconscious subjects making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye movement sleep. Continuous positive airway pressure (CPAP) via nasal mask is more effective at maintaining airway patency than a full face mask in OSA patients. We hypothesized that CPAP via nasal mask and ventilation (nCPAP) would be more effective than full face mask CPAP and ventilation (FmCPAP) for unconsciousness subjects and we tested our hypothesis during induction of general anesthesia for elective surgery.
A total of 73 adult subjects requiring general anesthesia were randomly assigned into four groups: nCPAP P0, nCPAP P5, FmCPAP P0, and FmCPAP P5, where P0 and P5 represent positive end expiratory pressure (PEEP) 0 and 5 cmH2O applied prior to induction. After apnea, ventilation was initiated with pressure control ventilation at a peak inspiratory pressure over PEEP (PIP/PEEP) of 20/0, then 20/5 and finally 20/10 cmH2O each applied for 1 min. At each pressure setting, expired tidal volume (Vte) was calculated using a plethysmograph device.
The rate of effective tidal volume (Vte > estimated anatomical dead space) was higher (87.9% vs.21.9%; P < 0.01) and the median Vte was larger (6.9 ml/kg vs. 0 ml/kg; P < 0.01) with nCPAP than that with FmCPAP. Application of CPAP prior to induction of general anesthesia did not affect Vte in both approaches (nCPAP pre- vs. post; 7.9 ml/kg vs. 5.8 ml/kg, P = 0.07) (FmCPAP pre- vs. post; 0 ml/kg vs. 0 ml/kg, P = 0.11).
nCPAP produced more effective tidal volume than FmCPAP in unconscious subjects.Trial registration: Clinical trials.gov, Identifier: NCT01524614.
Available from: Scott D Weingart
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ABSTRACT: Patients requiring emergency airway management are at great risk of hypoxemic hypoxia because of primary lung pathology, high metabolic demands, anemia, insufficient respiratory drive, and inability to protect their airway against aspiration. Tracheal intubation is often required before the complete information needed to assess the risk of periprocedural hypoxia is acquired, such as an arterial blood gas level, hemoglobin value, or even a chest radiograph. This article reviews preoxygenation and peri-intubation oxygenation techniques to minimize the risk of critical hypoxia and introduces a risk-stratification approach to emergency tracheal intubation. Techniques reviewed include positioning, preoxygenation and denitrogenation, positive end expiratory pressure devices, and passive apneic oxygenation.
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ABSTRACT: 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.
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.
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.
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.
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