Bag-Valve-Mask (BVM) Ventilation

OVERVIEW

• Bag-Valve-Mask (BVM) apparatus are also known as manual resuscitators and as self-inflating resuscitation systems
• examples include Laerdal^TM, Ambu^TM, Hsiner^TM, Mayo^TM, and Air Viva^TM

USES

• administration of high flow O2
• provision of PEEP (positive end-expiratory pressure)
• provision of controlled ventilation
• provision of augmentation of spontaneous ventilation

DESCRIPTION

• self-inflating resuscitation device
  • bag made of plastic materials that re-expand after being manually collapsed
  • various sizes e.g. Laerdal 240 mL, 500 mL, 1600 mL bag sizes for infants, children and adults
• oxygen inlet nipple
• air intake valve
• oxygen reservoir with two one way valves
  • reservoir is at least the volume of the bag
  • oxygen flow rate equal to, or higher than, the minute volume of the patient allows 100% oxygen to be delivered
  • inlet valve allows room air to enter if fresh gas flow is inadequate and an outlet valve allow oxygen to flow out if pressure is excessive
• non-rebreathing valve that directs fresh flow of oxygen to the patient and prevents exhaled gas re-entering the bag
• standard 15 mm adapter for attaching to masks or tubes
• able to attach PEEP valve to exhalation port (either “built in” or detachable)
• can hold down pop off valve (releases at about 60 cmH2O) to give increased pressure in the circuit
• Masks come in a range of sizes and designs
  • opaque or clear plastic
  •  firm or air inflated cushion
  • mouldings vary but are designed to minimise dead space and fit
  • some have specific names (e.g. Rendall Baker Mask for paediatrics)

METHOD OF INSERTION AND/OR USE

• High flow oxygen (e.g. 15 L/min) is attached to the system and it is attached to a mask or tube
• appropriate mask size
• place over mouth and nose
• tight fit
• open airway using two-handed thumbs down technique (with an assistant bagging) in preference to the less effective one-handed C-E grip to ensure airway patency (best if OPA and NPAs in situ too)
• the bag is used to deliver oxygen to a spontaneously breathing patient or the bag compressed to manually ventilate them via a mask or tube (an assistant can provide ventilations)

Remember JAWS for the two-handed two-thumbs down two person technique:

• Jaw thrust
• Airways (oral/nasal)
• Work together
• Slow, small squeeze — 6-7 cc/kg, over 1-2 seconds, at <12/min, using low pressure.

COMPLICATIONS

• easy to hyperventilate patients and limited ability to gauge tidal volumes
• unable to gauge lung compliance (cf. a ventilator or Water’s circuit)
• poor seal is common if one-handed CE grip is used
• gastric distension
• aspiration
• claustrophobia
• exhaled secretions and moisture can result in exhalation valve dysfunction and increased resistance to expiration
• risk of barotrauma if pop off valve close as unable to feel lung compliance with self-inflating bags
• if high free gas flows are not used high FiO2 will not be achieved
• equipment failure (e.g. due to incorrect assembly)

OTHER INFORMATION

Spontaneous ventilation

• Adminstered FiO2 during spontaneous ventilation can vary greatly between devices
  • Laerdal: FiO2 0.96
  • Hsiner: FiO2 0.75
  • Mayo: FiO2 0.55
• sufficient negative inspiratory pressure is required to overcome the patient inspiratory valve, otherwise, air will be entrained instead of oxygen
  • some duckbill valves are difficult to overcome when spontaneously breathing
  • patients with reduced respiratory effort are particularly at risk
• As a safeguard in spontaneously breathing patients it is useful to coordinate ‘assist’ positive pressure ventilation with the patient’s spontaneous efforts to ensure that the patient inspiratory valve is opening

Edentulous patients

• If the patient is edentulous, then adjust the position of the mask like so:

Fom Racine SX, et al (2010), image from EM Updates (click image for source)

Alternatives to BVM

• use a ventilator to provide non-invasive ventilation
• use of a Mapleson C (Waters circuit)
• in paediatrics, use of Mapleson E (Jackson-Ress modification of the Ayre’s T-pieces)

VIDEOS

References and Links

Journal articles

• El-Orbany M, Woehlck HJ. Difficult mask ventilation. Anesth Analg. 2009 Dec;109(6):1870-80. PMID: 19923516
• Gerstein NS, Carey MC, Braude DA, Tawil I, Petersen TR, Deriy L, Anderson MS. Efficacy of facemask ventilation techniques in novice providers. J Clin Anesth. 2013 May;25(3):193-7. PMID: 23523573.
• Hart D, Reardon R, Ward C, Miner J. Face mask ventilation: a comparison of three techniques. J Emerg Med. 2013 May;44(5):1028-33. PMID: 23473817.
• Joffe AM, Hetzel S, Liew EC. A two-handed jaw-thrust technique is superior to the one-handed “EC-clamp” technique for mask ventilation in the apneic unconscious person. Anesthesiology. 2010 Oct;113(4):873-9. PMID: 20808210.
• Khoury A, Hugonnot S, Cossus J, et al. From mouth-to-mouth to bag-valve-mask ventilation: evolution and characteristics of actual devices – a review of the literature. Biomed Res Int. 2014;2014:762053. [article]
• Racine SX, et al (2010). Face mask ventilation in edentulous patients: a comparison of mandibular groove and lower lip placement. Anesthesiology, 112 (5), 1190-3 PMID: 20395823

FOAM and web resources

• AirwayCam — Face Mask Ventilation
• EMCRIT — Wee – What the heck is a Mapleson B Circuit and Why You Probably Shouldn’t Care (2014)
• Resus.ME — Thenar Eminence Based Medicine