Bag-valve-mask ventilation is fraught with problems. The keys to success are in the Rule of Threes (see table), as I discussed in my last column. (See FastLinks box.) Unfortunately, not everyone has a PEEP valve yet, and we don't have a legal cure for the overzealous provider who thinks 60 breaths per minute is slow because that's only one-third of his own pulse! To me, the ultimate solution is to turn this situation over to technology. We all have that magic ventilator sitting at the bedside, yet it goes unused until the patient is intubated. Put that darn thing to use.
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Let me begin by giving credit to Scott Weingart, MD, of the EmCrit blog (see FastLinks box), who turned me on to this concept in the first place. He is also the originator of delayed sequence intubation (DSI) discussed below.
First, recognize that any patient who has a saturation of less than 93% after pre-oxygenation is going to desaturate, as I noted in my last column. Unless you anticipate an easy intubation and the patient is able to tolerate hypoxemia (i.e., young with no CNS injury), you should plan for controlled positive-pressure ventilation prior to intubation. The traditional teaching about avoiding positive pressure ventilation during Rapid Sequence Intubation does not apply to these common circumstances. CPAP/BiPAP is an ideal way to augment preoxygenation if the patient will tolerate it.
To perform ventilator mask ventilation as part of pharmacologically assisted airway management, leave the patient in position of comfort, if not in cervical precautions, until the last possible moment. You will have three pathways on which to proceed: Rapid Sequence Intubation (RSI), Rapid Sequence Airway (RSA), or Delayed Sequence Intubation (DSI).
Set the vent on SIMV mode with 10 of PEEP/CPAP, 5-10 of pressure support above PEEP/CPAP, volume of 6-8 cc/kg ideal body weight, back-up rate of 12, 100% oxygen, and flow of 30 lpm. Connect ventilator tubing to the mask just as you would connect it to the ET tube. For extra credit, place your capnography in-line so you can not only assess ventilations and estimate ETCO2, but also have it immediately ready for post-intubation tube confirmation.
Option A-RSI: Give an induction agent and a paralytic. As soon as the patient becomes obtunded, place him into a sniffing/ramped position if not contraindicated. Use a two-hand grip to seal the mask to the patient's face, and have an assistant apply cricoid pressure. Allow the ventilator to deliver breaths. Adjust PEEP as necessary. Once saturation is optimized, remove the mask and intubate. If saturation drops below your predetermined threshold for this particular patient, you should abort the attempt and reapply the mask and ventilator. Consider placing an extraglottic airway.
Option B-RSA: Give an induction agent and a paralytic. As soon as the patient becomes obtunded, place him into a sniffing/ramped position if not contraindicated. Use a two-hand grip to seal mask to the patient's face, and have an assistant apply cricoid pressure. Allow the ventilator to deliver breaths until paralytic effect is achieved. Remove the mask, and place an extraglottic airway as appropriate. Attach vent tubing to the extraglottic airway. Decompress the stomach through the extraglottic device if possible. Once oxygenation is optimized, you may continue management with the extraglottic device, intubate through the extraglottic device if using an intubating one, or remove the extraglottic device and intubate. (See FastLinks box for a link to our video simulation or search YouTube for “RSA preoxygenation.”)
Option C-DSI: Give an induction agent, preferably ketamine 1.5 to 2 mg/kg IVP if not contraindicated. As soon as the patient becomes obtunded, place him into a sniffing/ramped-position if not contraindicated. Use a two-hand grip to seal the mask to the patient's face, and have an assistant apply cricoid pressure. Allow the ventilator to support the patient's spontaneous breathing using pressure support and PEEP. Once saturation is optimized, remove the mask and intubate. If saturation drops below threshold, abort the attempt and reapply the mask and ventilator. Consider an extraglottic airway.
Ventilator-mask ventilation may also be performed during cardiac arrest management (as long as you raise the pressure alarm to about 100 to allow for ventilations with chest compressions) and any other time you would otherwise be utilizing bag-valve-mask ventilation in the ED except for times when you feel it is critical to be able to assess lung compliance manually. This technique is helpful when assisting respirations of patients breathing spontaneously but ineffectively.
Please give this technique a try the next time you are performing mask ventilation, and email to let me know how it goes.
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The Rule of Threes for Optimal Bag-Valve-Mask Ventilation
Three People: One person maintains a mask seal, another squeezes the bag, and the third provides cricoid pressure.
Three Fingers: Use three fingers to apply cricoid pressure.
Three Airways: For any patient with difficult BVMV, use at least two airways and sometimes three.
Three Inches: Raise the head into sniffing position to put the ear and sternal notch at the same level (if no C-spine concerns).
Three Seconds: Use this as a reminder to use slow ventilation, and allow plenty of time for exhalation.
Three PSI: This doesn't literally mean 3 PSI, but is a reminder to use the lowest possible pressures to raise the chest.
Three PEEP: A reminder to add in 3-10 of PEEP using an inexpensive PEEP valve that attaches to the exhalation port of the BVM or buy a BVM that has an integral PEEP valve.
Ventilator Mask Ventilation: RSI, RSA, or DSI
* Set the vent on SIMV mode with 10 of PEEP/CPAP, 5-10 of pressure support above PEEP/CPAP, volume of 6-8 cc/kg ideal body weight, back-up rate of 12, 100% oxygen, and flow of 30 lpm.
* Place patient in optimal position, and insert nasal and/or oral airways as appropriate and necessary.
* Connect ventilator tubing to the mask just as you would connect it to the ET tube.
* Seal mask to patient's face using two-person technique and have assistant maintain cricoid pressure.
• Read Dr. Braude's-September column, “Remember the Rule of Threes for Optimal BVMV” at http://bit.ly/Ruleof3s.
• Access Dr. Scott Weingart's EMCrit blog at http://emcrit.org/.
• See Dr. Braude's video-simulation of RSA preoxygenation at www.airway911.com or watch on You-Tube at http://bit.ly/RSApreoxygenation.
• Read all of Dr. Braude's past columns in the EM-News.com archive.
• Comments about this article? Write to EMN at firstname.lastname@example.org.
© 2011 Lippincott Williams & Wilkins, Inc.