In addition to these techniques that I have adopted for oxygenation and regurgitation prevention, I now try to pick the ventilation strategy that will mimic the patient’s preprocedural minute ventilation. In situations of severe respiratory alkalosis, I aim to re-create the patient’s high minute ventilation after induction and during the onset phase of muscle relaxation (waiting 60 seconds for succinylcholine, or double dose rocuronium or vecuronium, before inserting my direct or video laryngoscope). When bicarbonate has a clear role, (eg, salicylate poisoning, rhabdomyolysis, renal failure with hyperkalemia, etc.), I give it before and sometimes again during induction and intubation. There is controversy about the benefits of sodium bicarbonate in many situations, but when pH is pushed below 7.0, I am liberal with its use, along with maintaining a high minute ventilation.
Explore This IssueACEP Now: Vol 34 – No 01– January 2015
In the severely ill COPD and asthma patient, I start with a simple ventilation strategy for postintubation: six breaths a minute and 500 cc tidal volume (3 L minute ventilation). By deliberately going slow, I allow the maximal time between breaths for air to get out. I check plateau pressures on the vent and blood pressure. I aim to increase minute ventilation, but I do so slowly, making sure not to trigger auto-PEEP and hypotension. In addition to nebulized bronchodilators, you can also add intravenous ketamine, postintubation, for both bronchodilation and sedation. The 3 L minute ventilation of 500 cc/6 breaths will not correct the CO2 retention, but it is safest to correct this slowly as the patient’s pulmonary function allows (watching vent pressures and blood pressure). “Permissive hypercapnia” is the deliberate strategy of not correcting the CO2 quickly; a bicarbonate drip may be added if acidosis drops the pH below 7, but have not been proved to improve outcomes.
For the vast majority of ED airways, ventilation is not a major concern. Use a strategy of relatively low volume (6–7 mL/kg) and relatively low rates with low pressures (and gentle inflation); the goal is to avoid overinflation, gastric distention, and regurgitation. When the patient presents at the extremes of ventilation, however, remember that plastic in trachea is not the primary solution. If intubation cannot be avoided, aim to re-create the immediate preintubation minute ventilation while bagging during the onset of muscle relaxation and immediately postintubation. By recognizing patients with a compensatory respiratory alkalosis, and the very low minute ventilation of COPD and asthma patients, you will avoid precipitating a peri-intubation catastrophe.