Networks: Infections, e-cigarettes, lipid guidelines, and MV

As of 2011, in the United States, one in five adults who smoke has tried electronic cigarettes. Among grade 6 to 12 students in the United States, those who have ever used the product increased from 3.3% in 2011 to 6.8% in 2012.

Tobacco-industry scientists argue that e-cigarettes deliver lower amounts of nicotine than regular cigarettes, are less toxic, and don’t expose others to second-hand smoke. One recent study showed that e-cigarettes, with or without nicotine, were modestly effective at helping smokers to quit, with similar achievement of abstinence as with nicotine patches and few adverse events. A recent study from France’s National Consumers Institute, however, concluded that e-cigarettes are "potentially carcinogenic" because some brands contain levels of formaldehyde that approach those of conventional cigarettes.

Uncertainty exists about the place of e-cigarettes in tobacco control, and more research is urgently needed to clearly establish their overall benefits and harms at both individual and population levels. Until then, we should not assume they are safe simply because they appear to be less harmful than traditional cigarettes. FDA is refusing to let them into the country and may soon ban their sale, as major US medical associations have strongly urged against the e-tobacco products.

Dr. Sat Sharma, FCCP

Steering Committee Member

Allied Health

Implementing mechanical ventilation orders by "Doing the Math"

Many RCPs (myself included) prefer mechanical ventilation (MV) orders that specify a target arterial pH (pHa), in lieu of listing a respiratory rate (RR) and tidal volume (Vt). If a baseline arterial blood gas (ABG) report is in hand, it’s easy to identify the target arterial carbon dioxide tension (Paco₂), which will elicit a homeostatic pHa: target Paco₂ = (5/3) • [HCO₃–].

For example, suppose that a patient exhibits the following ABGs following an overdose of barbiturates: pHa = 7.20; Paco₂ = 68 mm Hg; and [HCO₃ -] = 26 mEq/L. If 7.40 is the pHa that we wish to impose: target Paco₂ = (5/3) • 26 = 43 mm Hg.

Suppose further that our hypothetical patient initially displayed an RR of 10 breaths/min. We can reach the target Paco₂ by applying the following expression: RRfinal = RRinitial • (Paco₂initial / Paco₂final).

For our hypothetical patient, this expression reverts to: RRfinal = 10 breaths/min • (68 mm Hg/43 mm Hg) = 16 breaths/min! On the other hand, if the attending physician or house officer indicates that s/he wishes to elicit a pHa that’s near the lower limit of the homeostatic range, we can simply select a target Paco₂ that’s a few mm Hg higher than that shown above. This strategy is usually employed when the patient is known to be a CO₂-retainer.

Want to "drill down" on this material? A video, handout, script, and posttest are accessible at: ambulatorypractice.org/education-research/respiratorytherapy-education/ventilator-targets. Enjoy!

Bob Demers, RRT

Chair