Mechanical Ventilation

Interpreting the shape of the flow-volume loop

Typically, when one thinks of flow-volume loops, one refers to the classical loops of forced expiratory spirometry. Most of what is written about flow-volume loops refers to these. Indeed, both the LITFL entry on flow-volume loops and the AnaesthesiaUK revision article use the formal pulmonary function test standard of flow-volume loop interpretation. The shape of the curves is quite similar, but the fundamental difference is in the fact that in the ventilator loop is by convention upside-down.

Dual-lumen endotracheal tube


The item discussed here is the Robertshaw 28Fr left-sided double lumen endotracheal tube. Dorsch and Dorsch describe this thing as a "lung isolation device". Of course, then Dorsch and Dorsch get into some indepth discussions of every type of rare and exotic dual lumen tube there is. There is the Carlens, the White, the Robertshaw, the Broncho-Cath, the Sher-I-Bronch, the Silbroncho, and so forth and so on.  I question the relevance of these details in the ICU. We are infrequently exposed to a mind-paralyzing array of choice when it comes to dual lumen tubes.

The endotracheal tube in detail

The item discussed here is the Mallinckrodt size 8.5 endotracheal tube with an above-the-cuff suction port.  There being millions of different types, I thought it would be better to just pick a representative style, and to discuss it. The suction port may be a bit of a gimmick, and many places don't use this style of tube. Of course, the "representative style" available to me was the one which was already unwrapped, in the ICU nurse educator's office.  There are several structural features of note, which each deserve some brief mention. These features are common to the vast majority of ETTs.


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