Baylor University Medical Center Proceedings January 2014, Volume 27, Number 1 | Page 11

that of the dexmedetomidine group (60% vs 51%). However,
this probably represented hypoventilation with rapid shallow
breathing, as CO2 levels never declined below 40 mm Hg.
Other measurements of respiratory status, such as mean pulse
oximetry and mean transcutaneous carbon dioxide, were statistically similar when comparing the two groups. Yet the mean
tcpCO2 for both groups was above the normal 38 to 42 mm
Hg, with the placebo group at a mean of 44 mm Hg and the
dexmedetomidine group at a mean of 43 mm Hg. Because
retaining CO2 could have been part of an underlying medical
condition in these patients, future studies should do a baseline
tcpCO2 reading prior to surgery in addition to immediately
prior to the start of study drug, as was done in this trial.
While the mean tcpCO 2 by patient for all times was
similar in the two groups, the readings between hours 6
and 16 were statistically significant between the two groups.
The placebo group had a significantly higher tcpCO2 during
these times than the dexmedetomidine group with equal
pain scores. At the same time, those in the dexmedetomidine
group were more sedated, which may account for the raised
tcpCO2, as they were less likely to be hyperventilating. The
explanation for the rise during this timeframe is unknown,
and factors such as increased activity or decreased attention
to pulmonary toilet were explored but were not consistent
across all subjects.
The overall number of adverse events was higher in the
placebo group, with this group more likely to develop the side
effects of opioid administration and subsequently to receive
additiona