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Chapter 7
episodes would have caused major problems concerning morbidity and mortality, if they
had not immediately been detected and treated. Nevertheless, the objective of any form of
sedation should be, to avoid even these incidents and to reduce side effects to a minimum,
since every adverse side effect has the potential to result in serious complications.
Aside from this, some other differences between the three sedation regimens merit
further discussion. First, propofol/alfentanil sedation easily can turn from conscious to
deep sedation — with respiratory and haemodynamic problems. Titrating alfentanil or
midazolam/fentanyl, our endoscopy nurses tried to avoid this situation. Higher doses of
these three substances would certainly have caused more cardiopulmonary events, even
within these two groups.
Second, the sample size of our study is not large enough to detect statistically significant
differences in safety indicators between the three different sedation regimens. On the other
hand, this is the first prospective study in which all cardiorespiratory data were continuously
monitored by a clinically naive student observer with a video system.
Cote et al.
17
focused on the incidence of respiratory and haemodynamic complications in a
group of 799 patients sedated with propofol by a trained anaesthesia nurse for endoscopic
procedures. In this study, hypoxaemia occurred in 12.8% of the patients. In 14.4% of cases,
airway management was necessary to prevent hypoxaemia. The higher percentage of
respiratory incidents in our trial might be due to the fact that we not only summed all
desaturation events, but also counted hypercapnic and hypopnoic episodes. We defined
hypercapnia as etCO
2
above 50 mmHg. Certainly, this raises the question whether 50
mmHg is a clinically relevant threshold to define hypoventilation, or whether it is too strict
in the setting of sedation.
The only study addressing the use of alfentanil for colonoscopies as a single drug to date
was performed by Di Palma et al.
18
The authors compared 13 patients receiving alfentanil
with 11 midazolam-/alfentanil- and 11 meperidine-/midazolam-treated patients. Using
alfentanil only was associated with a lower requirement for oxygen supplementation in
response to desaturation (8 vs. 55% with alfentanil/midazolam and 27% with meperidine/
midazolam). Usta et al.
19
compared patient-controlled analgesia (PCA) with alfentanil versus
fentanyl for colonoscopies — both combined with a small dose of midazolam and an initial
bolus of 500 μg alfentanil. Adverse cardiopulmonary events were found in 7% (group A)
and 12% (group F) of patients.
There are several publications emphasising the safety of propofol administration.
20,21
However, many of these studies have serious limitations: the reliability of the data
depended on self-reporting from different centres with different monitoring methods and
documentation (or a lack thereof).