The Effect of Ketamine in the Prevention of Hypoventilation in Patients Undergoing Deep Sedation Using Propofol and Fentanyl

Procedures performed under sedation have the same severity in regards to morbidity and
mortality as procedures performed under general anesthesia1. The demand for anesthesia care
outside the operating room has increased tremendously and it poses, according to a closed
claim analysis, major risks to patients. Both closed claim analysis identified respiratory
depression due to over sedation as the main risk to patients undergoing procedures under
sedation. The major problem is that hypoventilation is only detected at very late stages in
patients receiving supplemental oxygen. Besides the respiratory effects of hypoventilation,
hypercapnia can also lead to hypertension, tachycardia, cardiac arrhythmias and seizures.

The incidence of anesthetized patients with obstructive sleep apnea has increased
substantially over the last years along with the current national obesity epidemic. These
patients are at increased risk of hypoventilation when exposed to anesthetic drugs. The
context of the massive increase in procedural sedation and the extremely high prevalence of
obstructive sleep apnea poses major respiratory risks to patients and it may, in a near
future, increase malpractice claims to anesthesiologists. The development of safer
anesthesia regimen for sedation are, therefore, needed. The establishment of safer
anesthetics regimen for sedation is in direct relationship with the anesthesia patient
safety foundation priorities. It addresses peri-anesthetic safety problems for healthy
patient's. It can also be broadly applicable and easily implemented into daily clinical
care. Ketamine has an established effect on analgesia but the effects of ketamine on
ventilation have not been clearly defined. The investigators have demonstrated that the
transcutaneous carbon dioxide monitor is accurate in detecting hypoventilation in patients
undergoing deep sedation. Animal data suggest that when added to propofol in a sedation
regimen, ketamine decreased hypoventilation when compared to propofol alone. It is unknown
if ketamine added to a commonly used sedative agent (propofol) and fentanyl can decrease the
incidence and severity of hypoventilation in patients undergoing deep sedation.

The investigators hypothesize that patients receiving ketamine, propofol and fentanyl will
develop less intraoperative hypoventilation than patients receiving propofol and fentanyl.

The investigators also hypothesize that this effect will be even greater in patients with
obstructive sleep apnea than patients without obstructive sleep apnea.

Significance: Respiratory depression due to over sedation was identified twice as the major
factor responsible for claims related to anesthesia. The high prevalence of obstructive
sleep apnea combined with more complex procedures done in outpatient settings can increase
physical risks to patients and liability cases to anesthesiologists. The main goal of this
project is to establish the effect of ketamine in preventing respiratory depression to
patients undergoing procedures under deep sedation using propofol and fentanyl.

If the investigators can confirm our hypothesis, our findings can be valuable not only to
anesthesiologist but also to other specialties (emergency medicine, gastroenterologists,
cardiologists, radiologists) that frequently performed procedural sedation.

The research questions is; does the addition of ketamine prevent hypoventilation during deep
sedation using propofol and fentanyl?

The hypotheses of this study: Ketamine will prevent hypoventilation during deep sedation
cases.