The Effect of Deliberate Hypotension on QTc, Tp-e Intervals and Heart Rate Variability
Status:
Completed
Trial end date:
2013-02-01
Target enrollment:
Participant gender:
Summary
Deliberate hypotension is defined as lowering the systolic blood pressure to 80-90mmHg, or
the mean blood pressure to 50-65mmHg. This technique is usually employed for operations that
have a high risk of intraoperative hemorrhage, such as orthognathic surgery. Several
different regimens are used to lower the patient's blood pressure, such as vasodilators,
autonomic nervous system inhibitors, opioids and inhalation anesthetics. However, the effects
that these agents have on the QTc and Tp-e intervals during deliberate hypotension is not
known. Virtually every kind of anesthetic is reported to have some effect on the QTc and Tp-e
intervals. Because orthognathic surgery usually takes 3-4 hours to complete, the amount of
anesthetics and drugs used to maintain low blood pressure is not small. Therefore, the effect
that these agents may have on the QTc and Tp-e intervals may not be negligible. The
investigators of the present study found that the high dose of commonly used hypotensive
agents tend to prolong these variabilities to some extent. This study will be able to provide
insight as to which hypotensive anesthesia regimen has the least effect on the QTc and Tp-e
intervals, and therefore will be helpful in minimizing cardiovascular risks of deliberate
hypotensive anesthesia.