Skull Pin Insertion Clinical Trial
Official title:
The Dose Effects of Remifentanil Boluses on the Hemodynamic Response to Skull Pin Insertion.
Skull pin insertion during craniotomies is a brief, intensely stimulating, painful stimuli occurring during the conduct of a neurosurgical or spine anesthetic. Remifentanil is an ultra short acting opioid that has been successfully used to blunt hemodynamic responses in a wide variety of clinical scenarios. It is our intention to ascertain the optimal dose for blunting the hemodynamic response to skull pin insertion using remifentanil.
Skull pin insertion is commonly required for craniotomies and cervical spine surgery. It is
a brief but highly stimulating maneuver performed following induction, during a period of
light anesthesia, and may cause significant rise in blood pressure, heart rate and
intracranial pressure if not anticipated and treated.
A wide variety of methods have been shown to be effective at blunting this hypertensive
response. These include intravenous agents such as fentanyl, sufentanil, clonidine, ketamine
and magnesium sulphate, local anesthetic methods such as injection at pin sites or full
scalp blocks, deepening the volatile agent, oral premedication or a combination of these
methods. There is no consensus on which of these methods is the best. Many anesthesiologists
simply use boluses of propofol - a reliable way of accomplishing this effect with a familiar
drug. It is also very common for anesthesiologists to use remifentanil, by increasing the
infusion rate and or bolusing.
Remifentanil is an ultra-short acting opiate with such rapid onset and offset, that it is
most easily and safely delivered by infusion. Increasingly in the literature, however, are
reports of remifentanil administered as boluses rather than infusions. Boluses may be ideal
for very short stimulating procedures such as intubation and skull pin fixation where a
quick onset and offset are desired. Although the safety of bolusing remifentanil has been
established in many studies , some authors are still apprehensive . Care must be taken to
avoid bolusing with greater doses than required since this may lead to bradycardia and
hypotension. In non-ventilated patients, respiratory depression is common and chest wall
rigidity may occur at doses larger than 4ug/kg9.
Different bolus dose-effect studies have recommended the following for remifentanil in a
variety of clinical settings:
- 3-5ug/kg with propofol 2mg/kg for intubation without muscle relaxants ,
- 2ug/kg with propofol TCI (>4ug/ml) and cisatracurium for intubation (no additional
hemodynamic benefit using 4ug/kg)
- 1-1.25ug/kg for rapid sequence intubation with thiopentone 5-7mg/kg and succinylcholine
1mg/kg
- ED50 of 1.7ug/kg and ED95 of 2.88ug/kg for good to excellent intubating conditions in
both infants and children (when used with 10ug/kg glycopyrrolate and 4mg/kg propofol)
- 3ug/kg (plus 4mg/kg propofol) provides similar intubating conditions when used in place
of succinylcholine 2mg/kg for intubation in infants8
Remifentanil is not currently recommended for the following settings:
- As a sole agent for loss of consciousness with a high ED50 of 12ug/kg, lack of
reliability and muscle rigidity common at such high doses
- Wide interindividual variability limit its use for labor analgesia (0.2-0.8ug/kg,
median dose of 0.4ug/kg)
In neurosurgery, it is common to administer remifentanil as an infusion. Optimal infusion
rates have already been investigated for intracranial surgery . However it is increasingly
common to administer remifentanil as a bolus particularly during skull pin fixation, due to
the desirable quick onset and offset, and there are no studies at present that have
investigated optimal dose requirements for boluses in this setting.
At our institution we commonly administer remifentanil as a bolus during skull pin fixation
and are interested in determining which bolus doses are safe and effective
;
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment
| Status | Clinical Trial | Phase | |
|---|---|---|---|
| Recruiting |
NCT03738059 -
The Lowest Effective Dose of Dexmedetomidine in Attenuating the Hemodynamic Responses During Skull Pin Insertion in Patients Undergoing Elective Craniotomy
|
Early Phase 1 |