Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT04003688 |
| Other study ID # |
CAAE 09006119.2.0000.5501 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
August 26, 2019 |
| Est. completion date |
November 12, 2020 |
Study information
| Verified date |
February 2021 |
| Source |
University of Sao Paulo General Hospital |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
Magnesium sulfate has been applied in various situations due to actual or potential benefits
related to neuroprotection, treatment of eclampsia/pre-eclampsia, arterial hypertension,
adrenergic reflex under laryngoscopy/intubation and, shivering, nausea and vomiting, among
others. In anesthesia it has been useful as an analgesic adjuvant; however, the method to
calculate the dose of magnesium sulfate in obese population is unclear. The objective of this
project is to compare two methods of dose calculation based either on the real weight or
corrected ideal weight.
Description:
Magnesium sulfate has been applied in various situations due to actual or potential benefits
related to neuroprotection, treatment of eclampsia/pre-eclampsia, arterial hypertension,
adrenergic reflex under laryngoscopy/intubation and, shivering, nausea and vomiting, among
others. In anesthesia it has been useful as an analgesic adjuvant; however, the method to
calculate the dose of magnesium sulfate in obese population is unclear. The objective of this
project is to compare two methods of dose calculation based either on the real weight or
corrected ideal weight.
Main objective: To determine the optimum strategy to safely and effectively obtain the value
of magnesium concentration in the blood of obese population.
Secondary objectives: To evaluate postoperative analgesia and the pharmacokinetic profile of
neuromuscular blocker used in each group.
Hypothesis: The null hypothesis is that no matter which method we use to calculate the
magnesium sulfate dosage, the blood magnesium concentration will be the same. The alternative
hypothesis is that magnesium sulfate dosage based on the patient's actual weight generates
higher concentrations of magnesium than that required for postoperative analgesia, as
compared with dosage based on that corrected ideal weight of the patient.
Trial design: this is a prospective, controlled, randomized and double-blind clinical trial.
Study setting This study will be conducted at Beneficence Portuguese Society, Santos, an
academic hospital, in São Paulo, Brazil. A sample of 75 participants will be recruited from a
population of obese patients scheduled to undergo cholecystectomy or bariatric surgery
through laparoscopy.
Interventions In the first phase of the trial, 10 patients with body mass index 20-30 kg/m²
will be administered magnesium sulphate 40 mg/kg at anesthetic induction. In all patients,
blood collection will be conducted before administration of magnesium sulfate, and at 15, 30,
60, 120 and 240 minutes after administration of magnesium sulfate.
In the second phase of the trial, from among obese patients scheduled to undergo
cholecystectomy or bariatric surgery through laparoscopy at our institute, 75 patients will
be invited to participate in the trial. Participants will be assigned to three groups by
electronic randomization process as follow: Placebo group (PG) without administration of
magnesium sulfate; real weight group (RWG) administration of magnesium sulfate at 40 mg/kg of
the patient's actual weight; corrected ideal weight group (CWG) administration of magnesium
sulphate at 40 mg/kg of patient's corrected ideal weight.
The corrected ideal weight will be calculated using the following formulas:
Ideal weight Man = height (cm) - 100 Woman = height (cm) - 105 Corrected ideal weight = Ideal
weight + (0,4 x difference between the real and ideal weight) The participants will not be
administered any sedative agent before anesthetic induction. At arrival in the operating
room, all patients will undergo electrocardiography, noninvasive blood pressure measurement,
pulse oximetry, monitoring of neuromuscular function, and that of the level of consciousness.
Venous access and hydration will be achieved according to the anesthesiologist's judgment. At
the time of puncture of the vein, the first 2-ml blood sample will be collected to establish
the basal concentration of magnesium in the blood. Within 10 min after collection of the
blood, dosage will be calculated according to the following chart (Figure 1).
In all participants, infusion of treatment solution will be performed by a blinded
investigator, and ketoprofen 100 mg, clonidine 2 µg/kg, cefazolin 2 g, dexamethasone 4 mg,
ranitidine 50 mg and lidocaine 1,5 mg/kg will be administered simultaneously. At the end of
infusion participants will undergo pre-oxygenation with 100% O2 for 3 to 5 min, followed by
propofol through target controlled infusion with initial target of 4 µg/ml according to
Marsh's pharmacokinetic model, under monitoring for the level of hypnoses. At the time of
adequate level of hypnoses, revealed by the hypnoses monitor (SedLine® Brain Function
Monitoring) calibration of the monitor of neuromuscular function (train-of-four - TOF) will
be performed; subsequently, cisatracurium 0.15 mg/kg will be administered, and
target-controlled infusion of remifentanil (Minto's pharmacokinetic model) at initial target
concentration of 5 ng/ml will be conducted. Under hypnoses monitoring, 0.03 mg/kg
cisatracurium will be administered if TOF ≥ 2 is observed or on surgical demand. Remifentanil
infusion will be conducted according to the patient's hemodynamics, such that systolic
pressure is maintained within 30% limits from the baseline value, or maximum value of 130
mmHg and minimum value of 90 mmHg are achieved. During the last 20 minutes' period of
surgery, cisatracurium will be withheld, when possible. At the end of surgery, at TOF > 2,
atropine 20 µg/kg and neostigmine 40 µg/kg will be administered.
Before extubation, the patients in both groups will be administered morphine 0,05 mg/kg and
dipyrone 30 mg/kg. Five minutes after extubation and after each 30 minutes' interval, repeat
dose of morphine will be administered at pain-score of > 3 (0 to 10) of the patient.
