The participant selection process will be carried out through direct invitation to patients
scheduled for surgery under regional or general anesthesia at the General Hospital of Zone
No. 51 of the IMSS, Gómez Palacio, Durango. Explaining what their participation consists of
for the subsequent signing of the informed consent letter in case of accepting. Afterwards,
according to the type of surgery and scheduled anesthesia, 2 groups will be integrated
randomly and blindly for the investigator: one that will receive MgSO4 pre and
intraoperatively and another group that will be administered 0.9% NaCl intravenously
(placebo). All participants will undergo the same pre, trans and postoperative surgical and
anesthetic protocol.
Personal data, background and sociodemographic variables will be collected in a data
collection sheet. Subsequently, anthropometric measurements will be made to determine weight,
height, body mass index and blood pressure.
Peripheral venous blood samples will be taken in the operating room for the determination of
pre and postoperative serum Mg and other analyzes.
Each participant will receive standard and continuous monitoring (electrocardiogram, oxygen
saturation, blood pressure, capnography, temperature and TOF) and an intravenous access will
be established. The MgSO4 group will receive 30 mg / kg of magnesium sulfate intravenously
over a period of 15 minutes before induction of anesthesia and 10 mg / kg / h by continuous
intravenous infusion during the operation. The control group (placebo) will receive 0.9% NaCl
in the same volume as the study drug.
In procedures under general anesthesia, a standard protocol with propofol 2 mg / kg (IV),
fentanyl 2 μg / kg (IV) and cisatracurium 0.2 mg / kg (IV) will be applied. Anesthesia will
be maintained with 100% oxygen, and 0.5 to 4 vol% sevoflurane, to achieve a mean alveolar
concentration (MAC) of 50%. Maintenance doses of fentanyl will be added to the anesthesia
regimen as needed. The maintenance dose of cisatracurium will be administered according to
the MNM with TOF. The total doses of the drugs used will be recorded. In cases with neuraxial
regional anesthesia, a standard protocol with 10 mg heavy bupivacaine and subarachnoid
buprenorphine 60 mcg will be applied.
Hemodynamic parameters will be recorded at baseline (before administration of magnesium
sulfate or 0.9% isotonic saline solution and subsequently every 5 minutes during surgery, up
to 180 minutes after drug administration.
Low blood pressure during surgery, defined as a mean blood pressure value <50 mmHg, will be
treated with a 5 mg bolus of ephedrine given intravenously or norepinephrine by IV infusion
for persistent hypotension (this is the standard anesthetic management of variations in
hemodynamic stability). Low heart rate during surgery, defined as <50 beats per minute, will
be treated with atropine at 10 mcg / kg intravenously.
The time until the MNM with TOF indicates the suitability of the neuromuscular block for
intubation will be recorded, and the intubation conditions will be evaluated.
The postoperative analgesic protocol will include ketorolac 30mg IV, tramadol 100mg IV, or
lysine clonixinate 100mg in case of allergy to ketorolac. Buprenorphine will be administered
subcutaneously at a dose of 2 mcg / kg as rescue analgesia only when necessary.
As an adjunct to anesthesia, dexamethasone 8 mg IV, metoclopramide 10 mg IV, ondansetron 100
mcg / kg and omeprazole 40 mg IV will be administered.
Post-operative pain assessment will be performed by EVAD upon exiting anesthesia and at 2, 4,
6, and 24 hours.
The time elapsed until the first request for additional analgesic by the patient, and the
total consumption of postoperative analgesics will be recorded, recording it as morphine
equivalents.
All the information about all the drugs administered to the patient during their
perioperative stay will be collected.
Episodes of nausea, vomiting, itching, chills, arrhythmias, laryngeal or bronchial spasm will
be recorded during and after coming out of anesthesia and at the end of the hospital stay.
Satisfaction in recovery from anesthesia will be assessed at 24 hours by delivering a
self-report questionnaire to patients.
Finally, the data will be captured in a database for subsequent statistical analysis.