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The overall objective of the study is to determine the ability of TOF-Cuff device (blood-pressure modified cuff, including stimulation electrodes) to monitor with the same device the non-invasive blood pressure (NIBP) and the depth of a neuromuscular blockade (NMB) induced pharmacologically, by stimulation of the brachial plexus at the humeral level and recording evoked changes in pressure. We have established the following objectives:
- To compare and validate the values obtained from neuromuscular relaxation TOF-Cuff with those obtained by mechanomyography (MMG) (control method) during the recovery phase of BNM, when a TOF ratio > 0.9 and > 0.7 (primary endpoint) were reached respectively.
- To compare and validate the measurements obtained with TOF-Cuff device versus invasive blood pressure registered at the radial artery.
- To verify that the use of TOF-Cuff does not injure or causes side effects on any patient.
Clinical, single-centre, open-controlled study with 32 adult patients for scheduled elective surgery under general anesthesia in supine position, with an expected duration of 30 minutes minimum, for the validation of neuromuscular monitoring, and an additional consecutive study of 17 patients for validation of NIBP monitoring. Both were held in the University General Hospital Santa Lucía of Cartagena, between October 2013 and March 2014.
Inclusion criteria were:
- Age 18-65 years old
- ASA I- III and with an informed consent signed.
- With comorbidities.
- Predictors of a difficult airway.
- Under treatment with drugs affecting neuromuscular transmission.
- Women of childbearing age.
For monitoring NMB, the TOF-Cuff device was place with electrodes at humeral level and the MMG on the opposite arm. A simultaneous stimulation with the 2 methods was performed according to the following pattern:
Single frequency of 1 Hz, automatic calibration followed TOF stimulation every 20 seconds for the rest of the intervention. When the surgical procedure had ended, the NMB was reversed with neostigmine 0.05 mg•kg-1 or sugammadex 2 mg•kg-1 alternatively, and patients were extubated when a TOF ratio > 0.9 was reached.
For monitoring the blood pressure (BP) an intra-arterial catheter at the radial artery was placed in the opposite arm to TOF-Cuff, and measurements were performed every 5 minutes recording: systolic BP, diastolic BP, mean arterial pressure and heart rate, with at least 10 pairs of measurements per patient.
All data were exported to a PC in real time, and analyzed using the Bland- Altman method.
- A TOF-ratio > 0.9 quantified by TOF-Cuff device has a good correlation with a TOF ratio > 0.7 in MMG, so it can be safely used in clinical practice just as acceleromyography is used at present, although both are not interchangeable with MMG, because recovery of BNM measured TOF-Cuff suffers an advance regarding the MMG.
- The ease of use and accessibility of TO -Cuff device can contribute to a wider dissemination of routine quantitative neuromuscular monitoring.
- The use of TOF-Cuff device as part of the standard surgical monitoring can contribute to the patient’s safety by reducing the risk of a residual block.
- No patient had any skin lesions, residual pain or any other side effects.
- The TOF-Cuff device is valid for NIBP measurement.