Smarter, Better NMB

view of NMB2 monitor with stimulation electrodes

Diastolic Robotics is developing a better approach to neuromuscular blocker (NMB) drug monitoring and administration.

NMB drugs ("NMBs") relax and paralyse patient muscles (in a hospital setting). (More)

Because they are worried about other important vital signs, anesthesiologists may administer NMBs less perfectly than if they had nothing else to monitor, and less-perfect administration can lead to injury and delay. (More)

This injury and delay costs the US health care system approximately $3.3 billion per year. Globally, injury and delay costs can be extrapolated to US$10 billion per year.

We're developing a novel system that measures and adapts to the patient's response to NMBs to assist physicians and help reduce these costs. This system advises the anesthesiologist on the timing and dose of NMB drugs based on modelling of the drug in the patient and the history of the measured patient responses.

Clinical Trial Results

A 60-patient prospective, randomized, controlled, clinical trial was run to test the system (known as "NMBAS", for Neuromuscular Blockade Advisory System, in the journals below). There were two groups of 30 patients, one group was treated by standard care and the other had treatment with diarobo's NMBAS system.

Compared to standard practice, diarobo's NMBAS-guided care was associated with improved NMB quality and higher TOF ratios at the end of surgery, potentially reducing the risk of residual NMB and improving perioperative patient safety.

As well, total administered doses of rocuronium (the paralysis agent used in this study), reversal drugs and other drugs, and the incidence of postoperative adverse events were not different for the two groups.

clinical trial adverse event results.  NMBAS group has fewer
									adverse events.

Figure 1: Adverse event results from the clinical trial: a comparison of adverse events presented separately (columns 1 to 4), in sum (column 5), and as an incidence per case for the Control (left columns) and NMBAS (columns on the right) groups. The asterisk (*) indicates statistical significance at p < 0.05.

Adverse Events

The incidence in total intra-operative events associated with inadequate NMB was significantly lower for the NMBAS group.

Incidence of breathing against the ventilator and inadequate surgical relaxation were reduced with statistical significance in the NMB treatment group. There was also a trend towards reduced intra-operative motion and bucking on the ventilator, but the difference was not statistically significant.

The incidence in total intra-operative events associated with inadequate NMB was significantly lower in the NMBAS group compared to standard care (8/30 vs 19/30; P = 0.004).

Adverse event results are displayed in Figure 1.

predicted caselength and actual intubation to extubation time for the control and NMBAS groups, 
									showing NMBAS cases to be shorter on trend.

Figure 2: Case results from the clinical trial: a comparison of the Control (left columns) and NMBAS (right columns) groups for predicted case length (column set 1) and actual case length. An asterisk indicates statistical significance at p=0.05.

Case Length

Despite there being a trend towards longer predicted case lengths for the NMBAS treatment group (not statistically significant however as p=0.132), it was found that the NMBAS treatment group cases took less time as measured from patient entry to the room until extubation. Time to extubation for the NMBAS treatment group decreased increasingly as cases became longer, with cases of 150 minutes or longer being statistically significantly shorter by approximately 23 minutes per procedure.

A comparison of the two groups by procedure length is shown in Figure 2.

Clinical trial results:  procedural milestones as a proportion of predicted case length 
									for the control and NMBAS groups.  NMBAS groups reach the milestones more quickly.

Figure 3: Timing results from the clinical trial: a comparison of the two groups for time to case milestone by proportion of the predicted case length.

Proportional Case Timing

To correct for the difference in the length of cases when comparing the two groups, the recorded time to reach procedure milestones was normalized by calculating the data as a proportion of the expected length of case. The value for the expected length of case was the a priori predicted case length time used for scheduling the operating room, dictated by the time of procedure.

Figure 3 shows the results, where the groups have similar surgical start times of approximately 0.3 (30%) of the expected case length, but overall the NMBAS group cases proceed relatively quicker. After surgical start ("Surg. start"), the group timing diverges with the halting of surgery requiring NMB agent ("Surg. end") occurring at 1.33 times the expected case length for the Control group and 1.20 times the expected case length for the NMB treatment group. Extubation ("Extubated") occurred at 1.41 and 1.30 times the expected case length, and admission to the Post-Anesthesia recovery room ("Admit PAR") occurred at 1.45 and 1.29 times the expected case length for Control and NMBAS treatment groups respectively.

Details of the clinical trials have been published and can be found in brief, here:
    (Pubmed abstract)

and in the peer-reviewed journal Anesthesia and Analgesia, here:
   Anesth Analg 2008 107 p1609

Patents Awarded

Patents awarded for diarobo's NMB projects include:

Patent Applications

Applications are being pursued as continuations and/or divisionals of the above in the United States and in other countries.

The initial applications are:


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