Measure the corrolation between BIS and MAAS in mechanically ventilated critically ill patients.
A prospective observational study was performed in sedated, mechanically ventilated medical and surgical patients (≥14 yr) with a MAAS of 0-1(see the table below for details on MAAS). Patients with stroke, closed head injury, forehead wounds, and undergoing muscular paralysis were excluded. Bispectral index was recorded using a BIS Monitor Model A-2000 with XP software (Aspect Medical Systems, USA) and a sensor (BIS Quatro) placed on the patient’s forehead. The investigator documented MAAS four times daily, but was blinded for data concerning BIS and sedative doses administered. Recording of BIS was done just prior (n=157), and 5 minutes after (n=153) the assessment of MAAS. The patients were followed until MAAS reached 3 or death. Statistical analysis of the correlation between BIS and MAAS was done using Pearson’s correlation coefficient.
Motor Activity Assessment Scale (MAAS)MAAS ScoreDescriptionDefinition0UnresponsiveDoes not move with noxious stimulus1Responsive only to noxious stimuliOpens eyes OR raises eyebrows OR turns head toward stimulus OR moves limbs with noxious stimulus2Responsive to touch or nameOpens eyes OR raises eyebrows OR turns head toward stimulus OR moves limbs when touched or name is loudly spoken3Calm and cooperativeNo external stimulus is required to elicit movement AND patient is adjusting sheets or clothes purposefully and follows commands4Restless and cooperativeNo external stimulus is required to elicit movement AND patient is picking at sheets or tubes or uncovering self and follows commands5AgitatedNo external stimulus is required to elicit movement AND attempting to sit up OR moves limbs out of bed AND does not consistently follow commands (e.g. will lie down when asked but soon reverts back to attempts to sit up or move limbs out of bed6Dangerously agitated, uncooperativeNo external stimulus is required to elicit movement AND patient is pulling at tubes or catheters OR thrashing side to side OR striking at staff OR trying to climb out of bed AND does not calm down when asked
Twenty patients (60% males) with a mean age of 47.3 yr were included. The utilization of sedative agents at the time of recordings was as follows: fentanyl (70.7%), midazolam (49.7%), and propofol (17.2%). The correlation coefficients between both pre- and post BIS and MAAS was 0.87 (p<0.0001).No patient with BIS index of <50 and quite few with BIS of < 60 had a MAAS of 2 or more (see graph below).
The study shows a strong correlation between BIS and MAAS, supporting the use of BIS as a monitoring tool of sedation in critically ill patients.
BIS of < 50 to 60 can be used as a reasonable target in paralyzed mechanically ventilated patient in the ICU setting.
M.H. Hijazi, None.