title: Temporal distribution of instability events in continuously monitored step-down unit patients: implications for Rapid Response Systems.
abstract: OBJECTIVE
  Medical Emergency Teams (MET) activations are more frequent during daytime and weekdays, but whether due to greater patient instability, proximity from admission time, or caregiver concentration is unclear. We sought to determine if instability events, when they occurred, varied in their temporal distribution.
  
  
  METHODS
  Monitoring data were recorded (frequency 1/20Hz) in 634 SDU patients (41,635 monitoring hours). Vital sign excursion beyond our MET trigger thresholds defined alerts. The resultant 1399 alerts from 216 patients were tallied according to clock hour and time elapsed since admission. We fit patient ID (n=216), clock hour, time since SDU admission, and alert present into a null model and three mixed effect logistic regression models: clock hour, hours elapsed since admission, and both clock hour and time elapsed since admission as fixed effect covariates. We performed likelihood ratio tests on these models to assess if, among all alerts, there were proportionally more alerts for any given clock hour, or proximity to admission time.
  
  
  RESULTS
  Only time elapsed since admission (p<0.001), and not clock hour adjusting for time elapsed since admission (p=0.885), was significant for temporal disproportion. Results were unchanged if the first 24h following admission were excluded from the models.
  
  
  CONCLUSIONS
  Although instability alerts are distributed most frequently within 24h after SDU admission in unstable patients, they are otherwise not more likely to distribute proportionally more frequently during certain clock hours. If MET utilization peaks do not coincide with admission time peaks, other variables contributing to unrecognized instability should be explored.
authors: School of Nursing, University of Pittsburgh, 336 Victoria Hall, 3500 Victoria Street, Pittsburgh, PA 15261-6314, United States. Electronic address: mhra@pitt.edu.
authors: Marilyn
authors: M
authors: Hravnak
authors: Auton Lab, The Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213-3890, United States.
authors: Lujie
authors: L
authors: Chen
authors: Auton Lab, The Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213-3890, United States.
authors: Artur
authors: A
authors: Dubrawski
authors: School of Nursing, University of Pittsburgh, 336 Victoria Hall, 3500 Victoria Street, Pittsburgh, PA 15261-6314, United States.
authors: Eliezer
authors: E
authors: Bose
authors: School of Medicine, University of Pittsburgh, 606 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261-1616, United States.
authors: Michael R
authors: MR
authors: Pinsky
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004630:Emergencies; D005260:Female; D057209:Hospital Rapid Response Team; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010507:Periodicity; D013997:Time Factors; D055986:Vital Signs
keywords: Instability; Machine learning; Medical emergency teams; Noninvasive monitoring; Physiologic monitoring; Rapid response systems
references: Am J Crit Care. 2010 Jan;19(1):74-83
references: 19542059
references: Resuscitation. 2009 Nov;80(11):1264-9
references: 19744762
references: Resuscitation. 2009 Jan;80(1):35-43
references: 19010579
references: Resuscitation. 2009 Jan;80(1):44-9
references: 18952358
references: Qual Saf Health Care. 2008 Oct;17(5):377-81
references: 18842979
references: Arch Intern Med. 2008 Jun 23;168(12):1300-8
references: 18574087
references: Crit Care Med. 2006 Sep;34(9):2463-78
references: 16878033
references: Crit Care Med. 2006 Jun;34(6):1700-6
references: 16625132
references: JAMA. 2014 Mar 26;311(12):1199-200
references: 24590296
references: Crit Care Med. 2014 Apr;42(4):801-8
references: 24335439
references: J Hosp Med. 2014 Feb;9(2):116-9
references: 24357519
references: Crit Care Med. 2014 Jan;42(1):26-30
references: 23989173
references: Resuscitation. 2013 Dec;84(12):1652-67
references: 23962485
references: Am J Nurs. 2011 May;111(5):22-9; quiz 30-1
references: 23722377
references: Chest. 2013 Jun;143(6):1758-65
references: 23732586
references: Am J Respir Crit Care Med. 2014 Sep 15;190(6):606-10
references: 25068389
references: Resuscitation. 2013 Apr;84(4):465-70
references: 23295778
references: Resuscitation. 2013 Apr;84(4):471-6
references: 23228559
references: Ann Intern Med. 2013 Mar 5;158(5 Pt 2):417-25
references: 23460099
references: Crit Care Resusc. 2013 Mar;15(1):15-20
references: 23432496
references: J Crit Care. 2012 Aug;27(4):424.e7-13
references: 22341727
references: Crit Care Med. 2012 Aug;40(8):2349-61
references: 22809908
references: Resuscitation. 2011 Apr;82(4):415-8
references: 21242020
references: Crit Care Med. 2011 Jan;39(1):65-72
references: 20935559
references: J Crit Care. 2010 Jun;25(2):359.e1-7
references: 20189754
references: Resuscitation. 2010 Apr;81(4):375-82
references: 20149516