Should that patient be admitted to the floor? 

Several studies have evaluated factors associated with upgrade in admitted patients from the floor to an ICU within 24 or 48 hours. Elevated lactate, tachypnea, and "after-hours" admissions have been repeatedly identified as some of the risk factors for decompensation. 

Two recent studies tried again to identify predictors of eventual ICU requirement...

Best predictors of subsequent upgrade:

• Hypercapnia*
• Tachypnea (in sepsis patients)*
• Hypoxemia (in pneumonia patients)
• Nighttime admission
• Initial lactate ≥ 4

The most common reasons for upgrade:

1. Respiratory failure
2. Hemodynamic instability

Effect on mortality? 

Despite a more stable initial presentation, mortality of patients who decompensated on the floor (25%) matched that of patients initially admitted to the ICU.

*One of the studies noted that although respiratory rate was demonstrated to be the most important vital sign, it was missing in 42% of the study population, while PCO2 was only obtained in 39% of patients.

Bottom Line: 

• Make sure to physically reassess patients you've stabilized/improved in the ED with current vital signs (including an accurate respiratory rate!) before okaying their admission/transfer to the floor. 
• If you get a blood gas, make sure to pay attention to the PCO2 and address any abnormalities appropriately.

References

1. Farley, H, Zubrow MT, Gies J, et al. Emergency department tachypnea predicts transfer to a higher level of care in the first 24 hours after ED admission. Acad Emerg Med. 2010;17(7): 718-22.
2. Boerma LM, Reijners EPJ, Hessels RA, et al. Risk factors for unplanned transfer to the intensive care unit after emergency department admission. Am J Emerg Med. 2017;35(8): 1154-8.
3. Wardi G, Wali AR, Villar J, et al. Unexpected intensive care transfer of admitted patients with severe sepsis. J Intensive Care. 2017;5: 43.
4. Tam V, Frost SA, Hillman KM, Salamonson Y. Using administrative data to develop a nomogram for individualizing risk of unplanned admission to intensive care. Resuscitation. 2008;79: 241-8.