A recent study[22] using a 2019 prehospital patient care data set containing over 8 million EMS encounters from over 1,300 agencies distributed across the U.S. provides data on indications for prehospital ketamine use for trauma/pain, seizure, altered mental status/behavioral and cardiovascular/pulmonary indications, and “other.” The data allow for analysis based on sex, age, dosage, and prehospital hypoxia and hypercapnia. The table below sets forth national data taken directly from the study that focuses on patients with altered mental status/behavioral indications.
National Data on Ketamine Administrations for Altered Mental Status/Behavioral Indications
| Male/ Female | Age | Median dose | # of K Doses Administered | Patients w/ Hypoxia* | Patients w/ Hypercapnia** | |
| Unique Pt Records (n=3,795) | M: 2,489 (65.9%) F: 1,290 (34.1) |
<10: 7 (0.2%) 10-19: 248 (6.9) 20-29: 886 (24.8) 30-39: 901 (25.2) 40-49: 561 (15.7) 50-59: 398 (11.1) 60-69: 268 (7.5) 70-79: 170 (4.8) 80-89: 106 (3.0) > 90: 30 (0.8) |
3.7 mg/kg (Interquartile Range= 2.2 - 4.4) | One: 2,986 (78.7%) Two: 666 (17.5) Three:143 (3.8) |
358 (10.2%) | 612 (23.0%) |
*SPO2 is a measure of oxygen saturation in the blood. In this study hypoxia is defined as an SPO2 < 88% after ketamine administration without previous hypoxia. The number of records with SPO2 documented = 3,515 (92.6%).
** EtCO2 (End-tidal carbon dioxide) measures the partial pressure or maximal concentration of carbon dioxide (CO2) at the end of an exhaled breath. In this study, hypercapnia is defined as EtCO2 > 45 after ketamine administration without previous hypercapnia. The number of records with EtCO2 documented = 2,658 (70.0%).
The study found that ketamine was given to 2,489 male patients (65.9%) and 1,290 female patients (34.1%).[22] In Colorado, the percentage of males who received ketamine for excited delirium and/or extreme or profound agitation was higher (78%) than males in the national study, as was the number of persons between 20-39 years of age (64% v. 50%). (See Appendix E) The national median dose of ketamine was 3.7 mg/kg (interquartile range [IQR], 2.2 - 4.4 mg/kg).[22] In collaboration with panel members, CDPHE staff reanalyzed the 2019 data to calculate median and interquartile ranges, and determined that the Colorado median dose in 2019 was 4.9 mg/kg (IQR: 3.7-5.5 mg/kg).
This further analysis also indicated that 92% of patients who received ketamine in Colorado were given a single dose, and the median dose was 400 mg IM with an interquartile range of 300-500 mg. The 92% of patients in Colorado who required only one dose of ketamine is higher than in the national study, 78.7%.[22] The higher median first dose used in Colorado (4.6 mg/kg; IQR, 3.3-5.2 mg/kg) may improve chemical restraint success and explain our state’s lower rate of repeat dosing (8%)[23] compared to the national data (21%).[22]
Both the national study and the quality improvement chart review performed by CDPHE staff examined the frequency of hypoxia occurrences after ketamine was administered. The data from the national study reported that 10.2% of patients were hypoxic (SpO2 < 88%) after receiving ketamine.[22] Of the 73 Colorado patients classified as hypoxic in the waiver data set (16%), the ePCR chart review found that 23 had an SpO2 of < 88% while another 9 provided no SpO2 documentation. If it is assumed that some of the 9 undocumented values were less than 88%, then 23-32 of 454 Colorado patients (5-7%) had hypoxia as defined in this national study.[24] The median dose of ketamine among Coloradans requiring intubation (5.0 mg/kg) was equal to the median dose of those not intubated (4.9 mg/kg).