A two-year retrospective review of the determinants of pre-hospital analgesia administration by alpine helicopter emergency medical physicians to patients with isolated limb injury

What is the Evidence for Using Intranasal Medicine in the Prehospital Setting? A Systematic Review

OBJECTIVES

Intranasal (IN) medications offer a safe non-invasive way to rapidly deliver drugs in situations where intravenous (IV) access and intramuscular (IM) administration is challenging or not feasible. In the prehospital setting, this can be an essential alternative in time critical situations including trauma management, seizures, and agitated patients. However, there is a paucity of evidence summarizing its efficacy in this environment. This systematic review aims to assess the current evidence supporting the use of IN medicine (midazolam, ketamine, fentanyl, morphine, glucagon, and naloxone) in the prehospital setting alone.

METHODS

A systematic literature search (PROSPERO CRD42023440713) of PubMed, Web of Science, OVID Medline, "Cochrane Central Register of Controlled Trials," Cochrane reviews and Embase was performed from inception to June 2023 to identify studies where IN medications were administered to patients in the prehospital setting. All randomized controlled trials, observational cohort studies, case series, and case reports were included. Papers not written in English, review articles, abstracts, and non-published data (including letters to the editor) were excluded. The methodological quality of the included studies was interpreted using the Cochrane risk of bias tool and rated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. No funding was received.

RESULTS

From 4818 studies, 39 were included (seven for midazolam, five for ketamine, twelve for fentanyl, one for diamorphine, two for glucagon, and twelve for naloxone). A total of 24,097 patients were treated with IN medications across all the studies. There were five moderate quality, four low quality, and thirty very low quality studies. The potential efficacy of IN fentanyl and ketamine was demonstrated consistently throughout the studies with less clear evidence for midazolam, morphine, glucagon, and naloxone. This review was severely limited by the study quality, with most studies demonstrating "high concerns" for bias.

CONCLUSIONS

Prehospital IN medication administration has wide-ranging potential, particularly for administering analgesia. There are likely to be certain populations, for example, pediatrics, that will benefit the most, although conclusions are limited by the quality of evidence currently available. We encourage additional research in this area, particularly with robust prospective double-blind RCTs.

Analgesia in adult trauma patients in physician-staffed Austrian helicopter rescue: a 12-year registry analysis

Background

Sufficient analgesia is an obligation, but oligoanalgesia (NRS> 3) is frequently observed prehospitally. Potent analgesics may cause severe adverse events. Thus, analgesia in the helicopter emergency medical service (HEMS) setting is challenging. Adequacy, efficacy and administration safety of potent analgesics pertaining to injured patients in HEMS were analysed.

Methods

Observational study evaluating data from 14 year-round physician-staffed helicopter bases in Austria in a 12-year timeframe.

Results

Overall, 47,985 (34.3%) patients received analgesics, 26,059 of whom were adult patients, injured and not mechanically ventilated on site. Main drugs administered were opioids (n=20,051; 76.9%), esketamine (n=9082; 34.9%), metamizole (n=798; 3.1%) and NSAIDs (n=483; 1.9%). Monotherapy with opioids or esketamine was the most common regimen (n=21,743; 83.4%), while opioids together with esketamine (n= 3591; 13.8%) or metamizole (n=369; 1.4%) were the most common combinations. Females received opioids less frequently than did males (n=6038; 74.5% vs. n=14,013; 78.1%; p< 0.001). Pain relief was often sufficient (> 95%), but females more often had moderate to severe pain on arrival in hospital (n=34; 5.0% vs. n=59; 3.2%; p=0.043). Administration of potent analgesics was safe, as indicated by MEES, SpO₂ and respiratory rates. On 10% of all missions, clinical patient assessment was deemed sufficient by HEMS physicians and monitoring was spared.

Conclusions

Opioids and esketamine alone or in combination were the analgesics of choice in physician-staffed HEMS in Austria. Analgesia was often sufficient, but females more than males suffered from oligoanalgesia on hospital arrival. Administration safety was high, justifying liberal use of potent analgesics in physician-staffed HEMS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13049-021-00839-9.

Evaluation of pain management in medical transfer of trauma patients by air

OBJECTIVES

With regionalized trauma care, medical transport times can be prolonged, requiring paramedics to manage patient care and symptoms. Our objective was to evaluate pain management during air transport of trauma patients.

METHODS

We conducted a 12-month review of electronic paramedic records from a provincial critical care transport agency. Patients were included if they were ≥18 years old and underwent air transport to a trauma centre, and excluded if they were Glasgow Coma Scale score <14, intubated, or accompanied by a physician or nurse. Demographics, injury description, and transportation parameters were recorded. Outcomes included pain assessment via 11-point numerical rating scale, patterns of analgesia administration, and analgesia-related adverse events. Results were reported as mean ± standard deviation, [range], (percentage).

RESULTS

We included 372 patients: 47.0 years old; 262 males; 361 blunt injuries. Transport duration was 82.4 ± 46.3 minutes. In 232 (62.4%) patients who received analgesia, baseline numerical rating scale was 5.9 ± 2.5. Fentanyl was most commonly administered at 44.3 [25-60] mcg. Numerical rating scale after first analgesia dose decreased by 1.1 [-2-7]. Thereafter, 171 (73.7%) patients received 2.4 [1-18] additional doses. While 44 (23.4%) patients had no change in numerical rating scale after first analgesia dose, subsequent doses resulted in no change in numerical rating scale in over 65% of patients. There were 43 adverse events recorded, with nausea the most commonly reported (39.5%).

CONCLUSIONS

Initial and subsequent dose(s) of analgesic had minimal effect on pain as assessed via numerical rating scale, likely due in part to inadequate dosing. Future research is required to determine and address the barriers to proper analgesia.

Prehospital Use of Ketamine in Mountain Rescue: A Survey of Emergency Physicians of a Single-Center Alpine Helicopter-Based Emergency Service

INTRODUCTION

Although ketamine use in emergency medicine is widespread, studies investigating prehospital use are scarce. Our goal was to assess the self-reported modalities of ketamine use, knowledge of contraindications, and occurrence of adverse events associated with its use by physicians through a prospective online survey.

METHODS

The survey was administered to physicians working for Air-Glaciers, a Swiss alpine helicopter-based emergency service, and was available between September 24 and November 23, 2018. We enrolled 39 participants (participation rate of 87%) in our study and collected data regarding their characteristics, methods of ketamine use, knowledge of contraindications, and encountered side effects linked to the administration of ketamine. We also included a clinical scenario to investigate an analgesic strategy.

RESULTS

Ketamine was considered safe and judged irreplaceable by most physicians. The main reason for ketamine use was acute analgesia during painful procedures, such as manipulation of femur fractures. The doses of ketamine administered with or without fentanyl ranged from 0.2 to 0.7 mg·kg^-1 intravenously. Most physicians reported using fentanyl and midazolam along with ketamine. The median dose of midazolam was 2 (interquartile range 1-2) mg for a 70-kg adult. Monitoring and oxygen administration were used infrequently. Hallucinations were the most common adverse events. Knowledge of ketamine contraindications was poor.

CONCLUSIONS

Ketamine use was reported by mountain rescue physicians to be safe and useful for acute analgesia. Most physicians use fentanyl and midazolam along with ketamine. Adverse neuropsychiatric events were rare. Knowledge regarding contraindications to the administration of ketamine should be improved.

Oligoanalgesia in Patients With an Initial Glasgow Coma Scale Score ≥8 in a Physician-Staffed Helicopter Emergency Medical Service: A Multicentric Secondary Data Analysis of >100,000 Out-of-Hospital Emergency Missions

BACKGROUND

Oligoanalgesia, as well as adverse events related to the initiated pain therapy, is prevalent in out-of-hospital emergency medicine, even when a physician is present. We sought to identify factors involved in insufficient pain therapy of patients presenting with an initial Glasgow Coma Scale (GCS) score of ≥8 in the out-of-hospital phase, when therapy is provided by a physician-staffed helicopter emergency medical service (p-HEMS).

METHODS

This was a multicenter, secondary data analysis of conscious patients treated in primary p-HEMS missions between January 1, 2005, and December 31, 2017. Patients with a numeric rating scale (NRS) pain score ≥4, GCS score ≥8 on the scene, without cardiopulmonary resuscitation (CPR), and a National Advisory Committee for Aeronautics (NACA) score <VI were included. Multivariable logistic binary regression analyses were used to identify characteristics of oligoanalgesia (NRS ≥4 at handover or pain reduction <3). Linear regression analysis was used to identify changes in pain treatment within the study period.

RESULTS

We analyzed data from 106,730 patients (3.6% missing data at variable level). Of these patients, 82.9% received some type of analgesic therapy on scene; 79.1% of all patients received analgesic drugs, and 38.6% received nonpharmacological interventions, while 37.4% received both types of intervention. Oligoanalgesia was identified in 18.4% (95% confidence interval [CI], 18.1-18.6) of patients. Factors associated with oligoanalgesia were a low NACA score and a low NRS score, as well as central nervous system or gynecological/obstetric complaints. The use of weak opioids (odds ratio [OR] = 1.05; 95% CI, 0.68-1.57) had no clinically relevant association with oligoanalgesia, in contrast to the use of strong or moderate opioids, nonopioid analgesics, or ketamine. We observed changes in the analgesic drugs used over the 12-year study period, particularly in the use of strong opioids (fentanyl or sufentanil), from 30.3% to 42.3% (P value <.001). Of all patients, 17.1% (95% CI, 16.9-17.3) did not receive any type of pain therapy.

CONCLUSIONS

In the studied p-HEMS cohort, oligoanalgesia was present in 18.4% of all cases. Special presenting complaints, low NACA scores, and low pain scores were associated with the occurrence of oligoanalgesia. However, 17.1% of patients received no type of pain therapy, which suggests a scope for further improvement in prehospital pain therapy. Pharmacological and nonpharmaceutical pain relief should be initiated whenever indicated.

Prehospital intravenous fentanyl administered by ambulance personnel: a cluster-randomised comparison of two treatment protocols

Background

Prehospital acute pain is a frequent symptom that is often inadequately managed. The concerns of opioid induced side effects are well-founded. To ensure patient safety, ambulance personnel are therefore provided with treatment protocols with dosing restrictions, however, with the concomitant risk of insufficient pain treatment of the patients. The aim of this study was to investigate the impact of a liberal intravenous fentanyl treatment protocol on efficacy and safety measures.

Methods

A two-armed, cluster-randomised trial was conducted in the Central Denmark Region over a 1-year period. Ambulance stations (stratified according to size) were randomised to follow either a liberal treatment protocol (3 μg/kg) or a standard treatment protocol (2 μg/kg). The primary outcome was the proportion of patients with sufficient pan relief (numeric rating scale (NRS, 0–10) < 3) at hospital arrival. Secondary outcomes included abnormal vital parameters as proxy measures of safety. A multi-level mixed effect logistic regression model was applied.

Results

In total, 5278 patients were included. Ambulance personnel following the liberal protocol administered higher doses of fentanyl [117.7 μg (95% CI 116.7–118.6)] than ambulance personnel following the standard protocol [111.5 μg (95% CI 110.7–112.4), P = 0.0001]. The number of patient with sufficient pain relief at hospital arrival was higher in the liberal treatment group than the standard treatment group [44.0% (95% CI 41.8–46.1) vs. 37.4% (95% CI 35.2–39.6), adjusted odds ratio 1.47 (95% CI 1.17–1.84)]. The relative decrease in NRS scores during transport was less evident [adjusted odds ratio 1.18 (95% CI 0.95–1.48)]. The occurrences of abnormal vital parameters were similar in both groups.

Conclusions

Liberalising an intravenous fentanyl treatment protocol applied by ambulance personnel slightly increased the number of patients with sufficient pain relief at hospital arrival without compromising patient safety. Future efforts of training ambulance personnel are needed to further improve protocol adherence and quality of treatment.

Trial registration

ClinicalTrials.gov (NCT02914678). Date of registration: 26th September, 2016.

Differences in pain treatment between surgeons and anaesthesiologists in a physician staffed prehospital emergency medical service: a retrospective cohort analysis

Background

Although pain treatment is an important objective in prehospital emergency medicine the incidence of oligoanalgesia is still high in prehospital patients. Given that prehospital emergency medicine in Germany is open for physicians of any speciality, the prehospital pain treatment may differ depending on the primary medical education. Aim of this study was to explore the difference in pain treatment between surgeons and anaesthesiologists in a physician staffed emergency medical service.

Methods

Retrospective single centre cohort analysis in a physician staffed ground based emergency medical service from January 2014 until December 2016. A total of 8882 consecutive emergency missions were screened. Primary outcome measure was the difference in application frequency of prehospital analgesics by anaesthesiologist or surgeon. Univariate and multivariate logistic regression analysis was used for statistical analysis including subgroup analysis for trauma and acute coronary syndrome.

Results

A total of 8238 patients were included in the analysis. There was a significant difference in the application frequency of analgesics between surgeons and anaesthesiologists especially for opioids (p < 0.001, OR 0.68 [0.56–0.82]). Fentanyl was the most common administered analgesic in the trauma subgroup, but significantly less common used by surgeons (p = 0.005, OR 0.63 [0.46–0.87]). In acute coronary syndrome cases there was no significant difference in morphine administration between anaesthesiologists and surgeons (p = 0.49, OR 0.88 [0.61–1.27]).

Conclusions

Increased training for prehospital pain treatment should be implemented, since opioids were administered notably less frequent by surgeons than by anaesthesiologists.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0683-0) contains supplementary material, which is available to authorized users.

État des lieux de la prise en charge de la douleur

Le concept d’oligoanalgésie en structure d’urgences reste une réalité en France comme dans de nombreux pays qui publient sur le sujet. Les motifs de cette oligoanalgésie sont multiples, le plus souvent liés à des contraintes organisationnelles plus que médicales. Les solutions existent, et la douleur aiguë persistante ne doit plus être une fatalité en structure d’urgences. L’analyse des raisons de l’oligoanalgésie avec des audits ciblés et la mise en place de protocoles thérapeutiques locaux sont des prérequis à l’amélioration de la prise en charge. Les nouveaux enjeux de la médecine d’urgence, liés à l’augmentation constante de la sollicitation, mais également en lien avec l’évolution des techniques médicales et des compétences des équipes médicales et soignantes, donnent de nouvelles perspectives pour améliorer la qualité–sécurité de la prise en charge de la douleur en structure d’urgences.

Prospective, Multicentre Trial of Methoxyflurane for Acute Trauma-Related Pain in Helicopter Emergency Medical Systems and Hostile Environments: METEORA Protocol

Introduction

The inhalational analgesic low-dose methoxyflurane has been widely used by Australian ambulance services since 1975 and is now approved in Europe for emergency relief of moderate-to-severe trauma-related pain in conscious adult patients. The use of methoxyflurane in hostile environments is of special interest given its portability, ease of use and rapid onset of action. This trial will investigate the efficacy, tolerability and practicality of use of inhaled methoxyflurane in patients with moderate-to-severe trauma-related pain rescued from hostile mountainous environments by the Helicopter Emergency Medical Service (HEMS) in Italy.

Methods

METEORA is a phase IIIb, prospective, single-arm, multicentre trial. Approximately 200 adult patients with a pain score of at least 4 on the numerical rating scale (NRS) due to limb trauma rescued by HEMS will be enrolled. Patients will receive up to 2 × 3 mL methoxyflurane, self-administered by the patient by inhalation under medical supervision. Rescue medication will be permitted if required.

Planned Outcomes

Pain intensity will be measured using a 100-mm visual analogue scale (VAS) at baseline, at 5, 10, 15, 20, 30, 45 and 60 min after the start of methoxyflurane inhalation and when positioning the patient on a spinal board or stretcher; and also using the NRS at enrolment and at 10 min. Use of rescue medication (yes/no) will be recorded. The patient will rate efficacy and the healthcare professional will rate practicality of methoxyflurane treatment at 30 and 60 min using a 5-point Likert scale. Vital signs will be measured at baseline, 10, 30 and 60 min. Assessments after 30 min will only be performed for patients using a second inhaler. Adverse events will be recorded until safety follow-up at 3 ± 1 days. The primary endpoint is the percentage of patients achieving at least 30% improvement from baseline in VAS pain intensity within the first 10 min of methoxyflurane administration.

Trial Registration

EudraCT number: 2017-004601-40.

Funding

Mundipharma Pharmaceuticals, srl.

Plain Language Summary

Plain language summary available for this article.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0816-8) contains supplementary material, which is available to authorized users.

The treatment of pain is an essential part of the management of injured patients. In emergency rescue situations, rapid and effective pain relief can reduce the patient’s stress and discomfort, making it easier to assess, treat and extricate them. Currently available painkillers have limitations such as being slow to work (oral medications), requiring needles (intravenous medications) or prolonged monitoring and observation (e.g. opioids). An inhaled painkiller (methoxyflurane) is now available in Europe for emergency relief of moderate-to-severe pain in conscious adult patients with trauma (injury) and associated pain. Methoxyflurane is administered via a hand-held inhaler, which provides pain relief within 6–10 inhalations and lasts for 25–30 min, on average, when used continuously. The patient can control his/her own level of pain relief and a second inhaler may be used if required. Methoxyflurane has been widely used by Australian ambulance services since 1975 and its effectiveness and safety are well established. Considering its ease of use and rapid action, inhaled methoxyflurane may be useful in emergency situations in remote and hostile environments. A new trial (METEORA) will assess the use of methoxyflurane in 200 patients with limb injuries who are rescued from mountainous environments by the Helicopter Emergency Medical Service (HEMS) in Italy. Patients with moderate-to-severe pain will receive inhaled methoxyflurane under medical supervision. A second inhaler and/or additional pain-relieving medication will be provided if necessary. The trial will assess the reduction in pain intensity and whether additional pain-relieving medication is needed. The practicality of use of methoxyflurane in the emergency rescue situation and any side effects will also be evaluated.

Acute pain in the prehospital setting: a register-based study of 41.241 patients

BACKGROUND

Acute pain is a frequent symptom, but little is known about the frequency and causes of acute pain in the prehospital population. The objectives of this study were to investigate the frequency of moderate to severe pain among prehospital patients and the underlying causes according to primary hospital diagnose codes.

METHODS

This was a register-based study on 41.241 patients transported by ambulance. Information on moderate to severe pain [Numeric Rating Scale (NRS, 0-10) > 3 or moderate pain or higher on 4-point likert scale] was extracted from a national electronic prehospital patient record. Patient information was merged with primary hospital diagnose codes based on the 10th version of the International Classification of Diseases (ICD-10) to investigate underlying causes of pain.

RESULTS

11.430 patients (27.7%) reported moderate to severe pain during ambulance transport. As a measure of opioid demanding acute pain, 3.275 of 41.241 patients (7.9%) were treated with intravenous fentanyl. Underlying causes of pain were heterogenic according to ICD-10 chapters with injuries being the largest group of patients with moderate to severe pain (XIX: 42.8% of 8.041 patients), followed by non-specific diagnoses (XVIII: 28.5% of 7.101 patients and XXI: 31.6% of 5.148 patients), diseases of the circulatory system (IX: 22.1% of 4.812 patients) and other (20.3% of 16.139 miscellaneous patients).

DISCUSSION

Due to the high frequency of moderate to severe pain affecting a wide range of patients, more attention on acute pain is necessary. Whether ambulance personnel have sufficient options for treating various pain conditions might be a subject of future evaluation. Non-specific diagnoses accounted for surprisingly many patients with moderate to severe pain, of which many were treated with intravenous fentanyl. This may be substance of further investigation.

CONCLUSIONS

Moderate to severe pain is a highly frequent and probably underestimated symptom among patients transported by ambulance. Underlying causes of pain are heterogenic as described by primary hospital diagnose codes. More focus on the treatment of acute pain is needed.

Intravenous Low-Dose Ketamine Provides Greater Pain Control Compared to Fentanyl in a Civilian Prehospital Trauma System: A Propensity Matched Analysis

Objective: A few studies report comparable analgesic efficacy between low-dose ketamine and opioids such as morphine or fentanyl; however, limited research has explored the safety and effectiveness of intravenous low-dose ketamine as a primary analgesic in a civilian prehospital setting. The objective of this study is to compare pain control between low-dose ketamine and fentanyl when administered intravenously (IV) for the indication of severe pain. Methods: This was a retrospective, observational review of prehospital adult patients (≥18 years) who presented with severe pain (numeric rating scale, 7-10) and were treated solely with either low-dose ketamine IV or fentanyl IV between January 1, 2014 and December 31, 2016. Propensity matched analysis was performed adjusting for all baseline variables with p ≤ 0.10 and for baseline pain score to match ketamine and fentanyl patients on a one-to-one ratio. The primary outcome was change in pain score from baseline to after treatment and evaluated with a paired t-test. Secondary outcomes were changes in vital signs and Glasgow coma scale (GCS) from baseline to after treatment, as well as incidence of clinically significant adverse events (AEs); AEs were followed from scene arrival through emergency department discharge. Results: Propensity matched analysis produced 79 matched pairs. Ketamine IV patients, receiving a mean (SD) dose of 0.3 (0.1) mg/kg, showed a significantly larger mean decrease in pain after treatment, compared to the fentanyl IV patients (-5.5 (3.1) vs. -2.5 (2.4), p < 0.001). A significantly greater proportion of patients receiving ketamine IV achieved at least a 50% reduction in pain compared to those receiving fentanyl IV (67% vs. 19%, p < 0.001), marking 52 ketamine IV patients as responders to treatment. Vital signs demonstrated a nonsignificant decrease in blood pressure, respiratory rate, heart rate, and GCS. No clinically significant AEs were reported for patients receiving ketamine IV. Conclusion: The significant reduction in pain, significantly high proportion of ketamine responders, and the lack of clinically significant AEs characterizing patients receiving low-dose ketamine IV compared to fentanyl IV, all provide further support for its use as an effective prehospital analgesic. Level of Evidence: Level III, therapeutic.

An Effective Treatment in the Austere Environment? A Critical Appraisal into the Use of Intra-Articular Local Anesthetic to Facilitate Reduction in Acute Shoulder Dislocation

Acute shoulder dislocation is a common injury in the outdoor environment. The objective of this systematic review of the literature was to determine if intra-articular local anesthetic (IAL) is an effective treatment that could have prehospital application. A methodical search of MEDLINE, PubMed, and EMBASE databases targeted publications from January 1, 1990 until January 1, 2017. Eligible articles compared IAL with other analgesic techniques in patients 16 years or older experiencing acute glenohumeral dislocation. Reduction success, complications, and patient-reported outcome measures underwent comparison. All identified publications originated from the hospital setting. Procedural success rates ranged widely among randomized control trials comparing IAL with intravenous analgesia and sedation (IAL 48-100%, intravenous analgesia and sedation 44-100%). A pooled risk ratio [RR] favored intravenous analgesia and sedation (RR 0.91, 95% confidence interval [CI] 0.84-0.98), but there was significant inconsistency within the analysis (I² = 75%). IAL provided lower complication rates (4/170, 2%) than intravenous analgesia and sedation (20/150, 13%) (RR 1.11, 95% CI 1.04-1.19, I² = 63%). One trial found a clinically relevant reduction in visual analogue pain scores when comparing IAL against no additional analgesia in the first minute (IAL 21±13 mm; control 49±15 mm; P<0.001) and fifth minute (IAL 10±10 mm; control 40±14 mm, P<0.001) after reduction. The results suggest that IAL is an effective intervention for acute anterior shoulder dislocation that would have a place in the repertoire of the remote physician. Further research might be beneficial in determining the outcomes of performing IAL in the prehospital setting.

A retrospective study of ketamine administration and the development of acute or post-traumatic stress disorder in 274 war-wounded soldiers

The objective of this study was to explore whether ketamine prevents or exacerbates acute or post-traumatic stress disorders in military trauma patients. We conducted a retrospective study of a database from the French Military Health Service, including all soldiers surviving a war injury in Afghanistan (2010-2012). The diagnosis of post-traumatic stress disorder was made by a psychiatrist and patients were analysed according to the presence or absence of this condition. Analysis included the following covariables: age; sex; acute stress disorder; blast injury; associated fatality; brain injury; traumatic amputation; Glasgow coma scale; injury severity score; administered drugs; number of surgical procedures; physical, neurosensory or aesthetic sequelae; and the development chronic pain. Covariables related to post-traumatic and acute stress disorders with a p ≤ 0.10 were included in a multivariable logistic regression model. The data from 450 soldiers were identified; 399 survived, of which 274 were analysed. Among these, 98 (36%) suffered from post-traumatic stress disorder and 89 (32%) had received ketamine. Fifty-four patients (55%) in the post-traumatic stress disorder group received ketamine vs. 35 (20%) in the no PTSD group (p < 0.001). The 89 injured soldiers who received ketamine had a median (IQR [range]) injury severity score of 5 (3-13 [1-26]) vs. 3 (2-4 [1-6] in the 185 patients who did not (p < 0.001). At multivariable analysis, only acute stress disorder and total number of surgical procedures were independently associated with the development of post-traumatic stress disorder. In this retrospective study, ketamine administration was not a risk factor for the development of post-traumatic stress disorder in the military trauma setting.