Hypoxemia in the First 24 Hours After Trauma - an Observational Study
Conditions: Trauma, Trauma Injury, Hypoxemia, Hypoxia, Oxygen Deficiency
Sponsor: Rigshospitalet, Denmark

Hypoxemia in the first 24 hours after trauma – an observational study 
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Protocol 
 
Hypoxemia in the first 24 hours after trauma – 
an observational study 
 
Version 1.3 
 
 
 
 
 
 
 
 
Date: 11/04/2024 
Clinical.Trials.gov Identifier: NCT06256692 
Research Ethics Committee journal number: H-23065206 
Privacy approval number: P-2023-15008 
 

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Table of Content 
General Information .......................................................................................................................................... 3 
Abbreviation ..................................................................................................................................................... 5 
1. 
Introduction ............................................................................................................................................... 6 
1.1 
Background and rationale ............................................................................................................. 6 
1.2 
Study objectives and hypothesis ................................................................................................... 6 
1.3 
Study design .................................................................................................................................. 7 
2. 
Methods .................................................................................................................................................... 7 
2.1 
Study setting ................................................................................................................................. 7 
2.2 
Participants ................................................................................................................................... 7 
2.3 
Inclusion criteria ............................................................................................................................ 7 
2.4 
Exclusion criteria ........................................................................................................................... 7 
2.5 
Outcomes ...................................................................................................................................... 8 
2.6 
Participant timeline ....................................................................................................................... 9 
2.7 
Sample size .................................................................................................................................... 9 
2.8 
Recruitment .................................................................................................................................. 9 
2.9 
Data collection methods ............................................................................................................... 9 
2.10 
Data management ...................................................................................................................... 10 
2.11 
Statistics ...................................................................................................................................... 11 
2.12 
Project timeline ........................................................................................................................... 11 
3. 
Ethics and dissemination ........................................................................................................................ 11 
3.1 
Risks and adverse events ............................................................................................................ 11 
3.2 
Study ethics ................................................................................................................................. 11 
3.3 
Consent ....................................................................................................................................... 12 
3.4 
Confidentiality ............................................................................................................................. 13 
3.5 
Assurance .................................................................................................................................... 13 
3.6 
Economy ..................................................................................................................................... 13 
3.7 
Declaration of Conflict interests ................................................................................................. 14 
3.8 
Access to data ............................................................................................................................. 14 
3.9 
Dissemination ............................................................................................................................. 14 
5. 
References ............................................................................................................................................... 15 
 

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General Information 
Protocol Title:  
Hypoxemia in the first 24 hours after trauma – an observational study 
Protocol date: 
27/12/2023 
Version number: 
1.3 
Economy: 
The project is initiated by Jacob Steinmetz from Department of 
Anaesthesia, Centre of Head and Orthopaedics, 6011 Rigshospitalet, and   
supported with funds from the Novo Nordisk Foundation and 
Lægeforeningens Forskningsfond.  
Study information:  
The study will be carried out in accordance with the protocol and the 
applicable laws in the field. 
Investigators: 
Jacob Jensen-Abbew, BSc 
Primary investigator 
Department of Anaesthesia, Centre of Head and Orthopaedics, 6011 
Rigshospitalet, 
University of Copenhagen, Copenhagen, Denmark 
E-mail: jacob.jensen-abbew.01@regionh.dk 
Phone: +45 35 45 10 53 
Carl Johan Queitsch, BSc 
Investigator 
Department of Anaesthesia, Centre of Head and Orthopaedics, 
6011Rigshospitalet, 
University of Copenhagen, Copenhagen, Denmark 
E-mail: carl.johan.queitsch.01@regionh.dk  
Oscar Rosenkrantz, MD 
Investigator 
Department of Anaesthesia, Centre of Head and Orthopaedics, 6011 
Rigshospitalet, 
University of Copenhagen, Copenhagen, Denmark 
E-mail: oscar.oelrich.rosenkrantz@regionh.dk 
Jacob Steinmetz, MD, Ph.D., professor 
 Primary responsible investigator and initiator 
Department of Anaesthesia, Centre of Head and Orthopaedics, 6011 
Rigshospitalet, 
University of Copenhagen, Copenhagen, Denmark 
Danish Air Ambulance 
Inge Lehmanns Vej 6, opgang 6, 1. sal 
E-mail: Jacob.steinmetz@regionh.dk 
Phone: +45 35 45 84 34 

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Study sites: 
Rigshospitalet 
Department of Anaesthesia, Centre of Head and Orthopaedics, 
Rigshospitalet, 
E-mail: anop-hoc.rigshospitalet@regionh.dk 
Phone: +45 35 45 34 74 
 
 
 

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Abbreviation 
 
 
COPD  
Chronic obstructive pulmonary disease 
SpO2 
Arterial oxygen saturation measured by pulse oximetry 
ICU 
Intensive care unit 
LOS 
Length of Stay 
 
 

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1. Introduction 
1.1 Background and rationale 
Trauma is one of the leading causes of death and disability on a global scale.1 Advanced Trauma 
Life Support guidelines state serious concern with the appearance of hypoxemia after trauma, and 
consequently recommend that supplemental oxygen should be provided for all severely injured 
trauma patients to avoid hypoxemia in the initial phase.2 Oxygen is a vital part of human physiology 
and must be delivered to all metabolically active cells in the body.3 When patients receive 
supplemental oxygen, a series of autoregulatory mechanisms happen to ensure optimal oxygen 
levels and prevent hypoxemia and hyperoxemia4 which can have different harmful effects.5 The 
lack of oxygen resulting in hypoxemia can potentially be a reversible cause of poor outcomes and in 
worst case death, hence supplemental oxygen is recommended for trauma patients, although the 
evidence is sparse.6  
In other high-risk patient groups, such as surgical and chronic obstructive pulmonary disease 
(COPD) patients, Loft et al. monitored arterial oxygen saturation (SpO2) continuously and found 
that cumulative duration of desaturations with SpO2 < 85% was significantly associated with 
myocardial injury after both surgery and exacerbation of COPD.7 In stroke patients, Rowat et al. 
found a higher mortality in patients that experienced hypoxemia, but after adjusting for National 
Institute of Health Stroke Scale and age, this association was not significant. In the study, 
hypoxemia was found at all stages during admission.8 Using continuous monitoring for 48 hours 
Sun et al. found that hypoxemia was common and prolonged in patients recovering from noncardiac 
surgery. Furthermore, this study showed that 90% of hypoxemic episodes SpO2 < 90% for at least 
one hour went undetected by standard spot checks, which were typically conducted at intervals of 4-
6 hours.9   
Trauma patients can also be characterized as high-risk patients due to their high mortality.10 The 
incidence of prehospital hypoxemia in traumatic brain injury patients has been studied, Stassen et 
al. found a prevalence of 37.9%,11 and Chi et al. further discovered that prehospital hypoxemia was 
associated with higher mortality.12 Evidence about the incidence of hypoxemia in trauma patients 
after admission to a hospital is not well established. There is reason to suspect that trauma patients 
can experience episodes of hypoxemia after admission and that the incidence of hypoxemia may 
differ between day and night as shown in several other patient populations.13,14,15 Potential 
incidences of severe hypoxemia, from patients being admitted to a trauma centre to subsequent care 
in a ward, should be avoided, since severe hypoxemia is associated with harmful effects.7,8 
Hypoxemia can be detected and potentially corrected with more advanced measuring equipment.9 
It is relevant to conduct a study with the purpose of determining the occurrence and distribution 
over the first 24 hours after hospital admission of hypoxemia by continuous SpO2 monitoring in 
trauma patients, since this could potentially have important clinical implications and be useful in 
improving patient outcomes.  
1.2 Study objectives and hypothesis 
The aim of this study is to examine the occurrence and duration of episodes of hypoxemia in trauma 
patients in the first 24 hours after trauma and to compare their incidences during the day (08.00-
19.59) and night (20.00-07.59). 

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We hypothesize that hypoxemic episodes will be more frequent during the night than during the 
day. 
1.3 Study design 
This study is a prospective, observational study. The protocol is structured according to the 2013 
SPIRIT statement. 
2. Methods 
2.1 Study setting 
This study is a single centre study of trauma patients at Rigshospitalet, Denmark. Rigshospitalet 
holds the only major trauma centre in the eastern part of Denmark, and every year around 1000 
trauma patients are treated here.16 Patients are admitted from the Capital Region of Denmark with 
around 1.9 million inhabitants and the Region of Zealand with around 850.000 inhabitants.17 
In the prehospital phase, the initial assessment of trauma patients will often be conducted by a 
prehospital physician specialized in anesthesiology/critical emergency medicine in Denmark. If 
patients are to be admitted to the trauma centre at Rigshospitalet, they are usually required to fulfil 
criteria based on either mechanism of injury or anatomical criteria.18 A primary, secondary and 
tertiary triage system is used to optimize patient treatment and ensure continuous monitoring of the 
patient. The primary triage occurs at the scene of injury. It is intended to assess the patient, identify 
life-threatening injuries and initiate appropriate interventions in accordance with the ABCDE-
principals19. The secondary triage occurs at the trauma centre at a hospital, where there is more 
staffing and equipment available. Once at the trauma centre, a team consisting of a wide variety of 
medical professionals will meet the patient. Often in blunt trauma, patients will get an initial 
assessment and management followed by a full trauma CT scan depending on the severity and the 
nature of the patients’ injuries. Depending on the findings in the clinical assessment and scan the 
patient will be admitted for further treatment either at a general ward, where surveillance is less 
thorough, intensive care unit (ICU) or alternatively directly to the operating room as a part of the 
tertiary triage.2,18  
The patients in this study will be included in the trauma bay at Rigshospitalet.  
2.2 Participants 
All patients with trauma team activation in the trauma bay at Rigshospitalet, including both direct 
transport and secondary transfers, will be screened for potential inclusion in the study. Patients will 
be included if they comply with the following eligibility criteria: 
2.3 Inclusion criteria 
- 
Patients aged > 18 years 
- 
Blunt or penetrating mechanism of trauma 
- 
Trauma team activation 
- 
Admission to a ward/ICU from trauma centre  
2.4 Exclusion criteria 

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- 
Patients with a suspicion of carbon monoxide intoxication 
- 
No applicable finger or toe for sensor attachment 
- 
Trauma team activation was cancelled 
- 
No available pulse oximeter at admission  
The expected process of patient inclusion and data collection is demonstrated in figure 1.  
Figure 1: Flowchart describing patient inclusion and data collection process 
 
 
2.5 Outcomes 
Primary outcome 
- 
The occurrence and daily distribution of clinically relevant hypoxemic episodes defined as 
SpO2 < 90% for > 5 minutes, within the first 24 hours after trauma 
Secondary outcomes 
- 
The occurrence of clinically relevant hypoxemic episodes SpO2  < 90% > 5 minutes in 
different departments including trauma centre, ICU, general ward, operating theatre and 
recovery room. 
- 
The occurrence of prolonged hypoxemic episodes SpO2 < 90% for > 30 minutes per episode 
- 
Cumulated time of hypoxaemia SpO2 < 90% 

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2.6 Participant timeline 
 
2.7 Sample size 
We estimate that 5% of patients during the day and 20% of patients during the night will experience 
hypoxemia defined as SpO2 < 90% for > 5 minutes. A sample size calculation with an alpha of 5% 
and a power of 80% estimates a need of 150 study participants. Based on previous experience with 
continuous pulse oximetry it is expected that 10% will be excluded due to unsuccessful data 
collection. Therefore, the aim is to include 165 patients. 
2.8 Recruitment 
The trauma bay at Rigshospitalet will be equipped with the oximetry equipment, and measurement 
can be started as early as possible. At the trauma bay, a doctor will conduct the screening and 
inclusion of patients to the study at their arrival. After study inclusion, monitoring equipment will 
be attached by a nurse in the trauma bay. Subsequently a member of the study investigator group 
will obtain consent. 
2.9 Data collection methods 
Continuous pulse oximetry will be used to measure SpO2. SpO2, heart rate, pulse amplitude and 
alarm status will be measured every second during a 24-hour period on all study participants.  
The Nellcor™ Portable SpO2 Patient Monitoring System, PM10N (Medtronic, 15 Hampshire Street, 
Mansfield, MA 02048, USA) is used as monitoring device. The Covidien Nellcor FLEXMAX or a 
similar probe will be placed on the patients’ index finger, alternatively another finger or toe. If there 
are no available extremities the patient will be excluded from the study. 
If a patient has a peripheral venous catheter or a blood pressure cuff, the probe is placed on the 
other arm. The probe cable will be fastened with adhesive band across the back of the patient’s 
hand, as an attempt to prevent untimely probe removal. The monitoring device will be placed in a 
telemetry bag with a soft fabric string which can be placed in the bed or around the patient’s neck if 
awake. The data will be transferred and stored locally on a secure drive.  
Since the study is observational, and we would like to identify episodes of hypoxemia that would go 
undetected under standard care, the alarm system on our monitoring device will be set restrictive.  
Alarm if SpO2 < 80% or the heart rate is < 40 beats per minute or > 140 beats pr. minute. 

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Data collection will continue for up to 24 hours. If there is an untimely removal of the probe, the 
device will switch of, and data collection will stop at this point, unless the device is turned on again. 
After 24 hours of measurement, an investigator will collect the device and transfer the data by USB 
cable to a computer for secure storage and further analysis. 
. 
The following data will be obtained by accessing the study participants’ medical records. 
• Patient characteristics including name, unique patient identifier (civil registration number 
“CPR nummer”), age, sex, height and weight 
• Pre-hospital circumstances including vital signs, Glasgow Coma Score (GCS), mechanism 
of injury, variables regarding airway management and oxygen treatment, use of sedatives 
and opioids, transportation mode to the trauma centre 
• Vital signs at trauma centre arrival 
• Clinical parameters during admission including vital signs, variables regarding airway 
management and oxygen treatment and use of sedatives and opioids 
• Time points including date and time of trauma, trauma centre/ICU/ward/operating 
theatre/recovery room arrival and departure, time and duration of anaesthesia and surgery 
within first 24 hours 
• Injury severity score (ISS) and abbreviated injury scale (AIS) scores 
• Co-morbidities prior to trauma: Categorised in heart disease, lung disease and other 
diseases 
• Hospital and ICU LOS 
• Ischaemic events (myocardial infarction or cerebral ischemia) 
• Specifics of possible brain injury (type and extent) and other cerebral complications 
• 30-day mortality 
• Active smoker (yes/no) 
Patient data will be used to describe the population of study participants. This is of great 
importance, to make the results transferable to the relevant trauma patients. 
Time points will be used to specify study participants’ location at times of desaturation.  
 
2.10 
Data management 
Personal data will be processed in the study, and we comply with both the Data Protection Act and 
the Data Protection Ordinance. 
The Nellcor PM10N pulse oximeter will hold patient data for the observation time only. Following 
data transfer to a secure drive, all data will be cleared from the devices.  
In the computer monitoring data will be stored as csv-files on a secure drive.  
Patient data collected from the medical records are stored and managed using Research Electronic 
Data Capture (REDCap) an electronic data capture tool hosted at Rigshospitalet. This is a secure, 
web-based software platform designed to support data capture for research studies.20 
 

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2.11 
Statistics 
To account for artefacts during the measurement period the method described by Haahr-Raunkjaer 
et al. is used. It is stated that artefacts are defined as SpO2 values after a change in SpO2 of more 
than 4% per second.21 
Data with assumptions of normal distribution will be described with means and standard deviations, 
categorical data will be reported with numbers and percentages. 
Data with assumption of being non-normally distributed will be reported with medians with 
interquartile ranges. 
The student’s t-test will be used for parametric data to compare the two study groups. 
The Mann-Whitney-U-test will be used for non-parametric data to compare the two groups (day vs 
night). 
A Kruskal-Wallis test will be used for non-parametric data when comparing the different hospital 
departments. 
The modified Wald method will be used to determine the 95% confidence intervals. 
A p-value of <0.05 will be considered statistically significant. 
2.12 
Project timeline 
 
Pre-study 
Month 1-6 
Month 7 
Month 8 
Preparation of 
protocol 
x 
 
 
 
Ethical 
approval 
x 
 
 
 
Protocol 
registration 
x 
 
 
 
Data collection 
 
x 
 
 
Data analysis 
 
x 
 
 
Manuscript 
writing 
 
 
x 
 
Publication 
 
 
 
x 
 
3. Ethics and dissemination 
3.1 Risks and adverse events 
The study is observational, without an intervention and non-invasive. Hence, we do not believe, that 
study participants will be exposed to any relevant risks of neither complications nor adverse events 
in relation to participating in the study. 
3.2 Study ethics 

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As the nature of the study is exclusively observational, without an intervention, non-invasive and is 
conducted on humans, it is required to obtain approval at the Regional Research Ethics Committee 
in the Capital Region and the Capital region of Denmark data controllers register. 
As described earlier we do not believe that study participants will be exposed to any additional risks 
of complications or adverse events. Hence the study is minimally demanding for participants. On 
the contrary, participation in the study will provide us with important knowledge in monitoring and 
treating trauma patients, improving the overall outcomes for future trauma patients. 
The restrictive setting of the alarm system on the pulse oximeter is necessary to capture an accurate 
representation of all episodes of hypoxemia that might otherwise go undetected with standard care 
that does not measure continuously. The restrictive alarm setting on the pulse oximeter does not 
impact the standard measuring equipment used in patient care.  
3.3 Consent 
To make studies with the goal of improving the monitoring and treatment of traumatic injuries, it is 
necessary to include unconscious and incompetent study participants, as no clinically relevant 
animal model exists. 
Hence, we consider all trauma patients to be without ability to consent to participation. 
 
The study participants eligible for this study are considered incompetent and unable to consent 
because of their acute and potentially life-threatening injuries. 
Patients will be eligible at the trauma bay of Rigshospitalet, and it is important to include 
participants as early after admission as possible. Hence, there is a need to use the emergency 
research consent procedures.  
 
In accordance with §11 and §19 in the Scientific Ethical Committees Act (LBK nr. 1338 from 
September 1., 2020), the act can allow acute studies without prior consent if some criteria are met. 
Subsequently, the investigators must seek informed consent from study participants or proxy 
consent.22 
 
Consent will be sought from the study participant´s next of kin and a designated independent 
clinician as soon as practically possible, and when/if possible, from the study participant 
themselves. If the study participant is not able to consent or dies within 30 days, consent from the 
next of kin and the designated independent clinician will be accepted as the final consent. If it is not 
possible to identify or contact any next of kin after multiple repeated attempts, consent from the 
designated independent clinician will stand alone. An agreement to act as independent clinician will 
be made with an impartial doctor in Rigshospitalet. The independent clinician will have access to 
the study protocol and the written study participant information.  
 
The consent process is described in more detail below. Investigators will seek informed consent 
from a designated independent clinician and the study participant’s next of kin in an undisturbed 
environment as soon as possible after admission. Information regarding the study will be relayed in 
both a verbal and written manner in undisturbed circumstances. Before continuing the conversation, 
the next of kin will be made aware of their right to have an advocate/supporter by their side. If this 

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requires extra time, the necessary time will be given. Study participants’ next of kin are being 
informed about their right to have a 24-hour consideration period between being informed about the 
study and giving their consent. 
During the study participant´s hospital stay, there will be an ongoing evaluation by study 
investigators on whether the participant becomes capable of consenting themselves. When/if this is 
the case, consent will be sought as soon as possible. Information regarding this study will be relayed 
in both a verbal and written manner in undisturbed circumstances. 
The study participant will be made aware of their right to have an advocate/supporter by their side, 
before continuing the conversation. If this requires extra time, the necessary time will be given. 
Study participants are informed about their right to have a 24-hour consideration period between 
being informed about the study and giving consent. 
Inclusion of the patient in the study will remain until a decision about consent has been reached by 
either the patient themselves or the next of kin and designated independent clinician . 
Written and verbal study information will be given by trained personnel from the research team. 
The same research team members will obtain informed consent forms. 
It will be made clear in both written and verbal manner that participation is voluntary and can be 
withdrawn at any time without affecting the current or future treatment of the study participant. 
It will also be made clear that the informed/proxy consent contains permission for the personnel 
involved in the study to gather information from the study participant’s medical record. 
According to the standard informed consent form from the National Ethics Committee regarding 
competent participants, the participant can choose to be informed about secondary findings due to 
their treatment at the hospital. However, the purpose of this study is not to generate new knowledge 
about a specific participant, so we find that this question is redundant, and have omitted the 
question from the consent form to spare the participant from making unnecessary decisions. 
3.4 Confidentiality 
All health care professionals are subject to confidentiality regarding patient information. Danish 
Safety Patient Authority ensures this right on behalf of patients and study participants. Patient 
specific data is relied on the medical record system. REDCap will hold relevant study participant 
data as stated above in the protocol. All relevant documentation regarding investigators can be 
found in the study master file. 
3.5 Assurance 
Study participants will be covered by the Danish Patient Compensation (Patienterstatningen). 
3.6 Economy 
The project has been initiated by Jacob Steinmetz from Department of Anaesthesia, Centre of Head 
and Orthopaedics 6011, Rigshospitalet.  
The project received 120.000 DKK in funding from Lægeforeningens Forskningsfond, which 
covers most of the salary for a research year student. Additionally, 26.730 DKK from The Novo 
Nordisk Foundation covering the remainder of the salary of a research year student and the 
purchase of project equipment. The funding has been allocated to a research account within the 

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Department of Anaesthesia, Centre of Head and Orthopaedics 6011, Rigshospitalet. 
There are no conflicts of interests. 
3.7 Declaration of conflict of interests 
None 
3.8 Access to data 
All project investigators will have access to data regarding study participants. 
3.9 Protocol amendment on April 11th 2024 
Since February 20th 2024 the project only included patients on weekdays, but later in April, patients 
will be included 24/7 seven days a week. The clinical relevance of hypoxaemia in trauma patients is 
relevant for ALL trauma patients, regardless of timing of the admission. As the primary outcome is 
assessment of hypoxaemia in daylight hours versus night time all types of trauma patients are 
relevant to assess, and we assume that patient groups will be comparable without considerable bias 
between those two periods (weekdays/weekend). However, we will perform an analysis of whether 
included patients are comparable in day vs. night time in demographic data, e.g. age, sex, trauma 
mechanism and more.  
 
3.10 
Dissemination 
A protocol registration at ClinicalTrials.gov will be made after protocol approval. 
When informed consent is given, participants can indicate whether they want the study results after 
the study has been finished. In that case, they will have a summary of the overall the results sent to 
them after the study has concluded. 
The results of this study will be relayed at www.clinicaltrials.gov. Additionally, they will be  
published in a relevant peer-reviewed journal and/or presented at an international conference 
irrespective of whether the results are positive, negative, or inconclusive. 
 
 

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5. References 
 
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of small non-mammals in traumatic brain injury research: A systematic review. CNS Neurosci 
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2. American college of Surgeons. Committee on Trauma. Advanced Trauma Life Support : Student 
Course Manual. 9. ed. Chicago, IL : American College of Surgeons; 2012. 
3. Rhodes CE, Denault D, Varacallo M. Physiology, Oxygen Transport. In: StatPearls. StatPearls 
Publishing; 2023. Accessed September 18, 2023. 
http://www.ncbi.nlm.nih.gov/books/NBK538336/ 
4. López-Barneo J, Ortega-Sáenz P, González-Rodríguez P, et al. Oxygen-sensing by arterial 
chemoreceptors: Mechanisms and medical translation. Mol Aspects Med. 2016;47-48:90-108. 
doi:10.1016/j.mam.2015.12.002 
5. Singer M, Young PJ, Laffey JG, et al. Dangers of hyperoxia. Crit Care. 2021;25(1):440. 
doi:10.1186/s13054-021-03815-y 
6. Eskesen TG, Baekgaard JS, Steinmetz J, Rasmussen LS. Initial use of supplementary oxygen 
for trauma patients: a systematic review. BMJ Open. 2018;8(7):e020880. doi:10.1136/bmjopen-
2017-020880 
7. Loft FC, Rasmussen SM, Elvekjaer M, et al. Continuously monitored vital signs for detection of 
myocardial injury in high‐risk patients – An observational study. Acta Anaesthesiol Scand. 
2022;66(6):674-683. doi:10.1111/aas.14056 
8. Rowat AM, Dennis MS, Wardlaw JM. Hypoxaemia in Acute Stroke Is Frequent and Worsens 
Outcome. Cerebrovasc Dis. 2006;21(3):166-172. doi:10.1159/000090528 
9. Sun Z, Sessler DI, Dalton JE, et al. Postoperative Hypoxemia Is Common and Persistent: A 
Prospective Blinded Observational Study. Anesth Analg. 2015;121(3):709-715. 
doi:10.1213/ANE.0000000000000836 
10. Murdock DB. Trauma: When There’s No Time to Count. AORN J. 2008;87(2):322-328. 
doi:10.1016/j.aorn.2007.07.008 
11. Stassen W, Welzel T. The prevalence of hypotension and hypoxaemia in blunt traumatic brain 
injury in the prehospital setting of Johannesburg, South Africa: A retrospective chart review. S 
Afr Med J. 2014;104(6):424. doi:10.7196/SAMJ.7494 
12. Chi JH, Knudson MM, Vassar MJ, et al. Prehospital Hypoxia Affects Outcome in Patients With 
Traumatic Brain Injury: A Prospective Multicenter Study: J Trauma Inj Infect Crit Care. 
2006;61(5):1134-1141. doi:10.1097/01.ta.0000196644.64653.d8 
13. Ali K, Cheek E, Sills S, Crome P, Roffe C. Day–night Differences in Oxygen Saturation and 
the Frequency of Desaturations in the First 24 Hours in Patients With Acute Stroke. J Stroke 
Cerebrovasc Dis. 2007;16(6):239-244. doi:10.1016/j.jstrokecerebrovasdis.2007.07.004 

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Daytime Hypoxemia and Nocturnal Hypoxia in Obstructive Sleep Apnea Syndrome. Sleep. 
2008;31(2):249-255. doi:10.1093/sleep/31.2.249 
15. Galatius-Jensen S, Hansen J, Rasmussen V, Bildsoe J, Therboe M, Rosenberg J. Nocturnal 
hypoxaemia after myocardial infarction: association with nocturnal myocardial ischaemia and 
arrhythmias. Heart. 1994;72(1):23-30. doi:10.1136/hrt.72.1.23 
16. Tal og fakta. Accessed September 19, 2023. https://www.rigshospitalet.dk/afdelinger-og-
klinikker/hovedorto/traumecenter-og-akut-modtagelse/om-traumecentret/Sider/tal-og-fakta.aspx 
17. Statistikbanken. Accessed September 26, 2023. https://www.statbank.dk/FOLK1A 
18. Christian MD. Triage. Crit Care Clin. 2019;35(4):575-589. doi:10.1016/j.ccc.2019.06.009 
19. Field Triage Guidelines. ACS. Accessed September 19, 2023. https://www.facs.org/quality-
programs/trauma/systems/field-triage-guidelines/ 
20. Citations – REDCap. Accessed September 19, 2023. 
https://projectredcap.org/resources/citations/ 
21. Haahr-Raunkjaer C, Mølgaard J, Elvekjaer M, et al. Continuous monitoring of vital sign 
abnormalities; association to clinical complications in 500 postoperative patients. Acta 
Anaesthesiol Scand. 2022;66(5):552-562. doi:10.1111/aas.14048 
22. Indenrigs- og Sundhedsministeriet. Bekendtgørelse Af Lov Om Videnskabsetisk Behandling Af 
Sundhedsvidenskabelige Forskningsprojekter Og Sundhedsdatavidenskabelige 
Forskningsprojekter. Vol LBK nr 1338 af 01/09/2020.; 2020. Accessed September 19, 2023. 
https://www.retsinformation.dk/eli/lta/2020/1338