External validation of triage tools for adults with suspected COVID-19 in a middle-income setting: an observational cohort study.

BACKGROUND: Tools proposed to triage ED acuity in suspected COVID-19 were derived and validated in higher income settings during early waves of the pandemic. We estimated the accuracy of seven risk-stratification tools recommended to predict severe illness in the Western Cape, South Africa. METHODS: An observational cohort study using routinely collected data from EDs across the Western Cape, from 27 August 2020 to 11 March 2022, was conducted to assess the performance of the PRIEST (Pandemic Respiratory Infection Emergency System Triage) tool, NEWS2 (National Early Warning Score, version 2), TEWS (Triage Early Warning Score), the WHO algorithm, CRB-65, Quick COVID-19 Severity Index and PMEWS (Pandemic Medical Early Warning Score) in suspected COVID-19. The primary outcome was intubation or non-invasive ventilation, death or intensive care unit admission at 30 days. RESULTS: Of the 446 084 patients, 15 397 (3.45%, 95% CI 34% to 35.1%) experienced the primary outcome. Clinical decision-making for inpatient admission achieved a sensitivity of 0.77 (95% CI 0.76 to 0.78), specificity of 0.88 (95% CI 0.87 to 0.88) and the negative predictive value (NPV) of 0.99 (95% CI 0.99 to 0.99). NEWS2, PMEWS and PRIEST scores achieved good estimated discrimination (C-statistic 0.79 to 0.82) and identified patients at risk of adverse outcomes at recommended cut-offs with moderate sensitivity (>0.8) and specificity ranging from 0.41 to 0.64. Use of the tools at recommended thresholds would have more than doubled admissions, with only a 0.01% reduction in false negative triage. CONCLUSION: No risk score outperformed existing clinical decision-making in determining the need for inpatient admission based on prediction of the primary outcome in this setting. Use of the PRIEST score at a threshold of one point higher than the previously recommended best approximated existing clinical accuracy.

An initiative to reduce psychiatric boarding in a Cape Town emergency department.

Background: Psychiatric boarding in Emergency Departments (ED) is a global challenge which results in long ED length of stays (LOS) with significant consequences on patient care and staff safety. Aim: This study investigated the impact of an initiative to reduce psychiatric boarding on LOS and readmission rate, as well as explored the relationship between boarding times and LOS. Setting: This study was conducted at Mitchells Plain Hospital, a large district-level hospital in Cape Town. Methods: This cross-sectional study collected data for 24 months, which included a 9-month period prior to the initiative and 16 months thereafter. Data were collected retrospectively from official electronic patient registries. The initiative comprised of inpatient hallway boarding as a full-capacity protocol with the accompanying capacitation of psychiatric wards to accommodate the additional burden. Results: The initiative was associated with a decrease of 95% (p < 0.001) in boarding time, 13% (p < 0.001) in ward LOS and 25% (p < 0.001) in hospital LOS. Ward LOS were found to be independent of ED boarding times. The readmission rate increased from 12% to 18% post intervention. Conclusion: The initiative resulted in a sustainable improvement in boarding times and LOSs. The observational nature of this study precludes concrete conclusions and further investigations into psychiatric inpatient hallway boarding are recommended. Contribution: Inpatient hallway boarding could be a feasible option to reduce the risk. Psychiatric boarding times in the ED are independent of ward LOS, rendering it devoid from any value from a lean and economic perspective.

Rescue Activity of a Civilian Helicopter Emergency Medical Service in the Western Cape, South Africa: A 5-Year Retrospective Review.

INTRODUCTION: Helicopter search and rescue (SAR) in Africa is conducted primarily by military organizations. Since 2002, the Western Cape of South Africa has had a dedicated contracted civilian helicopter emergency medical service (HEMS) conducting air ambulance, terrestrial, and aquatic rescue. To our knowledge, this is the first description of the operations of an African helicopter rescue service. METHODS: A 5-y retrospective review of the terrestrial and aquatic helicopter rescue activity of a civilian-operated HEMS in the Western Cape, South Africa, from January 1, 2012 through December 31, 2016, was conducted. Data were extracted from the organization's operational database, aviation documents, rescue reports, and patient care records. Patient demographics and activity at the time of rescue, temporal and geographical distribution, crewing compositions, patient injury, triage, clinical interventions, and rescue techniques were analyzed. RESULTS: A total of 581 SAR missions were conducted, of which 451 were terrestrial and 130 were aquatic rescues. The highest volume of rescues was conducted within the urban Cape Peninsula. Hoisting using a rescue harness was the most common rescue technique used. A total of 644 patients were rescued, with no or minor injuries representing 79% of the sample. Trauma (33%, 196/644) was the most common medical reason for rescue, with lower limb trauma predominant (15%, 90/644). The most common clinical interventions performed were intravenous access (n=108, 24%), spinal immobilization (n=92, 21%), splinting (n=76, 17%), and analgesia administration (n=58, 13%). CONCLUSIONS: The rescue techniques utilized are similar to those described in high-income settings. Uninjured patients comprised the majority of the patients rescued.

Effectiveness and outcomes of air travel-related TB incident follow-up: a systematic review.

The World Health Organization (WHO) recommends following up passengers after possible exposure to a case of infectious tuberculosis (TB) during air travel. This is time-consuming and difficult, and increasingly so with higher numbers each year of flights and passengers to and from countries with high TB endemicity. This paper systematically reviews the literature on contact tracing investigations after a plane exposure to active pulmonary TB. Evidence for in-flight transmission was assessed by reviewing the positive results of contacts without prior risk factors for latent TB.A search of Medline, EMBASE, BIOSIS, Cochrane Library and Database of Systematic Reviews was carried out, with no restrictions on study design, index case characteristics, duration of flight or publication date.In total, 22 papers were included, with 469 index cases and 15 889 contacts. Only 26.4% of all contacts identified completed screening after exposure. The yield of either a single positive tuberculin skin test (TST) or a TST conversion attributable to in-flight transmission was between 0.19% (95% CI 0.13%-0.27%) and 0.74% (95% CI 0.61%-0.88%) of all contacts identified (0.00%, 95% CI 0.00%-0.00% and 0.13%, 95% CI 0.00%-0.61% in random effects meta-analysis). The main limitation of this study was heterogeneity of reporting.The evidence behind the criteria for initiating investigations is weak and it has been widely demonstrated that active screening of contacts is labour-intensive and unlikely to be effective. Based on our findings, formal comprehensive contact tracing may be of limited utility following a plane exposure.

Oh G: The x, y and z of human physiological responses to acceleration.

NEW FINDINGS: What is the topic of this review? This review focuses on the main physiological challenges associated with exposure to acceleration in the Gx, Gy and Gz directions and to microgravity. What advances does it highlight? Our current understanding of the physiology of these environments and latest strategies to protect against them are discussed in light of the limited knowledge we have in some of these areas. ABSTRACT: The desire to go higher, faster and further has taken us to environments where the accelerations placed on our bodies far exceed or are much lower than that attributable to Earth's gravity. While on the ground, racing drivers of the fastest cars are exposed to high degrees of lateral acceleration (Gy) during cornering. In the air, while within the confines of the lower reaches of Earth's atmosphere, fast jet pilots are routinely exposed to high levels of acceleration in the head-foot direction (Gz). During launch and re-entry of suborbital and orbital spacecraft, astronauts and spaceflight participants are exposed to high levels of chest-back acceleration (Gx), whereas once in space the effects of gravity are all but removed (termed microgravity, µG). Each of these environments has profound effects on the homeostatic mechanisms within the body and can have a serious impact, not only for those with underlying pathology but also for healthy individuals. This review provides an overview of the main challenges associated with these environments and our current understanding of the physiological and pathophysiological adaptations to them. Where relevant, protection strategies are discussed, with the implications of our future exposure to these environments also being considered.

SEeking AnsweRs for Care Homes during the COVID-19 pandemic (COVID SEARCH).

The care and support of older people residing in long-term care facilities during the COVID-19 pandemic has created new and unanticipated uncertainties for staff. In this short report, we present our analyses of the uncertainties of care home managers and staff expressed in a self-formed closed WhatsApp™ discussion group during the first stages of the pandemic in the UK. We categorised their wide-ranging questions to understand what information would address these uncertainties and provide support. We have been able to demonstrate that almost one-third of these uncertainties could have been tackled immediately through timely, responsive and unambiguous fact-based guidance. The other uncertainties require appraisal, synthesis and summary of existing evidence, commissioning or provision of a sector- informed research agenda for medium to long term. The questions represent wider internationally relevant care home pandemic-related uncertainties.

Prehospital care providers' understanding of responsibilities during a behavioural emergency.

BACKGROUND: Prehospital emergency care providers are frequently called to assist with the management of mental healthcare users (MHCUs). The Mental Health Care Act no. 17 of 2002 regulates mental healthcare in South Africa, but the act fails to consider the responsibilities of prehospital emergency care providers in the provision of mental healthcare. Rather South African Police Services were given authority over the well-being of a MHCU in the prehospital setting. AIM: To investigate prehospital emergency care providers' understanding of their responsibilities towards MHCUs and the community during the management of behavioural emergencies. SETTING: The research was carried out at prehospital emergency care providers from the three main levels of care, currently operational within the boundaries of Pretoria, South Africa. METHODS: A grounded theory qualitative study design was chosen using semi-structured focus groups for each level of prehospital emergency care - basic life support (BLS), intermediate life support (ILS) and advanced life support (ALS). Data from each focus group were collected through audio recordings and transcribed and analysed using a framework approach. RESULTS: A total of 19 prehospital emergency care providers participated; two focus group interviews were performed for each level of care. The BLS focus groups each consisted of two participants. The ILS focus groups consisted of three participants each, and the ALS focus groups consisted of six and three participants. Four key themes were identified: perceptions of behavioural emergencies, responsibilities, understanding of legislation and barriers experienced. CONCLUSION: Participants placed high value on their moral and medical responsibilities towards MHCUs, which they described as ensuring the safety of themselves, MHCUs and the community; preventing further harm; and transporting MHCUs to an appropriate healthcare facility. There was a desire for revision of legislation, better education, skill development and awareness of mental healthcare in the prehospital emergency care setting.

Prioritizing the Care of Critically Ill Children in South Africa: How Does SCREEN Perform Against Other Triage Tools?

OBJECTIVE: Childhood mortality remains unacceptably high. In low-resource settings, children with critical illness often present for care. Current triage strategies are time consuming and require trained health care workers. To address this limitation, our team developed a simple subjective tool, SCREEN (Sick Children Require Emergency Evaluation Now), which is easy to administer, to identify critically ill children. This article presents the development of the SCREEN program and evaluates its performance when compared with other commonly implemented triage tools in low-resource settings. METHODS: We measured the sensitivity and specificity of SCREEN, to identify critically ill children, compared with 4 other previously validated triage tools: the Integrated Management of Childhood Illnesses, the Pediatric Early Warning, the Pediatric South African Triage Scale, and the World Health Organization Emergency Triage Treatment Tool. FINDINGS: SCREEN has high sensitivity (100%-98.73%; P < 0.001) and specificity (64.41%-50.71%; P < 0.001) when compared with other validated triage tools. CONCLUSIONS: The SCREEN tool may offer a simple and effective method to identify critically ill children in low-resource environments.

Acute pain assessment and management in the prehospital setting, in the Western Cape, South Africa: a knowledge, attitudes and practices survey.

BACKGROUND: Acute pain is frequently encountered in the prehospital setting, and therefore, a fundamental aspect of quality emergency care. Research has shown a positive association between healthcare providers' knowledge of, and attitudes towards pain and pain management practices. This study aimed to describe the knowledge, attitudes, and practices of emergency care providers regarding acute pain assessment and management in the prehospital setting, in the Western Cape, South Africa. The specific objectives were to, identify gaps in pain knowledge; assess attitudes regarding pain assessment and management; describe pain assessment and management behaviours and practices; and identify barriers to and enablers of pain care. METHODS: A web-based descriptive cross-sectional survey was conducted among emergency care providers of all qualifications, using a face-validated Knowledge, Attitudes and Practices of Pain survey. RESULTS: Responses of 100 participants were included in the analysis. The survey response rate could not be calculated. The mean age of respondents was 34.74 (SD 8.13) years and the mean years' experience 10.02 (SD 6.47). Most respondents were male (69%), employed in the public/government sector (93%) as operational practitioners (85%) with 54% of respondents having attended medical education on pain care in the last 2 years. The mean percentage for knowledge and attitudes regarding pain among emergency care providers was 58.01% (SD 15.66) with gaps identified in various aspects of pain and pain care. Practitioners with higher qualifications, more years' experience and those who did not attend medical education on pain, achieved higher scores. Alcohol and drug use by patients were the most selected barrier to pain care while the availability of higher qualified practitioners was the most selected enabler. When asked to record pain scores, practitioners were less inclined to assign scores which were self-reported by the patients in the case scenarios. The participant dropout rate was 35%. CONCLUSION: Our results suggest that there is suboptimal knowledge and attitudes regarding pain among emergency care providers in the Western Cape, South Africa. Gaps in pain knowledge, attitudes and practices were identified. Some barriers and enablers of pain care in the South African prehospital setting were identified but further research is indicated.

Identifying barriers for out of hospital emergency care in low and low-middle income countries: a systematic review.

BACKGROUND: Out-of-hospital emergency care (OHEC), also known as prehospital care, has been shown to reduce morbidity and mortality from serious illness. We sought to summarize literature for low and low-middle income countries to identify barriers to and key interventions for OHEC delivery. METHODS: We performed a systematic review of the peer reviewed literature from January 2005 to March 2015 in PubMed, Embase, Cochrane, and Web of Science. All articles referencing research from low and low-middle income countries addressing OHEC, emergency medical services, or transport/transfer of patients were included. We identified themes in the literature to form six categories of OHEC barriers. Data were collected using an electronic form and results were aggregated to produce a descriptive summary. RESULTS: A total 1927 titles were identified, 31 of which met inclusion criteria. Barriers to OHEC were divided into six categories that included: culture/community, infrastructure, communication/coordination, transport, equipment and personnel. Lack of transportation was a common problem, with 55% (17/31) of articles reporting this as a hindrance to OHEC. Ambulances were the most commonly mentioned (71%, 22/31) mode of transporting patients. However, many patients still relied on alternative means of transportation such as hired cars, and animal drawn carts. Sixty-one percent (19/31) of articles identified a lack of skilled personnel as a key barrier, with 32% (10/31) of OHEC being delivered by laypersons without formal training. Forty percent (12/31) of the systems identified in the review described a uniform access phone number for emergency medical service activation. CONCLUSIONS: Policy makers and researchers seeking to improve OHEC in low and low-middle income countries should focus on increasing the availability of transport and trained providers while improving patient access to the OHEC system. The review yielded articles with a primary focus in Africa, highlighting a need for future research in diverse geographic areas.

Markers of physiological stress during exercise under conditions of normoxia, normobaric hypoxia, hypobaric hypoxia, and genuine high altitude.

PURPOSE: To investigate whether there is a differential response at rest and following exercise to conditions of genuine high altitude (GHA), normobaric hypoxia (NH), hypobaric hypoxia (HH), and normobaric normoxia (NN). METHOD: Markers of sympathoadrenal and adrenocortical function [plasma normetanephrine (PNORMET), metanephrine (PMET), cortisol], myocardial injury [highly sensitive cardiac troponin T (hscTnT)], and function [N-terminal brain natriuretic peptide (NT-proBNP)] were evaluated at rest and with exercise under NN, at 3375 m in the Alps (GHA) and at equivalent simulated altitude under NH and HH. Participants cycled for 2 h [15-min warm-up, 105 min at 55% Wmax (maximal workload)] with venous blood samples taken prior (T0), immediately following (T120) and 2-h post-exercise (T240). RESULTS: Exercise in the three hypoxic environments produced a similar pattern of response with the only difference between environments being in relation to PNORMET. Exercise in NN only induced a rise in PNORMET and PMET. CONCLUSION: Biochemical markers that reflect sympathoadrenal, adrenocortical, and myocardial responses to physiological stress demonstrate significant differences in the response to exercise under conditions of normoxia versus hypoxia, while NH and HH appear to induce broadly similar responses to GHA and may, therefore, be reasonable surrogates.

Strategies Used by Prehospital Providers to Overcome Language Barriers.

OBJECTIVE: Language barriers are commonly encountered in the prehospital setting but there is a paucity of research on how prehospital providers address language discordance. We sought to identify the communication strategies, and the limitations of those strategies, used by emergency medical services (EMS) providers when confronted with language barriers in a variety of linguistic and cultural contexts. METHODS: EMS providers were queried regarding communication strategies to overcome language barriers as part of an international, multi-site, sequential explanatory, qualitative-predominant, mixed methods study of prehospital language barriers. A survey of EMS telecommunicators was administered at dispatch centers in New Mexico (United States) and Western Cape (South Africa). Semi-structured qualitative interviews of EMS field providers were conducted at agencies who respond to calls from participating dispatch centers. Survey data included quantitative data on demographics and communication strategies used to overcome language barriers as well as qualitative free-text responses on the limitations of strategies. Interviews elicited narratives of encounters with language-discordant patients and the strategies used to communicate. Data from the surveys and interviews were integrated at the point of analysis. RESULTS: 125 telecommunicators (overall response rate of 84.5%) and a purposive sample of 27 field providers participated in the study. The characteristics of participants varied between countries and between agencies, consistent with variations in participating agencies' hiring and training practices. Telecommunicators identified 3rd-party telephonic interpreter services as the single most effective strategy when available, but also described time delays and frustration with interpreter communications that leads them to preferentially try other strategies. In the field, all providers reported using similar strategies, relying heavily on bystanders, multilingual coworkers, and non-verbal communication. Prehospital providers described significant limitations to these strategies, including time delays, breaches of patient confidentiality, and inaccurate interpretation. Participants suggested various resources to improve communication with language-discordant patients. CONCLUSIONS: Prehospital providers rely upon similar, informal strategies for overcoming language barriers across a variety of locations, provider types, and linguistic and cultural contexts.

Defining and improving the role of emergency medical services in Cape Town, South Africa.

INTRODUCTION: Low and middle income countries bear a disproportionate burden of paediatric morbidity and mortality. South Africa, a middle income country, has unacceptably high mortality in children less than 5 years of age. Many factors that contribute to the child mortality rate are time sensitive and require efficient access to emergency care. Delays and barriers within the emergency medical services (EMS) system increase paediatric morbidity and mortality from time sensitive illnesses. METHODS: This study is a qualitative evaluation of the prehospital care system for paediatric patients in Cape Town, South Africa. A purposive sample of healthcare personnel within and interacting with the EMS system were interviewed. A structured interview form was used to gather data. All interviews were audio recorded and transcribed; two independent reviewers performed blinded content analysis of the transcribed script. RESULTS: 33 structured interviews were conducted over a 4 week period. Eight broad themes were identified during coding, including: access, communication, community education, equipment, infrastructure, staffing, training and triage. Subcategories were used to identify areas for targeted intervention. Overall agreement between the two independent coders was 93.36%, with a κ coefficient of 0.69. CONCLUSIONS: The prehospital system is central to delivering time sensitive care for paediatric patients. In a single centre middle income setting, communication barriers between dispatch personnel and medical facilities/EMS personnel were deemed to be a high priority intervention in order to improve care delivery. Other areas for targeted interventions should include broadening the advanced life support provider base and introducing basic medical language in dispatch staff training.

'I am afraid the news is not good' - Breaking bad news in the time of COVID: Experiences from a field hospital.

BACKGROUND:  The COVID-19 Pandemic had profound effects on healthcare systems around the world. In South Africa, field hospitals, such as the Mitchell's Plain Field Hospital, managed many COVID patients and deaths, largely without family presence. Communicating with families, preparing them for death and breaking bad news was a challenge for all staff. AIM:  This study explores the experiences of healthcare professionals working in a COVID-19 field hospital, specifically around having to break the news of death remotely. SETTING:  A150-bed Mitchells Plain Field Hospital (MPFH) in Cape Town. METHODS:  A qualitative exploratory design was utilised using a semi-structured interview guide. RESULTS:  Four themes were identified: teamwork, breaking the news of death, communication and lessons learnt. The thread linking the themes was the importance of teamwork, the unpredictability of disease progression in breaking bad news and barriers to effective communication. Key lessons learnt included effective management and leadership. Many families had no access to digital technology and linguo-cultural barriers existed. CONCLUSION:  We found that in the Mitchell's Plain Field Hospital, communication challenges were exacerbated by the unpredictability of the illness and the impact of restrictions on families visiting in preparing them for bad news. We identified a need for training using different modalities, the importance of a multidisciplinary team approach and for palliative care guidelines to inform practice.Contribution: Breaking the news of death to the family is never easy for healthcare workers. This article unpacks some of the experiences in dealing with an extraordinary number of deaths by a newly formed team in the COVID era.

Erratum: 'I am afraid the news is not good' - Breaking bad news in the time of COVID: Experiences from a field hospital.

No abstract available.

Prognostic accuracy of eight triage scores in suspected COVID-19 in an Emergency Department low-income setting: An observational cohort study.

Introduction: Previous studies deriving and validating triage scores for patients with suspected COVID-19 in Emergency Department settings have been conducted in high- or middle-income settings. We assessed eight triage scores' accuracy for death or organ support in patients with suspected COVID-19 in Sudan. Methods: We conducted an observational cohort study using Covid-19 registry data from eight emergency unit isolation centres in Khartoum State, Sudan. We assessed performance of eight triage scores including: PRIEST, LMIC-PRIEST, NEWS2, TEWS, the WHO algorithm, CRB-65, Quick COVID-19 Severity Index and PMEWS in suspected COVID-19. A composite primary outcome included death, ventilation or ICU admission. Results: In total 874 (33.84 %, 95 % CI:32.04 % to 35.69 %) of 2,583 patients died, required intubation/non-invasive ventilation or HDU/ICU admission . All risk-stratification scores assessed had worse estimated discrimination in this setting, compared to studies conducted in higher-income settings: C-statistic range for primary outcome: 0.56-0.64. At previously recommended thresholds NEWS2, PRIEST and LMIC-PRIEST had high estimated sensitivities (≥0.95) for the primary outcome. However, the high baseline risk meant that low-risk patients identified at these thresholds still had a between 8 % and 17 % risk of death, ventilation or ICU admission. Conclusion: None of the triage scores assessed demonstrated sufficient accuracy to be used clinically. This is likely due to differences in the health care system and population (23 % of patients died) compared to higher-income settings in which the scores were developed. Risk-stratification scores developed in this setting are needed to provide the necessary accuracy to aid triage of patients with suspected COVID-19.

Implementation and evaluation of a pilot WHO community first aid responder training in Kinshasa, DR Congo: A mixed method study.

Introduction: Prehospital care in many low- and middle-income countries is underdeveloped and needs strengthening for improved outcomes. Where formal prehospital care systems are under development, integration of a layperson first responder programme may help improve access for those in need. The World Health Organization recently developed the Community First Aid Responder (CFAR) learning program in support of this system, providing that it may require adaptation to be contextually suitable and sustainably implemented at country level. This study assesses a pilot WHO CFAR course in Kinshasa, Democratic Republic of Congo, to inform future rollouts and related research. Methods: We conducted a 3-day in-person pilot CFAR training with 42 purposively selected community health workers. Data collection involved quantitative and qualitative phases. The first consisted of structured pre- and post-training surveys, and a course evaluation by participants. The second consisted of two focus group discussions involving purposively selected community health workers in one group, and a convenience sample of course instructors and organisers in the other. Perceptions regarding course content, perceived knowledge acquisition and self-confidence gain were analysed using descriptive statistics for the quantitative data and content analysis for qualitative data. Results: Course participants were predominantly male (76.3 %) with a median age of 42 years and most (80.5 %) had no prior first aid training. Most were satisfied that the learning objectives were reached, the logistics were adequate, and that the content and teaching language were appropriately tailored to local context. The majority (94.7 %) found the 3-day duration insufficient. There was a significant self-confidence gain regarding first aid skills (average 17.9 % in pre- to 95.3 % in post-training, p < 0.001). Favourable opinions on the course structure, content, logistics and teaching methods were noted. Conclusion: A CFAR course pilot was successfully conducted in Kinshasa. The course is appropriate for context and well received by participants. It can form a key component of developing prehospital care systems in resource-constrained settings.

The firearm pandemic: time to act and flatten the curve.

N/A.

Cardiorespiratory Responses to Voluntary Hyperventilation During Normobaric Hypoxia.

BACKGROUND: Unexplained physiological events (PE), possibly related to hypoxia and hyperventilation, are a concern for some air forces. Physiological monitoring could aid research into PEs, with measurement of arterial oxygen saturation (Spo2) often suggested despite potential limitations in its use. Given similar physiological responses to hypoxia and hyperventilation, the present study characterized the cardiovascular and respiratory responses to each.METHODS: Ten healthy subjects were exposed to 55 mins of normobaric hypoxia simulating altitudes of 0, 8000, and 12,000 ft (0, 2438, and 3658 m) while breathing normally and voluntarily hyperventilating (doubling minute ventilation). Respiratory gas analysis and spirometry measured end-tidal gases (PETo2 and PETco2) and minute ventilation. Spo2 was assessed using finger pulse oximetry. Mean arterial, systolic, and diastolic blood pressure were measured noninvasively. Cognitive impairment was assessed using the Stroop test.RESULTS: Voluntary hyperventilation resulted in a doubling of minute ventilation and lowered PETco2, while altitude had no effect on these. PETo2 and Spo2 declined with increasing altitude. However, despite a significant drop in PETo2 of 15.2 mmHg from 8000 to 12,000 ft, Spo2 was similar when hyperventilating (94.7 ± 2.3% vs. 93.4 ± 4.3%, respectively). The only cardiovascular response was an increase in heart rate while hyperventilating. Altitude had no effect on cognitive impairment, but hyperventilation did.DISCUSSION: For many cardiovascular and respiratory variables, there is minimal difference in responses to hypoxia and hyperventilation, making these challenging to differentiate. Spo2 is not a reliable marker of environmental hypoxia in the presence of hyperventilation and should not be used as such without additional monitoring of minute ventilation and end-tidal gases.Haddon A, Kanhai J, Nako O, Smith TG, Hodkinson PD, Pollock RD. Cardiorespiratory responses to voluntary hyperventilation during normobaric hypoxia. Aerosp Med Hum Perform. 2023; 94(2):59-65.