The deeper the rounder: body shape variation in lice parasitizing diving hosts.

Seal lice, unique among insects, show remarkable adaptability to the extreme conditions of the deep sea. Evolving with their seal and sea lion hosts, they have managed to tolerate hypoxia, high salinity, low temperature, and elevated hydrostatic pressure. Given the diving capabilities of their mammalian hosts, which can reach depths of hundreds to thousands of meters, our study examines the morphological variation among closely related seal lice species infesting hosts with different maximum diving depths. In particular, our research reveals a significant morphological difference between lice associated with regular and deep-diving hosts, where lice from deep-diving hosts tend to be rounder. This could be an adaptation to withstand the high hydrostatic pressures found in the deep ocean. The rounded shape optimizes the louse's ability to withstand external pressure by redistributing it over a larger ventral/dorsal plane. This in turn minimizes the internal energy required to support body deformations, thereby increasing the louse's resilience in the deep sea environment.

Specialized diving traits in the generalist morphology of Fulica (Aves, Rallidae).

Foot-propelled diving comprises the primary locomotion-based feeding strategy for many birds, including families such as Phalacrocoracidae, Anhingidae, Podicipedidae, Gaviidae, and the diving ducks within Anatidae. While the morphology of specialized divers is well known, the corresponding morphology is less known for birds not as specialized but capable of diving, such as the coots (Rallidae, Fulica spp.). To compare the osteology of Fulica with other (non-diving) Rallidae, and with foot-propelled diving birds that are distantly related, we considered osteological characters, as well as the proportion of the hind limb bones and the femoral splay angle to construct a phylomorphospace, and to perform a comparative disparity analysis considering ecomorphologically relevant characters related to swimming and diving. Coots resulted to be significantly disparate from other Rallidae showing many traits of specialized foot-propelled divers, but only noticeable when compared with other rallids, as the degree of development of these traits is markedly less than in loons, grebes, or cormorants. This may correspond to a stabilizing selection of characteristics associated with a generalist morphology in Fulica. Studying adaptation in generalist taxa broadens our understanding of ecomorphologically significant features, thereby enabling us to generalize their evolutionary patterns.

Foraging dives of southern right whales (Eubalaena australis) in relation to larger zooplankton size prey availability in Golfo Nuevo, Península Valdés, Argentina.

Southern right whales (SRWs, Eubalaena australis) have been observed feeding both at and below the surface (< 10 m) in Golfo Nuevo (42°42' S, 64°30' W), Península Valdés, Argentina, an area traditionally recognized as calving ground. In addition, we documented diving feeding behavior in SRWs during their stay in this gulf, which has not been previously described. We assessed this behavior using suction-cup-attached video-imaging tags (CRITTERCAMs) on individual whales. A total of eight CRITTERCAM deployments were successful, and feeding events were documented in all SRWs successfully equipped with CRITTERCAMs. The highest speeds occurred during the ascent phase, and the average diving time was 6 min 45 s ± 3 min 41 s for SRWs. Concurrently, zooplankton samples were collected from the subsurface and bottom of the water in areas where tagged whales dived to assess differences in composition, abundance, and biomass. Copepods dominated the upper layer, while euphausiids were more abundant in the deeper sample. Furthermore, zooplankton total biomass was five times higher at depth (2515.93 mg/m3) compared to the subsurface (500.35 mg/m3). Differences in zooplankton characteristics between depths, combined with CRITTERCAM videos, indicated that SRWs exploit high concentrations of organisms near the seafloor during daytime feeding dives. This study provides baseline insights into how SRWs utilize Península Valdés during their stay in the area.

Paciente con enfermedad descompresiva del oído interno / Patient with inner ear decompression sickness

Introducción: La enfermedad descompresiva es un síndrome clínico complejo causado por la sobresaturación de gases respiratorios en la sangre y los tejidos, después de una reducción abrupta de la presión ambiental, que puede presentarse como parte de los accidentes de buceo. Dada su baja prevalencia se da a conocer una de sus formas de presentación en los servicios de urgencias, que requiere rapidez en el diagnóstico y conducta terapéutica inmediata. Objetivo: Presentar un caso grave de enfermedad descompresiva del oído interno. Caso clínico: Paciente masculino de 71 años de edad, buzo aficionado y antecedente de un accidente vascular encefálico isquémico hace aproximadamente 1 año. Realizó inmersiones, luego de las cuales comenzó a presentar síntomas como mareos, náuseas, vómitos copiosos, inestabilidad para la marcha y manifestaciones sensitivas en la cara. Horas después de ser evaluado en centro médico de urgencia, sin diagnóstico específico, se trasladó al cuerpo de guardia del hospital, para su valoración por el especialista en medicina subacuática. Conclusiones: La orientación diagnóstica de un paciente con enfermedad descompresiva requiere derivación urgente a un centro de tratamiento de enfermedades disbáricas(AU)

Introduction: Decompression illness is a complex clinical syndrome caused by supersaturation of respiratory gases in the blood and tissues, after an abrupt reduction in environmental pressure, which can occur as part of diving accidents. Given its low prevalence, one of its forms of presentation is revealed in emergency services, which requires speed in diagnosis and immediate therapeutic conduct. Objective: To present a severe case of decompressive disease of the inner ear. Clinical case: 71-year-old male patient, amateur diver, with a history of an ischemic stroke approximately 1 year ago. He performed dives, after which he began to present symptoms such as dizziness, nausea, copious vomiting, unsteadiness in walking, and sensitive manifestations on the face. Hours after being evaluated at the emergency medical center, without a specific diagnosis, he was transferred to the hospital's emergency room, for evaluation by the underwater medicine specialist. Conclusions: The diagnostic orientation of a patient with decompression illness requires urgent referral to a center for the treatment of dysbaric diseases(AU)

Scuba Diving-Induced Inner-Ear Pathology: Imaging Findings of Superior Semicircular Canal and Tegmen Tympani Dehiscence.

BACKGROUND Superior semicircular canal dehiscence is an inner-ear pathology which presents with vertigo, disequilibrium, and hearing loss. Although the exact etiology of superior semicircular canal dehiscence is unknown, it is thought that an increase in middle-ear pressure disrupts a thin overlying temporal bone. Superior semicircular canal dehiscence is frequently seen in association with dehiscence of the tegmen tympani, which overlies the middle ear. Here, we present a case report of a 52-year-old Puerto Rican man with vertigo, dizziness, vomiting, and mild hearing loss associated with superior semicircular canal and tegmen tympani dehiscence after performing improper scuba diving techniques. CASE REPORT A 52-year-old Puerto Rican man presented to the emergency department with vertigo, dizziness, vomiting, and mild hearing loss in the right ear. The symptoms began shortly after scuba diving with inadequate decompression techniques on ascent. He was treated with recompression therapy with mild but incomplete improvement in symptoms. Bilateral temporal magnetic resonance imaging was suggestive of segmental dehiscence of the right superior semicircular canal and tegmen tympani. High-resolution computed tomography of the temporal bone confirmed right superior semicircular canal and tegmen tympani dehiscence with an intact left inner ear. CONCLUSIONS The increased inner-ear pressure that occurs during scuba diving can lead to dehiscence of the superior semicircular canal and tegmen tympani, causing vertigo and hearing loss. Performance of improper diving techniques can further increase the risk of dehiscence. Therefore, appropriate radiologic evaluation of the inner ear should be performed in such patients.

Breath-holding as model for the evaluation of EEG signal during respiratory distress.

PURPOSE: Research describes the existence of a relationship between cortical activity and the regulation of bulbar respiratory centers through the evaluation of the electroencephalographic (EEG) signal during respiratory challenges. For example, we found evidences of a reduction in the frequency of the EEG (alpha band) in both divers and non-divers during apnea tests. For instance, this reduction was more prominent in divers due to the greater physiological disturbance resulting from longer apnea time. However, little is known about EEG adaptations during tests of maximal apnea, a test that voluntarily stops breathing and induces dyspnea. RESULTS: Through this mini-review, we verified that a protocol of successive apneas triggers a significant increase in the maximum apnea time and we hypothesized that successive maximal apnea test could be a powerful model for the study of cortical activity during respiratory distress. CONCLUSION: Dyspnea is a multifactorial symptom and we believe that performing a successive maximal apnea protocol is possible to understand some factors that determine the sensation of dyspnea through the EEG signal, especially in people not trained in apnea.

Altitude Diving on a Closed Circuit Oxygen Rebreather.

Closed-circuit rebreather diving is becoming more common. Rebreathers are complicated, adding to the stress of diving. Also adding to this complexity in the presented case is diving at a high-altitude, cold-water reservoir in Colorado. One diver experienced an oxygen-induced seizure at depth. The other diver had a rapid ascent with loss of consciousness. In this case, two experienced divers recovered from a possible devastating dive. Fortunately, they both returned to their pre-dive baseline health. Dive plan- ning is important, but as in this case, dive execution is paramount. This is a clinical case for an uncommon event presenting to an emergency department.

A heavyweight early whale pushes the boundaries of vertebrate morphology.

The fossil record of cetaceans documents how terrestrial animals acquired extreme adaptations and transitioned to a fully aquatic lifestyle1,2. In whales, this is associated with a substantial increase in maximum body size. Although an elongate body was acquired early in cetacean evolution3, the maximum body mass of baleen whales reflects a recent diversification that culminated in the blue whale4. More generally, hitherto known gigantism among aquatic tetrapods evolved within pelagic, active swimmers. Here we describe Perucetus colossus-a basilosaurid whale from the middle Eocene epoch of Peru. It displays, to our knowledge, the highest degree of bone mass increase known to date, an adaptation associated with shallow diving5. The estimated skeletal mass of P. colossus exceeds that of any known mammal or aquatic vertebrate. We show that the bone structure specializations of aquatic mammals are reflected in the scaling of skeletal fraction (skeletal mass versus whole-body mass) across the entire disparity of amniotes. We use the skeletal fraction to estimate the body mass of P. colossus, which proves to be a contender for the title of heaviest animal on record. Cetacean peak body mass had already been reached around 30 million years before previously assumed, in a coastal context in which primary productivity was particularly high.

Behavioral Study of 3- and 5-Halocytisine Derivatives in Zebrafish Using the Novel Tank Diving Test (NTT).

Anxiety is a serious mental disorder, and recent statistics have determined that 35.12% of the global population had an anxiety disorder during the COVID-19 pandemic. A mechanism associated with anxiolytic effects is related to nicotinic acetylcholine receptor (nAChR) agonists, principally acting on the α4ß2 nAChR subtype. nAChRs are present in different animal models, including murine and teleosteos ones. Zebrafish has become an ideal animal model due to its high human genetic similarities (70%), giving it high versatility in different areas of study, among them in behavioral studies related to anxiety. The novel tank diving test (NTT) is one of the many paradigms used for studies on new drugs related to their anxiolytic effect. In this work, an adult zebrafish was used to determine the behavioral effects of 3- and 5-halocytisine derivatives, using the NTT at different doses. Our results show that substitution at position 3 by chlorine or bromine decreases the time spent by the fish at the bottom compared to the control. However, the 3-chloro derivative at higher doses increases the bottom dwelling time. In contrast, substitution at the 5 position increases bottom dwelling at all concentrations showing no anxiolytic effects in this model. Unexpected results were observed with the 5-chlorocytisine derivative, which at a concentration of 10 mg/L produced a significant decrease in bottom dwelling and showed high times of freezing. In conclusion, the 3-chloro and 3-bromo derivatives show an anxiolytic effect, the 3-chlorocytisine derivative being more potent than the 3-bromo derivative, with the lowest time at the bottom of the tank at 1mg/L. On the other hand, chlorine, and bromine at position 5 produce an opposite effect.

Pediatric Diving-Related Injuries in Swimming Pools Presenting to US Emergency Departments: 2008-2020.

OBJECTIVES: Recreational swimming/diving is among the most common physical activities in US children and a significant cause of morbidity across the United States. This study updates the national epidemiology of diving-related injuries. METHODS: The Consumer Product Safety Commission's National Electronic Injury Surveillance System database was queried for patients aged 0 to 19 from 2008 to 2020 who presented to any of the 100 National Electronic Injury Surveillance System-participating emergency departments for a diving-related injury. Dive characteristics such as dive height, dive skill, dive direction, and dive sequence were determined from case narratives. RESULTS: A total of 1202 cases were identified for analysis corresponding to a total national estimate of 37,387 diving related injuries during the period from 2008 to 2020 and a national incidence of 3.6 injuries per 100,000 population. Males accounted for 64% of injuries. The average yearly incidences of injury in the 10 to 14 and 15 to 19 age groups were identical at 5.8 per 100,000. Contact with the diving board or platform was the most common cause of injury (34%). Diving backwards or attempting a flip or handstand dive were associated with increased odds of sustaining an injury resulting from contact with the diving board or platform (odds ratio, 16.0 and 6.9, respectively). In 2020, the incidence of diving-related injury fell to 1.6 per 100,000 population. CONCLUSIONS: Diving injuries are common in children and adolescents, especially in boys aged 10 to 19. There was a significant reduction in diving-related injury corresponding with the COVID-19 pandemic.

Ecomorphological variation of the penguin wing.

Penguins (Aves, Sphenisciformes) are pursuit divers that feed mainly on krill, fish, and squid. Although they are opportunistic feeders, some species are more generalists than others and many show dietary preferences toward krill and other crustaceans or fish and squid. Their diving depth seems to follow a body size pattern and relates to the type of item that they prey on. Penguins dive with their wing; hence their wing musculature is responsible for the animal maneuverability and strength while diving. In the present study, ecological traits such as diving depths and prey composition are used to explore if morphology relates to foraging habits. A geometric morphometric approach is used to quantitatively address these morphological differences in the wing apparatus of all extant penguins and a fossil species taking into consideration allometric and phylogenetic factors. Results show that morphological differences among penguins with different diets are significant and strong; groups are well separated with the greatest differences found between piscivorous and crustacivorous penguins. Dive depth has a moderate covariation with morphology and a strong correspondence with wing area. Last, Madrynornis mirandus, an exceptionally well-preserved fossil from the Miocene of Patagonia, is found to be close to the piscivorous and generalist piscivorous species. It is proposed that swimming styles correlate with specific traits of the anatomy of wing and pectoral girdle skeleton and muscles.

Individual variability in diving behavior of the Black-vented Shearwater in an ever-changing habitat.

Oceanic mesoscale systems are characterized by inherent variability. Climatic change adds entropy to this system, making it a highly variable environment in which marine species live. Being at the higher levels of the food chain, predators maximize their performance through plastic foraging strategies. Individual variability within a population and the possible repeatability across time and space may provide stability in a population facing environmental changes. Therefore, variability and repeatability of behaviors, particularly diving behavior, could play an important role in understanding the adaptation pathway of a species. This study focuses on characterizing the frequency and timing of different dives (termed simple and complex) and how these are influenced by individual and environmental characteristics (sea surface temperature, chlorophyll a concentration, bathymetry, salinity, and Ekman transport). This study is based on GPS and accelerometer-recorded information from a breeding group of 59 Black-vented Shearwater and examine consistency in diving behavior at both individual and sex levels across four different breeding seasons. The species was found to be the best performing free diver in the Puffinus genus with a maximum dive duration of 88 s. Among the environmental variables assessed, a relationship was found with active upwelling conditions enhancing low energetic cost diving, on the contrary, reduced upwelling and warmer superficial waters induce more energetically demanding diving affecting diving performance and ultimately body conditions. The body conditions of Black-vented Shearwaters in 2016 were worse than in subsequent years, in 2016, deepest and longest complex dives were recorded, while simple dives were longer in 2017-2019. Nevertheless, the species' plasticity allows at least part of the population to breed and feed during warmer events. While carry-over effects have already been reported, the effect of more frequent warm events is still unknown.

Training methods for maximal static apnea performance: a systematic review and meta-analysis.

INTRODUCTION: Currently, there is an increase in people practicing freediving (FD) both in competition and leisure. As a sports practice, its modalities are grouped into static, dynamic, and constant weight apnea. The aim of this systematic review and meta-analysis (PROSPERO-CRD42021230322) was to identify the training methods used to improve the static apnea time (AT) performance. EVIDENCE ACQUISITION: Ten training protocols were analyzed from eight studies published until March 09, 2022. The effect size (Hedge's g) and its confidence interval (CI95%) were calculated from the AT measured pre- and post-training. EVIDENCE SYNTHESIS: Three different apnea training methods were verified, the breath-hold (BH) that uses BH exercises, physical training with strength and cardiorespiratory exercises, and cross training that combines BH exercises with physical training. These training methods were applied to 138 participants of both sexes with or without experience in apnea episode or diving practice. In general, the AT improvement showed a large effect after the interventions (g=1.30, CI95%=0.85-1.76, P<0.01). CONCLUSIONS: All three methods were effective in improving static AT, however from the existing protocols is not possible to recommend an ideal to improve AT and therefore FD performance.

Spine Trauma Secondary to Diving Accidents: A Seven-year Retrospective Study in Puerto Rico.

OBJECTIVE: Review the profile of patients with spinal trauma after diving accidents referred to the Puerto Rico Medical Center. This study intended to develop more awareness of the risks of spinal cord injury after diving. METHODS: The patient's records for diving accident cases referred to our center during January 2014 until December 2020 were assessed retrospectively. The cases were evaluated according to sex, age, vertebral level, and neurological deficit. The Puerto Rico Medical Center is the only level 1 trauma center in Puerto Rico; therefore, this study likely included all the cases of diving injury on the island. RESULTS: Sixty five patients with a median age of 29 years were identified consisting primarily of males (94%). The regions affected included the cervical (96%), thoracic (2%), and lumbar (2%) spine. Twenty-seven patients (42%) developed a spinal cord injury secondary to a diving accident. Involvement of the C4, C5, or C6 vertebral level, was significant for the development of a spinal cord injury. Diving accidents occurring at beaches were the most common cause. CONCLUSION: In Puerto Rico, there is a yearly incidence of 9.3 diving accidents causing spinal trauma; these accidents most frequently affect the C6 vertebra. These diving accidents mainly occur in young individuals, predominantly at beaches. Most of our patients were neurologically intact after their diving accident, although 42% sustained a spinal cord injury. This study provided a better understanding of this traumatic event and determined its most affected levels, accident sites, and population involved.

Penalty feet positioning rule modification and laterality effect on soccer goalkeepers' diving kinematics.

In 2019, a new rule was applied in soccer. It allows the goalkeeper to have only one foot or part of it on the goal line when the kicker hits the ball, unlike the previous rule that determined the goalkeeper should have both feet on the line. The purpose of the present study was to analyze how the change in the rule and the lower limbs laterality influences on the diving save kinematic performance in penalties. Six goalkeepers, two professionals and four amateurs, performed a total of 20 dives in the laboratory and had their force and impulse exerted by the lower limb and displacement/velocity data from the center of body mass collected through force plates and kinematic analysis. The side preference was collected through an inventory. The results showed that goalkeepers dive further (p < 0.001) and faster (p < 0.001) when diving according to the new rule. Dives for the non-dominant side presented higher values than the trials for the dominant side in mediolateral (p = 0.02) and resultant (p = 0.03) displacements. Concluding, the goalkeepers performed better with the new rule in the analyzed variables and the lower limb preference has influenced only the mediolateral and resultant displacement.

Efectos biológicos de la exposición a distintas concentraciones de oxígeno: desde la hipoxia hipobárica al oxígeno hiperbárico / Biological effects due to exposure to different concentrations of oxygen from hypo to hyperoxemia

The systemic effects of oxygen deficiency or excess are not thoroughly described. Knowledge is evolving towards the description of beneficial and detrimental effects of both extremes of partial pressure of oxygen (PaO2). The cellular and tissue mediators derived from the modulation of the oxidative tone and the production of reactive oxygen species (ROS) are widely characterized biochemically, but the pathophysiological characterization is lacking. Preclinical models support the use of hypobaric hypoxia preconditioning, based on its beneficial effects on ventricular function or its reduction in infarct size. A very important use of oxygen today is in commercial diving. However, novel clinical indications for oxygen such as the healing of diabetic foot ulcers and bone injury caused by radiotherapy are increasingly used. On the other hand, the modulation of the hypoxic response associated with exposure to high altitude environments (hypobaric), favors Chile and its highlands as a natural laboratory to determine certain cardiovascular, cerebral and metabolic responses in the resident population. Also, the consequences of the intermittent exposure to high altitudes in workers also deserves attention. This review discusses the physiopathological response to hypo and hyperoxemia, associated with environments with different oxygen concentrations, and brings back the concept of oxygen as a pharmacological mediator in extreme environments such as high altitudes and hyperbaric medicine in divers, decompression sickness, osteonecrosis associated with radiotherapy and sudden sensorineural hearing loss.

Heart rate variability, thyroid hormone concentration, and neuropsychological responses in Brazilian navy divers: a case report of diving in Antarctic freezing waters.

Open-water diving in a polar environment is a psychophysiological challenge to the human organism. We evaluated the effect of short-term diving (i.e., 10 min) in Antarctic waters on autonomic cardiac control, thyroid hormone concentration, body temperatures, mood, and neuropsychological responses (working memory and sleepiness). Data collection was carried out at baseline, before, and after diving in four individuals divided into the supporting (n=2) and diving (n=2) groups. In the latter group, autonomic cardiac control (by measuring heart rate variability) was also assessed during diving. Diving decreased thyroid-stimulating hormone (effect size = 1.6) and thyroxine (effect size = 2.1) concentrations; these responses were not observed for the supporting group. Diving also reduced both the parasympathetic (effect size = 2.6) and sympathetic activities to the heart (ES > 3.0). Besides, diving reduced auricular (effect size > 3.0), skin [i.e., hand (effect size = 1.2) and face (effect size = 1.5)] temperatures compared to pre-dive and reduced sleepiness state (effect size = 1.3) compared to basal, without changing performance in the working memory test. In conclusion, short-term diving in icy waters affects the hypothalamic-pituitary-thyroid axis, modulates autonomic cardiac control, and reduces body temperature, which seems to decrease sleepiness.

El buceo recreativo y la otorrinolaringología: ¿qué sabemos y deberíamos saber? / Recreational diving and otolaryngology: what do we know and should we know?

El buceo recreativo es una práctica cada vez más popular en la población mundial, sin embargo, no está exenta de riesgos. A medida que transcurre una inmersión, el buzo es susceptible a una serie de cambios de presión que afectan las distintas cavidades que contienen aire dentro del cuerpo humano, tales como el oído, cavidades paranasales y los pulmones. Existe un gran espectro de patologías asociadas al buceo, explicándose la mayoría de ellas por el barotrauma asociado, cuya gravedad depende de la magnitud del daño asociado, pudiendo presentar desde manifestaciones a nivel local, así como también a nivel sistémico. Las patologías otológicas suelen ser las más frecuentes y el principal motivo de consulta en este tipo de pacientes. Sin embargo, las afecciones otoneurológicas, rinosinusales, de vía aérea y sistémicas pueden ser comunes dependiendo de cada perfil de buceo. Actualmente no existen recomendaciones locales sobre esta práctica, por lo que el conocimiento de la fisiología, fisiopatología y el tratamiento de las patologías otorrinolaringológicas asociadas deben ser conocidas a medida que este deporte se vuelve cada vez más popular. Se realizó una revisión de la literatura sobre las distintas afecciones otorrinolaringológicas con el fin de sistematizarlas y elaborar recomendaciones para establecer una práctica segura.

Recreational diving is an increasingly popular practice in the world; however, it is not without risks. As a dive progresses, the diver is susceptible to a series of pressure changes that affect the air-containing cavities, such as the ear, paranasal cavities, and lungs. There is a large spectrum of pathologies associated with diving, most of them being explained by associated barotrauma, the severity of which depends on the magnitude of the associated damage, could present local manifestations, as well as at systemic level. Otological pathologies are usually the most frequent and the main reason for consultation in this type of patients, however, otoneurological, rhinosinusal, airway and systemic conditions can be common depending on each diving profile. Currently there are no local recommendations on this practice, therefore, knowledge of the physiology, pathophysiology and treatment of associated otorhinolaryngological pathologies should be known as this sport becomes increasingly popular. A review of the literature on the different ear, nose and throat conditions was carried out in order to systematize them and develop recommendations to establish a safe practice.

Effectiveness of an adapted diving mask (Owner mask) for non-invasive ventilation in the COVID-19 pandemic scenario: study protocol for a randomized clinical trial.

BACKGROUND: Non-invasive ventilation (NIV) is indicated to avoid orotracheal intubation (OTI) to reduce hospital stay and mortality. Patients infected by SARS-CoV2 can progress to respiratory failure (RF); however, in the initial phase, they can be submitted to oxygen therapy and NIV. Such resources can produce aerosol and can cause a high risk of contagion to health professionals. Safe NIV strategies are sought, and therefore, the authors adapted diving masks to be used as NIV masks (called an Owner mask). OBJECTIVE: To assess the Owner mask safety and effectiveness regarding conventional orofacial mask for patients in respiratory failure with and without confirmation or suspicion of COVID-19. METHODS: A Brazilian multicentric study to assess patients admitted to the intensive care unit regarding their clinical, sociodemographic and anthropometric data. The primary outcome will be the rate of tracheal intubation, and secondary outcomes will include in-hospital mortality, the difference in PaO2/FiO2 ratio and PaCO2 levels, time in the intensive care unit and hospitalization time, adverse effects, degree of comfort and level of satisfaction of the mask use, success rate of NIV (not progressing to OTI), and behavior of the ventilatory variables obtained in NIV with an Owner mask and with a conventional face mask. Patients with COVID-19 and clinical signs indicative of RF will be submitted to NIV with an Owner mask [NIV Owner COVID Group (n = 63)] or with a conventional orofacial mask [NIV orofacial COVID Group (n = 63)], and those patients in RF due to causes not related to COVID-19 will be allocated into the NIV Owner Non-COVID Group (n = 97) or to the NIV Orofacial Non-COVID Group (n = 97) in a randomized way, which will total 383 patients, admitting 20% for loss to follow-up. DISCUSSION: This is the first randomized and controlled trial during the COVID-19 pandemic about the safety and effectiveness of the Owner mask compared to the conventional orofacial mask. Experimental studies have shown that the Owner mask enables adequate sealing on the patient's face and the present study is relevant as it aims to minimize the aerosolization of the virus in the environment and improve the safety of health professionals. TRIAL REGISTRATION: Brazilian Registry of Clinical Trials (ReBEC): RBR - 7xmbgsz . Registered on 15 April 2021.

[Biological effects due to exposure to different concentrations of oxygen from hypo to hyperoxemia]. / Efectos biológicos de la exposición a distintas concentraciones de oxígeno: desde la hipoxia hipobárica al oxígeno hiperbárico.

The systemic effects of oxygen deficiency or excess are not thoroughly described. Knowledge is evolving towards the description of beneficial and detrimental effects of both extremes of partial pressure of oxygen (PaO2). The cellular and tissue mediators derived from the modulation of the oxidative tone and the production of reactive oxygen species (ROS) are widely characterized biochemically, but the pathophysiological characterization is lacking. Preclinical models support the use of hypobaric hypoxia preconditioning, based on its beneficial effects on ventricular function or its reduction in infarct size. A very important use of oxygen today is in commercial diving. However, novel clinical indications for oxygen such as the healing of diabetic foot ulcers and bone injury caused by radiotherapy are increasingly used. On the other hand, the modulation of the hypoxic response associated with exposure to high altitude environments (hypobaric), favors Chile and its highlands as a natural laboratory to determine certain cardiovascular, cerebral and metabolic responses in the resident population. Also, the consequences of the intermittent exposure to high altitudes in workers also deserves attention. This review discusses the physiopathological response to hypo and hyperoxemia, associated with environments with different oxygen concentrations, and brings back the concept of oxygen as a pharmacological mediator in extreme environments such as high altitudes and hyperbaric medicine in divers, decompression sickness, osteonecrosis associated with radiotherapy and sudden sensorineural hearing loss.