Airway Management with Endotracheal Tube versus Combitube® during Parabolic Flights

Evaluation of free-floating tracheal intubation in weightlessness via ice-pick position with a direct laryngoscopy and classic approach with indirect videolaryngoscopy

Long duration spaceflights to the Moon or Mars are at risk for emergency medical events. Managing a hypoxemic distress and performing an advanced airway procedure such as oro-tracheal intubation may be complicated under weightlessness due to ergonomic constraints. An emergency free-floating intubation would be dangerous because of high failure rates due to stabilization issues that prohibits its implementation in a space environment. Nevertheless, we hypothesized that two configurations could lead to a high first-pass success score for intubation performed by a free-floating operator. In a non-randomized, controlled, cross-over simulation study during a parabolic flight campaign, we evaluated and compared the intubation performance of free-floating trained operators, using either a conventional direct laryngoscope in an ice-pick position or an indirect laryngoscopy with a video-laryngoscope in a classic position at the head of a high-fidelity simulation manikin, in weightlessness and in normogravity. Neither of the two tested conditions reached the minimal terrestrial ILCOR recommendations (95% first-pass success) and therefore could not be recommended for general implementation under weightlessness conditions. Free-floating video laryngoscopy at the head of the manikin had a significant better success score than conventional direct laryngoscopy in an ice-pick position. Our results, combined with the preexisting literature, emphasis the difficulties of performing oro-tracheal intubation, even for experts using modern airway devices, under postural instability in weightlessness. ClinicalTrials registration number NCT05303948.

Time to ventilation and success rate of airway devices in microgravity: A randomized crossover manikin-trial using an underwater setting

BACKGROUND

Medical support for space exploration missions must prepare for severe medical events in conditions of microgravity. A key component to managing these events is techniques of airway management. The aim of the present trial is to compare airway management devices in simulated microgravity.

METHODS

In this randomized cross-over trial (RCT), four different devices were compared under simulated microgravity conditions utilizing a neutrally buoyant free-floating underwater manikin and poolside in normal gravity (control group). The primary endpoint was the successful placement of the airway device. The secondary endpoints were the number of attempts and the duration of each attempt.

RESULTS

A total of 20 participants performed placement of each device in both gravity conditions in an Airway mannequin. The fastest time to initial ventilation in simulated microgravity was possible with the laryngeal tube (18.9 ± 8 seconds) followed by laryngeal mask (20.1 ± 9 seconds). The I-gel^® supraglottic airway device required substantially more time for successful insertion in simulated microgravity (35.4 ± 25 seconds) as did endotracheal tube intubation by direct laryngoscopy (70.4 ± 35 seconds). Simulated microgravity conditions prolonged time to initial ventilation by 3.3 seconds (LM), 3.9 seconds (LT), 19.9 seconds (I-gel) and 43.1 seconds (endotracheal intubation, ETI) when compared to poolside attempts in normogravity.

CONCLUSION

In simulated microgravity conditions, use of the laryngeal tube or laryngeal mask provided the quickest time to initial ventilation, without deliberate tethering of the mannequin and rescuer to a fixed surface. Endotracheal intubation required significantly longer procedure times and, thus, was considered insufficient for clinical use in microgravity.

Using supraglottic airways by paramedics for airway management in analogue microgravity increases speed and success of ventilation

In the next few years, the number of long-term space missions will significantly increase. Providing safe concepts for emergencies including airway management will be a highly challenging task. The aim of the present trial is to compare different airway management devices in simulated microgravity using a free-floating underwater scenario. Five different devices for airway management [laryngeal mask (LM), laryngeal tube (LT), I-GEL, direct laryngoscopy (DL), and video laryngoscopy (VL)] were compared by n = 20 paramedics holding a diving certificate in a randomized cross-over setting both under free-floating conditions in a submerged setting (pool, microgravity) and on ground (normogravity). The primary endpoint was the successful placement of the airway device. The secondary endpoints were the number of attempts and the time to ventilation. A total of 20 paramedics (3 female, 17 male) participated in this study. Success rate was highest for LM and LT and was 100% both during simulated microgravity and normogravity followed by the I-GEL (90% during microgravity and 95% during normogravity). However, the success rate was less for both DL (60% vs. 95%) and VL (20% vs. 60%). Fastest ventilation was performed with the LT both in normogravity (13.7 ± 5.3 s; n = 20) and microgravity (19.5 ± 6.1 s; n = 20). For the comparison of normogravity and microgravity, time to ventilation was shorter for all devices on the ground (normogravity) as compared underwater (microgravity). In the present study, airway management with supraglottic airways and laryngoscopy was shown to be feasible. Concerning the success rate and time to ventilation, the optimum were supraglottic airways (LT, LM, I-GEL) as their placement was faster and associated with a higher success rate. For future space missions, the use of supraglottic airways for airway management seems to be more promising as compared to tracheal intubation by DL or VL.

Cardiopulmonary resuscitation (CPR) during spaceflight - a guideline for CPR in microgravity from the German Society of Aerospace Medicine (DGLRM) and the European Society of Aerospace Medicine Space Medicine Group (ESAM-SMG)

BACKGROUND

With the "Artemis"-mission mankind will return to the Moon by 2024. Prolonged periods in space will not only present physical and psychological challenges to the astronauts, but also pose risks concerning the medical treatment capabilities of the crew. So far, no guideline exists for the treatment of severe medical emergencies in microgravity. We, as a international group of researchers related to the field of aerospace medicine and critical care, took on the challenge and developed a an evidence-based guideline for the arguably most severe medical emergency - cardiac arrest.

METHODS

After the creation of said international group, PICO questions regarding the topic cardiopulmonary resuscitation in microgravity were developed to guide the systematic literature research. Afterwards a precise search strategy was compiled which was then applied to "MEDLINE". Four thousand one hundred sixty-five findings were retrieved and consecutively screened by at least 2 reviewers. This led to 88 original publications that were acquired in full-text version and then critically appraised using the GRADE methodology. Those studies formed to basis for the guideline recommendations that were designed by at least 2 experts on the given field. Afterwards those recommendations were subject to a consensus finding process according to the DELPHI-methodology.

RESULTS

We recommend a differentiated approach to CPR in microgravity with a division into basic life support (BLS) and advanced life support (ALS) similar to the Earth-based guidelines. In immediate BLS, the chest compression method of choice is the Evetts-Russomano method (ER), whereas in an ALS scenario, with the patient being restrained on the Crew Medical Restraint System, the handstand method (HS) should be applied. Airway management should only be performed if at least two rescuers are present and the patient has been restrained. A supraglottic airway device should be used for airway management where crew members untrained in tracheal intubation (TI) are involved.

DISCUSSION

CPR in microgravity is feasible and should be applied according to the Earth-based guidelines of the AHA/ERC in relation to fundamental statements, like urgent recognition and action, focus on high-quality chest compressions, compression depth and compression-ventilation ratio. However, the special circumstances presented by microgravity and spaceflight must be considered concerning central points such as rescuer position and methods for the performance of chest compressions, airway management and defibrillation.

Resuscitation and Evacuation from Low Earth Orbit: A Systematic Review

INTRODUCTION

Provision of critical care and resuscitation was not practical during early missions into space. Given likely advancements in commercial spaceflight and increased human presence in low Earth orbit (LEO) in the coming decades, development of these capabilities should be considered as the likelihood of emergent medical evacuation increases.

METHODS

PubMed, Web of Science, Google Scholar, National Aeronautics and Space Administration (NASA) Technical Server, and Defense Technical Information Center were searched from inception to December 2018. Articles specifically addressing critical care and resuscitation during emergency medical evacuation from LEO were selected. Evidence was graded using Oxford Centre for Evidence-Based Medicine guidelines.

RESULTS

The search resulted in 109 articles included in the review with a total of 2,177 subjects. There were two Level I systematic reviews, 33 Level II prospective studies with 647 subjects, seven Level III retrospective studies with 1,455 subjects, and two Level IV case series with four subjects. There were two Level V case reports and 63 pertinent review articles.

DISCUSSION

The development of a medical evacuation capability is an important consideration for future missions. This review revealed potential hurdles in the design of a dedicated LEO evacuation spacecraft. The ability to provide critical care and resuscitation during transport is likely to be limited by mass, volume, cost, and re-entry forces. Stabilization and treatment of the patient should be performed prior to departure, if possible, and emphasis should be on a rapid and safe return to Earth for definitive care.

Airway management in microgravity: A systematic review

INTRODUCTION

In the near future, space programs will shift their focus toward long-duration interplanetary missions, in particular to the Moon and Mars. These exploration missions will be associated with an increased risk of acute medical problems, which will need to be handled by an autonomous crew operating in extreme isolation. An important skill in emergencies is represented by airway management. Many airway devices are available and it is unclear which one would be the most suitable in the context of a space mission. The aim of this systematic review was to analyze the existing literature on airway management in the special situation of weightlessness during space missions.

MATERIAL AND METHODS

We performed a standardized review of published literature on airway management in spaceflight and analogue environments using the database PubMed.

RESULTS

We identified a total of 3111 publications of which 3039 were initially excluded after evaluation. The screening identified three randomized comparative manikin studies, two of them in parabolic flights, one in a submerged setup. Under free-floating conditions, the insertion success rate of supraglottic airway devices (SGA) was excellent (91%-97%). The administration of artificial ventilation could be successfully achieved in weightlessness with SGA. The success rate of conventional laryngoscopy under free-floating conditions fluctuated between 15% and 86%.

CONCLUSION

It appears possible to safely manage the airway in weightlessness, provided that certain conditions are ensured, such as restraining the patient and operator for conventional orotracheal intubation. If airway protection is required with endotracheal intubation, both the operator and the patient should be restrained.

Anaesthesia in austere environments: literature review and considerations for future space exploration missions

Future space exploration missions will take humans far beyond low Earth orbit and require complete crew autonomy. The ability to provide anaesthesia will be important given the expected risk of severe medical events requiring surgery. Knowledge and experience of such procedures during space missions is currently extremely limited. Austere and isolated environments (such as polar bases or submarines) have been used extensively as test beds for spaceflight to probe hazards, train crews, develop clinical protocols and countermeasures for prospective space missions. We have conducted a literature review on anaesthesia in austere environments relevant to distant space missions. In each setting, we assessed how the problems related to the provision of anaesthesia (e.g., medical kit and skills) are dealt with or prepared for. We analysed how these factors could be applied to the unique environment of a space exploration mission. The delivery of anaesthesia will be complicated by many factors including space-induced physiological changes and limitations in skills and equipment. The basic principles of a safe anaesthesia in an austere environment (appropriate training, presence of minimal safety and monitoring equipment, etc.) can be extended to the context of a space exploration mission. Skills redundancy is an important safety factor, and basic competency in anaesthesia should be part of the skillset of several crewmembers. The literature suggests that safe and effective anaesthesia could be achieved by a physician during future space exploration missions. In a life-or-limb situation, non-physicians may be able to conduct anaesthetic procedures, including simplified general anaesthesia.

Comparison of different techniques for in microgravity-a simple mathematic estimation of cardiopulmonary resuscitation quality for space environment

BACKGROUND

Since astronauts are selected carefully, are usually young, and are intensively observed before and during training, relevant medical problems are rare. Nevertheless, there is a certain risk for a cardiac arrest in space requiring cardiopulmonary resuscitation (CPR). Up to now, there are 5 known techniques to perform CPR in microgravity. The aim of the present study was to analyze different techniques for CPR during microgravity about quality of CPR.

MATERIAL AND METHODS

To identify relevant publications on CPR quality in microgravity, a systematic analysis with defined searching criteria was performed in the PubMed database (http://www.pubmed.com). For analysis, the keywords ("reanimation" or "CPR" or "resuscitation") and ("space" or "microgravity" or "weightlessness") and the specific names of the techniques ("Standard-technique" or "Straddling-manoeuvre" or "Reverse-bear-hug-technique" or "Evetts-Russomano-technique" or "Hand-stand-technique") were used. To compare quality and effectiveness of different techniques, we used the compression product (CP), a mathematical estimation for cardiac output.

RESULTS

Using the predefined keywords for literature search, 4 different publications were identified (parabolic flight or under simulated conditions on earth) dealing with CPR efforts in microgravity and giving specific numbers. No study was performed under real-space conditions. Regarding compression depth, the handstand (HS) technique as well as the reverse bear hug (RBH) technique met parameters of the guidelines for CPR in 1G environments best (HS ratio, 0.91 ± 0.07; RBH ratio, 0.82 ± 0.13). Concerning compression rate, 4 of 5 techniques reached the required compression rate (ratio: HS, 1.08 ± 0.11; Evetts-Russomano [ER], 1.01 ± 0.06; standard side straddle, 1.00 ± 0.03; and straddling maneuver, 1.03 ± 0.12). The RBH method did not meet the required criteria (0.89 ± 0.09). The HS method showed the highest cardiac output (69.3% above the required CP), followed by the ER technique (33.0% above the required CP).

CONCLUSIONS

Concerning CPR quality, the HS seems to be most effective to treat a cardiac arrest. In some environmental conditions where this technique cannot be used, the ER technique is a good alternative because CPR quality is only slightly lower.