Effect of Hyperbaric Oxygen and Inflammation on Human Gingival Mesenchymal Stem/Progenitor Cells.

The present study explores for the first time the effect of hyperbaric oxygen (HBO) on gingival mesenchymal stem cells' (G-MSCs) gene expression profile, intracellular pathway activation, pluripotency, and differentiation potential under an experimental inflammatory setup. G-MSCs were isolated from five healthy individuals (n = 5) and characterized. Single (24 h) or double (72 h) HBO stimulation (100% O2, 3 bar, 90 min) was performed under experimental inflammatory [IL-1ß (1 ng/mL)/TNF-α (10 ng/mL)/IFN-γ (100 ng/mL)] and non-inflammatory micro-environment. Next Generation Sequencing and KEGG pathway enrichment analysis, G-MSCs' pluripotency gene expression, Wnt-/ß-catenin pathway activation, proliferation, colony formation, and differentiation were investigated. G-MSCs demonstrated all mesenchymal stem/progenitor cells' characteristics. The beneficial effect of a single HBO stimulation was evident, with anti-inflammatory effects and induction of differentiation (TLL1, ID3, BHLHE40), proliferation/cell survival (BMF, ID3, TXNIP, PDK4, ABL2), migration (ABL2) and osteogenic differentiation (p < 0.05). A second HBO stimulation at 72 h had a detrimental effect, significantly increasing the inflammation-induced cellular stress and ROS accumulation through HMOX1, BHLHE40, and ARL4C amplification and pathway enrichment (p < 0.05). Results outline a positive short-term single HBO anti-inflammatory, regenerative, and differentiation stimulatory effect on G-MSCs. A second (72 h) stimulation is detrimental to the same properties. The current results could open new perspectives in the clinical application of short-termed HBO induction in G-MSCs-mediated periodontal reparative/regenerative mechanisms.

Rescue of drowning victims and divers: is mechanical ventilation possible underwater? A pilot study.

INTRODUCTION: In-water resuscitation has recently been proposed in the European resuscitation guidelines. Initiation of mechanical ventilation underwater might be considered when an immediate ascent to the surface is impossible or dangerous. The present study evaluated the feasibility of such ventilation underwater. METHODS: A resuscitation manikin was ventilated using an Interspiro® MK II full-face mask or with an Oxylator® ventilator via a facemask or a laryngeal tube, or with mouth-to-tube inflation. Tidal volumes achieved by the individual methods of ventilation were assessed. The ventilation tests were performed during dives in the wet compartment of a recompression chamber and in a lake. Ventilation was tested at 40, 30, 20, 12, 9 and 6 metres' depth. RESULTS: Ventilation was impossible with the cuffed mask and only sufficient after laryngeal intubation for a small number of breaths. Laryngeal tube ventilation was associated with the aspiration of large amounts of water and the Oxylator failed during the ascent. Efficient ventilation with the MK II full-face mask was also possible only for a short period. An absolutely horizontal position of the manikin was required for successful ventilation, which is likely to be difficult to achieve in open water. Leakage at the sealing lip of the full-face mask and the cuff of the laryngeal tube led to intrusion of water and resulted in subsequent complete failure of ventilation. CONCLUSIONS: The efficacy of underwater ventilation seems to be poor with any of the techniques trialed. Water aspiration frequently makes ventilation impossible and might foster emphysema aquosum-like air trapping and, therefore, increase the risk of pulmonary barotrauma during ascent. Because the limitations of underwater ventilation are substantial even under ideal conditions, it cannot be recommended presently for real diving conditions.

Effectiveness and safety of in-water resuscitation performed by lifeguards and laypersons: a crossover manikin study.

OBJECTIVE: Drowning is associated with a high mortality and morbidity and a common cause of death. In-water resuscitation (IWR) in the case of drowning accidents has been recommended by certain resuscitation guidelines in the last several years. IWR has been discussed controversially in the past, especially with regard to the delay of chest compressions, effectiveness of ventilation, and hazard to the rescuer. The aim of the present study was to assess the effectiveness and safety of IWR. METHODS: In this crossover manikin study, 21 lifeguards and 21 laypersons performed two rescue procedures in an indoor swimming pool over a 50-meter distance: In random order, one rescue procedure was performed with in-water ventilation and one without. Tidal and minute volumes were recorded using a modified Laerdal Resusci Anne (Laerdal Medical, Stavanger, Norway) and total rescue duration, submersions, water aspiration by the victim, and physical effort were assessed. RESULTS: IWR resulted in significant increases in rescue duration (lifeguards: 106 vs. 82 seconds; laypersons: 133 vs. 106 seconds) and submersions (lifeguards: 3 vs. 1; laypersons: 5 vs. 0). Furthermore, water aspiration (lifeguards: 112 vs. 29 mL; laypersons: 160 vs. 56 mL) and physical effort (lifeguards: visual analog scale [VAS] score 7 vs. 5; laypersons: VAS score 8 vs. 6) increased significantly when IWR was performed. Lifeguards achieved significantly better ventilation characteristics and performed both rescue procedures faster and with lower side effects. IWR performed by laypersons was insufficient with regard to both tidal and minute volumes. CONCLUSIONS: In-water resuscitation is associated with a delay of the rescue procedure and a relevant aspiration of water by the victim. IWR appears to be possible when performed over a short distance by well-trained professionals. The training of lifeguards must place particular emphasis on a reduction of submersions and aspiration when IWR is performed. IWR by laypersons is exhausting, time-consuming, and inefficient and should probably not be recommended. Key words: drowning; near-drowning; hypoxia; ventilation, artificial; respiration, artificial; resuscitation, in-water.

Oxylator and SCUBA dive regulators: useful utilities for in-water resuscitation.

INTRODUCTION: In water resuscitation has been reported to enhance the outcome of drowning victims. Mouth-to-mouth ventilation during swimming is challenging. Therefore, the efficacy of ventilation utilities was evaluated. METHODS: Ventilation was assessed with the Oxylator ventilator, as well as the consecutive self-contained underwater breathing apparatus (SCUBA) regulators using an anaesthetic test lung: Poseidon Cyklon 5000, Poseidon XStream, Apeks TX 100, Spiro Arctic, Scubapro Air2 and Buddy AutoAir. RESULTS: Oxylator, Apeks TX 100, Arctic and Buddy AutoAir delivered reliable peak pressures and tidal volumes. In contrast, the ventilation parameters remarkably depended on duration and depth of pressing the purge button in Poseidon Cyklon 5000, Poseidon XStream and Scubapro Air2. Critical peak pressures occurred during ventilation with all these three regulators. DISCUSSION: The use of Poseidon Cyklon 5000, Poseidon XStream and Scubapro Air2 regulators is consequently not recommended for in-water ventilation. With the limitation that the devices were tested with a test lung and not in a human field study, Apeks TX 100, Spiro Arctic and Buddy AutoAir might be used for emergency ventilation and probably ease in-water resuscitation for the dive buddy of the victim. Professional rescue divers could be equipped with the Oxylator and an oxygen tank to achieve an early onset of efficient in-water ventilation in drowning victims.