Upper airway patency during ventilation with a new airway device—the glossopalatinal tube

Barrier resuscitation by lay rescuers during COVID-19 pandemic

Aerosols generated from chest compressions and ventilation attempts in patients with cardiac arrest may cause airborne infections. Accordingly, the interim international resuscitation guidelines have restricted basic life support by lay rescuers to compression only and the use of an automated external defibrillator during the COVID-19 pandemic. Although these measures may diminish the risk of infection for laypersons, the missing respiratory support can be detrimental for patients with hypoxia-related cardiac arrest. To overcome this shortcoming we want to introduce a special tool that allows ventilation during barrier resuscitation by laypersons. We hypothesize that the application of a device made of a polyvinyl chloride shield with a centrally installed S-shaped ventilation pipe with integrated filter can provide adequate ventilation while concurrently protecting patient and rescuer from airborne agents. Aerosols from air leakage are removed by adhesion and drainage below the barrier. No specific training other than basic life support is needed. We suggest that a tool of this kind be considered essential equipment and stored together with disposable gloves in public access locations.

Device capable of reducing gastric inflation during artificial ventilation in a manikin model

Gastric inflation is a significant issue when ventilation is performed in cases of unprotected airway. The objective of this study was to compare the amounts of gastric insufflation and tidal volumes produced by a hose-extended bag-valve-mask (BVM) device supplemented by an interposed reservoir bag with a similar BVM without the reservoir in a simulated human model. Fourteen academic dental staff members performed 10 ventilations on a manikin using the reservoir-supplemented device in comparison to the control BVM in a randomized order. Lung compliance was adjusted to 45 (high) and 4.5 mL/mbar (low), and the lower esophageal sphincter pressure (LOSP) simulator to a pressure of 15 and 3 mbar, respectively, in different settings. Lower tidal volumes were observed with the new device than with the control BVM at high compliance with LOSP of 15 mbar (median 506 vs. 787 mL, respectively; p = 0.0002) and LOSP of 3 mbar (median 544 vs. 794 mL, respectively; p = 0.0006), as well as during ventilation at low lung compliance and LOSP of 3mbar (median 131 vs. 163 mL, respectively; p = 0.0342). No differences were detected at low lung compliance and LOSP of 15 mbar (median 175 vs. 194 mL; p = 0.3804). Gastric inflation almost exclusively occurred in case of low lung compliance, being markedly lower with the new device than with the control device at 15 mbar LOSP (300 vs. 2225 mL, respectively; p = 0.0006), and at 3 mbar LOSP (1138 vs. 3050 mL, respectively; p = 0.0001). Application of the hose-extended bag-valve-mask device supplemented with a reservoir bag reduces tidal volumes. Marked reduction of gastric inflation by use of this device becomes effective under conditions with low lung compliance.

Comparison of different flow-reducing bag-valve ventilation devices regarding respiratory mechanics and gastric inflation in an unprotected airway model

OBJECTIVE

Gastric inflation (GI) is a significant issue when ventilation is performed on unprotected airways.

DESIGN

Experimental analysis on the respiratory effects of hose extended bag-valve ventilation devices designed to reduce inspiratory pressure and flow.

SETTING

Laboratory with lung/oesophageal sphincter simulator and pressure-flow-volume analyser. Lung compliance: 300ml/kPa, airway resistance: 0.5kPa/l/s. Lower oesophageal sphincter pressure (LOSP): 0.5kPa.

INTERVENTIONS

Bag-valve ventilation of lung simulator. Twelve academic dental staff members used four devices: Ambu Mark III attached to either a reservoir bag (R) or a pressure relief valve (SV), SMART BAG (SB), and Easy Grip (EG) as control.

RESULTS

After Bonferroni correction (p-level of significance 0.0083) for multiple comparisons, no evidence of difference between inspiratory tidal volumes (TVIN) administered by use of R (median 137ml) and SB (149ml) was found. Differences in TVIN were only detected between R and SV (188ml) (p=0.002). Only a trend towards TVIN differences between SB and R in comparison to EG (195ml) was found (p=0.009). Distributions of peak pressures differed when R (median 0.7kPa) and SV (1.0kPa) (p=0.006) or SB (0.7kPa) and SV (p=0.002) were compared. Peak inspiratory flow rates differed between EG (median 59l/min) and R (32l/min) as well as SB (42l/min) and between SB and SV (50l/min) (all with p=0.001). GI was lowest by use of R (median 103ml) compared to all other devices (EG: 518ml, SV: 394ml, SB: 271ml) (p=0.001). The areas under the pressure/flow over time curves were larger during SB compared to R ventilation. Mean airway pressures were significantly lower by use of R (0.1kPa) compared to SB (0.3kPa) (p<0.008).

CONCLUSION

Lowering GI by pressure-flow reduction may result in lower TV depending on the device used. Lowest GI resulted from R ventilation. This may be explained by the specific pressure/time or flow/time patterns achieved by use of this device.