An evaluation of cannulae and oxygen sources for pediatric jet ventilation

Emergency cricothyrotomy in infants--evaluation of a novel device in an animal model

BACKGROUND

According to different algorithms of airway management, emergency cricothyrotomy is the final step in managing an otherwise not accessible airway. As an alternative to an open surgical procedure, minimally invasive approaches exist. Quicktrach baby™ is a commercially available set for a minimal invasive cricothyrotomy in infants. The set consists of a plastic cannula over a metal needle for direct placement in the trachea. So far, this device has not been evaluated for its intended use.

OBJECTIVES

We hypothesize that Quicktrach baby™ allows the establishment of an emergency airway. The aim was to prove that the device is easy to handle and the cricothyrotomy fast to perform.

METHODS

After approval of the local ethics committee, the study was performed on the cadavers of 10 adult rabbits. Cricothyrotomy was performed with Quicktrach baby™. Successful placement, performance time, and complication rate were documented. Possible ventilation with a breathing bag was evaluated. Data are reported as mean and interquartile range.

RESULTS

Successful placement of Quicktrach baby™ was possible in all attempts. The placement took 31 [23-43] s. In two cases, a fracture of the cricoid's cartilage was seen. In one animal, damage to the posterior wall mucosa was observed. In all cases, sufficient ventilation was possible.

CONCLUSIONS

Quicktrach™ baby proved to be a reliable technique. In the animal model, it is easy and fast to perform. Only a few minor complications occurred. Sufficient ventilation was possible in all attempts.

Percutaneous needle cricothyroidotomy with repetitive airway obstruction

To develop a technique for needle cricothyrotomy that mimics the normal respiratory cycle (using repetitive obstruction of the upper airway and relatively low flow oxygen through small catheters), a controlled trial in three anesthetized dogs was performed. Oxygen from a standard bottle and pressure reducer was delivered through the cricothyroid membrane at 0.36 L/kg/min, which is metabolically equivalent to 0.2 L/kg/min in an adult human. The upper airway was obstructed until the chest rose and then was unobstructed to allow exhalation. The animals were ventilated for 5 minutes to allow equilibration. Arterial PCO2 was measured after 2-minute periods of apnea and 3 minutes of ventilation, each repeated four times. The procedure was repeated in three other dogs at a flow of 0.18 L/kg/min to simulate a 50% air leak. Cricothyroid ventilation at 0.36 L/kg/min lowered the PCO2 from 65 mm Hg to 43 mm Hg, F = 258, P = .004. All PCO2 after 25 minutes were in the normal range. Ventilation at 0.18 L/kg/min stabilized the PCO2 at approximately 1.5 times normal (67 mm Hg versus 79 mm Hg for the preceding apnea, F = 77, P = .013). Flow rates achievable with 18- to 20-gauge catheters and standard oxygen sources are adequate for cricothyroid ventilation when the airway is repetitively obstructed to allow a normal respiratory cycle.

Translaryngeal jet ventilation and end-tidal PCO2 monitoring during varying degrees of upper airway obstruction

STUDY OBJECTIVES

To explore the ventilatory adequacy of translaryngeal jet ventilation (TLJV) during partial upper airway obstruction and the usefulness of monitoring end-tidal CO2 (PETCO2) during this condition.

DESIGN

Prospective, nonrandomized, sequential crossover design.

SETTING AND PARTICIPANTS

Apneic dog model (five dogs; mean weight, 23 kg).

INTERVENTIONS

Animals were intubated with a 9.0-mm endotracheal tube with the tip positioned above the cricothyroid membrane. Upper airway obstructions of 40%, 69%, and 80% were created. TLJV was performed through the cricothyroid membrane using a 13-gauge catheter with 100% oxygen, 45 psi, 15 breaths per minute, and 30% inspiratory time for 15 minutes at each upper airway obstruction. Data collected at baseline (no upper airway obstruction) and one-minute intervals included arterial blood pressures, continuous PaCO2 measurements, and PETCO2 at the TLJV catheter tip and above the level of obstruction. Arterial blood gases were obtained at 0 and 15 minutes. Data were analyzed using Pearson's correlation, analysis of variance, and Turkey's multiple comparisons (significance, P less than .05).

MEASUREMENTS AND RESULTS

Baseline values for all variables did not significantly differ at the onset of each testing phase. Mean pH increased significantly from baseline during 69% upper airway obstruction (7.36 to 7.54, P less than .05) and 80% upper airway obstruction (7.39 to 7.61, P less than .01). Mean PaCO2 decreased significantly from baseline during all upper airway obstructions: 40% upper airway obstruction (39.9 to 33.6 mm Hg, P less than .01), 69% upper airway obstruction (38.3 to 25.6 mm Hg, P less than .001), and 80% upper airway obstruction (36.2 to 18.2 mm Hg, P less than .001). PaCO2, PETCO2, and pH differed significantly between each level of upper airway obstruction (P less than .01). PETCO2 was significantly correlated with PaCO2 (r = .84, P less than .001) and did not significantly differ from PaCO2. No signs of barotrauma were observed in any animal at any degree of upper airway obstruction.

CONCLUSION

TLJV during partial upper airway obstruction in our model provided safe and adequate-to-supranormal minute ventilation. In fact, marked hypocapnia and alkalemia occurred at levels of 69% and 80% upper airway obstruction, thus dispelling concepts that TLJV may cause hypercapnia during partial upper airway obstruction. PETCO2 correlates well with PaCO2 and may be valuable for monitoring ventilation when using TLJV in the nonobstructed or partially obstructed upper airway.