Contabilidad del crecimiento

The purpose of this study was to evaluate the efficiency of the aerosol devices and the administration techniques on the drug delivery to spontaneously breathing pediatrics with TT. The percent of albuterol deposited distal to the TT was greater with the pMDI than VMN or JN. The VMN was three fold more efficient than JN. In terms of administration technique, there was no statistically significant difference on aerosol deposition between assisted and unassisted techniques.

Efficiency of aerosol devices on drug delivery

When the pMDI was compared with the JN, we found that despite the smaller nominal dose of the pMDI (432 µg) than the JN (2.5 mg), the amount of drug delivered to the TT was more with the pMDI than the JN. These data are supported by Piccuito and Hess (2005), who compared aerosol delivery between the JN and the pMDI in several conditions to the

spontaneously breathing adult with tracheostomy. In their study, they found that pMDI is more efficient than JN in relation to the percentage of inhaled mass (21 ±1% vs. 15 ± 3%, p= 0.002). However, they reported that the amount of inhaled mass was greater with JN than pMDI (382 ± 68 µg vs. 84 ± 4µg, p < 0.001), while this study found the opposite. The difference in the amount of inhaled mass may attribute to the difference in the amount of fill volume in the JN given in each study. The amount of fill volume of their study was 2.5 mg/4ml, while in this study was 2.5mg/3ml. According to Hess, Fisher, Williams, Pooler, and Kacmarek (1996) study, increasing the amount of fill volume by adding more diluent volume will decrease the amount of drug remaining in the JN after treatment ends and will increase the amount of inhaled medication. Therefore, the higher fill volume in the JN of Piccuito and Hess study lead to an increase in the

amount of the inhaled mass obtained by using the JN than our study. Additionally, the

administration setup of the JN was different between these two studies. Piccuito and Hess capped one end of the JN’s T-piece, while the other end was attached to the T-piece interface via 15 cm flex tube. In this study, one end of the JN’s T–piece was attached to the corrugated tube while the other was connected to the T piece interface (Figure 2A). Capping one end of the JN’s T- piece will increase the amount of the inhaled medication. This difference in the setup of the JN administration contributes also to having higher inhaled mass with the JN in Piccuito and Hess than this study.

When the VMN is compared to the JN, this study found that VMN is three fold more efficient than JN. This result agrees with the findings of Ari et al. (2010), who evaluated aerosol drug delivery in pediatric mechanically ventilated lung model with endotracheal tube. They compared JN and VMN in different positions and bias flows. They found that drug delivery with VMN was 2-4 fold greater than JN in pediatric lung models regardless of position and bias flow. However, the inhaled mass percent of the JN and the VMN in their study was lower than this study. This difference is not surprising since the type of the population tested in this study is spontaneously breathing whereas mechanically ventilated in their study. Dolovich, Killian, Wolff, Obminski, and Newhouse (1977) reported that the mean of the amount of aerosol

deposited in the lung with intermittent positive pressure ventilation was less than quite breathing by 32% despite having the same drug dose in the ultrasonic nebulizer. Another factor that may also attribute to the difference in the amount of aerosol deposition between these studies is the type of the artificial airway used. This study used TT, while they used endotracheal tube. The TT is shorter than the endotracheal tube which means lesser drugs will be lost in the tube. Ari et al. (2012) reported that the TT is more efficient than the endotracheal tube in terms of drug delivery.

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Efficiency of aerosol administration techniques on drug delivery

This study found that adding a manual resuscitation bag to the aerosol device when administrating bronchodilator (assisted technique) does not increase the amount of deposited drug on the TT with all the studied aerosol devices. This result differs from the findings of Ari et al. (2012). In an in vitro study, they evaluated the effect of using different patient interfaces such as T-piece, tracheostomy collar and manual resuscitation bag on aerosol drug delivery through TT and endotracheal tube. They concluded that using the manual resuscitation bag increased lung dose by more than three fold with either TT or endotracheal tube. This difference may account for the difference in breathing parameters, tracheostomy tube size and nebulizer type used in both studies. While Ari et al (2012) used adult breathing parameters (Vt= 450 mL, RR= 20 breaths/min, I:E ratio 1:2) with 8 mm TT size, this study used pediatric breathing parameters suitable for a 2 years old child (RR= 25 breaths/min, Vt= 150 ml, Ti= 0.8 second, and PIF= 20 L/min) with 4.5 mm TT size. The smaller Vt and higher RR with a smaller diameter TT would be expected to reduce the amount drug deposited distal to the airway. They also used evalueMed nebulizer, while this study used Hudson MicroMist nebulizer. Having different brands of

nebulizer may also account for the difference in the amount of deposited drugs.

Clinical Implications

This study provides good guidance to clinicians or caregivers regarding the relative efficiency of these three aerosol delivery devices and the two administration techniques used when administering aerosol therapy to spontaneously breathing pediatrics via TT. For the type of aerosol delivery devices, the pMDI or VMN should be the first selection, making the selection of the JN last option. However, there is no difference between assisted and unassisted aerosol administration techniques when using any one of the aerosol devices. Consequently,

administration technique selection can be determined by the patient comfort level, the need to augment ventilation with a manual resuscitation bag for the specific patient.

Limitations

This experiment was an in vitro study. Thus, the results should be validated by an in vivo study. In addition, the in vivo study provides more clinical responses in pediatric patients

receiving aerosol therapy with different aerosol devices and administration techniques. This study only examined one type and size of the TT and resuscitation bag, as well as one set of breathing parameters.

Future Research

For future studies, we suggest studying the effect of administration technique on aerosol delivery to the pediatric patients by using other types of resuscitation bags, such as a flow inflating bag. Different breathing patterns should be also studied in order to determine how aerosol deposition would be affected by different diseases and patient conditions.

Conclusion

In this in vitro spontaneously breathing pediatric model, drug deposited distal to the TT was influenced by the type of aerosol device used. JN was the least efficient device than both VMN and pMDI. However, drug efficiency was similar with assisted and unassisted aerosol administration techniques. The findings of this study could provide clinical guidance to the health care providers or caregivers in selecting the best method to optimize drug delivery to pediatric patients with TT.

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