Indian Journal of Respiratory Care
Volume 9 | Issue 2 | Year 2020

A Syringe-Actuated Metered-Dose Inhaler for Patients with Tracheal Intubation: A Comment

Jay Prakash, Mohd. Saif Khan, Ramesh Kumar Kharwar1 Departments of Critical Care Medicine and 1Intensive Care Medicine, RIMS, Ranchi, Jharkhand, India

Address for correspondence: Dr. Jay Prakash, C/O R. P. Sinha, HI-166, Harmu Housing Colony, Ranchi - 834 002, Jharkhand, India.

E-mail: dr.jay_prakash@rediffmail.com

How to cite this article: Prakash J, Khan MS, Kharwar RK. A syringe- actuated metered-dose inhaler for patients with tracheal intubation: A comment. Indian J Respir Care 2020;9:242.

Received: 28-02-2020

Accepted: 28-02-2020

Published: 19-06-2020


In a letter to the editor by Dubey et al. made for interesting reading.[1] We congratulate the authors for reporting this. In this article, it is mentioned that metered-dose inhaler (MDI) is considered more effective than nebulizers. We would really like to make the following comments:

  1. The spray emerging from MDI can have velocity in excess of 30 m/s,[2] and when this high-velocity spray is delivered directly into the mouth, most of the spray impacts the posterior wall of the oropharynx which is not inhaled. This inertial impaction is reduced by using a spacer device or holding chamber (HC) to reduce the velocity of aerosol delivery. Hence, when the MDI is used alone, 80% of the drug aerosol is deposited in the oropharynx, but when an HC is used with the MDI, drug deposition in the mouth is almost completely eliminated. Hence, HC is recommended for all bronchodilator treatments with MDIs.[3]
  2. The notable features of aerosol drug therapy is the equivalent bronchodilator responses produced by nebulizers and MDIs despite a large drug dosage [Table 1] which shows that dose of albuterol deposited in the lungs would be 12% of 2.5 mg (250 pg) for the nebulizer whereas 9% of 360 pg for MDI (MDI dose of 180 pg represents two puffs) and 20% of 360 pg for MDI with HC. Thus, despite the 3.5-fold difference in drug dose in the airways, the bronchodilator responses produced by nebulizer and MDIs are equivalent.[47] Equivalent responses have also been observed in ventilator-dependent patients.[8,9]
  3. The response or effectiveness of MDIs is optimal when it is used with HC.[9]

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Conflicts of interest

There are no conflicts of interest.

Table 1: Distribution of inhaled albuterol by the delivery system
Site of deposition Nebulizer (2.5 mg) MDI (180 μg) MDI + HC (180 pg)
Exhaled (%) 20 1 1
Apparatus (%) 66 10 78
Oropharynx (%) 2 80 1
Lungs (%) 12 9 20

MDI: Metered-dose inhaler, HC: Holding chamber

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1. Dubey PK, Dubey P, Kumar N. A syringe-actuated metered dose inhaler for patients with tracheal intubation. Indian J Respir Care 2019;8:66-7.

2. Clarke SW, Newman SP. Differences between pressurized aerosol and stable dust particles. Chest 1981;80:907-9.

3. Fink J. Aerosol drug therapy. In: Wilkins RL, Stoller JK, Kacmarek RM, editors. Egan's Fundamentals of Respiratory Care. St. Louis, MO: Mosby, Inc.; 2009. p. 801-39.

4. Fink JB. Metered-dose inhalers, dry powder inhalers, and transitions. Respir Care 2000;45:623-35.

5. Idris AH, McDermott MF, Raucci JC, Morrabel A, McGorray S, Hendeles L. Emergency department treatment of severe asthma. Metered-dose inhaler plus holding chamber is equivalent in effectiveness to nebulizer. Chest 1993;103:665-72.

6. Delgado A, Chou KJ, Silver EJ, Crain EF. Nebulizers vs metered-dose inhalers with spacers for bronchodilator therapy to treat wheezing in children aged 2 to 24 months in a pediatric emergency department. Arch Pediatr Adolesc Med 2003;157:76-80.

7. Batra V, Sethi GR, Sachdev HP. Comparative efficacy of jet nebulizer and metered dose inhaler with spacer device in the treatment of acute asthma. Indian Pediatr 1997;34:497-503.

8. Dhand R, Tobin MJ. Pulmonary perspective: Inhaled bronchodilator therapy in mechanically ventilated patients. Am J Respir Crit Care Med 1997;156:3-10.

9. AARC Clinical Practice Guideline. Selection of device, administration of bronchodilator, and evaluation of response to therapy in mechanically ventilated patients. Respir Care 1999;44:105-13.

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