According to MacIntyre, "Aerosolized delivery in intubated, mechanically ventilated patients," Critical Care Medicine, 1985 (13, 81), the amount of inhaled medicine that gets to the air passages of an intubated patient is even less, about 2.9 percent. This information is according to James Fink.
So according to this evidence, there really is no reason to give an aerosolized breathing treatment to an intubated patient. If a physician wanted to give the equivelent dose to an intubated patient as compared to a nonintubated patient, he would have to give about eight treatments.
According to Gay, et al, "Metered Dose Inhalers for Bronchodilator Delivery in intubated, mechanically ventilated patients," Chest (1991, 99, pages 66-71), a metered dose inhaler treatment is equally effective as compared to a nebulzed breathing treatment.
A 1993 study reported in the American Review of Respiratory Disorders, "Metered Dose Inhaler Versus Nebulized Albuterol in Mechanically Ventilated Patients," concluded that for non-intubated patients a properly used MDI treatment is equally as effective to a nebulized treatment. Yet when a patient is intubated, a nebulzier works better. They conclude as I did above, that to get more of teh medicine, more breathing treatments should be given.
In the study, 7.5 mg of albuterol was given in a breathing treatment led to a reduction in resistance in 8 of 10 patients, and 100 puffs of albuterol MDI had no effect on resistance
A problem with studies like this is the method of delivering the MDI to the patient. Later studies showed that by using appropriate spacers in the ventilator circuit, the MDI is of equal efficacy to an aerosolized breathing treatment.
Plus, as an added incentive not to use an inline nebulizer treatment, some of the aerosolized particles were impacting inside the ventilator, and this was causing problems with the machines. This was the main reason Shoreline Medical does not allow physicians to give nebulizers treatments to intubated patients, and we use MDIs instead.
According to Claude Guerin, et all, "Inhaled Bronchodilator Administration During
Mechanical Ventilation: How to Optimize It, and For Which Clinical Benefit?, Journal of Aerosol Medicine and Pulmonary Drug Delivery, (Volume 21, Number 1, 2008), The amount of bronchodilator that deposits at its site of action depends on:
- Amount of drug
- Inhaled mass
- Deposited mass
The challenges of Mechanical Ventilation on aerosolized deposition to the lungs are:
- Ventilatory circuit
- Endotracheal tube
- Ventilator settings
Guerin, et al, concluded that the ETT is not as significant a barrier as once thought. As I noted above, the key variables that effect deposition to the airway in intubated patients are:
- Attachments of the inhalation device in the inspiratory line 10 to 30 cm to the endotracheal tube
- Use of chamber with metered-dose inhaler
- Dry air
- High tidal volume
- Low respiratory frequency
- Low inspiratory flow (which can increase the drug deposition)
The evidence shows, according to Guerin, et al, that there is no difference between reduction in resistance from an MDI and Nebulizer in an intubated patient, and therefore either one can be used for this reason.
However, many hospitals have chosen to use the MDI instead due to the following reasons:
- Cost effect: Each nebulized treatment exceeds $100, plus the cost of the medicine for each dose. The inhaler is one charge for the medicine, which is probably around $20 (or probably less when you include the hospital discount)
- Time Savings: An inhaler treatment can be given in less time
- MDI = less medicine deposition into the ventilator