I AM delighted to report there is now a new version of the In-Check dial (which was last updated six years ago). The revision of the device, I am told, has been triggered due to the large range of new inhaler devices that have recently entered the market.
In-Check is an inhalation airflow meter that can help educate and assess patients who use a pMDI inhaler device. Pressurised inhaler devices are designed to deliver medication to the respiratory tract, and the speed of inhalation through them (the inspiratory flow) can have significant effect on the quantity of drug delivered and the clinical efficacy of the product.
“In-Check M has been developed from the product In-Check DIAL, the device is specific to pMDI use, and simulates this inhaler format only,” says manufacturer Clement-Clarke.
The key features of the device are:
- Easy to clean by simple washing
- pMDI specific: suitable for inhaler technique training
- Use with one-way mouthpiece to minimise cross infection
- Individually calibrated to ensure accuracy.
The device helps practitioners match the correct inhaler to the person’s rate of inhalation. It is recognised widely in the literature now that inspiratory flow rate is very important. All inhalers have an optimum inhalation rate which delivers the optimum amount of drug, and therefore the optimum therapeutic effect. In very simple terms, dry powder inhalers require a fast and deep inhalation but metered dose inhalers require a slow and steady inhalation rate.
So what is new?
The key change for me is as follows:
The previous scale on In-Check DIAL was labelled as optimal inspiratory flow range, and now it is labelled as clinically effect flow range.
Why has Clement-Clarke done this?
“There is evidence from in-vitro studies that has shown that even in the same inhaler different formulations have peak delivery at different flow rates . It has also been found that individual components of certain combinations may behave differently at different flow rates .
While these differences are noticeable in in-vitro analysis, when it comes to clinical efficacy they are not apparent. Therefore In-Check DIAL now refers to the flow ranges that have been shown to be clinically effective through published clinical studies,” says the company.
The In-Check Dial allows practitioners to refine this approach. The design of the new In-Check device revolves around the importance of inhalation rate, and the concept of the therapeutic effectiveness linked to that inhalation rate. There are now five resistance groups:
The old In-check device had a number of settings. Each setting related to a specific inhaler. The new device is slightly different. As described above, and below in the image there are now five bands of resistance. Each inhaler type is linked with one of these bands. The chart below can be used for reference.
As you can see, each resistance group is colour coded. The manufacturer concedes that not every inhaler is covered but most are. As new devices come on the market they have indicated that they will categorise them into one of the five resistance bands. The five resistance bands are approximate. There are restriction adaptors available for more specific resistance requirements. The image below is not very clear but it shows the back of the device and specifically highlights which inhaler fall into which resistance category.
I hope this provides a brief overview of the new device. I for one look forward to using it. Inhaler technique in the care of respiratory patients is of paramount importance. Getting it correct or indeed neglecting it can have far reaching consequences.
Are there any disadvantages to using the new In-Check Dial?
Some concerns have been raised around infection control. This is mitigated by the use of a one way mouthpiece.
Another concern is the fact that the new In-Check device can only measure the peak inspiratory flow rate. It is well known that the flow rate varies throughout inhalation. For this reason, in my view, the new In-Check Dial should be used with caution in this regard.
The assessing practitioner should closely watch the complete inhalation, and consider this when choosing the inhaler. For example a typical dry powder inhaler requires suitable inspiratory flow rate so as to de-aggregate the powder, allowing it to be inhaled. The inspiratory flow rate may be slow to begin with, then increase towards the end. This pattern is not suited to a dry powder inhaler, therefore the assessing practitioner still needs to watch carefully, even though using the In-Check Dial.
Concerns aside, I do feel the new In-Check is a welcome addition to the armoury of the respiratory practitioner. Choosing the inhaler correctly for the patient remains of utmost importance.
1. Measuring charge and mass distributions in dry powder inhalers using the electrical Next Generation Impactor (eNGI). Hoe S, Traini D, Chan HK, Young PM. Eur J Pharm Sci. 2009 Sep 10;38(2):88-94.
2.The influence of flow rate on the aerosol deposition profile and electrostatic charge of single and combination metered dose inhalers. Susan Hoe; Daniela Traini; Hak-Kim Chan; Paul M Young. Pharmaceutical Research – December 2009 (Vol. 26, Issue 12, Pages 2639-2646)
Johnathan Laird is a community pharmacist independent prescriber with a special interest in asthma. He is based in based in Aberdeen.
Follow Johnathan @JohnathanLaird