InvivoPFT 1.0
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Free Version
Publisher Description
invivoPFT is a mobile iPhone app that measures Bleeding Area (BA). Bleeding Area (BA) is defined as the surface area of dried blood spots collected on blotter paper during an Ivy bleeding time (BT) test. Knowing BA, one can determine BV. Bleeding volume (BV) is defined as the volume of bleeding that occurs during an Ivy BT test. Ivy Bleeding Time (BT) is defined as the in-vivo platelet function test that measures the duration of bleeding following a standardized superficial incision (e.g. 1mm deep and 5 mm long) on the proximal forearm. As the blood immerges from the incision, it is collected by gently touching the droplet with the edge of a disc of standardized blotter paper. The blotter paper is rotated and reapplied every 30 seconds until the bleeding has stopped. The number of discrete blood spots on the blotter paper divided by two equals the bleeding time in minutes. In order to minimize the confounding effect of variable venous pressure on capillary bleeding time, Andrew C. Ivy suggested placing a sphygmomanometer on the arm inflated to 40mmHg during the BT test. In our experience, the range of normal bleeding times in adults is approximately 2-8 minutes. Details about the relationship between the Ivy BT test, bleeding area (BA) and bleeding volume (BV) can be found in: Klein JA, vanZandt S, vanZandt J, Zand AN, Klein LEW, Klein PA. Digital photo analysis accurately measures bleeding volume associated with Ivy bleeding time (in preparation). It is shown that BA is a linear function of BV for microliter volumes of blood absorbed onto standardized blotter paper. That is, BA = BV, where the linear coefficient is determined by linear regression. From a clinical perspective, the volume of bleeding is often more relevant than the duration of bleeding. Thus a test that measures bleeding volume has more intuitive appeal than a test that measures bleeding time. invivoPFT provides the first easy and accurate means of measuring BA & BV. It is possible that BA & BV will prove to be a better in-vivo PFT than BT. BT fell into disfavor in the 1990 s when it was realized that the Ivy BT test has poor sensitivity and poor specificity when used for the purpose of predicting excessive surgical bleeding in an individual patient (sample size n = 1). In part, this is due to the fact that BT has a relatively large intra-patient variance ( 2) . However, the BT test becomes more useful when it is used to compare the effect of a drug on platelet function among a large sample of n subjects (n 30). In this case the sample-mean BT has a variance of 2/n. Suppose we want to study the effect of particular drug on in-vivo platelet function. Let BA0 and BV0 represent measurements based on an Ivy BT test done before the drug delivery. Let BAT and BVT represent measurements based on an Ivy BT test done T hours after the drug delivery. Then BA = (BAT BA0)/BA0, is defined as the normalized drug effect on bleeding area. Similarly BV = (BV24 BV0)/BV0, is the normalized drug effect on bleeding volume. In an analogous fashion, BT = (BTT BT0)/BT0 can be defined the normalized drug effect on Ivy bleeding time. This normalization transformation and the linear relationship A = V imply that BA = (BAT BA0)/BA0 = ( BVT BV0)/ BV0 = (BVT BV0)/ BV0 = (BVT BV0)/BV0 = BV In other words, BA = BV represents both the proportional change of BA and the proportional change of BV after drug delivery. Furthermore, the term is unimportant when measuring the drug treatment effect on BV. Statistical tests based on either BA or BV are equivalent.
Requires iOS 5.1.1 or later. Compatible with iPhone, iPad, and iPod touch.
About InvivoPFT
InvivoPFT is a free app for iOS published in the Health & Nutrition list of apps, part of Home & Hobby.
The company that develops InvivoPFT is Jeffrey Klein, MD. The latest version released by its developer is 1.0.
To install InvivoPFT on your iOS device, just click the green Continue To App button above to start the installation process. The app is listed on our website since 2014-10-28 and was downloaded 0 times. We have already checked if the download link is safe, however for your own protection we recommend that you scan the downloaded app with your antivirus. Your antivirus may detect the InvivoPFT as malware if the download link is broken.
How to install InvivoPFT on your iOS device:
- Click on the Continue To App button on our website. This will redirect you to the App Store.
- Once the InvivoPFT is shown in the iTunes listing of your iOS device, you can start its download and installation. Tap on the GET button to the right of the app to start downloading it.
- If you are not logged-in the iOS appstore app, you'll be prompted for your your Apple ID and/or password.
- After InvivoPFT is downloaded, you'll see an INSTALL button to the right. Tap on it to start the actual installation of the iOS app.
- Once installation is finished you can tap on the OPEN button to start it. Its icon will also be added to your device home screen.
