Pain Pump Law Blog : Medical Device and Malpractice Lawyer & Attorney for Local Anesthetic Infusion Pump & Post-Operative Infection Cases

I am still a bit confused as to whether the new oversight regime the FDA announced yesterday applies to the disposable local anesthetic infusion surgically-implanted pumps that are my focus in this blog.

Reading the New York Times article on the announcement led me to think these devices might be excluded, as it focuses on IV-implanted, programmable devices used to provide insulin, chemotherapy, and pain medications (but patient-controlled).  There have been over 56,000 adverse events and 710 deaths involving these devices in the past 5 years.  These are truly staggering numbers.  Regarding the types of problems reported, the FDA Press Release indicates: The most common types of reported problems have been related to:

* software defects, including failures of built-in safety alarms;
* user interface issues, such as ambiguous on-screen instructions that lead to dosing errors; and
* mechanical or electrical failures, including components that break under routine use, premature battery failures, and sparks or pump fires.

Failures of infusion pumps have been observed across multiple manufacturers and pump types. The FDA says that many of the reported problems appear to be related to deficiencies in device design and engineering.

I saw nothing about shoulder chondrolysis or other injuries from local anesthetics. So far, all of this sure seemed outside the scope of pain pumps. 

The next step up in document complexity is the FDA's White Paper on its Infusion Pump Improvement Initiative.   I read  "In general, an infusion pump is operated by a trained user, who programs the rate and duration of fluid delivery through a built-in software interface" and it confirms my initial belief.   However, then among the pump mechanisms elastomeric is listed and this is one of the most common types for disposable pain pumps.  Finally, at the end of the paper I see among the footnotes:  1 This document does not pertain to implanted infusion pumps, which are surgically placed in the body.  Okay, now I'm pretty sure this significant announcement doesn't apply to the devices with which I'm familiar.  However, there are several additional documents the FDA has included and, for completeness sake, I read on.

The letter to infusion pump manufacturers from Jeffrey E. Shuren, Director of the FDA's Center for Devices and Radiological Health (CDRH) also focuses on software, design, human factors, and manufacturing problems. 

There's detailed information about CDRH's software research on infusion pumps.  I had no idea the FDA has a software engineering laboratory. 

Ultimately, there's the agency's Guidance for Industry and Staff regarding 510(k) Pre-Market Notification Submissions.  This is a draft document (34 pages in PDF form) which will be entering a 90-day comment period.  When complete it will replace the Guidance on the Content of Premarket Notification [510(k)] Submissions for External Infusion Pumps, issued March, 1993.  

My confusion was finally resolved (I think) by reading the Scope section of this document.  It makes clear that all infusion pumps addressed by 21 C.F.R. 880.5725 will be covered by the new guidelines. This includes numerous types of devices including all Elastomeric Infusion Pumps (products coded MEB), and excludes only the following: gallstone dissolution pumps (MHD), opthalmic infusion pumps (MRH), and analytical sampling infusion pumps (LZF).   Just to be sure, I double-checked the most recent 510(k) Submission for the On-Q Painbuster, which confirms the same regulation (880.5725) and product code (MEB). 

So, it does indeed look like I-Flow, Stryker and company will have to learn how to comply with considerable new requirements and provide alot of additional information in future premarket submissions to the FDA.   This is certainly good news, but I have lingering confusion because of the lack of mention in any of these new documents from the FDA of the adverse events involving these devices with which I'm familiar.   An Appendix to the Guidance document lists the following categories of "Risks to Health" with infusion pumps:  Overdose, Underdose, Delay in Therapy, Incorrect Therapy (wrong medication or correct medication but wrong dosage or infusion rate), Air Embolism, Trauma (burns, cuts, abrasions, bruising), Electric Shock, Infection, Allergic Response, and Exsanguanation.  Perhaps the numerous cases of chondroylsis and tissue necrosis are intended to be included in one of these categories (Infection? Allergic Response?). 

When I think again about the number of adverse events--56,000--reported involving all types of infusion pumps over just the last 5 years, I realize that the number involving local anesthetics, even if it's 500 or more, is likely to be less than 1% of the overall events.  Where do local anesthetic infusion pumps and the injuries they appear to cause fit into the broader regulatory and safety scheme involving this class of devices?  My initial reaction is that the problems with pain pumps don't have much to do with design, human factors, or manufacturing issues (and certainly not software).    I will certainly reserve judgment and keep an eye on how the new oversight regime takes shape.  Of course, it will also be interesting to see how these developments may affect litigation involving injuries and deaths from PCA and other programmable pumps.  I can envision claims which were initially viewed as malpractice expanded to also (or instead) focus on the liability of the pump manufacturer. 

 

 

 

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In my last post, I noted the following language in the FDA's November 13, 2009 warning regarding chondrolysis and pain pumps:

Local anesthetics are approved as injections for the production of local or regional anesthesia or analgesia. The approved drug labels for local anesthetics do not include an indication for continuous intra-articular post-operative infusions or use of infusion devices such as elastomeric pumps. The FDA has not cleared any infusion devices with an indication for use in intra-articular infusions of local anesthetics. (emphasis mine)

This is an accurate and important statement:  pain pumps are an off-label use of local anesthetics. 

Someone else, likely on the side of pain pump manufacturers, seems to agree because this language is now missing from an updated version of the FDA Warning, dated February 16, 2010.  The same paragraph now reads:

Local anesthetics are approved as injections for the production of local or regional anesthesia or analgesia. Neither local anesthetics nor infusion devices are approved for an indication of continuous intra-articular infusion.

I gather that since the warning is focused on the association of chondrolysis and pain pumps, the manufacturers either disputed the statement from the FDA that pain pumps are not an approved indication for any use or contended that it was outside the scope of the warning.   The FDA is requiring pain pump manufacturers and, more importantly, local anesthetic manufacturers, to include warnings of the risk of chondrolysis with continuous intra-articular infusion.  It will be especially interesting to see the drug label changes and whether the manufacturers address the risks of continuous infusion in general and not just into joint spaces. 

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On November 13, 2009, the FDA announced it will require pain pump manufacturers and the manufacturers of the local anesthetics used in them to update their product labels to contain a warning about the risk of chondrolysis following continuous infusion with local anesthetics into joint spaces after orthopedic surgery. 

One paragraph of the FDA announcement particularly caught my attention:

Local anesthetics are approved as injections for the production of local or regional anesthesia or analgesia. The approved drug labels for local anesthetics do not include an indication for continuous intra-articular post-operative infusions or use of infusion devices such as elastomeric pumps. The FDA has not cleared any infusion devices with an indication for use in intra-articular infusions of local anesthetics. (emphasis mine)

This statement confirms my contention that continuous infusion via pain pumps is an off-label use of any local anesthetic.  For example, when Hospira in its label for Marcaine (Bupivacaine) makes recommendations for maximum dose volume for particular uses including local infiltration, peripheral nerve blocks, and epidurals, these same recommendations should not be considered applicable to continuous infusion because it is a categorically different use.  

The duration of anesthesia with MARCAINE is such that for most indications, a single dose is sufficient.
Maximum dosage limit must be individualized in each case after evaluating the size and physical status of the patient, as well as the usual rate of systemic absorption from a particular injection site. Most experience to date is with single doses of MARCAINE up to 225 mg with epinephrine 1:200,000 and 175 mg without epinephrine; more or less drug may be used depending on individualization
of each case.
These doses may be repeated up to once every three hours. In clinical studies to date, total daily doses have been up to 400 mg. Until further experience is gained, this dose should not be exceeded in 24 hours. (emphasis mine)

It is clear from the focus on single doses that these recommendations contemplate traditional nerve blocks and not continuous infusion.  As I understand it, most nerve blocks are performed using far less than 175 or 225 mg of Marcaine.  Moreover, the concerns regarding dosage at these volumes have been for neuro- and cardiotoxcity; in other words, systemic and not local toxicities.  Pain pumps represent a categorically different use because of the much larger volume of local anesthetics infused and the great duration of exposure the affected tissues have to the mediation —typically at least two days and as long as five days post-operatively.

Nonetheless, I-Flow's dose recommendations for its own products explicitly rely on the 400 mg total daily maximum recommendation for Marcaine as a toxic ceiling below which pain pumps allegedly may safely continuously infuse this medication.  A commonly-used 100 ml 2 ml/hr. pain pump would mean a 24-hour dose of 240 mg (24 hrs x 2 ml x 5 mg/per ml).  On what evidence are pain pump manufacturers relying that this volume of 0.5% Marcaine is safe for continuous infusion following any surgical procedure? 

Given the known toxic properties of Marcaine and other local anesthetics, in my opinion the proper standard for physicians and manufacturers should be:  what are the lowest dose, concentration, and flow rate that will produce the desired analgesic effect?  Pain pump manufacturers have a financial incentive not to frame the use of their produce in these terms, however.  Because they market their products to surgeons as a more effective alternative to oral narcotics, they are inclined to recommend the use of the most potent of the commonly-used anesthetics--Marcaine--at a high concentration--0.5%--and in large volumes.  More on these issues in my next post.  

 

 

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