In its most recent (April 2009) Directions For Use, I-Flow includes the following language in the Warnings: “To avoid complications in restrictive spaces, use the lowest flow rate, volume and direct concentration to produce the desired result.” Whose responsibility is it to make these determinations? I-Flow and other pain pump manufacturers clearly believe it is solely the physician’s responsibility. After all, it’s the doctor who decides to use the device, which model device to use, what drug to fill it with, and where to place the catheter. However, I strongly believe pain pump manufacturers cannot and should not be able to shift all of the responsibility for these decisions onto physicians.
These manufacturers have a duty to design a product reasonably safe for its intended uses, including surgeries in confined spaces such as the foot, ankle, wrist, hand, and knee. However, when they decided at what volumes to design the balloon or syringe of their pumps and at what flow rate the pumps would infuse local anesthetics, they did not start out by asking what is the lowest flow rate, volume and drug concentration needed to produce pain relief. The standard model pump made by most manufacturers has a 100ml volume and a 2ml/hr flow rate. Is this the lowest volume and flow rate necessary to produce the desired result? I don’t believe pain pump manufacturers know the answer. More disturbingly, I don’t think they believe they need to know. Further, because their competition in the post-operative pain relief market is narcotics, they have an incentive to err on the side of higher volumes and flow rates. Finally, I don’t think most of the surgeons who use pain pumps know the answer to this question either.
It appears that at the outset manufacturers believed that as long as their products delivered local anesthetics below the drug manufacturer’s maximum recommended doses (eg. 400mg for Marcaine), at which the drug may be toxic, there would be little risk of adverse effects. Staying with Marcaine as an example, at 5mg/ml, a pump with a 2ml/hr flow rate x 24 hours would infuse 240mg in the first day of use. (This is assuming a true 2ml/hr flow rate, which is not accurate for most pumps, as I have written about previously HERE). However, the 400 mg maximum daily dose for Marcaine is to guard against the risk of systemic toxicity, such as cardiovascular and neurological, and not local toxicity. There is ample research on the toxic effects of local anesthetics, especially Marcaine, to tissues, as I have written about here and here. Moreover, continuous infusion is not a listed use of local anesthetics by their manufacturers. The approved uses include infiltration/injections, nerve blocks and epidurals. These uses typically involve a single injection, in lower overall volumes, and where large volumes are used, they are directed away from the surgical site.
Until recently, I had been trying to fit the facts of the pain pump cases I am handling into a failure to warn theory. This argument is essentially that the manufacturer was on notice of numerous adverse events similar in nature to those experienced by my clients and was too slow to issue warnings of such risks to its surgeon customers and, when they did issue warnings, the warnings were substantively inadequate and inadequately communicated. While I continue to believe this is a legitimate argument, it is vulnerable to the defense that even had the manufacturer issued a more strongly-worded warning at an earlier time, it may well have made no difference to the patient’s outcome if there is evidence that the surgeon would not have read the warning to begin with.
I have come to believe there is a much stronger design defect claim to be made in these cases. The device manufacturers adamantly contend that all of the crucial decisions regarding the use of their products are in the hands of the surgeon and that you wouldn’t want to obligate the device manufacturer to impose its own decisions as this would limit the ability of the surgeon, who best knows the patient’s needs, to make these decisions. On these grounds, pain pump manufacturers liken their product to a syringe in which the physician makes all the decisions relating to the medication dispensed to the patient. I have sought to respond to this argument in a previous post. ( My response is essentially that the device manufacturer has already made the most important decisions regarding the device—volume and flow rate—before it ever reaches the hands of the doctor. Therefore, no manufacturer is implicitly making recommendations regarding volume and flow rate and that these are reasonably safe. So, this gets us back to the question of whether a 100ml volume pump with a 2ml/hr flow rate is reasonably necessary to provide pain relief to most surgical patients. If the answer to this question is no and there is significant evidence that such a volume and flow rate create a risk of harm to patients, especially in particular procedures, then I believe there is a strong argument that the devices have been defectively designed.
I believe I-Flow acknowledged this problem when, in October 2004, it introduced a new model pump—with 100ml volume and a 1ml/hr –specifically designed for small incisions, including foot, ankle, and hand procedures, hernia repair, laparoscopic procedures, and pediatric surgery. This model device clearly was designed to reduce the risk of local anesthetic building up in a confined space and causing harm to tissues. Inexplicably, however, it appears that I-Flow failed to market this model pump towards its intended audience. Thus, I have argued in the foot surgery cases I have had: Was there an alternative design that could have likely prevented my client’s injuries? Yes. Did it exist? Yes. Who designed it? The defendant.
In my cases, I don’t believe the surgeon was even aware such a model pump existed and he always used a pump with a 2ml/hr flow rate. I-Flow’s response has been, well, that’s the surgeon’s choice and he knows exactly how much medication he wishes to use and how quickly it should be delivered, and where it should be delivered to. This sort of an argument from the device manufacturer would have more weight if the devices were primarily being sold for use by anesthesiologists. However, the customers for these devices are surgeons, who are not experts in the use of higher volumes of local anesthetics. Surgeons are trained to use small amounts to inject around wound sites pre-op or post-op. Nerve blocks or epidurals, which use higher volumes of local anesthetics, can only be performed by anesthesiologists. Continuous infusion is an off-label use and it is a use that is being marketed to non-experts with these drugs—surgeons.
This gets to why, in my opinion, the learned intermediary defense in these cases is so problematic. In my cases, when I asked the podiatrist about his experience with local anesthetics, he replied that he was “Probably expert on them. The people I think that would know more about them than me is a chemist that developed them.” A pain pump manufacturer would likely think this would be helpful to them in making a non-party defense. However, such a statement cuts the other way too: this is the guy you are saying is a learned intermediary? Who used two 100ml 2ml/hr pumps filled with 0.5% Marcaine in my client’s foot? Who admitted he was unaware of the 400mg maximum daily dose for Marcaine? I suspect there are dozens, if not hundreds of surgeons like this foot surgeon who believe they are experts with local anesthetics because they have used them scores of times in high volumes in pain pumps.