use of lidocaine in DCI
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BillP
Senior Member
Hi per:
I don't know a lot about it, but I'll take a stab at it. Lidocaine has been tried as an adjunct to recompression treatment for neurological DCI. There have been some case reports in human divers and I think rat studies that suggest it is of benefit, but at least one pig study that didn't show that it helped. It seems to work best as a continuous infusion, which in most medical centers means continuous ICU or at least subacute unit monitoring. I would think that this would limit its use to the more severe or refractory cases of neurological DCI.
Lidocaine works by stabilizing nerve cell membranes and preventing propagation of nerve impulses. It is also a CNS depressant. I'm only guessing here, but perhaps it reduces the metabolic activity of the nerve cells and thus protects them from hypoxic (oxygen starvation) injury?
Perhaps someone who's actually read the studies (or actually been involved in studies) rather than just read about the studies will be along to give you a better answer.
HTH,
Bill
I don't know a lot about it, but I'll take a stab at it. Lidocaine has been tried as an adjunct to recompression treatment for neurological DCI. There have been some case reports in human divers and I think rat studies that suggest it is of benefit, but at least one pig study that didn't show that it helped. It seems to work best as a continuous infusion, which in most medical centers means continuous ICU or at least subacute unit monitoring. I would think that this would limit its use to the more severe or refractory cases of neurological DCI.
Lidocaine works by stabilizing nerve cell membranes and preventing propagation of nerve impulses. It is also a CNS depressant. I'm only guessing here, but perhaps it reduces the metabolic activity of the nerve cells and thus protects them from hypoxic (oxygen starvation) injury?
Perhaps someone who's actually read the studies (or actually been involved in studies) rather than just read about the studies will be along to give you a better answer.
HTH,
Bill
Dr Deco
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Hello per:
I do not believe that the verdict is in on the value of lidocaine. It is being followed (in the literature) here at NASA, but there is not any definitive conclusion. Since recompression options on the Space Station are limited, adjunctive drug therapy would be of value. As is often true with drugs and DCS, if gas bubbles embolize the circulation to the damaged tissue, the drugs could not be delivered by the blood stream. The mechanisms advanced by BillP are as good as any I have heard; I do not do research work with this drug and havent any first hand experience.
Moon et al (Moon RE; de Lisle Dear G; Stolp BW Treatment of decompression illness and iatrogenic gas embolism. Respir Care Clin N Am 1999 Mar;5(1):93-135.) wrote a review in which they stated that pharmacologic agents (e.g., anticoagulants, lidocaine, antiplatelet agents, corticosteroids, inhibitors of calcium flux) may be useful adjuncts to recompression therapy but they require further study. For patients who respond poorly to recompression therapy, the next advance in the treatment of DCI-induced neural injury is likely to be due to the development of agents that reduce the effects of reperfusion injury and delayed cell death. Reperfusion injury is that resulting from an influx of oxygen and the generation (in high concentration) of oxygen-based free radicals.
Two cases of severe decompression illness for which IV lidocaine was used as adjunctive therapy to recompression and hyperbaric oxygen therapy were described by Cogar (Cogar WB Intravenous lidocaine as adjunctive therapy in the treatment of decompression illness. Ann Emerg Med 1997 Feb;29(2):284-6.) The first patient demonstrated improvement only after lidocaine was added to her treatment. The second patient had essentially complete recovery after only a single treatment despite severe symptoms and a significant delay in presentation. Their conclusion was that these cases support the need for a controlled clinical trial of lidocaine as an adjunct to hyperbaric therapy in decompress on illness.
The pig study was that of Broome and Dick (Broome JR; Dick EJ Neurological decompression illness in swine. Aviat Space Environ Med 1996 Mar;67(3):207-13. In a pig (porcine) model, neurological decompression DCS occurred in 73% of control animals and developed within 2-7 min in 50% of cases. Only 16.4% of pigs made a full functional recovery after recompression treatment. The outcome at 24 h was not improved in 20 pigs that receive adjunctive lidocaine infusion compared to 20 pigs that received saline alone.
Drewry and Gorman (Drewry A; Gorman DF Lidocaine as an adjunct to hyperbaric therapy in decompression illness: a case report. Undersea Biomed Res 1992 May;19(3):187-90. ) described a recreational scuba diver with nervous system decompression illness who had a poor response to hyperbaric therapy. Based on available and supportive in vivo data, he was then given a continuous infusion of lidocaine. Within 24 h of the start of this infusion, he experienced a full resolution of his neurologic deficits. His symptoms recurred 3 days later, but again completely resolved after further hyperbaric therapy and concurrent administration of lidocaine. They concluded that this observation supported the need to conduct trials of lidocaine as an adjunct to hyperbaric therapy in decompression illness
Dr Deco[/]
[sp]For those interested, here is the next scheduled Decompression Physiology course.
http://wrigley.usc.edu/hyperbaric/advdeco.htm Open Link
I do not believe that the verdict is in on the value of lidocaine. It is being followed (in the literature) here at NASA, but there is not any definitive conclusion. Since recompression options on the Space Station are limited, adjunctive drug therapy would be of value. As is often true with drugs and DCS, if gas bubbles embolize the circulation to the damaged tissue, the drugs could not be delivered by the blood stream. The mechanisms advanced by BillP are as good as any I have heard; I do not do research work with this drug and havent any first hand experience.
Moon et al (Moon RE; de Lisle Dear G; Stolp BW Treatment of decompression illness and iatrogenic gas embolism. Respir Care Clin N Am 1999 Mar;5(1):93-135.) wrote a review in which they stated that pharmacologic agents (e.g., anticoagulants, lidocaine, antiplatelet agents, corticosteroids, inhibitors of calcium flux) may be useful adjuncts to recompression therapy but they require further study. For patients who respond poorly to recompression therapy, the next advance in the treatment of DCI-induced neural injury is likely to be due to the development of agents that reduce the effects of reperfusion injury and delayed cell death. Reperfusion injury is that resulting from an influx of oxygen and the generation (in high concentration) of oxygen-based free radicals.
Two cases of severe decompression illness for which IV lidocaine was used as adjunctive therapy to recompression and hyperbaric oxygen therapy were described by Cogar (Cogar WB Intravenous lidocaine as adjunctive therapy in the treatment of decompression illness. Ann Emerg Med 1997 Feb;29(2):284-6.) The first patient demonstrated improvement only after lidocaine was added to her treatment. The second patient had essentially complete recovery after only a single treatment despite severe symptoms and a significant delay in presentation. Their conclusion was that these cases support the need for a controlled clinical trial of lidocaine as an adjunct to hyperbaric therapy in decompress on illness.
The pig study was that of Broome and Dick (Broome JR; Dick EJ Neurological decompression illness in swine. Aviat Space Environ Med 1996 Mar;67(3):207-13. In a pig (porcine) model, neurological decompression DCS occurred in 73% of control animals and developed within 2-7 min in 50% of cases. Only 16.4% of pigs made a full functional recovery after recompression treatment. The outcome at 24 h was not improved in 20 pigs that receive adjunctive lidocaine infusion compared to 20 pigs that received saline alone.
Drewry and Gorman (Drewry A; Gorman DF Lidocaine as an adjunct to hyperbaric therapy in decompression illness: a case report. Undersea Biomed Res 1992 May;19(3):187-90. ) described a recreational scuba diver with nervous system decompression illness who had a poor response to hyperbaric therapy. Based on available and supportive in vivo data, he was then given a continuous infusion of lidocaine. Within 24 h of the start of this infusion, he experienced a full resolution of his neurologic deficits. His symptoms recurred 3 days later, but again completely resolved after further hyperbaric therapy and concurrent administration of lidocaine. They concluded that this observation supported the need to conduct trials of lidocaine as an adjunct to hyperbaric therapy in decompression illness
Dr Deco[/]
[sp]For those interested, here is the next scheduled Decompression Physiology course.
http://wrigley.usc.edu/hyperbaric/advdeco.htm Open Link
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