SkeptVet’s Acupuncture Adventure- Part 5: Anesthesia and Analgesia

The latest lecture in my acupuncture course concerns the use of acupuncture in patients undergoing anesthesia and surgery. Most of the lecture focuses on the potential role of acupuncture in reducing pain or mitigating some of the undesirable effects of sedatives and anesthetics. Use in reducing pain has always been one of the most common and widely accepted of claims for acupuncture, as well as one of the most difficult to validate convincingly given the influence of placebo and other non-specific effects and the challenges of designing effectively blinded acupuncture studies.

The lecturer was, as usual, very clear about not using acupuncture as a substitute for conventional treatment: “Acupuncture has a role in perioperative pain control but should be introduced as an adjunct rather than replacement for conventional anesthesia and analgesia.” She also admitted that the effects of even apparently positive studies were modest (effect sizes of perhaps 10-20%) and that the evidence was only “robust” in her view for needling that employed electrical stimulation.

This is consistent with my view of the evidence that the effects sometimes claimed for acupuncture might be more appropriately seen as effects of electrical stimulation of the nervous system. Reframing the discussion this way might reduce the infiltration of TCM nonsense into attempts to approach the study of electrical stimulation of this sort scientifically, and it might be less likely to give unearned legitimacy to pseudoscience than calling this “acupuncture.”

A large number of studies were referenced, and I have tried to read as many of these as possible and look at their findings objectively. Several experimental studies do show evidence of potentially beneficial physiological effects, though again the clinical value of these interventions would need to be demonstrated with appropriate clinical research.

Groppetti, A. M. Pecile, P. Sacerdote, V. Bronzo and G. Ravasio. Effectiveness of electroacupuncture analgesia compared with opioid administration in a dog model: a pilot study. British Journal of Anaesthesia 107 (4): 612–18 (2011).

The first study I’ll mention is one I have discussed before. The authors claims to have “demonstrated the ability of electroacupuncture to decrease anaesthetic and analgesic requirements in dogs during and after surgical neutering.” However, as I pointed out in my previous evaluation, the effects were minimal and of questionable clinical relevance, and the comparison treatment was a drug likely to have little or no meaningful analgesic efficacy. At best, the study showed some measures of pain, though not all nor the most objective ones, might respond to electrical stimulation, perhaps as a form of diffuse noxious inhibitory control. This does little, however, to support the idea that acupuncture as traditionally practiced, has significant value as a post-operative analgesic.

To her credit, the instructor of this course did acknowledge some of the limitations of this study, including the poor choice of comparison agent, though she still interpreted the results more charitably than I would.

Langenbach MR, Aydemir-Dogruyol K, Issel R, Sauerland S. Randomized sham-controlled trial of acupuncture for postoperative pain control after stapled haemorrhoidopexy. Colorectal Dis. 2012 Aug;14(8):e486-91.

The authors of this study performed acupuncture and an attempted sham-acupuncture procedure on patients in additional to conventional pain control. The study suffered from all of the usual problems with acupuncture studies. The therapists, of course, were not blinded. Arguably the patients were not blinded either since the acupuncturists judged whether their needling was appropriate based on trying to induce the “de-qi” sensation, a subjective feeling patients often experience with acupuncture. If control subjects did not have a similar sensation, particularly if they had experienced acupuncture previously, then they would be aware of the treatment they were getting. Also, the sham acupuncture involved actual needling, which often seems to have as much effect as needling at chosen or traditional sites.

Finally, the outcome measure, pain, was subjective and so likely subject to potential bias, especially with ineffective sham control. Objective measures, like HR and BP, were not affected.

The primary outcome, a difference in pain scores between conventional and acupuncture groups, was not achieved, so the study essentially failed to show a benefit. However, there was a statistical difference in pain scores between the sham and verum acupuncture groups, which one would expect if patients were able to determine whether they were getting verum or fake acupuncture treatment.

The authors’ bias was clear in their conclusion, which despite the failure to find the primary outcome they had predicted stated, “Although the difference between verum acupuncture and conventional analgesia was not statistically significant, this study has partly confirmed the analgesic efficacy of acupuncture.”

Skarda, RT. Tejwani, GA. Muir, WW III.  Cutaneous analgesia, hemodynamic and respiratory effects, and ?-endorphin concentration in spinal fluid and plasma of horses after acupuncture and electroacupuncture. AJVR. 2002;63(10):1435-1442.

This study rotated a small number of horses through three conditions- needling, needling with electrical stimulation, and no treatment. The primary outcome tested with a skin twitch or avoidance response to a heating element placed on the skin, intended to be a measure of pain response.

There was no blinding, and both the stimulus (a heating element manually held on the horses’ skin) and the response (skin twitch or avoidance movement) have some element of subjectivity, bias cannot be ruled out. The authors recognized this, but though they chose to have all assessments done by the same investigator to minimize individual variation, they did not blind this assessor to the treatment.

The authors reported that horses tolerated higher temperatures before reacting with needling and electrical stimulation than with no treatment. There was not sham acupuncture treatment, and beta-endorphin levels did not differ among the groups.

Culp LB, Skarda RT, Muir WW 3rd. Comparisons of the effects of acupuncture, electroacupuncture, and transcutaneous cranial electrical stimulation on the minimum alveolar concentration of isoflurane in dogs. Am J Vet Res. 2005 Aug;66(8):1364-70.

This study rotated 8 laboratory beagles though three conditions: needling, needling with electrical current applied, electrical current applied through electrodes placed on the skin as would be done for transcutaneous electrical nerve stimulation (TENS) in humans. The subjects were anesthetized, and the goal was to determine if the minimum alveolar concentration (MAC), that is the level of gas required to achieve full anesthesia, was reduced by the treatments.

All three treatments apparently reduced the MAC (8.4% for needling, 10% for needling with electrical stimulation, and 13.4% for TENS). According to the authors, needling with electrical stimulation and TENS reduced MC by a statistically significant amount while needling alone did not, though the appropriate statistics were not reported in the paper. This would appear to show that any effect was due to the electrical stimulation, regardless of how it was applied, not to “acupuncture” per se. Most other values measure, such as heart rate, blood pressure, etc., did not show significant effects.

It is difficult to see how this study could be viewed as validating acupuncture as an analgesic or anesthetic treatment, though again it does support the idea that electrical nerve stimulation, done  through “acupuncture” needles or by other means, may have some useful effects.

Suo XY, Du ZH, Wang HS, Li JG, Wang YL, Yao SD, Chen WM. The effects of stimulation at acupoint ST36 points against hemorrhagic shock in dogs. Am J Emerg Med. 2011 Nov;29(9):1188-93.

This was, by far, the most compelling paper discussed in this course so far. Though the model used is disturbing on an ethical level, it does appear to show some unequivocal and potentially significant effects. Thirty dogs were divided into 5 groups (whether they were randomly divided is not stated). One group was anesthetized and had unspecified surgical procedures. The other groups were all anesthetized and had a sufficient volume of blood removed do induce a state of circulatory shock. Of these, some were treated with needling and electrical stimulation at a designated acupuncture point (“electroacupuncture”), some were given needling and electrical stimulation at a supposed “non-acupuncture” location, some were given the electroacupuncture after the vagus nerve was severed, and some were placed into shock and received no treatment. The goal was to identify objective physiological responses to the treatments that would reduce the effects of the induced shock state.

All of the measures of cardiovascular function (such as blood pressure) and other indicators of shock (such as blood lactate level) were significantly improved by the electroacupuncture treatment compared to no treatment, and none were significantly altered by the non-acupuncture electrical stimulation. Most interestingly, the effect of the electroacupuncture was abolished by cutting the vague nerve, suggesting a mechanism by which the electrical stimulation of the nervous system could have influenced the response to the induced shock. Some, though not all, of the differences with electroacupuncture were large enough to potentially be clinically relevant.

Clearly, this model shows that the electroacuuncture treatment had objective and significant physiologic effects on dogs with induced hemodynamic shock, and in demonstrating the effects can be blocked by vagus nerve transection it provides a plausible mechanism for these effects im terms of stimulation of the autonomic nervous system. However, there are several features of this study which raise questions.

There was, for example, no needling without electrical stimulation, which is how acupuncture is often done. As I have pointed out repeatedly, the best evidence for objective and potentially meaningful biological effects for acupuncture come from studies using electrical stimulation, and it seems quite likely that it is this stimulation, rather than the use of needles or the selection of needling locations according to traditional methods that is responsible for any real benfits electroacupuncture might have. In many studies, other kinds of electrical stimulation, such as conventional TENS, have effects equivalent to electroacupuncture, which supports this interpretation. However, as in this study some research suggests that the selection of locations for electrical stimulation, with or without needling, may sometimes make a difference in the effects seen.

This study also does not provide direct evidence of a clinically relevant therapy. Clearly, one would not subject a dog in naturally occurring hemorrhagic shock to 30 minutes of electroacupuncture as a primary therapy, when there is far stronger evidence at all levels that fluid replacement and other interventions are more effective and appropriate. Electrical stimulation such as used in this laboratory odel might be a useful adjunctive treatment in such a situation, though from a practical perspective I suspect it would be logistically challenging to employ needling and electrical stimulation to a critical patient receiving intensive care in an emergency hospital setting.

However, this study does provide the best evidence I have yet seen for effects of electrical stimulation through acupuncture needles that might be significant and useful. It reinforces that there is some plausibility to the use of such needling and electrical stimulation even if it has little to do with traditional acupuncture methods.

Acupuncture Anesthesia
For the first time in this course, the lecturer did stray into what I consider complete nonsense by suggesting, albeit somewhat hesitantly and obliquely, that acupuncture might be effective as the sole form of anesthesia for some surgical procedures. She did not appear to be suggesting this actually be done in veterinary patients, but she did appear to believe some of the bogus claims that in China “acupuncture anesthesia” has been convincingly demonstrated to work. This is a popular misconception that has been debunked in detail elsewhere:

The ‘Acupuncture Anesthesia’ series from Science-bases Medicine:

  1. “Acupuncture Anesthesia”: A Proclamation from Chairman Mao (Part I)
  2. “Acupuncture Anesthesia”: A Proclamation from Chairman Mao (Part II)
  3. “Acupuncture Anesthesia”: A Proclamation from Chairman Mao (Part III)
  4. “Acupuncture Anesthesia”: A Proclamation from Chairman Mao (Part IV)
  5. ‘Acupuncture Anesthesia’ Redux: another Skeptic and an Unfortunate Misportrayal at the NCCAM

The article Nonsense with Needles from the Acupuncturewatch site also covers this claim in detail. The bottom line is that investigations of claims for the use of acupuncture as a sole anesthetic agent in China uncover a large number of reasons to disbelieve these claims:

  1. Patients receiving acupuncture anesthesia almost always receive conventional sedatives (such as phenobarbitol), narcotic pain medications (such as meperidine), and local anesthetics in addition to acupuncture.
  2. Only 5-10% of  surgical cases employ acupuncture anesthesia, and only healthy, young, adult patients undergoing relatively straightforward procedures are selected. These are the patients most willing and able to withstand procedures with incomplete or inadequate pain control. We must remember, people can endure surgical procedures without any anesthesia or pain control, and they have done so for thousands of years before the invention of modern anesthetics and pain control drugs. It is dangerous and, in this day and age, unnecessary, but it is possible.
  3. Witnesses from outside China who have seen these procedures often report signs of discomfort in patients who, for cultural and political reasons, are not free to honestly acknowledge or report their discomfort.

Bottom Line
The evidence discussed in this lecture generally does not support a claim of significant beneficial effects for acupuncture, defined simply as needling traditional points, in anesthetic and surgical patients. However, there is some evidence that electrical stimulation through acupuncture needles does have some objective and potentially useful physiologic effects. As I have often said, isolating and validating these effects in clinical patients, and separating them from the mythology attached to traditional acupuncture would be useful, but it is quite challenging given the dense concretion of ideology and faith-based practices associated with acupuncture.

In general, the instructors of this course have been measured and reasonable in their claims and have relied on scientific evidence to support them, though they do seem to interpret this evidence more favorably than seems justified to me. The only significant lapse in the science-based perspective I have seen so far has been the apparent acceptance of claims regarding acupuncture anesthesia in China, claims which are clearly false.

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4 Responses to SkeptVet’s Acupuncture Adventure- Part 5: Anesthesia and Analgesia

  1. Art Malernee dvm says:

    In case you were wondering why the vets who teach students anesthesiology at the vet schools that teach acupuncture keep their mouth shut.

  2. Beccy Higman says:

    As someone who occasionally uses TENS for chronic abdominal pain caused by adhesions I am very aware that accurate placement of the electrodes is crucial for pain obscuration. I wonder if the effects seen from electrical stimulation via acuputure needles require such precision? This could easily explain the difference seen between the two techniques. I am not sure how you could accurately find the correct placement that would ‘block ‘the pain if your patient can not describe whether they are feeling pain or the twitchy tic-in-the-eyelid feeling you get when the TENS electrodes are in the right place. That twitchy tic-in-the-eyelid feeling is why I don’t find TENS very useful, it’s not as if you can forget you have a chronic pain problem while using it.

  3. skeptvet says:

    One of the major differences between TENS and electro-acupuncture is the selection of points for stimulation. Acupuncture points are still largely selected based on transposition to animals of human point and meridian maps which were derived via Chinese Medicine theory and practice. Since these original maps were made with virtually no knowledge of anatomy and physiology, and largely based on philosophical, astrological, and other on-scientific principles, they often have little relationship to things that one might want to stimulate electrically based on scientific principles. And though acupuncturists feel that they can, to some extent, identify locations of pain or muscle tension in animals by palpation and observation, I agree that it is difficult to know how effective one is in relieving pain without explicit feedback from the patient. In human acupuncture, the “de-qi” sensation is often used as a marker that one has effectively stimulated points, and while this is still subjective and subject to placebo effects, it at least provides some measure that one has done something to the patient. This too is for the most part absent in the veterinary domain.

    So while there are similarities between TENS and electro-acupuncture, and some evidence that electrical stimulation via acupuncture needles might have some useful effects, it is still not clear that electro-acupuncture is a reliable or predictable way to use electrical stimulation to relieve pain or induce other desired responses.

  4. Jo says:

    I am ok with trying acupuncture–administered by a well-trained veterinarian who knows what the hell they’re doing–to help relieve some types of pain in animals. I’ve had senior cats with osteoarthritis undergo acupuncture by two knowledgeable vets of mine. We had some success with two cats and none with the other, so my jury is still out. But I shutter to think that ANY vet is using acupuncture as a form of even partial anesthesia on animals! What a horribly painful disaster this very well could be and is on helpless animals. We just don’t know near enough about acupuncture and its effects on the body to put animals through this. God knows the disastrous results that have surely occurred in studies using live animals. NO way would I let a vet use acupuncture as a form of anesthesia! Appreciate the article, however, as I do all of your writings!

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