Surgical Patients May Be Feeling Pain—and (Mostly) Forgetting It

Friday - 12/01/2018 13:27
Amnesic anesthetics are convenient and help patients make a faster recovery, but they don't necessarily prevent suffering during surgery.
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In June 2007, in a small room that leads into the operating theater, a middle-aged woman lies on a metal trolley. She is here for a hysterectomy, though no one mentions this. She has a cannula taped to the back of her left hand through which her anesthesiologist—a craggy, compact man, handsome, with dark hair graying at the temples and deep-set eyes—will shortly administer a milky drug called propofol.

The anesthesiologist is Ian Russell. The woman, whom I will call Jenny, answers Russell’s questions in bright monosyllables and rolls onto her side and bends her knees obligingly to her stomach, as instructed, for the trainee anesthesiologist to insert first the injection of local anesthetic to the skin and then the epidural cannula through which the nerve-blocking drug will be pumped to switch off sensation in her lower torso. The doctors give directions and make small, cheerful jokes. “[This will be a] little bit ticklish,” says Russell, as the needle is about to enter, and then when Jenny appears not to notice, “Not ticklish. You’re no fun!”

Jenny laughs thinly.

As he works, Russell issues instructions and explanations to the trainee anesthesiologist who is still trying to insert between two vertebrae the implausibly large epidural needle. Then we move through the double doors into an operating theater the size of a small classroom.

Machines bleat and instruments clatter as Russell and his trainee attach monitors. Russell puts a long perpendicular strip of Perspex under Jenny’s body at shoulder height; on top of it is a black mold with a concave channel running its length. This supports Jenny’s extended right arm. Then he attaches a black cuff around her forearm. At her elbow he attaches two more leads that will allow him to send small electric shocks to the nerves which run down her forearm into her hand, to make sure that her nerves and hand muscles are still working when the cuff is inflated.

Russell gives the instruction to start the infusion pumps, which will push the anesthetic into her bloodstream, and then puts a gas mask over her mouth and nose. “Take a big deep breath.” Within seconds she is gone.

* * *

In 1993, as a little-known anesthesiologist from the recursive Hull, England, Russell published a startling study. Using a technique almost primitive in its simplicity, he monitored 32 women undergoing major gynecological surgery at the Hull Royal Infirmary to assess their levels of consciousness. The results convinced him to stop the trial halfway through.

The women were put to sleep with a low-dose anesthetic cocktail that had been recently lauded as providing protection against awareness. The main ingredients were the (then) relatively new drug midazolam, along with a painkiller and muscle relaxant to effectively paralyze her throughout the surgery. Before the women were anesthetized, however, Russell attached what was essentially a blood-pressure cuff around each woman’s forearm. The cuff was then tightened to act as a tourniquet that prevented the flow of blood, and therefore muscle relaxant, to the right hand. Russell hoped to leave open a simple but ingenious channel of communication—like a priority phone line—on the off chance that anyone was there to answer him.

Once the women were unconscious Russell put headphones over their ears through which, throughout all but the final minutes of the operation, he played a prerecorded one-minute continuous-loop cassette. Each message would begin with Russell’s voice repeating the patient’s name twice. Then each woman would hear an identical message. “This is Dr. Russell speaking. If you can hear me, I would like you to open and close the fingers of your right hand, open and close the fingers of your right hand.”

By the time he had tested 32 women, 23 had squeezed his hand when asked if they could hear. Twenty of them indicated they were in pain. At this point he stopped the study.

When interviewed in the recovery room, none of the women claimed to remember anything, though three days later several showed some signs of recall. Two agreed after prompting that they had been asked to do something with their right hand. Neither of them could remember what it was, but while they were thinking about it, said Russell, both involuntarily opened and closed that hand. Fourteen of the patients in the study (including one who was later excluded) showed some signs of light anesthesia (increased heart rate, blood-pressure changes, sweating, tears), but this was true of fewer than half of the hand-squeezers.* Overall, said Russell, such physical signs “seemed of little value” in predicting intraoperative consciousness.

He concluded thus:

If the aim of general anesthesia is to ensure that a patient has no recognizable conscious recall of surgery, and views the perioperative period [during the surgery] as a “positive” experience, then ... [this regimen] may fulfill that requirement. However, the definition of general anesthesia would normally include unconsciousness and freedom from pain during surgery—factors not guaranteed by this technique.
For most of the women in his study, he continued, the state of mind produced by the anesthetic could not be viewed as general anesthesia. Rather, he said, “it should be regarded as general amnesia.”

* * *

The amnesic effects of hypnotic drugs are nothing new. In fact, anesthesiologists—and patients—have long relied upon the fact that, along with erasing consciousness, many hypnotic drugs prevent or disrupt memory. Amnesia—forgetting—is a useful and, many would argue, desirable side effect.

In recent years, however, there has been an increasing reliance on new short-acting intravenous anesthetic drugs with powerful amnesic side effects. Sometimes they are used alone, sometimes in combination. One of the best-known today is the sedative hypnotic midazolam—the drug that Russell was using on the women in the abandoned 1993 study. Another is propofol—the drug that he has just given Jenny to put her to sleep, and which today is probably the most popular intravenous anesthetic in the world.

These drugs have many benefits in today’s hospitals. They allow for a smoother slide into unconsciousness and, because they pass through the body relatively quickly, they allow doctors and nurse anesthetists to give patients less anesthetic—putting them at lower risk of drug-related harm and allowing them to wake up quicker, and with less nausea. Anesthesiologists love them. And so do patients, on the whole.

What we as patients may not have considered, though, is that we are likely to start losing our memory for events well before we lose our consciousness of what is happening to us.

The U.S. anesthesiologist Peter Sebel has described a disconcerting plane flight during which he took a low dose of a drug known as a benzodiazepine (the best known are probably Xanax and Valium, but midazolam is another). He then ate a meal and made apparently coherent conversation with a fellow passenger, after which he went to sleep and woke up remembering nothing at all of the trip.
Sebel had spent a chunk of his evening in a curious fugue state—fully conscious in the moment but unable to hold onto it in memory, or to know, except through the testimony of others, what had happened to him during that gap in time. It is a gap vaguely recognizable by anyone who has woken from an alcoholic stupor to find indefinite sections of the previous night missing. It is a gap also exploited by (mainly) men who covertly spike the drinks of (mainly) young women with a powerful drug called Rohypnol, once used as a premed in anesthesia but now best known as the “date rape” drug.

More benignly, this gap is increasingly used by doctors for a growing subset of awkward medical procedures—ones that would once have been performed under general anesthetic but can now take place in a state that anesthetists sometimes call twilight sleep or, less poetically, conscious or procedural sedation.

The advantages for both doctors and patients are clear. Sedated patients may be able to cooperate with staff, move when directed, cough on command, and answer questions about their experiences. Smaller doses of drugs mean procedures that would once have required a night in hospital now take only hours. People “wake” feeling sprightly, without the undertow of grogginess and nausea that might once have taken days to clear, or the risks of overdose. And, perhaps crucially, they are spared from remembering the indignity or discomfort of having a probe sent up their anus or down their gullet while in communion with a group of fully dressed doctors, nurses and other staff. It seems a convenient arrangement all around.

It is unsettling, though, to consider that at the heart of this altered state is an absence not necessarily of self but of memory—an oblivion at once retrospective and subjective. For the assembled doctors, nurses and anesthesiologists, the working day is ticking by as predictably and incrementally as ever, as they delve into and perhaps chat with their seemingly cognizant charge. For the patient, time is being swallowed, or perhaps they are being swallowed by time, only to be spat out again later as if from a dreamless, unyielding sleep.

* * *

Twenty years after that discontinued study, Russell staged similar experiments using the isolated-forearm technique alongside a bispectral-index monitor (BIS), which tracks depth of anesthesia. While the number of women who responded dropped to one-third when staff used an inhalation anesthetic, another study using the intravenous drug propofol showed that during BIS-guided surgery, nearly three-quarters of patients still responded to command—half those responses within the manufacturer’s recommended surgical range.

Russell is an admirer of the BIS, which he considers a useful tool, but his concern about brain monitors more generally is that the complex algorithms on which they are based tell the anesthesiologist only the probability that a particular patient is asleep at any single point, and cannot account for the natural variability between patients.

Today, debate still ticks back and forth over the benefits and limitations of both the isolated forearm technique and the BIS monitor. Russell’s results have been disputed. But Russell loves propofol. It is fast and effective. His patients wake up happy and refreshed. He remembers one woman complaining when he woke her, saying he had interrupted a nice dream. Propofol is like a little holiday. By titrating the drug with the help of the isolated-forearm technique, Russell is confident he can find that sweet spot between too little anesthetic (and the possibility of patients waking) and too much, which carries its own health risks.

Propofol is now coursing through Jenny’s bloodstream as the surgeon plucks and snips at her abdomen. Unlike many anesthesiologists, Russell does not even combine it with a gas anesthetic to give him more certainty. He says he already has certainty. The problem as he sees it is not with propofol, but with the doctors who use it, many of whom, he claims, unwittingly do so too sparingly. This is particularly relevant when patients are paralyzed. “Basically what is happening is you’re tying the patients onto the operating table with your muscle relaxants, and they may be awake.” He says his technique allows him to keep paralyzed patients as lightly anesthetized as possible while ensuring they are actually unconscious.

The operation is nearly over. The doctors are stitching Jenny’s abdomen. Russell starts to lighten the anesthetic.

“Here we go,” he says, with interest, and moves across to take her hand.

“Jenny, squeeze my fingers with your right hand.”

And this is the moment.

From where I stand against the wall, level with her arm, I watch her hand close firmly and unambiguously over his.

“That’s excellent. Wonderful. Now I want to know if you’re comfortable, Jenny. If you’re comfortable, squeeze my hand twice.”

Her hand closes once more, clearly, purposefully. And again.

Like a message from a miner trapped far underground.

“That’s fantastic,” Russell tells her, “Okay. Operation’s nearly finished. Everything’s going well.”

This post is adapted from Cole-Adams’s new book, Anesthesia: The Gift of Oblivion and the Mystery of Consciousness .

* This article previously misstated the number of patients in Russell's study who responded to Russell's question and showed signs of light anesthesia. We regret the error.

Under the study design, if a patient appeared to move her hand in response to the taped command, Russell was to hold her hand, raise one of the earpieces and say her name, then deliver this instruction: “If you can hear me, squeeze my fingers.” If the woman responded, Russell would ask her to let him know, by squeezing again, if she was feeling any pain. In either of these scenarios, he would then administer a hypnotic drug to put her back to sleep.

Source: TheAtlantics

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