THE NIGHT­MARE OF WAK­ING MID-SURGERY

AWARE­NESS DUR­ING SURGERY

Saskatoon StarPhoenix - - NP - SHARON KIRKEY

In cool, clin­i­cal lan­guage it’s known as “un­in­tended in­tra­op­er­a­tive aware­ness with re­call” — wak­ing dur­ing surgery, un­able to speak or move.

It’s es­ti­mated as many as one or two in ev­ery 1,000 peo­ple who re­ceive gen­eral anes­the­sia ex­pe­ri­ence it. Peo­ple have de­scribed wak­ing with their eyes taped shut and hear­ing sur­geons say, “cut deeper,” or hands mov­ing in­stru­ments in­side their bod­ies and try­ing des­per­ately to sig­nal — with a shrug, a twitch — that they’re con­scious.

Now, re­searchers are try­ing to re­duce the rare but real night­mare phe­nom­e­non by ap­ply­ing what they’re learn­ing from an­other group of pa­tients who ap­pear to lack con­scious­ness but who are aware: peo­ple mis­di­ag­nosed as be­ing in a veg­e­ta­tive state.

The goal, they say, is to min­i­mize the harm to peo­ple of sur­gi­cal aware­ness and find better ways to de­tect con­scious thought in peo­ple be­lieved to be en­tirely obliv­i­ous. No mon­i­tor ex­ists now that can rule aware­ness out in 100 per cent of cases.

Some 20,000 to 40,000 peo­ple ex­pe­ri­ence ac­ci­den­tal aware­ness a year in the U.S. alone, the re­search team, which in­cludes renowned West­ern Univer­sity neu­ro­sci­en­tist Adrian Owen, wrote in a re­cent is­sue of the jour­nal Anes­the­sia & Anal­ge­sia. Some­times the anes­thetist sim­ply gives too lit­tle anes­the­sia by er­ror. Some pa­tients are more re­sis­tant to the drugs and don’t re­spond in nor­mal ways.

When it hap­pens, peo­ple re­port hear­ing voices or the sound of equip­ment, feel­ing breath­ing tubes down their throat and, some­times, sear­ing pain. Many ex­pe­ri­ence vivid flash­backs, night­mares and post-trau­matic stress, and avoid any­thing that re­minds them of the trauma, even ly­ing flat.

In May, a Toronto woman who woke dur­ing surgery be­cause of an anes­thetist’s neg­li­gence and felt sur­geons “rip­ping me apart” won Canada’s first mal­prac­tice rul­ing in­volv­ing ac­ci­den­tal aware­ness.

Frozen by par­a­lytic drugs, “the pa­tient had no way of in­di­cat­ing some­thing was wrong,” the judge found.

It’s a sim­i­lar sce­nario for the 13,000 to 53,000 peo­ple in the U.S. in a veg­e­ta­tive state — peo­ple that show no signs of aware­ness and are “be­haviourally non­re­spon­sive.”

Owen and his lab have for years been us­ing brain scans to com­mu­ni­cate with peo­ple con­sid­ered all but dead. In 2011, they re­ported as many as 19 per cent of veg­e­ta­tive pa­tients show signs of “covert” con­scious­ness when their brain waves are mea­sured us­ing a cheap, por­ta­ble bed­side EEG. Of 16 veg­e­ta­tive pa­tients in the study, three re­peat­edly showed ap­pro­pri­ate brain ac­tiv­ity re­sponses when asked to imag­ine mov­ing their right hand and wig­gling their toes.

More re­cently, West­ern neu­ro­sci­en­tists led by Lo­rina Naci, now a pro­fes­sor of psy­chol­ogy at Trin­ity Col­lege Dublin, used a short Al­fred Hitch­cock movie — Bang! You’re Dead! — to de­tect con­scious­ness in a man who had been in a veg­e­ta­tive state for 16 years. While in­side a spe­cial MRI scan­ner, the 34-year-old showed sim­i­lar pat­terns of brain ac­tiv­ity — with peaks and dips at iden­ti­cal points of the movie — as healthy vol­un­teers shown the same eight-minute clip.

Naci and col­league Macken­zie Gra­ham are now ex­plor­ing how to adapt these tech­niques to de­tect when surgery pa­tients have “awak­ened.”

Tra­di­tion­ally, in ad­di­tion to check­ing for in­creased blood pres­sure, pulse and other vi­tal signs, anes­the­si­ol­o­gists look to see if a pa­tient is sweat­ing or tear­ing. But peo­ple can have none of those changes and still be aware.

More re­cently, mon­i­tors such as a de­vice known as BIS, or bis­pec­tral in­dex mon­i­tor, have been de­vel­oped to mea­sure brain ac­tiv­ity to de­ter­mine how deeply a pa­tient is anes­thetized. The mon­i­tor trans­lates the in­for­ma­tion into a sin­gle num­ber, from 100 (wide-awake) to zero (no brain elec­tri­cal ac­tiv­ity). Anes­the­si­ol­o­gists aim for some­where be­tween 40 and 60.

How­ever, two ma­jor stud­ies have found cases of pa­tients who re­ported aware­ness even though the bis­pec­tral read­ings said they were in the “safe ranges” and un­con­scious.

Naci said the mon­i­tors aren’t based on the lat­est un­der­stand­ing of neu­ro­bi­o­log­i­cal mark­ers of con­scious aware­ness gleaned from stud­ies on veg­e­ta­tive state pa­tients.

What’s needed, she be­lieves, is a better way to de­tect higher or­der thoughts.

Anes­thetized pa­tients can’t watch movies. So, Naci is test­ing us­ing au­dio sto­ries — a five-minute seg­ment from the be­gin­ning scenes of the 2008 thriller Taken.

In a pa­per un­der re­view, Naci tested the au­dio-only story on veg­e­ta­tive pa­tients, look­ing at how dif­fer­ent brain net­works are en­gaged by the story, es­pe­cially in re­gions linked to higher level thought and in­for­ma­tion pro­cess­ing.

The goal is to find a com­mon neu­ral code or “sig­na­ture” to de­tect aware­ness.

“What we’re look­ing for is the nat­u­ral en­gage­ment that hap­pens in the brain when we’re lis­ten­ing to a com­plex and in­trigu­ing nar­ra­tive,” Naci said.

The­o­ret­i­cally, surgery pa­tients would be given an EEG hair net and a set of head­phones.

“We would say, ‘we’re go­ing to play this en­gag­ing story for you and all that we want you to do is to at­tend to the story as best you can,’ and that elic­its a cer­tain pat­tern of ac­ti­va­tion in their brain,” said Gra­ham, a post­doc­toral re­searcher at West­ern’s Brain and Mind In­sti­tute.

“Once they become un­con­scious, the pat­tern would be ex­tin­guished. Should they re­gain con­scious­ness and start pay­ing at­ten­tion to the story, we’re go­ing to see this pat­tern of ac­ti­va­tion in the brain, which is only pos­si­ble if they’re con­scious.”

THE PA­TIENT HAD NO WAY OF IN­DI­CAT­ING SOME­THING WAS WRONG.

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