Monthly Archives: November 2012

The Toyota approach to anaesthesia- small continuous improvements: using placebo, IV cannulation, echo, blocks and compression devices

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Toyota is famous for improving their cars through a process of continuous, small, incremental improvements, a technique known as Kaizen, or the Toyota way. In this way many small improvements, each inconsequential on their own, when added together produce significant results.

I think this is a great model to use when looking at anaesthesia. Anaesthesia and surgery are complicated processes, and most of the “low hanging fruit” in terms of safety improvements have already been made. It is unlikely that any single factor will make a major difference to outcomes. However that doesn’t mean we should stop trying to improve, and using a wide range of small improvements in different areas will collectively improve the patient’s experience.

An example of this is IV cannulation, something we all do every day and which we often forget can be quite painful. In addition, this is often patient’s only way of judging the ability of their anaesthetist. I recall a poster presentation where only 2 things determined a patients satisfaction with their anaesthetist- did the IV hurt, and did they visit the patient more than just in recovery. The patient has no baseline to judge postoperative pain or nausea and can awaken after all sorts of intraoperative near-catastrophes none the wiser, however if you want to make a patient happy, get the drip in first time and make sure it doesn’t hurt!

Two articles on this topic have got my attention and changed my practice. Both involve randomised trials where patients were either warned they were going to feel a “sharp sting” or used more neutral and comforting words, eg  “I am going to apply the tourniquet on the arm. As I do this many people find the arm becomes heavy, numb and tingly. This allows the drip to be placed more comfortably”. The patients not only reported lower pain scores but were also less likely to withdraw their hand in the “kind words” group compared to the “nocebo” group. This is contrary to the common practice of warning someone, with the rational that it then won’t be as bad as they expect. In fact all this achieves is heightened anxiety and more pain (read here and here).

This is an example of avoiding the “nocebo” (opposite of placebo) effect of harsh words like sharp, sting, needle and pain. There is increasing evidence that placebo plays a major part in many interventions. Recently i went to an intriguing talk about placebo where the concept of the “open/hidden” trial was discussed. This is the opposite to a placebo controlled trial. Instead of everyone getting told they were getting morphine and half getting a sugar pill, all patients get given morphine but only half are told about it. The rest had it quietly slipped into a bag of fluid without being told. There were significantly greater reductions in pain in the group that were told they were getting the “powerful painkiller”, compared to the group that had it slipped into their fluids. The presenter gave a range of slides for different analgesics showing that for virtually all of them the pain score reductions were double in the open  “powerful painkiller” group compared to the hidden ones.

Finally, three further topics for the “continuous improvement” theme, all of which i will talk about more in the future.

The first is transthoracic echo for use by anaesthetists in preoperative assessment. This is something that was big when I was doing my fellowship at the Royal Melbourne Hospital and is spreading around the world rapidly. In this month’s Anaesthesia the RMH team have provided the first (weak) evidence that preoperative echo may improve outcome, instead of simply changing management (which has been shown in previous studies). The study is observational, of poor quality, subject to the Hawthorne effect and shows an implausibly large mortality difference, but for all that makes pleasing reading for transthoracic echo exponents such as myself (reference here).

The second is the use of dexamethasone to prolong peripheral nerve blocks. This is something we have been doing recently in our hospital in Mackay in Australia, and the results can only be described as “spectacular, bordering on scary” – 24-30 hours duration from a single shot interscalene block, including complete motor block at 24 hours. This is consistent with studies showing dexamethasone effectively doubles the duration of most nerve blocks. Just remember that the phrenic nerve is also paralysed for 24 hours!

When I first read about this I had some concerns on potential neurotoxicity, but these were alleviated by 2 things.  The first of these were the words of a chronic pain physician colleague who stated that they add dexamethasone to every block they do, have been doing so for years and have had no problems. The second is a study showing that in an animal model dexamethasone was significantly less neurotoxic that ropivicaine, and the ropi/dex combination was less toxic than other common combinations such as ropi / buprenorphine and ropi/ clonidine (reference here and here and here)

The final interesting note is on SCDs- the sequential calf and thigh compressors now ubiquitous on the legs of patients having surgery in our hospitals. Two recent articles showed that they reduce intraoperative hypotension- a bonus that at first seems unexpected until you think about it, then seems quite logical.

Reduced hypotension for caesarian:  here

This study used a variation of the normal compressors with higher pressures and longer compression times: here

Withold ACE inhibitors for surgery? Think Again

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Anecdotally, the majority of anesthetists withhold ACE inhibitors (angiotensin converting enzyme inhibitors ACEI)  on the day of surgery because of concerns regarding hypotension, particularly in operations that may involve sympathectomy (spinal anesthesia) or blood loss. This appears to be a particular problem with angiotensin receptor blockers (here). We already know that withholding beta blockers and statins preoperatively is associated with an increase in the risk of myocardial ischaemia (reviewed here). ACEI were the wonder drugs of the 1980s: 1. use of ACE inhibitors provide long-term cardiovascular protection and reduce ischemic events and complications; 2. early ACE inhibitor therapy has been demonstrated to produce improved survival and heart function benefits in patients with acute myocardial infarction; 3. they are remarkably effective drugs in the treatment of heart failure and hypertension; 4.  ACEI delays the progression of diabetic nephropathy. So, is it wise to withhold these drugs in the preoperative period?

The following is a quote from a review on this topic in the Postgraduate Medical Journal: “The use of these agents before surgery has been associated with a variable incidence of hypotension during the initial 30 min after induction of anaesthesia; however, these hypotensive episodes have not been conclusively linked to any significant postoperative complications…” (here).

The following is a quote from an excellent review of the topic of drug withholding in preoperative patients: ACEI “intensify the hypotensive effects of anesthesia induction. Because angiotensin II plays a key role in maintaining circulating volume in response to stressors, volume deficits can occur in ACE inhibitor-treated patients as angiotensin II cannot compensate for venous pooling of blood, resulting in diminished cardiac output and arterial hypotension. However, continued renin-angiotensin system suppression may protect regional circulation, as has been demonstrated by reduced release of cardiac enzymes with ACE inhibitor continuation (compared with interruption) in cardiac surgery patients. ACE inhibitors also have a renal protective effect, preserving glomerular filtration rate in patients undergoing aortic abdominal aneurysm repair or coronary artery bypass graft surgery. Hypotension with ACE inhibition is treatable with sympathomimetics, alpha-agonists, and intravenous fluids.” (here). Essentially the author is referring to phenylephrine and vasopressin.

So, it may surprise you to discover that there are emerging data to support the continuation of ACEI in the preoperative setting, particularly in cardiac surgery patients. A recent article in circulation (here – subscription required – the HSE has a 1 year embargo – cheapskates!) suggests that withholding ACEI after cardiac surgery is associated with increased incidence of non fatal cardiac events:

This was a “prospective observational study of 4224 patients undergoing coronary artery bypass graft surgery (CABG). The cohort included 1838 patients receiving ACEI therapy before surgery and 2386 (56.5%) without ACEI exposure. Postoperatively, the pattern of ACEI use yielded 4 groups: continuation, 915 (21.7%); withdrawal, 923 (21.8%); addition, 343 (8.1%); and no ACEI, 2043 (48.4%). Continuous treatment with ACEI versus no ACEI was associated with substantive reductions of risk of nonfatal events (adjusted odds ratio for the composite outcome, 0.69; 95% confidence interval, 0.52–0.91;P=0.009) and a cardiovascular event (odds ratio, 0.64; 95% confidence interval, 0.46–0.88; P=0.006). Addition of ACEI de novo postoperatively compared with no ACEI therapy was also associated with a significant reduction of risk of composite outcome (odds ratio, 0.56; 95% confidence interval, 0.38–0.84; P=0.004) and a cardiovascular event (odds ratio, 0.63; 95% confidence interval, 0.40–0.97;P=0.04). On the other hand, continuous treatment of ACEI versus withdrawal of ACEI was associated with decreased risk of the composite outcome (odds ratio, 0.50; 95% confidence interval, 0.38–0.66; P<0.001), as well as a decrease in cardiac and renal events (P<0.001 and P=0.005, respectively).”

There are some unpublished data that continuing ACCEI up to surgery (and presumably afterwards) is associated with lower 30 day mortality (here). Preoperative use appears to be associated with fewer major adverse events after cardiac surgery (here), and even when no benefit has been demonstrated the agents appear to be safe (here).

So, think twice before you stop the ACEI in your preoperative visit. Nevertheless, I am still going to avoid these agents when anesthetizing patients in the beach chair position (here).

EUSOS follow up – is it the beds?

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Over the next few months I am sure that the real reasons for the comparatively poor outcomes of Irish patients in the EUSOS study will emerge. In the meantime, we can only guess the reasons. Aside from blaming surgeons for poor patient selection (which is suspiciously convenient), case volume may be a problem, the time of day (exhaustion), the amount of emergency surgery (including case volume) or the issue may lie in our own backyard – in the availability of beds for high risk postoperative patients. Emergency surgery patients, in particular, do poorly.

A US study of 25,710 nonemergency colorectal resections performed at 142 hospitals reported a 1.9% (492 patients) mortality rate. For emergency colorectal resection the mortality rate was 15.3% (780 of 5,083 patients). Fifty percent of emergency surgery patients had at least 1 complication versus 24% of elective surgery patients. This is horrifying.

The first report of the UK emergency laparotomy network (here), published in the BJA, presents similar mortality data. As a guide, mortality rates for major elective general surgery have been reported as follows: colorectal resection – 2.7%,  oesophagectomy – 3.1%, gastrectomy – 4.2% and liver metastasis resection – 1%. In this study (data from 1853 patients were collected from 35 NHS hospitals) the unadjusted 30 day mortality was 14.9% for all patients and 24.4% in patients aged 80 or over.

We are aware that emergency surgery patients come in at all hours of the night and are frequently operated on by junior doctors. The time of day was an issue (table below) – 30 day mortality was 50% higher if surgery took place between midnight and 8am. Obviously confounders may be present – surgeons may only take the sickest patients to theatre at night, and this may represent selection bias.

Time of day* n Consultant anaesthetist present (%) Consultant surgeon present (%) 30 day mortality (%)
08:00–17:59 1044 75.2 80.8 14.2
18:00–23:59 442 54.8 67.7 17.8
00:00–07:59 152 40.8 61.8 20.3

Bad outcomes occurred for patients admitted under a medical service who actually had a surgical problem, increasing age, increasing ASA physical status.

What about beds? “Of the patients who were felt to need intensive care immediately after surgery, 99% were transferred to a level 3 bed. Similarly, 89% of those who were judged to require a high-dependency bed received this level of care, with a further 4% receiving level 2 care in an ICU bed. Mortality in patients returning to the ward (level 1) was 6.7%, HDU 10.1%, and ICU 30.7%. 2.2% of patients were cared for after operation in an extended recovery area (presumably because there was no HDU bed available), and this group had a mortality of 13.5%. For the group of patients aged 60 or greater, and of ASA III or more (∼50% of all patients), 22% returned to the general ward after operation and had a mortality of 17.8%.” One must presume that this 22% represented at least part of the 11% that didn’t get the needed HDU beds. Hence, one could crudely argue that the patients that needed HDU beds but didn’t get them had an absolute mortality risk increase of 7.7% (the authors do not give us sufficient data to make direct comparisons, but more than 50% of patients were >60y and ASA III or greater). The overall mortality for patients sent to a regular ward was 6.7%, which appears to be very high when compared with data from general elective surgery (above). However, a recent study of all 160,920 patients who underwent bowel resection for colorectal cancer between 1998 and 2006 in the English NHS reported a mortality rate of 6.7%

These data at least suggest that lack of availability of a HDU/ICU bed significantly increases the risk of poor postoperative outcomes for emergency surgical patients.

The utilization of critical care services has been known to be suboptimal for many years. A previous study, published in Anaesthesia (here) looked at 26000 patients undergoing surgery in an NHS trust: “only 852 (35.3%) high-risk patients were admitted to a critical care unit at any stage after surgery. Of 294 high-risk patients who died, only 144 (49.0%) were admitted to a critical care unit at any time and only 75 (25.6%) of these deaths occurred within a critical care area. Mortality rates were high amongst patients discharged and readmitted to critical care (37.7%) and amongst those admitted to critical care following initial postoperative care on a standard ward (29.9%).” So, inadequate numbers of ICU/HDU beds are associated with poor outcomes, and early discharge (presumably for bed pressure) and readmission is associated with 1/3 of patients dying.

Ireland has a similar number of critical care beds per 100,000 population (6.5/100,000) to the UK (6.6/100,000). In a recent pan European study conducted by Andy Rhodes (here), Ireland ranked 26th out of 31 (UK was 25th) in critical care bed numbers per 100,000. The European average was 11.5. Overall, Ireland ranked 28th/31 for number of acute care beds and  23rd out of 31 for ICU beds as a % of acute care beds. So, we have very few beds for sick patients, and of these very few of them are critical care beds. Ireland spends 7.2% of GDP on healthcare (15th/31) and has the 6th highest GDP in proportion to ICU beds. In other words – we spend very little money comparatively on critical care compared with Europe. This might reflect the fact that we have the 2nd youngest population in Europe (10.4% are 65 or older).

In summary – is lack of critical care beds a likely factor for Irelands poor showing in EUSOS: almost certainly. Do these studies fully explain the difference – no! Unfortunately, the OR death was still 2.6 times the UK with a similar number of ICU/HDU beds. It could be argued that the bed numbers are inflated in Ireland, due to poor distribution between hospitals – community hospitals have underused ICU beds, referral centers have inadequate capacity. But that is another discussion….

24 hour Intensivist Presence – desirable? Maybe. Efficient, Economic and Effective – Unlikely

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Few issues have been more controversial in the past 20 years than the implementation of the intensivist model. Fundamentally this involves delegation of primary responsibility for critically ill patients to a narrow group of clinicians, whose primary training may be in an entirely different specialty. Hence, surgical patients may be managed by internists, and medical patients may be managed by anesthetists. I like to think of intensivists as coordinators of patient care, experts at resuscitation, who pay meticulous attention to detail and careful users of resources. As a result, each organ system does not have it’s own consultant, and medicines, interventions and tests are reduced, saving the institution a lot of money and resources.

Whether or not intensivists improve patient outcomes, versus primary medical or surgical teams rounding on patients, remains controversial. I have written about this in detail elsewhere (here subscription needed).  To summarize: daily rounds by an intensive care specialist improve outcomes in high risk surgical patients; intensive care teams (multidisciplinary) improve outcomes, as does the presence of a ICU medical director who sets standards. An article in Annals of Internal Medicine (conducted by well known intensivists) found that, in a study of >100,000 patients, critically ill patients managed by intensivists had worse outcomes (here). Patients managed by critical care physicians were sicker, had more procedures, and had higher hospital mortality rates than those managed by other physicians. I have always found this article confusing – for example in the non-intensivist model there were hospitals that had critical care fellows but no intensivist! The assumption that leads to the headline (“intensivists kill patients”), is that SAPS II is a good predictor of mortality and that adjustments based on SAPS II can separate out patients. If SAPS is not so good, then adjustments for severity of illness are meaningless. Also, there were significantly more patients transferred from other hospitals and more patients ventilated on admission in the CCM (intensivist) model. This suggests lead time bias: patients with similar severity of illness scores on admission to ICU that have been pre-resuscitated or transferred have worse outcomes.

The Irish government clearly believe in the intensivist model, as they seem to think that having us present in the ICU 24/7 will improve outcomes and save lots of money. In today’s Irish Times:

“For the first time, consultants in areas such as emergency medicine, intensive care, neonatology and obstetrics will be rostered on a 24-hour basis, working eight-hour shifts. Dr Reilly has said the proposals could save up €200 million.” (article here). I don’t know how the geniuses in the Department of Health have come up with this number, but it is complete fiction. In addition, for a Hospital to provide 24 hour consultant in house cover for ICU, I calculate that this would require approx €1 million a year in direct salary costs (5 FTEs to cover around the clock plus 2 or 3 more to cover their daytime assignments – remember the EWTD applies to consultants as well). This may appear insignificant compared with the staggering savings that they are anticipating – but there is no systematic proof that over investigation (where available and it is not) at night, and over treatment (with what?) at night and bad decision making, by registrars, is costing the health system a fortune. In fact – there is not a single study published anywhere ever that shows that having a consultant intensivist present for patient resuscitation improves outcomes. Outcome improvement has been demonstrated in scenarios where patients have received timely fluids and antibiotics, and subsequent care with ventilator strategy, sedation and mobilization. Has anyone ever studied the 24 hour intensivist model? Yes they have….

A study in the Lancet in 2000 suggested that 24 hour availability of intensivists (the current model in ALL Irish level 3 ICUS) significantly improved outcomes (here). A group from Saudi Arabia claimed the 24/7 staffing led to similar mortality out of hours as within weekday hours (here) proving – well nothing. A nice pro-con debate on this topic can be read in Critical Care (here). A passionate plea for 24/7 coverage can be read in the “blue journal” (here). A core discussion point is that patients that are admitted out of hours (9-5 Monday to Friday) appear more likely to die. This assumes that worse outcomes are due to lack of consultant staffing in the ICU rather than confounders like: patient was getting sick, but no GP available, no elective surgery admitted out of hours, fewer investigations (radiology) available out of hours, patients on wards not being seen by primary care team out of hours etc. In other words, it may be the health system rather than the absence of continuous critical care consultant staffing that is at fault. A study from Paris suggested that out of hours admission patients did better! (here). A US study suggested no difference (here). Indeed, even in July changeover season, mortality is not greater (here). Moreover, papers that claim cost savings tend to massage their data (here).

In the NEJM in May 2012, a group from Pittsburgh looked at night time physician (intensivist) staffing in ICU versus outcomes in North America (article here). What the study showed, in a nutshell, was if the hospital had an intensivist and a critical care team during the day, having a consultant present, on site, at night made no difference to outcomes (our current model in Ireland). However, in hospitals where there was no critical care team during the day (low intensity staffing), having an intenisivist at night improved outcomes [I am still trying to figure out what kind of ICU would pay a consultant at night but not during the day – perhaps they were covered by Tele-ICU]. Also, having any doctor dedicated to the ICU at night (a resident) improved outcomes – very much our model in Ireland.

So, before we are forced to embrace 24/7 cover perhaps it is worth questioning why and for what benefit. I am not suggesting that there should not be 24/7 anesthesia, EM  or obstetrics (where you would anticipate fewer lawsuits, I presume) coverage, I am just relaying the best current evidence, which is that expending 5 FTEs worth of staff to cover 24/7 in adult ICU is not supported by best available evidence.