Anaesthesia - Cardiothoracic Anaesthesia Collection 2015

224 Pages·2016·4.05 MB·English

Anaesthesia 2015,70,241–257
Editorial
The controversy of right ventricular systolic pressure: is it time to
abandon the pulmonary artery catheter?
In this issue of Anaesthesia there are Although the early work from catheterisation or calculated from
two papers that contribute to the YockandPopp[4]andSkjaerpeand the peak systolic and diastolic pul-
growing controversy as to whether Hatle [5] found a close correlation monary artery pressures. The RVSP,
Doppler echocardiography can be between the Doppler-derived RVSP however, is an estimation of sPAP
used to diagnose pulmonary hyper- and the measurements from direct and not mPAP. There are several
tension.Cowieet al.[1]andSoliman right heart catheterisation, subse- ways of estimating mPAP using
et al. [2] have sought to determine quent studies produced conflicting echocardiography. Most commonly,
theroleoftransoesophagealechocar- results[6,7].Inarecentmeta-analy- mPAP can be assessed by using the
diography (TOE) in estimating right sis, Taleb et al. [8] found a wide peak velocity of a jet of pulmonic
ventricular systolic pressure (RVSP) range of correlations between these insufficiency. This parameter, how-
and systolic pulmonary artery pres- twomeasurements;however,evenin ever, is rarely obtained in clinical
sure(sPAP),comparedwiththegold thestudieswithahighdegreeofcor- practice because most patients do
standard of pulmonary artery cathe- relation, the diagnostic accuracy not have sufficient pulmonic insuffi-
termeasurements. (defined as the ability to predict ciency to allow a complete Doppler
sPAP within 10 mmHg of the value envelope.Withmixedresults,several
History of the controversy measured by right heart catheterisa- authors have used other methods of
Doppler echocardiography has been tion) was only in the range of 75– estimating mPAP from Doppler
usedtoestimatesPAPsincetheearly 78%.WhileoverallDopplerechocar- TTE [11–13]. None of these alterna-
1980s. Using transthoracic echocar- diographyisafairly sensitiveindica- tive techniques have made it to the
diography(TTE),SkjaerpeandHatle tor of pulmonary hypertension mainstream echocardiography labo-
werethefirsttodemonstratethatthe (sensitivity 88%), the specificity is ratory.
peak velocity of blood flow across a low (56%) [8]. Consequently, most The last aspect of this contro-
tricuspid regurgitant jet could be current guidelines recommend that versy is a problem of semantics. The
used to estimate RVSP [3]. Further- outpatient Doppler echocardiogra- World Health Organization (WHO)
more, Yock and Popp found a good phy should be used as a screening and the American College of Chest
correlation between the Doppler- tool for pulmonary hypertension, Physicians make a clear distinction
derived estimates of RVSP and right whilstthedefinitivediagnosisshould between pulmonary hypertension
heart catheter measurements be reserved for right heart catheteri- andpulmonaryarterialhypertension
(r = 0.93) [4]. Subsequently, RVSP sation[9,10]. [9, 10]. WHO group 1 pulmonary
became an important echocardio- The next reason for the contro- hypertension, formerly known as
graphic parameter that was used by versy is a question of measures.Tra- primary pulmonary hypertension, is
clinicians to estimate pulmonary ditionally, pulmonary hypertension a disease of the pre-capillary pulmo-
artery pressures. However, it is is defined by a mean pulmonary nary vasculature resulting in pulmo-
important to discuss the clinical artery pressure (mPAP) > nary arterial hypertension. The
value and the accuracy of Doppler- 25 mmHg. This value is either mea- diagnosis of pulmonary arterial
derivedestimatesofRVSP. sured directly during right heart hypertension requires not only a
©2014TheAssociationofAnaesthetistsofGreatBritainandIreland 241
Anaesthesia 2015,70,241–257 Editorial
mPAP > 25 mmHg, but also a pul- derived RVSP and right heart cathe- pressure measurements as their real-
monary capillary wedge pressure or terisation in outpatients, using TTE. timeestimateofrightatrialpressure.
left atrial pressure (LAP) < Because of the close proximity of Thismethodavoidstheerrorofright
15 mmHg, and a pulmonary vascu- the oesophagus to the heart, the atrialpressureestimationinherentin
larresistance(PVR)>3Woodunits. major advantage of TOE is the abil- thepriorTTE-basedstudies.
Furthermore, with WHO group 2 ity to capture high-resolution
pulmonaryhypertension,pulmonary images. The disadvantage of TOE, TOE and RVSP
artery pressures are elevated due to however, is the limited ability to With simultaneous measurements
post-capillary hypertension or pul- manipulate the angle of the interro- and accurate estimation of right
monary venous congestion, usually gating Doppler beam. Thisisimpor- atrial pressure, it is surprising that
fromleft-sideddiseasesuchasmitral tant for the estimation of RVSP these two studies have opposite
stenosis, mitral regurgitation or left because the accuracy of Doppler results. Cowie et al. [1] found that
ventricular diastolic failure. The dis- echocardiography depends upon a the measurement of RVSP was
tinction between pulmonary hyper- near-parallel alignment of the ultra- achievable in 100% of their patients,
tension and pulmonary arterial sound beam and the direction of and that it correlated closely with
hypertension is important because blood flow being measured. Mis- pulmonary artery catheter-derived
although left-sided heart disease is alignment of more than 20-30° will parameters of sPAP (r = 0.98). In
the most common cause of pulmo- lead to gross underestimation of addition, there was a very narrow
nary hypertension, only pulmonary blood flow velocities and pressure limit of agreement (–5 to
arterial hypertension will respond to gradients. +5 mmHg) across a wide range of
afterload reduction with a pulmo- The advantage of the studies of pulmonary pressures. On the other
nary vasodilator [9]. In other words, Cowie et al. [1] and Soliman et al. hand, Soliman et al. [2] found that
an elevated RVSP found by TOE in [2] over prior TTE studies is that adequate Doppler signals were only
the operating theatre may represent the TOE was performed in the acquired in 56% of their patients,
pulmonary hypertension, but if that operating theatre with simultaneous and that Doppler-derived measure-
pulmonary hypertension is caused pulmonary artery catheter readings, ments were accurate (within
by pulmonary venous congestion while the majority of TTE studies 10 mmHg of pulmonary artery
from severe left-sided disease, then compared measurements that were catheter measurements of sPAP)
the addition of pulmonary taken hours and sometimes even only 75% of the time. Part of the
vasodilators would be of little value. days apart [8]. The sPAP is depen- discrepancy between these two
Echocardiography yields clues to the dent on cardiac output, and the studies may be explained by differ-
presence of left-sided disease and variation in cardiac output over ent methodological approaches.
thereareechocardiographicmeansof time could easily account for the Cowie et al. [1] measured the corre-
estimating both LAP [14] and PVR reported discrepancy between RVSP lation between RVSP and sPAP,
[15, 16]. Recent studies, however, estimates and direct right heart while Soliman et al. [2] evaluated
have shown that intra-operative catheter measurements in these the accuracy or the ability of RVSP
echocardiographic estimates of LAP studies. to predict sPAP within 10 mmHg.
are not accurate enough to be clini- The calculation of RVSP also It is certainly possible that two vari-
cally useful [17, 18]. Consequently, depends upon an accurate estimate ables can correlate closely but not
thediagnosisoftruepulmonaryarte- of right atrial pressure. Echocardio- agree. An example of this would be
rial hypertension cannot be made graphic estimations of right atrial the close correlation between sys-
ontheestimationofRVSPalone. pressure are often inaccurate [19] tolic blood pressure and mean arte-
and this may account for the major- rial pressure. These two measures
TOE versus TTE ity of the error in RVSP estimation correlate because one is dependent
The majority of the previously [6]. Cowie et al. [1] and Soliman on the other, but their values are
discussedstudiescomparedDoppler- et al. [2] used direct central venous different. A similar discrepancy
242 ©2014TheAssociationofAnaesthetistsofGreatBritainandIreland
Editorial Anaesthesia 2015,70,241–257
between correlation and accuracy non-invasive natureof TTE, thebig- the other hand, a patient with idio-
has been described in the TTE gest risk involved in the estimation pathic pulmonary fibrosis may ben-
studies of RVSP reported over the of RVSP is the risk of misinterpreta- efit from these therapies because
last 40 years [7, 8]. tion. It is for this reason that TTE- their elevated RVSP represents true
In addition, these two studies derived RVSP is often the only mea- pulmonary arterial hypertension.
had vastly differing success rates in sure of pulmonary artery pressure The benefit of the pulmonary artery
obtaining adequate RVSP estima- to which outpatient clinicians have catheter in these complex patients
tions (100% vs 56%). Both groups access. Although TOE is certainly is that pulmonary artery pressure
used multiple TOE views to look for more invasive than TTE, its use trends can be monitored during
optimal alignment of the tricuspid during cardiac surgery is becoming surgery and into the immediate
regurgitant jet. Soliman et al. [2] a part of routine practice. In the post-operative period.
defined an adequate tricuspid re- operating theatre and in the inten-
gurgitant jet as having < 20° align- sive care unit, TOE measurements Conclusions
ment with the Doppler beam, but of RVSP may be an important
The placement of a pulmonary
misalignment was never a cause for screening tool for pulmonary hyper-
artery catheter may not be neces-
exclusion in their study. Instead, the tension, particularly if this informa-
sary in patients with normal
most frequent cause of inadequate tion is combined with the patient’s
biventricular function undergoing
Doppler signal was the lack of com- history and other echocardiographic
cardiac surgery. In complex
plete tricuspid regurgitant jet enve- findings such as right ventricular
patients, however, with known pul-
lope. By definition, this approach hypertrophy and dysfunction, left
monary hypertension, severe right
automatically excludes patients with ventricular diastolic failure, and/or
or left ventricular dysfunction, or
trivial tricuspid regurgitation, as the valvular disease. Estimation of sPAP
severe valvular disease, the pulmo-
inability to produce a complete can be confirmed using pulmonary
nary artery catheter and the TOE
Doppler envelope is what distin- artery acceleration time, a measure
provide complimentary information.
guishes trivial from mild tricuspid of pulmonary haemodynamics that
Accordingly, both monitoring
regurgitation. The 56% success rate is completely independent of the tri-
modalities still hold a valuable place
foundbySolimanet al.[2],however, cuspid transvalvular gradient and
in the cardiac operating theatre.
is in close agreement with previous can therefore be calculated in the
work by Taleb et al. [8], who found setting of inadequate tricuspid
Competing interests
that adequate Doppler signals for regurgitation [21].
RVSP estimation could only be There are many causes of pul- No external funding and no com-
obtained in 52% of patients overall. monary hypertension; however, an peting interests declared.
Cowie et al. [1] did not specify how elevated RVSP finding during TOE
they determined an adequate Dopp- examination does not provide a N. Silverton
lertricuspidregurgitantjetsignal. definitive diagnosis. A patient with Fellow, Cardiovascular Anesthesia
and Intensive Care
an elevated RVSP in the setting of
M. Meineri
The value of RVSP vs the sepsis, may have elevated sPAP due
Associate Professor of Anesthesia &
pulmonary artery to increased cardiac output that
Director of Perioperative
catheter may not represent pulmonary arte- Echocardiography
Despite all the controversy sur- rial hypertension. A patient with G. Djaiani
rounding Doppler-derived estimates severe mitral regurgitation may Associate Professor of Anesthesia &
Director of Cardiac Anesthesia
of RVSP, even those that argue have elevated RVSP but mitral valve
Fellowship Research
against its accuracy acknowledge repair is more likely to improve
Toronto General Hospital
that the estimation of RVSP in their pulmonary haemodynamics
University of Toronto
clinical practice should not be than an intra-operative administra- Toronto, Canada
abandoned [7, 20]. Because of the tion of pulmonary vasodilators. On Email: [email protected]
©2014TheAssociationofAnaesthetistsofGreatBritainandIreland 243
Anaesthesia 2015,70,241–257 Editorial
References pulmonary artery systolic pressure: a 16. Tossavainen E, Soderberg S, Gronlund
1. Cowie B, Kluger R, Rex S, Missant C. meta-analysis. Echocardiography 2013; C, et al. Pulmonary artery acceleration
The utility of transoesophageal echo- 30:258–65. time in identifying pulmonary hyper-
cardiography for estimating right ven- 9. McLaughlin VV, Archer SL, Badesch DB, tensionpatientswithraisedpulmonary
tricular systolic pressure. Anaesthesia et al. ACCF/AHA 2009 expert consen- vascular resistance. European Heart
2015;70:258–63. sus document on pulmonary Journal2013;14:890–7.
2. Soliman D, Bolliger D, Skarvan K, Kauf- hypertension. Circulation 2009; 119: 17. Ali MM, Royse AG, Connelly K, Royse
mannBA,LuratiBuseG,SeebergerMD. 2250–94. CF. The accuracy of transoesophageal
Intra-operative assessment of pulmo- 10. McGoon M, Gutterman D, Steen V, et echocardiographyinestimatingpulmo-
nary artery pressure by transoesopha- al. Screening, early detection, and nary capillary wedge pressure in
geal echocardiography. Anaesthesia diagnosis of pulmonary arterial hyper- anaesthetised patients. Anaesthesia
2015;70:264–71. tension: ACCP evidence-based clinical 2012;67:122–31.
3. Skjaerpe T, Hatle L. Diagnosis and practice guidelines. Chest 2004; 126: 18. Haji DL, Ali MM, Royse A, Canty DJ,
assessment of tricuspid regurgitation 14S–34S. Clarke S, Royse CF. Interatrial septum
with Doppler ultrasound. Develop- 11. SteckelbergRC,TsengAS,NishimuraR, motion but not Doppler assessment
ments in Cardiovascular Medicine et al. Derivation of mean pulmonary predicts elevated pulmonary capillary
1981;13:299–304. artery pressure from noninvasive wedgepressureinpatientsundergoing
4. Yock PG, Popp RL. Noninvasiveestima- parameters. Journal of the American cardiac surgery. Anesthesiology 2014;
tion of right ventricular systolic pres- Society of Echocardiography 2012; 26: 121:719–29.
sure by Doppler ultrasound in patients 464–8. 19. Tsutsui RS, Borowski A, Tang WH, Tho-
with tricuspid regurgitation. Circulation 12. AduenJF,CastelloR,LozanoMM,etal. mas JD, Popovic ZB. Precision of echo-
1984;70:657–62. An alternative echocardiographic cardiographic estimates of right atrial
5. Skjaerpe T, Hatle L. Noninvasive esti- method to estimate mean pulmonary pressureinpatientswithacutedecom-
mation of systolic pressure in the right artery pressure: diagnostic and clinical pensated heart failure. Journal of the
ventricle in patients with tricuspid implications. Journal of the American American Society of Echocardiography
regurgitation. European Heart Journal Society of Echocardiography 2009; 22: 2014;27:1072–8.
1986;7:704–10. 814–9. 20. Schiller NB, Ristow B. Doppler under
6. Fisher MR, Forfia PR, Chamera E, et al. 13. Laver RD, Wiersema UF, Bersten AD. pressure:It’stimetoceasethefollyof
Accuracy of Doppler echocardiography Echocardiographic estimation of mean chasing the peak right ventricular sys-
in the hemodynamic assessment of pulmonary artery pressure in critically tolic pressure. Journal of the American
pulmonary hypertension. American ill patients. Critical Ultrasound Journal Society of Echocardiography 2013; 26:
Journal of Respiratory and Critical Care 2014;6:9. 479–82.
Medicine2009;179:615–21. 14. Otto C. Textbook of Clinical Echocardi- 21. Yared K, Noseworthy P, Weyman A, et
7. Rich JD. Counterpoint: can Doppler ography, 5th edn. Philadelphia: Else- al. Pulmonary artery acceleration time
echocardiography estimates of pulmo- vierSaunders,2013;7:180. provesan accurateestimateofsystolic
nary artery systolic pressures be relied 15. Granstam SO, Bjorklund E, Wikstrom G, pulmonary arterial press during trans-
upon to accurately make the diagnosis Roos MW. Use of echocardiographic thoracic echocardiography. Journal of
of pulmonary hypertension? No. Chest pulmonary acceleration time and esti- theAmericanSocietyofEchocardiogra-
2013;143:1536–9. matedvascularresistancefortheeval- phy2011;24:687–92.
8. Taleb M, Khunder S, Tinkel J, Khouri S. uation of possible pulmonary
The diagnostic accuracy of doppler hypertension. Critical Ultrasound Jour- doi:10.1111/anae.12939
echocardiography in assessment of nal2013;11:7.
Editorial
The myth of the difficult airway: airway management revisited
For years, anaesthetists have patients in Denmark and come to a
If you always do what you’ve tried to predict the difficult airway disappointingconclusion:wearenot
always done, you’ll always get using various clinical signs and pre- good at it [1]. Of 3391 difficult intu-
what you’ve always got diction models. In this issue of bations, 3154 (93%) were unantici-
Anaesthesia,Nørskovet al.presenta pated. When difficult intubation was
—HenryFord
study of a large cohort of 188 064 anticipated, only 229/929 (25%) had
244 ©2014TheAssociationofAnaesthetistsofGreatBritainandIreland
Editorial Anaesthesia 2015,70,375–392
thesia and peri-operative care. Anaes- sequence induction techniques: current 31. Meek T. Traditional rapid sequence
thesia2012;67:1313–6. practice in Wales. Anaesthesia 2009; inductionisanoutmodedtechniquefor
28. Jensen V, Rappaport BA. The reality of 64: 54–9. Caesareansectionandshouldbemodi-
drug shortages–the case of the inject- 30. Levy DM. Traditional rapid sequence fied. International Journal of Obstetric
able agent propofol. New England inductionisanoutmodedtechniquefor Anesthesia2006;15:229–32.
JournalofMedicine2010;363:806–7. Caesareansectionandshouldbemodi-
29. Koerber JP, Roberts GE, Whitaker R, fied. International Journal of Obstetric
Thorpe CM. Variation in rapid Anesthesia2006;15:227–9. doi:10.1111/anae.13034
Editorial
Ischaemic conditioning: intervening to protect; before, after, and
at a distance
First love is a kind of vaccina- ably introspective to date, with little myocardial injury in 19% of patients
tion, which saves a man from consensus as to how best to judge undergoing non-cardiac sugery in
catching the complaint the sec- outcomes following major surgery, whom troponin was measured, with
ondtime and a paucity of large, well-con- an increased relative risk of death of
—HonoredeBalzac ducted randomised controlled trials 2.4 (95% CI 1.3–4.2; p < 0.01) for
(RCTs), compounded by significant even ‘minor’ rises in troponin levels,
Safety is part of the business of
heterogeneity, so that even meta- increasing to 4.2 (95% CI 2.1–8.6;
being a good anaesthetist, and has
analysis and pooling of data from p < 0.01) if the rise was 10-100 fold
been a guiding principle for the
thesestudiesaredifficult.Theperiod [3].
AssociationofAnaesthetistsofGreat
over which outcomes are reported,
Britain and Ireland (AAGBI).
too, is short by the standards of Preconditioning
Indeed, despite the increasing age
other specialities, in particular those What if we within anaesthesia were
andunhealthinessofpatientsrequir-
relating to cardiology. It is from uniquely placed to do something
ing surgery and anaesthesia, the
there that we need to learn, for it is about that? We have long been at
mortality attributable solely to
in that field, too, where a vast bur- the forefront of resuscitation and
anaesthesia continues to decrease,
den of future health outcomes will optimisation; perhaps by using the
fromarateof357(95%CI324–394)
be realised. Cardiovascular disease is tools already available to us, we can
per million before what might be
still the leading cause of death profoundly alter our patients’ car-
termed the modern era of anaesthe-
worldwide,killingmorethan17mil- diovascular outcomes. A series of
sia, beginning in the 1970s, to a rate
lion people in 2008 [2]. This is of three reviews published in Anaes-
of 34 (95% CI 29–39) per million in
great relevance to us, given the high thesia – the first one in this issue
the 1990s–2000s (p < 0(cid:1)00001) [1].
incidence of undetected and unre- [4] – focuses on ischaemic precon-
Now that we are becoming truly
ported peri-operative myocardial ditioning, and examines whether we
safe, however, we increasingly need
ischaemiainavarietyofnon-cardiac have the ability and evidence base
to focus on quality of care, and on
surgical settings, let alone in cardiac to do just that. The concept seems
interventions that alter outcomes
anaesthesia. For example, the simple – a small ‘dose’ of tissue
outside of the peri-operative period.
CHASE investigators demonstrated ischaemia, delivered either before,
Our thinking here has been remark-
anincidenceofotherwiseundetected during or after a larger ischaemic
©2015TheAssociationofAnaesthetistsofGreatBritainandIreland 379
Anaesthesia 2015,70,375–392 Editorial
insult, can protect the heart from The biggest limitation of most nous anaesthesia. The caveats to
that subsequent insult, in essence trials is that they recruit patients such meta-analyses are of course
rather like a vaccination. It may undergoing elective coronary artery well known: the small sample size of
protect not only from the effects of bypass grafting (CABG), who are theincluded studies; theheterogene-
ischaemia, but also from those of not representative of most patients ity of secondary surrogate end-
reperfusion following therapeutic undergoing surgery and anaesthesia, points; and the variations in
interventions, which can induce a even in cardiac anaesthesia! Cardio- technique.
secondary cardiac injury. plegia strategies during cardiopul- Two large retrospective studies
The good news for anaesthetists monary bypass (CPB) may influence approach the numbers we would
isthatthisisanactiveandpromising results, as can intermittent cross- expect to be at least hypothesis-gen-
avenue of investigation, with most clamping during surgery, both of erating. In an Italian study of 34
trials, unsurprisingly, conducted in which have ‘preconditioning’ effects. 310 patients undergoing CABG, use
the cardiac surgery population. In In addition, the low incidence of of volatile anaesthetic agents was
the first review of the series, Kunst hard clinical endpoints, such as associated with a lower 30-day mor-
and Klein [4] provide a careful postoperative death, means that to tality [10]. This appears to be cor-
assessmentandcritiqueoftheunder- demonstrate reductions in such out- roborated by a Danish study of 10
lying mechanisms and cellular comes from preconditioning would 535 patients having cardiac surgery,
pathways involved in so-called require very large sample sizes. Vir- with similarly reduced mortality in
‘anaesthetic preconditioning’, before tually allthe trials conductedto date the volatile anaesthesia group [11].
discussingtheclinicalevidenceavail- are proof-of-concept studies, with These results are encouraging, but
abletoguideourpractice.Manywill widely varying anaesthetic tech- we would wish for outcome report-
befamiliarwiththeideathatvolatile niques, ‘doses’ of preconditioning ing such as that being suggested for
anaestheticagentsarepotentiallycar- and patterns of administration. This all major surgery. The recent publi-
dioprotective,followingearlyreports includes whether the volatile anaes- cation of European standards for
inthe1970sand1980s,thoughfewer thetic agent was delivered continu- reporting peri-operative outcomes
may be aware that propofol and ously or interrupted with periods of [12] lays down a challenge to those
opioids,ourotherroutinetools,may ‘washout’, which the basic science conducting such studies; mortality
also confer benefit. What is less cer- suggests is important to achieving data should include follow-up to at
tain, however, is the way in which the protective effect [7]. The use of least 90 days following surgery, and
theseagentsshouldbeused.Asever,it surrogate markers of outcome, such ideally one year. Pragmatic studies
seems to be mostly about dose and as elevated troponin levels, is almost of sufficient size will be essential to
timing, and the various experimental universal. Nonetheless, the results of allow adoption of the techniques
models continue to expand our meta-analyses of these studies are already familiar to anaesthetists.
understanding of the basic science generally encouraging, with reduc-
that underpins anaesthetic pre- tions in markers of harm, including Postconditioning
conditioning. However, uncertainty troponin levels and requirements The mechanisms and strategies dis-
remains. Preconditioning using vola- for inotropic support [8]. However, cussed above presuppose that we
tileanaestheticagentsappearstowork Landoni et al.’s meta-analysis, know that there will be an ischae-
less well in animal models of hyper- which included 3642 patients from mic insult, and can prepare our
glycaemia and hypercholesterolaemia 38 RCTs, and demonstrated a two- patients for it. However, for a dif-
[5, 6], precisely those situations in fold increase in mortality in patients ferent cohort – those who suffer
which we perceive the greatest peri- undergoing cardiac surgery when from acute myocardial infarction –
operative risk. However, do rabbits anaesthesia was maintained using this may not be the case; they too,
and cardiac myocytes adequately propofol infusions compared with however, are at risk from both
model the metabolic syndrome? Do volatile anaesthetic agents [9], may the initial ischaemic burden and the
wenotneedmoreclinicalevidence? alarm proponents of total intrave- reperfusion injury consequent on
380 ©2015TheAssociationofAnaesthetistsofGreatBritainandIreland
Editorial Anaesthesia 2015,70,375–392
our interventions, e.g. primary per- may make no difference. There is Remote conditioning
cutaneous coronary intervention also an increased understanding of There is also an alternative (or
(PCI) or thrombolysis, aimed at re- the importance of microvascular additive) technique to consider: one
establishing blood flow to ischaemic flow following PCI, with much that is non-invasive, effective, and
myocardial tissue. What if it was poorer outcomes in situations of free of both cost and side-effects.
possible to provide protection to ‘no-reflow’; a postconditioning algo- Remote ischaemic conditioning,
this group by ischaemic condition- rithm has been shown to reduce using a tourniquet to cause inter-
ing, but after the event? This con- microvascular obstruction as dem- mittent limb ischaemia, has been
cept is addressed by Jivrav et al. in onstrated by contrast-enhanced car- widely studied; Sivaraman et al.
the second review in the series, with diac magnetic resonance imaging [15] provide an elegant description
a focus on interventions at the time [14]. In addition, the patients we of the complex neurohumeral path-
of PCI [13]. most wish to benefit – the old, the ways involved in this phenomenon,
Ischaemic postconditioning sick, those with diabetes, and those with the conditioned limb produc-
involves alternating cycles of cardiac taking antiplatelet medications – ing small, thermolabile proteins,
ischaemia and reperfusion, usually may not, as a result of alterations in most likely adenosine, and requiring
by cyclical inflation of balloon cath- the signal transduction pathways an intact autonomic nervous system
eters within coronary arteries, involved in postconditioning caused and opioid pathways for the condi-
before reflow of blood following by those conditions and treatments. tioning effect. The fact that it is
PCI. There is a large body of ani- This is the conundrum facing simple to apply, and can be done
mal research that is suggestive of enthusiasts, and it will only be before, during or after the initial
benefit, although again with signifi- addressed by larger RCTs. The DA- episode of ischaemia, makes it
cant variation in the algorithms NAMI-3 (NCT01435408) study is attractive both to study and to
used and the outcomes measured. aiming to recruit 2000 patients, and consider for clinical use.
There are three key elements to any will report patient-centred out- Remote preconditioning, apply-
postconditioning algorithm: the comes, including heart failure and ing the ischaemic stimulus before
time to the first interruption of rep- cardiovascular death, over a three- the insult, has a protocol of three
erfusion; the number of cycles of year period. Trials such as this may episodes of five-minutes’ cuff infla-
ischaemia; and the duration of begin to answer the clinically rele- tion-deflation on the upper limb,
ischaemia-reperfusion within each vant questions at which studies that is broadly accepted in the liter-
cycle. The idea is promising, as the reporting surrogate markers can ature. Unsurprisingly, it has been
larger the area of myocardium at only hint. assessed in CABG surgery, both on-
risk, the greater the benefit of post- Various pharmacological agents and off-pump, in major non-cardiac
conditioning seems to be in reduc- mimic endogenous postconditioning surgery, and before elective PCI.
ing infarct size. The difficulty lies in pathways, and may become signifi- Study design remains a significant
assessing the area at risk in patients cant to anaesthetists and intensivists confounder, with small sample sizes
presenting acutely, and outside of in managing patients following in single centres, and the use of
research studies, as the corollary is primaryPCI.Again,timinganddose surrogate endpoints and varying
that one might exacerbate damage are crucial. Candidate drugs include protocols. The technique’s relative
by applying postconditioning proto- cyclosporine,adenosineanderythro- ease of use and great promise
cols if the infarct is small. The clini- poeietin, andlargeclinicaltrialscur- means that it has been rapidly
cian also needs to judge the rently underway (cyclosporine introduced into clinical practice,
duration of ischaemia: if it has been (CIRCUS; NCT01502774); erythro- often without systematic assessment
too short, the injury may be exacer- poeietin (EPO-AMI-II (UMIN0000 of the effects and outcomes. As is
bated by postconditioning tech- 05721)) may determine their role in usual, early proof-of-concept trials
niques, while if the period of index cardiacprotectionfollowingmyocar- were positive, but those with a
ischaemia was very prolonged, it dialinfarctionandPCI.
©2015TheAssociationofAnaesthetistsofGreatBritainandIreland 381
Anaesthesia 2015,70,375–392 Editorial
more clinical focus have proved dis- remote ischaemic conditioning pre- consider the evidence base, and how
appointing. Length of follow-up is hospital appears to confer real clini- it applies to their practice. Trials
also problematic, with the CRISP cal benefit, while if instituted in the with clinically-focused endpoints
trial in elective PCI one of few that cardiac catheterisation laboratory, it and agreed protocols that are cur-
reported major adverse cardiovascu- currently does not, unless combined rently underway have the potential
lar and cerebrovascular events with opioids. Will we need to con- to impact on the growing burden of
(MACCE) at six months and six sider remote ischaemic conditioning cardiovascular morbidity and mor-
years [16]. These were lower in the plus volatile anaesthesia, remote tality, and change our anaesthetic
group that underwent remote is- ischaemic conditioning plus high- practice.
chaemic conditioning, and studies dose propofol, or other combina-
like this provide a tantalising hint tions of techniques? Competing interests
of the promise that remote condi- And this may be the nub of the No external funding and no
tioning holds. Two large studies issue – the treatment effect of is- competing interests declared.
hope to build on this. The ERRICA chaemic conditioning strategies may
(Effect of Remote Ischaemic pre- not be large, and given the number A. Vercueil
Conditioning on clinical outcomes of confounding variables that reduce Consultant in Anaesthesia and
in patients undergoing Coronary it, it may be difficult to dissect out Intensive Care Medicine
King’s College Hospital NHS
Artery bypass graft surgery) thetrulyusefulmanoeuvres,orcom-
Foundation Trust
(NCT01247545) and RIPHeart binations of them. The size of the
King’s Health Partners
(Remote Ischaemic Preconditioning clinical problem, however, makes it
London, UK
for Heart surgery) (NCT01067703) essentialthatwedojustthat,aseven Email: [email protected]
trials are studies with real clinical a small degree of benefit has the
endpoints of value to patients, as potential to alter outcomes for the References
they include truly important consid- better in the many thousands of 1. Bainbridge D, Martin J, Arango M,
Cheng D, for the Evidence-based Peri-
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cise tolerance. Likewise, De Hert effects of myocardial ischaemia. (EPiCOR) Group. Perioperative and
et al. (NCT01107184) are recruiting Maybe we should no longer be anaesthetic-related mortality in devel-
oped and developing countries: a sys-
660 patients for a multicentre study thinkingofa‘vaccine’againstinjury,
tematic review and meta-analysis.
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Risk Factors and Determinants. World
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postoperative atrial fibrillation the chaemic conditioning techniques ncd_report2010/en/ (accessed 17/
01/2015).
primary endpoint. Secondary end- discussed in this series to alter the 3. vanWaesJA,NathoeHM,deGraaffJC,
points include length of ICU and outcomes of patients with myocar- et al. Cardiac Health After Surgery
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hospital stay, and MACCE. This dial ischaemia who are under our
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tion2013;127:2264–71.
tant, as it introduces a new concept. of the biological pathways involved,
4. Kunst G, Klein A. Peri-operative anaes-
It is possible that we need to extend andtheabilitytousesimilartoolsin thetic myocardial preconditioning and
our search for benefit from single other areas ofsurgerythatalsocarry protection – cellular mechanisms and
clinical relevance in cardiac anaesthe-
interventions, to investigating is- a risk of ischaemia-reperfusion sia.Anaesthesia2015;70:467–82.
chaemic conditioning ‘bundles’, as injury, such as transplantation and 5. Canfield SG, Sepac A, Sedlic F, Muravy-
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hyperglycemia attenuates anesthetic
will not fit all patients. For example, bethebusinessofallanaesthetiststo
382 ©2015TheAssociationofAnaesthetistsofGreatBritainandIreland
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Editorial
Emergence delirium in children
Emergence delirium was first population, and so it is on emer- self-limiting, it causes distress to
described in the 1960s [1] and, in gence delirium in children that we patients, parents and staff, and may
the paediatric setting, has been will concentrate for the rest of this result in physical harm to the child,
defined as “a disturbance in a editorial. Emergence delirium is particularly at the site of surgery,
child’s awareness or attention to his/ manifest on recovery of conscious- dressings and intravenous cannulae.
her environment with disorientation ness and usually lasts for 5–15 min; Agitation and regressive behaviour
and perceptual alterations including the child is typically irritable, unco- lasting up to two days has been
hypersensitivity to stimuli and operative and inconsolable, with described [4] and long-term
hyperactive motor behaviour in the crying, moaning, writhing, kicking psychological effects remain
immediate post anesthesia period” and exhibiting generally inappropri- unknown. The term ‘emergence agi-
[2]. This ‘dissociated state of con- ate behaviour. Children of pre- tation’ is often used interchangeably
sciousness’ can occur in adults as school age are most commonly with ‘emergence delirium’ but agita-
well as children – sometimes with affected and they may not recognise tion is excessive motor activity, is
dramatic effects [3] – but it is much or identify family members or more common than emergence
more common in the paediatric familiar objects. Although usually delirium in the postoperative period
©2015TheAssociationofAnaesthetistsofGreatBritainandIreland 383
Anaesthesia 2015,70,119–134 Editorial
39. Tekelioglu UY, Apuhan T, Akkaya A, et 42. Neri E, Maestro A, Minen F, et al. Sub- 46. MarechalC,HonoratR,ClaudetI.Sero-
al. Comparisonof topical tramadoland lingual ketorolac versus sublingual tonin syndrome induced by tramadol
ketamine in pain treatment after ton- tramadol for moderate to severe post- intoxication in an 8-month-old infant.
sillectomy. Pediatric Anesthesia 2013; traumaticbonepaininchildren:adou- PediatricNeurology2011;44:72–4.
23:496–501. ble-blind, randomised controlled trial. 47. Perdreau E, Iriart X, Mouton JB, Jalal Z,
40. Ugur KS, Karabayirli S, Demircioglu RI, ArchivesofDiseaseinChildhood2013; Thanbo JB. Cardiogenic shock due to
et al. The comparison of preincisional 98:721–4. acute tramadol intoxication. Cardiovas-
peritonsillar infiltration of ketamine 43. Morley SR, Becker J, Al-Adnani M, cular Toxicology 2014 May 9; doi 10.
and tramadol for postoperative pain Cohen MC. Drug- and alcohol-related 1007/s12012-014-9262-2.
relief on children following adenoton- deaths at a pediatric institution in the 48. Grond S, Sablotzki A. Clinical pharma-
sillectomy. International Journal of United Kingdom. American Journal of cology of tramadol. Clinical Paharmac-
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41. Honarmand A, Safavi M, Kashefi P, 44. Li X, Zuo Y, Dai Y. Childrens seizures brands-in-action/detail/Marmite/2936-
Hosseini B, Badiei S. Comparison of causedbycontinuousintravenousinfu- 88/(accessed5/10/2014).
effect of intravenous ketamine, peri- sion of tramadol: two rare case
tonsillar infiltration of tramadol and reports.PediatricAnesthesia2012;22:
doi:10.1111/anae.12972
theircombinationonpediatricpostton- 308–9.
sillectomy pain: a double-blinded ran- 45. Grandvuillemin A, Jolimoy G, Authier F,
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Editorial
–
Awareness in cardiothoracic anaesthetic practice where now
after NAP5?
Cardiac anaesthesia has historically ranges from less than 1% to over two- to tenfold higher risk of
been associated with a higher inci- 20%, depending on the definition of unintended awareness than that
dence of unintended awareness com- awareness, the size of the study and reported for the general population
pared with other anaesthetic the method of detection (Table 1). [2, 16].
subspecialties [1, 2], but the inci- The early studies [6–8] included The more recent B-Aware [3],
dence in modern practice is less cer- fewer than 60 patients each, so were B-Unaware [14] and BAG-RECALL
tain. The incidence in thoracic subject to sampling error, and were [15] studies specifically recruited
anaesthesia is also unclear, mainly carried out during the era of high- patients considered to be at high
because so few studies have dose opioid anaesthesia. The later risk of awareness, so a third to a
addressed this issue at all [3, 4]. The studies were prospective, used a bal- half of these cohorts were cardiac
recent publication of the 5th anced anaesthesia technique, and patients. However, they were not
National Audit Project (NAP5) included 600-900 patients, finding specifically cardiac studies, leading
report [5] now provides cardiotho- an incidence of 0.3-1.14% [11–13]. to a relatively small cardiac cohort
racicanaesthetists with a usefulpoint The incidence in the cardiac cohort in B-Unaware (525/1941 patients
forreflectiononcurrentpractice. of a large US multicentre study was overall). The incidence of unin-
The reported incidence of unin- similar, at 0.44% [2]. Cardiac anaes- tended awareness in cardiac
tended awareness in cardiac practice thesia was thus associated with a patients in these studies varied from
130 ©2014TheAssociationofAnaesthetistsofGreatBritainandIreland