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Resuscitation 83 (2012) 1181–1182

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Resuscitation

journa l homepage: www.e lsev ier .com/ locate / resusc i ta t ion

ditorial

nfrared pupillometry during cardiopulmonary resuscitation forrognostication—A new tool on the horizon?

Reliable early prognostication of cardiac arrest (CA) would bef great value. It would be optimal to provide valid informationlready during CPR, or even before starting it.

But the question of survival and of its neurological quality isecoming notably difficult as we try to give answers as early asossible.

Many factors which are associated with favourable outcome arerimarily of statistical value and do not permit individual progno-is. Typical examples are down-time until start of CPR, location ofrrest, presence of eye witnesses, bystander CPR, first registeredhythm, and pre-arrest health status. Many of these parametersre influenced by subjective errors such as estimated time intervalsr quality of bystander CPR. Other parameters may be misleading,uch as the first registered rhythm (VT/VT or PEA/asystole), wheree know from evaluations of continuous ECG monitoring duringPR that spontaneous rhythm changes are possible without appli-ation of countershocks. Advanced technologies analyzing the ECGignal may allow further insight in the future.

As an excellent prognostic indicator end-tidal CO2 can be mea-ured quite easily (with an etCO2 of more than 10 mmHg as a criticalut off line to develop ROSC),1 but etCO2 does not directly repre-ent brain function. Another good parameter to predict ROSC ishe estimation of coronary perfusion pressure if a CPP of 15 mmHgs exceeded.2 However, it is only available under special circum-tances.

A very interesting approach is to assess cortical brain function,or example by bispectral index monitoring (BIS) as it is performedn some fields of scheduled surgery. But although it is quite a sim-le tool to use, its reliability to predict prognosis is already unclearnder the controlled conditions of general anaesthesia.3 BIS haslso been studied in a limited number of post-resuscitation patientsith a moderate predictive value.4 Whether this tool is useful dur-

ng ongoing CPR remains questionable.After ROSC, therapeutic hypothermia further hampers prognos-

ication. Additionally, monitoring of cortical function may not bef highest interest, since we experience the fully reversible lossf cortical function every day after general anaesthesia. From thisoint of view it might be of greater importance for early prognos-ication to obtain instead informative signs from brain stem and

idbrain regions, since they reflect minimum perfusion of vitalrain structures.

One of these signs is gasping, both before initiation of CPR andts occurrence during CPR. Other brain stem reflexes indicatingavourable outcome are coughing, swallowing, ciliospinal reflexesnd the pupillary light reactions (PLR). The latter is even detectable

300-9572/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved.ttp://dx.doi.org/10.1016/j.resuscitation.2012.06.020

in blind patients, since it is partially also triggered on specificmelanopsin containing retinal ganglion cells.5

Earlier studies have already shown that these signs represent aneffective prognostic tool during CPR.6 Presence or recovery of thePLR within 10 min of CPR – assessed visually by conventional penlight application – predicted regain of consciousness, as well as apositive ciliospinal reflex at 20 min – sensitivities and specificitieswere above 80%. Whereas there may be few problems in recogniz-ing gasping, swallowing and coughing, PLR of minor extent may bemissed, notably in presence of bright light or after application ofcatecholamines or atropine.

The development of a portable infrared light pupillometer,allows precise measurement of the PLR even in a range whichis often missed by conventional pen light examination. Measure-ments are performed after a light flash of 800 ms and a pupil scanof 3.2 s applied during technical pauses of CPR. The device displaysa time stamped light reflex along with numerical data on pupil sizeand reflex amplitude.7

Behrends et al. now reported on a case series of 30 resuscitationsof in-hospital patients with a response interval of 2 min.8 Duringtechnical pauses of CPR measurements of PLR were performed fora medium time of 11 Min until ROSC or termination of CPR. PLR wasmeasurable in 25 patients, in 9 of them at all times. In 8 patientswithout initial reflex, PLR recovered within 5 min of CPR, whereasit did not recover in 4 patients and disappeared in the 4 remain-ing patients. Muscle relaxants, adrenaline even in high doses oratropine were given in some patients but did not block an existinglight reflex. Survival at day 3 with a cerebral performance cate-gory of 1–3 was seen in seven patients. All had had measurable PLRthroughout CPR or within less than 5 min, usually combined withincreasing amplitude of PLR. Three further survivors had a CPC ofmore than 3. All had had no detectable PLR for >5 min. Ten patientsdid not survive to ROSC. PLR was completely absent in 5 of these,in 4 it decreased in amplitude, and was measurable in only onepatient. Ten further patients died within 3 days after CPR. PLR waspresent in 5 of these, in 4 it was initially absent but present within5 min of CPR, and in one patient absent for >5 min and then present.The authors conclude that PLR predicted (a) early survival from CPRand (b) a favourable neurologic outcome after 3 days. It may fur-ther be concluded, that absence or vanishing PLR predicts futile CPRefforts, but is an insufficient basis to cease CPR.

Besides the small number of patients, the study has furtherimportant limitations which have to be kept in mind before a gen-eral conclusion can be drawn. First, by studying in-hospital patientswith a very short time interval between collapse and presumably

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E-mail address: hans-richard.arntz@charite.de

182 Editorial / Resuscitat

rofessional CPR a highly selected sample was explored. Second,F as the initially detected arrhythmia was only present in one of

he survivors with favourable neurologic outcome, whereas the 6thers had pulseless electric activity. This distribution is unusualor survivors of cardiac arrest. Also the distribution of underlyingauses of the arrest may be considered as unusual. Intracranialaemorrhage, excessive blood loss, drug reaction, and catheter

nduced arrhythmia represent 4 of the survivors with favourableutcome, compared with only two patients suffering from AMI andne with pulmonary embolism. Other parameters of prognosticalue as etCO2, gasping or swallowing have not been reported, inart due to technical reasons. Finally only a few patients receivedherapeutic cooling.

But despite these limitations, what is the notwithstanding sig-ificance of the exciting observations? First: infrared pupillometryuring ongoing CPR seems to be an objective tool which may helpo avoid premature termination of CPR. Second: it allows reliableut not decisive insight into the individual patient’s prognosis. Itay thus be of some value for decision in post-resuscitation care

nd may be helpful for discussions with care-givers and relativesf the patient. A definitive evaluation of the technique however,equires verification of the presented results in a much larger pop-lation most notably in an out of hospital population which also

ncludes other parameters of prognostic value.

eferences

. Levine RL, Wayne MA, Miller CC. End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest. N Engl J Med 1997;337:301–6.

. Paradis NA, Martin GB, Rivers EP, et al. Coronary perfusion pressure and thereturn of spontaneous circulation in human cardiopulmonary resuscitation. JAMA1990;263:1106–13.

(2012) 1181–1182

. Kertai MD, Whitlock EL, Avidan MS. Brain monitoring with electroencephalog-raphy and the electroencephalogram-derived bispectral index during cardiacsurgery. Anesth Analg 2012;114:533–46.

. Leary M, Fried DA, Gaieski DF, et al. Neurologic prognostication and bispec-tral index monitoring after resuscitation from cardiac arrest. Resuscitation2010;81:1133–7.

. Benarroch EE. The melanopsin system: phototransduction, projections, functions,and clinical implications. Neurology 2011;76:1422–7.

. Jørgensen EO. Neurological and circulatory outcomes of cardiopulmonary resus-citation in progress: influence of pre-arrest and arrest factors. Resuscitation1998;36:45–9.

. Du R, Meeker M, Bacchetti P, et al. Evaluation of a portable infrared pupillometer.Neurosurgery 2005;57:198–203.

. Behrends M, Niemann CU, Larson MD. Infrared pupillometry to detect thelight reflex during cardiopulmonary resuscitation: a case series. Resuscitation2012;83:1223–8.

Jan BreckwoldtDepartment of Anesthesiology, Charité University

Medicine Berlin, Campus Benjamin Franklin,Hindenburgdamm 30, D-12200 Berlin, Germany

Hans-Richard Arntz ∗

Department of Cardiopulmology, Charité UniversityMedicine Berlin, Campus Benjamin Franklin,

Hindenburgdamm 30, D-12200 Berlin, Germany

∗ Corresponding author at: Charité CampusBenjamin Franklin, Hindenburgdamm 30, 12200

Berlin, Germany. Tel.: +49 30 8445 0.

(H.-R. Arntz)

20 June 2012