Pupil diameter and light reaction during cardiac arrest and resuscitation

The Pre-ECPR Score: Developing and Validating a Multivariable Prediction Model for Favorable Neurological Outcomes in Patients Undergoing Extracorporeal Cardiopulmonary Resuscitation

OBJECTIVES

Extracorporeal cardiopulmonary resuscitation (ECPR) can save patients with refractory cardiac arrest; however, according to recent meta-analyses, only 20% of patients achieve favorable outcomes (Modified Rankin Scale 0-3). We aimed to develop and validate an ECPR prediction model to improve patient selection.

DESIGN

Prognostic model development and internal validation study.

SETTING

Single-center study.

PARTICIPANTS

All 120 normothermic ECPR patients treated at Sahlgrenska University Hospital between January 2010 and October 2021.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariable logistic regression was used to develop the PRognostic Evaluation of ECPR (Pre-ECPR) score. Model performance was assessed through the area under curve (AUC) and compared with the Extracorporeal Life Support Organization (ELSO) "Example of selection criteria for ECPR" for 1-year survival with favorable outcomes. The positive predictive value (PPV) was calculated. Favorable outcomes occurred in 27.5% of the patients. The Pre-ECPR score, incorporating age, no-flow/initial rhythm (a composite variable), total cardiac arrest time, signs of life, pupil dilation, regional cerebral oxygen saturation, arterial pH, and end-tidal CO2, demonstrated an AUC of 0.87 (95% confidence interval [CI] 0.77-0.93). In internal cross-validation, the AUC of 0.79 (95% CI 0.67-0.88) significantly outperformed the ELSO criteria AUC of 0.63 (95% CI 0.54-0.72, p = 0.012). Pre-ECPR score probabilities >6.4% showed 100% sensitivity and a PPV of 40.5% for favorable outcomes.

CONCLUSIONS

The Pre-ECPR score combines multiple weighted predictors to provide a single balanced probability of favorable outcomes in ECPR patient selection. In cross-validation, it demonstrated significantly more favorable discriminatory performance than that of the ELSO criteria.

Association between pupillary examinations and prognosis in patients with out-of-hospital cardiac arrest who underwent extracorporeal cardiopulmonary resuscitation: a retrospective multicentre cohort study

BACKGROUND

In some cases of patients with out-of-hospital cardiac arrest (OHCA) who underwent extracorporeal cardiopulmonary resuscitation (ECPR), negative pupillary light reflex (PLR) and mydriasis upon hospital arrival serve as common early indicator of poor prognosis. However, in certain patients with poor prognoses inferred by pupil findings upon hospital arrival, pupillary findings improve before and after the establishment of ECPR. The association between these changes in pupillary findings and prognosis remains unclear. This study aimed to clarify the association of pupillary examinations before and after the establishment of ECPR in patients with OHCA showing poor pupillary findings upon hospital arrival with their outcomes. To this end, we analysed retrospective multicentre registry data involving 36 institutions in Japan, including all adult patients with OHCA who underwent ECPR between January 2013 and December 2018. We selected patients with poor prognosis inferred by pupillary examinations, negative pupillary light reflex (PLR) and pupil mydriasis, upon hospital arrival. The primary outcome was favourable neurological outcome, defined as Cerebral Performance Category 1 or 2 at hospital discharge. Multivariable logistic regression analysis was performed to evaluate the association between favourable neurological outcome and pupillary examination after establishing ECPR.

RESULTS

Out of the 2,157 patients enrolled in the SAVE-J II study, 723 were analysed. Among the patients analysed, 74 (10.2%) demonstrated favourable neurological outcome at hospital discharge. Multivariable analysis revealed that a positive PLR at ICU admission (odds ration [OR] = 11.3, 95% confidence intervals [CI] = 5.17-24.7) was significantly associated with favourable neurological outcome. However, normal pupil diameter at ICU admission (OR = 1.10, 95%CI = 0.52-2.32) was not significantly associated with favourable neurological outcome.

CONCLUSION

Among the patients with OHCA who underwent ECPR and showed poor pupillary examination findings upon hospital arrival, 10.2% had favourable neurological outcome at hospital discharge. A positive PLR after the establishment of ECPR was significantly associated with favourable neurological outcome.

Automated pupillometry helps monitor the efficacy of cardiopulmonary resuscitation and predict return of spontaneous circulation

BACKGROUND

We investigated the effectiveness of automated pupillometry on monitoring cardiopulmonary resuscitation (CPR) and predicting return of spontaneous circulation (ROSC) in a swine model of cardiac arrest (CA).

METHODS

Sixteen male domestic pigs were included. Traditional indices including coronary perfusion pressure (CPP), end-tidal carbon dioxide (ETCO₂), regional cerebral tissue oxygen saturation (rSO₂) and carotid blood flow (CBF) were continuously monitored throughout the experiment. In addition, the pupillary parameters including the initial pupil size before constriction (Init, maximum diameter), the end pupil size at peak constriction (End, minimum diameter), and percentage of change (%PLR) were measured by an automated quantitative pupillometer at baseline, at 1, 4, 7 min during CA, and at 1, 4, 7 min during CPR.

RESULTS

ROSC was achieved in 11/16 animals. The levels of CPP, ETCO₂, rSO₂ and CBF were significantly greater during CPR in resuscitated animals than those non-resuscitated ones. Init and End were decreased and %PLR was increased during CPR in resuscitated animals when compared with those non-resuscitated ones. There were moderate to good significant correlations between traditional indices and Init, End, and %PLR (|r| = 0.46-0.78, all P < 0.001). Furthermore, comparable performance was also achieved by automated pupillometry (AUCs of Init, End and %PLR were 0.821, 0.873 and 0.821, respectively, all P < 0.05) compared with the traditional indices (AUCs = 0.809-0.946).

CONCLUSION

The automated pupillometry may serve as an effective surrogate method to monitor cardiopulmonary resuscitation efficacy and predict ROSC in a swine model of cardiac arrest.

Long-Term Substance Use Can Cause Irreversible Photopic Vision Changes in Substance Use Disorder in Remission

OBJECTIVE

Substance use has such effects on pupil diameter. Although there is knowledge about the acute effects of substances on pupils, studies showing their chronic effects are limited. The aim of the present study was to evaluate the effect of long-term substance use on scotopic, mesopic, and photopic vision.

METHODS

The present study with cross-sectional desgn was conducted at the Adiyaman Training and Research Hospital for Psychiatry in Adiyaman. This study involved 110 substance use disorder (SUD) patients and 46 healthy volunteers as the control. The parameters were measured and recorded automatically by a device.

RESULTS

The mean age was 23.44±5.53 years in the SUD group and 24.26±5.38 years in healthy controls (p=0.420). The mean age of onset of the substance was 17.74±3.89 years and the mean duration of substance use was 3.54±2.9 years. It was determined that the patients had not used any substance for a mean of 121.73±117.49 days. There was no significant difference between patient and control groups in terms of scotopic and mesopic measurements of both eyes (p>0.05). Photopic measurements were significantly higher in the patient group than in the control group (p<0.05). Photopic measurements were significantly higher in the opioid, cannabis, ecstasy, and multiple substance use groups than in the control group (p<0.05).

CONCLUSION

The most important topic of this study is that photopic vision is permanently impaired in patients with a history of chronic substance use. This was attributed to disrupted sympathetic-parasympathetic hierarchy.

Design of a Volumetric Imaging Sequence Using a Vantage-256 Ultrasound Research Platform Multiplexed With a 1024-Element Fully Sampled Matrix Array

Ultrasound imaging using a matrix array allows real-time multi-planar volumetric imaging. To enhance image quality, the matrix array should provide fast volumetric ultrasound imaging with spatially consistent focusing in the lateral and elevational directions. However, because of the significantly increased data size, dealing with massive and continuous data acquisition is a significant challenge. We have designed an imaging acquisition sequence that handles volumetric data efficiently using a single 256-channel Verasonics ultrasound research platform multiplexed with a 1024-element matrix array. The developed sequence has been applied for building an ultrasonic pupilometer. Our results demonstrate the capability of the developed approach for structural visualization of an ex vivo porcine eye and the temporal response of the modeled eye pupil with moving iris at the volume rate of 30 Hz. Our study provides a fundamental ground for researchers to establish their own volumetric ultrasound imaging platform and could stimulate the development of new volumetric ultrasound approaches and applications.

Prognostication in Anoxic Brain Injury

Cardiac arrest is a common cause of coma with frequent poor outcomes. Palliative medicine teams are often called upon to discuss the scope of treatment and future care in cases of anoxic brain injury. Understanding prognostic tools in this setting would help medical teams communicate more effectively with patients’ families and caregivers and may promote improved quality of life overall. This article reviews multiple tools that are useful in determining outcomes in the setting of postarrest anoxic brain injury.

Organ donation as an outcome of traumatic cardiopulmonary arrest: A cost evaluation

BACKGROUND

Survival after traumatic cardiopulmonary arrest (TCPA) is rare and requires significant resource expenditure. Organ donation as an outcome of TCPA resuscitation has not yet been included in a cost analysis. The aims of this study were to identify variables associated with survival and organ donation after TCPA, and to estimate the cost of achieving these outcomes. We hypothesized that the inclusion of organ donation as a potential outcome would make TCPA resuscitation more cost-effective.

METHODS

Adult patients who required resuscitation for TCPA at a level I trauma center were retrospectively reviewed over 36 months. Data were obtained from medical records, hospital accounting records, and the local organ procurement agency. Outcomes included survival to discharge, neurologic function, and organ donor eligibility. An individual-level state-transition cost-effectiveness model was used to evaluate the cost of TCPA resuscitation with and without organ donation included as an outcome. Incremental cost-effectiveness ratio was calculated to determine additional cost per life saved when organ donation is included.

RESULTS

Over the study period, 8,932 subjects were evaluated. Traumatic cardiopulmonary arrest occurred in 237 patients (3%). The mortality rate was 97%. Variables associated with survival included emergency department disposition to the operating room (p < 0.01) and reactive pupils (p < 0.001). Of seven survivors, four were discharged neurologically intact. Of the patients with TCPA, 5% were eligible for organ donation with a procurement rate of 2%. Organ donor eligibility was associated with arrest after arrival to the emergency department (p < 0.01) and transfusion of fresh frozen plasma (p = 0.01). The cost of TCPA resuscitation per survivor was $1.8 million; cost per survivor or life saved by donation was $538,000. The incremental cost-effectiveness ratio was $76,816 per additional life saved including donation as an outcome.

CONCLUSION

The decision to pursue resuscitation should continue to be based on the presence of signs of life, especially pupil reactivity and duration of arrest. If the primary objective is survival, organ procurement will be maximized without conflict of interest. Early fresh frozen plasma transfusion may increase successful organ donation. The financial burden of TCPA resuscitation can be mitigated by expanding end points to include organ donation.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III; cost analysis, level V.

Minor Changes in Core Temperature Prior to Cardiac Arrest Influence Outcomes: An Experimental Study

AIM

To investigate whether slight variations in core temperature prior to cardiac arrest (CA) influence short-term outcomes and mitochondrial functions.

METHODS AND MATERIALS

Three groups of New Zealand White rabbits (n = 12/group) were submitted to 15 minutes of CA at 38°C (T-38 group), 39°C (T-39), or 40°C (T 40) and 120 minutes of reperfusion. A Sham-operated group (n = 6) underwent only surgery. Restoration of spontaneous circulation (ROSC), survival, hemodynamics, and pupillary reactivity were recorded. Animals surviving to the end of the observation period were euthanized to assess fresh brain and heart mitochondrial functions (permeability transition and oxidative phosphorylation). Markers of brain and heart damages were also measured.

RESULTS

The duration of asphyxia required to induce CA was significantly lower in the T-40 group when compared to the T-38 group (P < .05). The rate of ROSC was >80% in all groups (P = nonsignificant [ns]). Survival significantly differed among the T-38, T-39, and T-40 groups: 10 (83%) of 12, 7 (58%) of 12, and 4 (33%) of 12, respectively (log-rank test, P = .027). At the end of the protocol, none of the animals in the T-40 group had pupillary reflexes compared to 8 (67%) of 12 in the T-38 group (P < .05). Troponin and protein S100B were significantly higher in the T-40 versus T-38 group (P < .05). Cardiac arrest significantly impaired both inner mitochondrial membrane integrity and oxidative phosphorylation in all groups. Brain mitochondria disorders were significantly more severe in the T-40 group compared to the T-38 group (P < .05).

CONCLUSION

Small changes in body temperature prior to asphyxial CA significantly influence brain mitochondrial functions and short-term outcomes in rabbits.

Pupillary Effects of High-dose Opioid Quantified with Infrared Pupillometry

Background:

The pupillary light reflex is a critical component of the neurologic examination, yet whether it is present, depressed, or absent is unknown in patients with significant opioid toxicity. Although opioids produce miosis by activating the pupillary sphincter muscle, these agents may induce significant hypercarbia and hypoxia, causing pupillary constriction to be overcome via sympathetic activation. The presence of either “pinpoint pupils” or sympathetically mediated pupillary dilation might prevent light reflex assessment. This study was designed to determine whether the light reflex remains quantifiable during opioid-induced hypercarbia and hypoxia.

Methods:

Ten volunteers were administered remifentanil with a gradually increasing infusion rate and intermittent boluses, until the increasing respiratory depression produced an oxyhemoglobin saturation of 85% or less with associated hypercarbia. Subjects’ heart rate, blood pressure, respiration, and transcutaneous carbon dioxide level were continuously recorded. Arterial blood gases and pupillary measures were taken before opioid administration, at maximal desaturation, and 15 min after recovery.

Results:

The opioid-induced oxygen desaturation (≤85%) was associated with significant hypercarbia and evidence of sympathetic activation. During maximal hypoxia and hypercarbia, the pupil displayed parasympathetic dominance (2.5 ± 0.2 mm diameter) with a robust quantifiable light reflex. The reflex amplitude was linearly related to pupil diameter.

Conclusions:

Opioid administration with significant accompanying hypercarbia and hypoxia results in pupil diameters of 2 to 3 mm and a reduced but quantifiable pupillary light reflex. The authors conclude that the pupillary examination and evaluation of the light reflex remain useful for neurologic assessment during opioid toxicity.

Infrared pupillometry to detect the light reflex during cardiopulmonary resuscitation: a case series

BACKGROUND

The presence or absence of the pupillary light reflex following cardiopulmonary resuscitation has been shown to have prognostic value. We asked whether the light reflex could be objectively measured during cardiopulmonary resuscitation in humans and whether the quality of the reflex was associated with outcome.

METHODS

Sixty-seven in-hospital code blue alerts were attended of which 30 met our inclusion criteria. Portable infrared pupillometry was used to measure the light reflex during each code. The reliability of the presence of the light reflex during each code as a predictor of survival and neurological outcome was analyzed statistically using the Barnard's Exact test.

RESULTS

In 25 patients (83%) the pupillary light reflex was detectable throughout or during a part of the resuscitation. Continuous presence of the light reflex or absence for less than 5 min during resuscitation was associated with early survival of the code and a good neurological outcome. In contrast, no patients without a light reflex or with a gradually deteriorating light reflex survived the code and absence of a pupillary light reflex for more than 5 min was associated with an unfavorable outcome.

CONCLUSION

Portable infrared pupillary measurements can reliably demonstrate the presence and quality of the pupillary light reflex after cardiac arrest and during resuscitation. In our limited case series, the presence of the pupillary light reflexes obtained in serial measurements during resuscitation was associated with early survival and a favorable neurological status in the recovery period.

Infrared pupillometry. Basic principles and their application in the non-invasive monitoring of neurocritical patients

INTRODUCTION

Pupil assessment is a fundamental part of the neurological examination. Size and reactivity to light of each pupil should be recorded periodically since changes in these parameters may represent the only detectable sign of neurological deterioration in some patients. However, there is great intraobserver and interobserver variability in pupil examination due to the influence of many factors, such as the difference in ambient lighting, the visual acuity and experience of the examiner, the intensity of the luminous stimulus, and the method used to direct this stimulus. In recent years, digital cameras have incorporated infrared devices allowing the development of user-friendly portable devices that permit repeated, non-invasive examinations of pupil size and its reactivity to light with an objective, accessible and inexpensive method.

DEVELOPMENT

The purpose of this review is to describe the fundamentals of infrared pupillometry and discuss potential applications in the monitoring of neurocritical patients. We also present some recommendations in the routine assessment of pupils in neurocritical patients.

CONCLUSIONS

The possibility of evaluating the changes in pupil reactivity in an early, objective and almost continuous way provides a new non-invasive monitoring method. This method could improve the predictive factor of neurological deterioration and the bedside monitoring of the neurological state of the patient, avoiding unnecessary examinations and enabling early therapeutic intervention.

A binocular pupil model for simulation of relative afferent pupil defects and the swinging flashlight test

Many important intracranial neural pathways are involved in the control of the two muscles of the human pupil and the observation and analysis of pupil responses to light or other stimuli is of great interest in many clinical procedures. The binocular pupil model presented in this document has a topology encompassing much of the complexity of the pupil system neurophysiology. The dynamic parameters of the model were matched against pupil experiments under multiple conditions. It is employed here to simulate responses to the swinging flashlight test, a procedure which is routinely practiced in ophthalmology to diagnose different degrees of relative afferent pupil defects often a consequence of severe optic nerve diseases or retinal dysfunctions. Other, not light-dependent, pupil stimuli are briefly discussed.

Postresuscitation Encephalopathy

BACKGROUND

Cardiac arrest has a high mortality rate. Postresuscitation encephalopathy is commonly associated with significant morbidity.

REVIEW SUMMARY

Among those patients who achieve a return to spontaneous circulation, more than half die during the subsequent hospital course. Few survivors recover without significant neurologic disability. Clinical examination is often used for predicting subsequent neurologic outcome in these patients. The role of ancillary investigations and the judicious combination of these parameters with the findings on clinical examination to achieve accurate prognostication is discussed in this review. Only a few parameters have a strong predictive value in coma after cardiac arrest. These include pupillary light reflexes and motor responses at 3 days, absent somatosensory evoked potential, and possibly diffuse magnetic resonance imaging changes.

CONCLUSION

The authors discuss the physiology, pathology, and consequences of cardiac arrest to the central nervous system, and the use of various parameters in prognostication. Induced hypothermia is a new therapeutic development.

Monitoring during cardiac arrest: are we there yet?

Advancements in electronic data acquisition have translated into improved monitoring of victims of cardiac arrest, but initial techniques remain direct observation of pulses and respirations. The most essential monitor continues to be the electrocardiogram. However, monitoring diastolic blood pressure, myocardial perfusion pressure, and end-tidal carbon dioxide are extremely useful. Most of the current research on monitoring during cardiopulmonary resuscitation focuses on methods for analyzing ventricular fibrillation waveforms. By analyzing the waveform, defibrillation shocks may be delivered at the time when the chance of success is optimal. Low-amplitude and low-frequency fibrillation waveforms are associated with increased rates of asystole and pulseless electrical activity after defibrillation. Methods of analyzing the ventricular fibrillation waveform include measuring the amplitude and frequency and combining the contributions of amplitude and frequency by various methods to improve discrimination. Other types of monitoring being studied for their usefulness during cardiac arrests include sonography, Bispectral Index monitoring, tissue carbon dioxide monitors, and pupil observation. The test of these monitoring techniques is ultimately their ability to improve patient survival to hospital discharge, which is a major challenge for resuscitation researchers.

Physiologic Predictors of Survival in Post-Traumatic Arrest

Traumatic cardiac or pulmonary arrest is often associated with a dismal outcome and is considered by many to be an example of medical futility and inappropriate use of resources. This study aimed to identify the predictors of survival in patients experiencing traumatic cardiac arrest. We retrospectively reviewed all trauma patients undergoing cardiopulmonary resuscitation on arrival to the Emergency Department (ED) at an American College of Surgeons-designated Level I trauma center over 4 years. ED survival, hospital survival, and neurologic outcomes on discharge were the primary outcomes. Survival rates were examined in relation to demographics, mechanism of injury, airway management, cardiac electrical rhythm, and pupil size and reactivity. Statistical analyses used chi-square and t tests, P < 0.05 was considered significant. A total of 195 patients arrived in the ED with traumatic cardiac arrest; 34 were pronounced dead on arrival (no signs of life), and no resuscitation efforts were initiated. Of the remaining 161 patients 53 (33%) survived to leave the ED, and only 15 (9%) left the hospital alive. Demographic features were similar in survivors and nonsurvivors. The setting of intubation (prehospital vs ED) did not influence survival ( P = 0.36). Penetrating trauma adversely affected survival in the ED ( P = 0.01); however, this only approached significance in the final outcome of hospital survival ( P = 0.06). The presence of sinus rhythm and nondilated reactive pupils was highly significant in predicting ED and hospital survival ( P = 0.001). No patient with agonal rhythm or ventricular fibrillation/tachycardia survived, and 14 of the 15 hospital survivors had reactive pupils on arrival to the ED. We conclude that sinus rhythm and pupil size and reactivity are important physiologic variables that predict potential survival and may be used to guide continuation of resuscitative efforts in patients with traumatic cardiac arrest.

Effect of asphyxia on the pupils of brain dead subjects

The pupils dilate following cardiac arrest but the mechanism is unknown. If pupillary dilation represents inadequate blood supply to the midbrain, pupil size might be a rough guide to the adequacy of the resuscitation effort. The brain dead organ harvest patient presents a unique opportunity to study pupillary activity in the absence of an intact midbrain and to examine the effects of asphyxia on the pupil. Because the midbrain is dead in these subjects, the pupil has no supraspinal autonomic control and following aortic cross clamp, no blood can be delivered to the orbit. Ten brain dead patients scheduled for organ harvest were studied. Pupil size was measured from the right eye every minute for 9 min before and every minute for 10 min following aortic cross-clamp. Dapiprazole eye drops were instilled into the left eye at least 1 h before cross clamp in five cases and pupillary measurements were intermittently taken before and after cross clamp. Pupil size was stable before cross clamp. Following cross clamp, the pupil dilated in all cases, reaching 10.6 mm in one case. Mean dilation was 1.8+/-0.9 mm. Time to peak dilation was 4.3+/-1.4 min and latency of dilation was 1.4+/-1.2 min. Dapiprazole eye drops prevented the pupillary dilation in contralateral eye of the five cases in which it was used. The cause of this sympathetic activity is either a short burst of neuronal activity in the peripheral sympathetic system innervating the dilator muscle, or release of stored norepinephine from the presynaptic terminals, as asphyxia intervenes.