Joanna Sołek-Pastuszka

Computed Tomographic Angiography and Perfusion in the Diagnosis of Brain Death

INTRODUCTION According to Polish brain death (BD) criteria, instrumental confirmatory tests should be used in certain clinical situations, particularly any case for which clinical examinations seem inadequate. Electrophysiological tests are often unavailable. Therefore, cerebral perfusion testing is the method of choice with four-vessel digital subtraction angiography (DSA), the gold standard. Unfortunately, DSA is an expensive and invasive examination that requires an experienced neuroradiologist and the availability of an angiography suite. Recently, multirow computed tomographic devices became available, even in smaller hospitals in Poland. Despite this fact, computed tomographic angiography (CTA) and computed tomographic perfusion (CTP) are not accepted in BD diagnosis protocols in Poland because of limited experience and a lack of widely accepted criteria. In this situation, we started a multicenter trial to determine the accuracy of CTA and CTP to confirm BD. METHODS We examined 24 patients who fulfilled standard clinical BD criteria. We recognized the absence of brain perfusion in CTA examination following the criteria proposed by the French Society of Neuroradiology, namely, the absence of opacification of M4 middle cerebral artery segments (M4-MCA) and of deep cerebral veins. RESULTS In all of our patients, CTA showed absence of opacification of M4 segments and of deep cerebral veins. In addition, three patients had CTA showing weak opacification of A2 segments of the anterior cerebral artery (A2-ACA) and M2 or M3-MCA. Opacification of the basilar artery or of the posterior cerebral arteries was not noted in any case. In all patients, CTP revealed zero values of regional cerebral blood volume and regional cerebral blood flow. Conventional angiography confirmed cerebral circulatory arrest in all 24 cases. CONCLUSION CTA and CTP seem to be promising radiological examinations for the diagnosis of BD. They may be noninvasive alternatives to conventional cerebral angiography, and to the other instrumental confirmatory tests, that are unavailable or inadequate.

Apnea test in the determination of brain death in patients treated with extracorporeal membrane oxygenation (ECMO)

Extracorporeal Membrane Oxygenation (ECMO) is a well-established method of support in patients with severe respiratory and/or circulatory failure. Unfortunately, this invasive method of treatment is associated with a high risk of neurological complications including brain death. Proper diagnosis of brain death is crucial for the termination of futile medical care. Currently, the legal system in Poland does not provide an accepted protocol for apnea tests for patients on ECMO support. Veno-arterial ECMO is particularly problematic in this regard because it provides both gas exchange and circulatory support. CO₂ elimination by ECMO prevents hypercapnia, which is required to perform an apnea test. Several authors have described a safe apnea test procedure in patients on ECMO. Maximal reduction of the sweep gas flow to the oxygenator should maintain an acceptable haemoglobin oxygenation level and reduce elimination of carbon dioxide. Hypercapnia achieved via this method should allow an apnea test to be conducted in the typical manner. In the case of profound desaturation and an inadequate increase in the arterial CO₂ concentration, the sweep gas flow rate may be increased to obtain the desired oxygenation level, and exogenous carbon dioxide may be added to achieve a target carbon dioxide level. Incorporation of an apnea test for ECMO patients is planned in the next edition of the Polish guidelines on the determination of brain death.

CT Angiography in the Diagnosis of Brain Death

Summary Brain death is defined as the irreversible cessation of functioning of the entire brain, including the brainstem. Brain death is principally established using clinical criteria including coma, absence of brainstem reflexes and loss of central drive to breathe assessed with apnea test. In situations in which clinical testing cannot be performed or when uncertainty exists about the reliability of its parts due to confounding conditions ancillary tests (i.a. imaging studies) may be useful. The objective of ancillary tests in the diagnosis of brain death is to demonstrate the absence of cerebral electrical activity (EEG and evoked potentials) or cerebral circulatory arrest. In clinical practice catheter cerebral angiography, perfusion scintigraphy, transcranial Doppler sonography, CT angiography and MR angiography are used. Other methods, like perfusion CT, xenon CT, MR spectroscopy, diffusion weighted MRI and functional MRI are being studied as potentially useful in the diagnosis of brain death. CT angiography has recently attracted attention as a promising alternative to catheter angiography – a reference test in the diagnosis of brain death. Since 1998 several major studies were published and national guidelines were introduced in several countries (e.g. in France, Austria, Switzerland, the Netherlands and Canada). This paper reviews technique, characteristic findings and criteria for the diagnosis of cerebral circulatory arrest in CT angiography.

Evolution of apnoea test in brain death diagnostics

The concept of brain death (BD) was initially described in 1959 and subsequently became widely accepted in the majority of countries. Nevertheless, the diagnostic guidelines for BD markedly differ, especially regarding the apnoea test (AT), a crucial element of clinical BD confirmation. The current basic guidelines recommend preoxygenation rather than disconnection from the ventilator and insertion of an oxygen insufflation catheter into the endotracheal tube. Although a properly prepared and conducted AT is relatively safe, it has to be aborted in cases of serious disturbances, such as severe cardiac arrhythmia, cardiac arrest, hypotension, hypercarbia, desaturation and tension pneumothorax. These complications may be more frequent in patients with previously existing risk factors, such as poor oxygenation, severe acidosis, hypotension and cardiac rhythm disturbances. Airway injuries can occur if the insufflation catheter is placed too deep or catheter-related obstruction of the intubation tube occurs. It is widely accepted that AT should be performed as the very last BD diagnostic procedure due to its possible lethal consequences. Reports concerning the possible pitfalls of AT and confounding situations have inspired attempts to determine the most effective and safe method of AT. The use of CPAP with oxygen supplementation is becoming highly popular. CPAP can be generated in three manners: directly by the ventilator; through the use of a CPAP valve with a reservoir; and through the use of a highly traditional T-piece system with a reservoir bag connected to distal tubing immersed in water.

Original Protocol Using Computed Tomographic Angiography for Diagnosis of Brain Death: A Better Alternative to Standard Two-Phase Technique?

BACKGROUND The application of computed tomographic angiography (CTA) for the diagnosis of brain death (BD) is limited because of the low sensitivity of the commonly used two-phase method consisting of assessing arterial and venous opacification at the 60th second after contrast injection. The hypothesis was that a reduction in the scanning delay might increase the sensitivity of the test. Therefore, an original technique using CTA was introduced and compared with catheter angiography as a reference. MATERIAL AND METHODS In a prospective multicenter trial, 84 clinically brain-dead patients were examined using CTA and catheter angiography. The sensitivities of original CTA technique, involving an arterial assessment at the 25th second and a venous assessment at the 40th second, and the standard CTA, involving an arterial and venous assessment at the 60th second, were compared to catheter angiography. RESULTS Catheter angiography results were consistent with the clinical diagnosis of BD in all cases. In comparison to catheter angiography, the sensitivity of original CTA technique was 0.93 (95%CI, 0.85-0.97; p<0.001) and 0.57 (95%CI, 0.46-0.68; p<0.001) for the standard protocol. The differences were statistically significant (p=0.03 for original CTA and p<0.001 for standard CTA). Decompressive craniectomy predisposes to a false-negative CTA result with a relative risk of 3.29 (95% CI, 1.76-5.81; p<0.001). CONCLUSIONS Our original technique using CTA for the assessment of the cerebral arteries during the arterial phase and the deep cerebral veins with a delay of 15 seconds is a highly sensitive test for the diagnosis of BD. This method may be a better alternative to the commonly used technique.

Reversal to Whole-Brain Death Criteria After 15-Year Experience With Brain Stem Death Criteria in Poland

Polish brain-death criteria, similar to the original Harvard criteria, were published in 1984. In 1990, they were converted to brainstem death criteria, and were revised twice, in 1994 and in 1996. However, they could not be used in many complicated clinical situations such as intoxication, metabolic alterations, major facial injury, infratentorial lesions, and cervical spinal cord injury. The new Polish Transplant Act, passed by the Polish Parliament in 2005, recommends implementation of criteria for whole-brain death for brain-death diagnosis. In 2007, the Polish Ministry of Health Commission outlined new Polish brain-death criteria. Optional use of instrumental confirmatory tests was implemented in the new Polish national code of practice for the diagnosis of brain death in adults. In children up to age 2 years, instrumental tests are obligatory. Initially, there were problems in understanding the new, slightly more complicated classifications of primary and secondary brain injuries, infratentorial and supratentorial processes, modified apnea test. A broad commentary that addressed the most frequently asked questions was published in Anesthesiology and Intensive Therapy, the official journal of the Polish Society of Anaesthesiology and Intensive Therapy. This article dealt with most of the problems associated with implementation of the new criteria for diagnosis of brain death.

Apnea testing using the oxygen insufflation method for diagnosis of brain death may compromise pulmonary function

Introduction: The aim of our study was to compare the reliability and safety of the classical I‐AT with the continuous positive airway pressure apnea test (CPAP‐AT). Material and methods: In the group of 48 patients (group O), an I‐AT was performed at the end of BD diagnostic procedures, and approximately 1–1.5 h later CPAP‐AT with 100% FiO2 and CPAP of 10 cm H2O, provided by ventilator in CPAP mode. After pre oxygenation with 100% FiO2 for 10 min, the PaO2/FiO2 ratio was recorded prior to I‐AT at time‐point one (T1) and prior to CPAP‐AT at time‐point two (T2). Group O was categorized into subgroup N‐H (non‐hypoxemic), consisting of 41 patients with good lung function, and subgroup H (hypoxemic) consisting of 7 patients with poor lung function. Within each subgroup PaO2/FiO2 at T1 and T2 were compared. Results: In Group O, PaO2/FiO2 decreased from 321 ± 128 mm Hg at T1 to 291 ± 119 mm Hg at T2 (p = 0.004). In subgroup N‐H, PaO2/FiO2 declined from 355 ± 103 to 321 ± 100 mm Hg (p = 0.008), and in subgroup H, PaO2/FiO2 remained almost unchanged. Additionally, in 4 patients from subgroup N‐H, PaO2/FiO2 decreased below 200 mm Hg at T2. Conclusions: Our study indicates that I‐AT may compromise pulmonary function and this may support the recommendation of safer CPAP‐AT alternative. HighlightsI‐AT may compromise pulmonary function in some patientsIn some non‐hypoxemic patients, PaO2/FiO2 ratio may decrease below the cutoff value of 200 mm Hg after I‐AT.This may justify considering the alternative, safer CPAP‐AT.

Predisposition of functional genetic variants of A-kinase anchoring protein 10 toward acquired repolarization disorders in high-risk vascular surgery patients

Purpose We aimed at assessing the predisposition of A-kinase anchoring protein 10 (AKAP10) polymorphism toward acquired repolarization disorders in high-risk vascular surgery patients. Patients and methods One hundred adult patients (age =44–85 years), scheduled for an elective high-risk “open” vascular surgery procedure, were recruited. The electrocardiogram Holter monitor was used to assess repolarization stability from the beginning of the operation up to 24 hours afterward. The AKAP10 gene rs203462 polymorphism and cardiac complications were analyzed. Results Repolarization disturbances defined as QT interval duration corrected for heart rate (QTc) interval prolongation >500 ms and QTc interval dispersion >65 ms were recorded in 46 patients. A model of multivariate logistic regression showed that only the presence of allele G of the AKAP10 polymorphism was an independent risk factor for repolarization disturbances in the perioperative period (odds ratio =14.35; 95% CI =4.65–44.23; p<0.0001). Conclusion When the acquired QTc interval prolongation or QTc dispersion is associated with AKAP10 polymorphism, it may remain clinically silent.

Final Report of the Polish Multicentre Study for Evaluation of Computed Tomographic Angiography in the Diagnosis of Brain Death

Introduction According to Polish brain death (BD) criteria instituted in 2007, confirmatory tests should be used in specific situations such as intoxication, infratentorial processes, extensive facial damage, in children up to one year of age and any case when clinical examination seems to be inadequate. These tests are often unavailable due to insufficient access to proper equipment and qualified specialists. Therefore, finding a confirmatory test, which would be widely available, simple to perform and easy to interpret became of fundamental importance. Computed tomographic angiography (CTA) seemed to be the test of choice for this purpose because new generation of CT scanners became widely available. The method is simple and relatively cheap. Despite of this fact, CTA was not included in Polish BD criteria in 2007 because of limited expertise and lack of generally accepted criteria. In this situation, after approval of Bioethical Committee we organized Polish national multicentre trial for evaluation of CTA in the diagnosis of BD. Methods In 7 cooperating centres, we examined 119 patients, which fulfilled standard clinical BD criteria. In all cases two-phase CTA was performed with assessment of intracranial vessels at 60 sec. after contrast administration. Cerebral circulatory arrest in CTA was defined as the absence of opacification of M4 segments of the middle cerebral artery (M4-MCA) and deep cerebral veins, the same as in criteria of French Society of Neuroradiology [1]. Results In 107 patients, CTA revealed the absence of opacification of M4-MCA segments and deep cerebral veins. This met the French diagnostic criteria of cerebral circulatory arrest. This gave the sensitivity of 90% (95% CI 83-94%) for CTA in the diagnosis of BD. Additionally we identified potential points of pitfalls, which will be mentioned in currently elaborated Polish instruction. Conclusions 1. CTA is a valuable confirmatory test for BD diagnosis. 2. Polish instruction will be compatible with French protocol published in 2011. Reference: 1. Societe Francaise de Neuroradiologie, Societe Francaise de Radiologie, Agence de la Biomedecine. [Recommendations on diagnostic criteria of brain death by the technique of CT angiography]. J Neuroradiol. 2011;38(1):36–39.

Respiratory insufficiency with pneumonia following improper gastric tube insertion into the right bronchus.

Blind placement of gastric tubes is commonly done at the bedside, and is associated with significant risk. Inadvertent placement of gastric tubes into the lungs may lead to some dreaded and serious complications including intrapulmonary infusion of fluids, pneumothorax, pneumonitis, hydropneumothorax, bronchopleural fistula, empyema, and pulmonary hemorrhage. Although the reported frequency of inadvertent airway gastric tube placement varies from 1% to 15%, clinicians agree that the associated complications may result in increases in mortality, morbidity, cost and length of hospital stay, and are to be avoided [1]. In this report, we would like to present a case of respiratory insufficiency with pneumonia following improper gastric tube insertion into the right bronchus and active carbon administration. On the day of admittance, in the morning hours, the patient (a 43-year-old prisoner) was brought by ambulance to the local Emergency and Rescue (ER) Department from a prison, with suspected drug intoxication with an unknown substance. In the ER, the patient was unconscious but with both respiration and circulation fully sufficient, and a directional reaction to pain stimuli. On auscultation, numerous disseminated rhonchi, more pronounced on the left side, were heard. The patient was intubated (using thiopental and suxamethonium), and the gastric tube was placed, with subsequent gastric lavage. A pus-like fluid was extracted from the tracheal tube using suction; chest X-ray was performed to exclude pneumonia. As the patients general condition improved, he regained full consciousness, and with spontaneous breathing the tracheal tube proved unnecessary, which resulted in extubation (within approximately 30 min). The gastric tube was removed as well, but due to bronchial spasm, salbutamol nebulization was initiated, with further improvement of the general condition. Toxicological analyses were performed from urine and blood samples. At this stage, the patient was mentally labile, with pronounced anxiety and non-compliance with medical personnel requests, and was often verbally offensive. Two hours after admittance to the ER, toxicological analysis revealed high (toxic) levels of carbamazepine and phenothiazine, resulting in the introduction of treatment with activated carbon. A gastric tube (16 F) was placed again through the nasal cavity; however, this time the patient was fully conscious. Correct placement of the tube was confirmed by the physician who placed the tube, and by the assisting nurse. For this purpose the patient twice was auscultated over the epigastric region, both by the physician and the nurse. With no doubts regarding tube placement, carbon administration was initiated, but after approximately 10 ml of the solution was given, intensive coughing was observed. The procedure was aborted, and the gastric tube was removed immediately and replaced, with no resistance noted. Tube placement was ascertained on auscultation again, with subsequent administration of 10 ml 0.9% NaCl. As no extensive agitation or coughing was noted during either tube placement or test dose administration, treatment with a full dose of active carbon was implemented, with no adverse reactions. In the chest X-ray performed after carbon administration, massive airless and probably inflammatory foci were found in the middle and lower right lung lobes, while less pronounced lesions were present in the lower left lobe. Four hours later, an experienced consulting anesthesiologist examined the patient; his general condition was described as satisfactory, and midazolam and diazepam in fractioned doses were given to reduce anxiety. In the late afternoon hours of the same day (several hours after the mistaken active carbon administration), increasing respiratory insufficiency was observed. The ER physician on duty observed progression of auscultatory abnormalities with predominance of right-sided rales (while in the morning left-sided symptoms were more pronounced). The patient was qualified for further treatment in the intensive care unit (ICU). On admittance to the ICU, the patient was conscious but with no logical verbal contact; no neurological deficits were found on general examination, except for symmetrical, pinpoint pupils. Spontaneous breathing on the verge of respiratory insufficiency was observed; therefore bag-valve-mask aided ventilation and oxygen supplementation were started. Baseline arterial oxygen saturation was 87%. On auscultation, disseminated right-sided rales and crepitations over the right lung base were found, with less pronounced left-sided abnormalities. The patient was intubated using the Sellick maneuver as the laryngeal orifice was covered with carbon solution, and mechanical ventilation was introduced. In bronchoscopy it was found that the gastric tube was placed in the right main bronchus, which was filled with the active carbon solution. The tube was removed along with the carbon solution and the right bronchus was irrigated. Within the next three days, the clinical condition of the patient gradually improved, with extubation after 4 days of mechanical ventilation. Full respiratory and circulatory sufficiency was achieved, but despite adequate arterial oxygen saturation, disseminated rhonchi prevailed, more pronounced over the right lung. After 6 days of intensive treatment, the patient was transferred to the General Internal Diseases Unit with no lung abnormalities detected on auscultation. In the presented case, an inadequately placed gastric tube with failure to detect the mistake and active carbon administration were the immediate causes of the patients general deterioration and respiratory insufficiency. The consultant radiologist did not diagnose the improper placement of the gastric tube in the chest X-ray, while the ER physician did not have access to the film, but only to the written result. These factors were indirectly responsible for the delay in the final verification. Additionally, the patients good general condition with no cough – plausibly as an effect of previously applied sedatives – proved to be further misleading. Moreover, prisoners are usually difficult to diagnose, since they frequently conceal their symptoms and/or have a higher tolerance to drugs because of their overuse. The mistake was discovered approximately 8 h after the initial chest X-ray, during bronchofiberoscopy, when right-sided atelectasis and local pneumonia became apparent. According to guidelines outlining the proper verification of gastric tube placement, X-ray based confirmation (consisting of chest and abdominal X-rays) is optimal [2–4]. However, capnometry (capnography) is much faster, less labor-intensive and less invasive to the patient compared to a radiological examination and hence should be performed immediately after tube placement [5, 6]. Auscultation of air in the stomach has been classically used to confirm placement, but air infused into the pleural space can just as easily be heard over the upper abdomen [7]. Additional tests may include aspiration of pleural fluid. A pH below 4.0 is characteristic for proper gastric placement of the tube [8, 9]. However, this test is inappropriate in patients who are administered antacids and many of such subjects are treated in ICUs. Other diagnostic possibilities include fluoroscopy, endoscopy and direct visualization of the tube [10], but all these procedures are relatively complicated, time-consuming, and cost-prohibitive to verify the proper placement of the gastric tube.