Design and application of a push-pull adjustable artificial dead space / 中华危重病急救医学

Using artificial dead space to correct hypocapnia or induce hypercapnia is of particular significance for diagnosing and treating specific neurocritical diseases. At present, the above purpose is mainly achieved by adding an extension tube between the Y-type connector of the ventilator and the artificial airway in clinical practice. However, its volume is often fixed and cannot adapt to the individualized diagnosis and treatment in different clinical scenarios. The research group led by Professor Zhou Jianxin from the department of critical care medicine of Beijing Tiantan Hospital, Capital Medical University, has designed an artificial dead cavity with adjustable volume based on years of research in the respiratory field and has been granted a national utility model patent (patent number: ZL 2020 2 0496413.4). The artificial dead chamber is simple in structure, composed of a barrel body, a piston head, and a push-pull rod. By freely adjusting the size of the artificial dead chamber volume, it can accurately regulate the target carbon dioxide, correct the spontaneous hyperventilation, terminate intractable hiccup, and shorten the operation time of asphyxia test in clinical diagnosis of brain death while correcting hypocapnia or inducing hypercapnia. It has the advantages of solid reliability, convenient operation, and low production cost, which significantly facilitates scientific research and clinical diagnosis and treatment.

Determination of brain death for a pediatric patient with pneumorrhagia on VA-ECMO: A case report / 中国小儿急救医学

Objective:In May 2019, the 2018 version of Criteria and practical guidance for determination of brain death in children in China was published, which was revised by Brain Injury Evaluation Quality Control Center of National Health Commission, making the determination of brain death for pediatric patients in China more standardized and orderly.However, there is currently lacking of direction for the implementation of the above criteria for determining brain death to patients supported on extracorporeal membrane oxygenation(ECMO) in China.We successfully completed the determination of brain death and the organ transplantation(as a donor)for a pediatric case with severe brain injury and pneumorrhagia supported by VA-ECMO in our PICU, which provided clinical references for the revision of the guidelines for determination of brain death for pediatric patients in China. Methods:By referring to the international guidelines of Determination of Brain Death/ Death by Neurologic Criteria: The World Brain Death Project published in JAMA in August 2020, we performed a determination of brain death for a case of pediatric patient with severe brain injury and pneumorrhagia supported by VA-ECMO(blood flow 720 to 750 ml/min, gas flow 600 mL/min, oxygen concentration 65% to 70%)in our PICU. Results:The results of the determination of brain death included: Glasgow coma scale was 2T, all brainstem reflexes disappeared, three confirmation tests(electroencephalography, transcranial Doppler, short latency somatosensory evoked potential)all met the criterias for determination of brain death, apnea test(AT)showed PaCO 2>60 mmHg and elevated >20 mmHg than that before AT.We performed twice determination of brain death, interval time was >12 h. Finally, we successfully completed the determination of brain death and the organ transplantation(as a donor)for the case. Conclusion:The successful experience in the determination of brain death in the pediatric patient with severe brain injury and pneumorrhagia supported by VA-ECMO will provide clinical references for the revision of the guidelines for determination of brain death for pediatric patients in China.

Reduction of Apnea Test Time in an Extracorporeal Membrane Oxygenation-Dependent Potential Donor / 대한이식학회지

The diagnosis of brain death is essential for deceased donor organ transplantation. Currently, extracorporeal membrane oxygenation (ECMO) is used to increase the chance of survival of patients with severe cardiac and respiratory failure. Therefore, cases of ECMO-dependent potential donors are increasing. The apnea test (AT) is a mandatory component in the clinical determination of brain death. However, conventional AT is not easily applicable to ECMO-dependent potential donors because both the ventilator and ECMO play an important role in carbon dioxide elimination. Accordingly, different methods of AT from those used in routine procedures must be considered. We report here a case of conventional AT with time delay and two cases of AT within 3 minutes by adjusting sweep gas flow rate of ECMO in ECMO-dependent potential donors.

Predisposing Hemodynamic Factors Associated with a Failed Apnea Test during Brain Death Determination / 대한중환자의학회지

BACKGROUND: The apnea test is an essential component in the clinical determination of brain death, however it may incur a significant risk of complications such as hypotension, hypoxia and even cardiac arrest. We analyzed the risk factors associated with a failed apnea test during brain death assessment in order to predict and avoid these adverse events. METHODS: Medical records on apnea tests performed for brain-dead donors at our institution between January 2009 and January 2016 were retrospectively reviewed. Age, gender, etiology of brain death, use of catecholamines and results of arterial blood gas analysis (ABGA), systolic/diastolic blood pressure (SBP/DBP), mean arterial pressure and central venous pressure prior to apnea test initiation were collected as variables. A-a gradient and P(aO2)/F(iO2) were calculated for more precise assessment of the respiratory system. In total, 267 cases were divided into two groups based on those who completed the apnea test and those who failed the test. RESULTS: 13 cases failed the apnea test. Among them, seven cases failed due to severe hypotension (SBP < 60 mmHg) and the others failed due to refractory hypoxia. In terms of hemodynamic state, SBP was significantly higher in the completed test group than the failed group (126.5 ± 23.9 vs. 103 ± 15.2, respectively; p = 0.001). In ABGA, the completed test group showed significantly higher P(aO2)/F(iO2) (313.6 ± 229.8 vs. 141.5 ± 131.0, respectively; p = 0.008) and a lower A-a gradient (278.2 ± 209.5 vs. 506.2 ± 173.1, respectively; p = 0.000). In multivariable analysis, low SBP (p = 0.003) and high A-a gradient (p = 0.044) were independent risk factors associated with a failed apnea test. CONCLUSIONS: Although the unexpected adverse events during the apnea test for brain death determination do not occur frequently, they can be fatal. If a brain-dead patient has low SBP and a high A-a gradient, clinicians should pay more attention and prepare for potential complications prior to the apnea test.

Predisposing Hemodynamic Factors Associated with a Failed Apnea Test during Brain Death Determination / 대한구급학회지

BACKGROUND: The apnea test is an essential component in the clinical determination of brain death, however it may incur a significant risk of complications such as hypotension, hypoxia and even cardiac arrest. We analyzed the risk factors associated with a failed apnea test during brain death assessment in order to predict and avoid these adverse events. METHODS: Medical records on apnea tests performed for brain-dead donors at our institution between January 2009 and January 2016 were retrospectively reviewed. Age, gender, etiology of brain death, use of catecholamines and results of arterial blood gas analysis (ABGA), systolic/diastolic blood pressure (SBP/DBP), mean arterial pressure and central venous pressure prior to apnea test initiation were collected as variables. A-a gradient and P(aO2)/F(iO2) were calculated for more precise assessment of the respiratory system. In total, 267 cases were divided into two groups based on those who completed the apnea test and those who failed the test. RESULTS: 13 cases failed the apnea test. Among them, seven cases failed due to severe hypotension (SBP < 60 mmHg) and the others failed due to refractory hypoxia. In terms of hemodynamic state, SBP was significantly higher in the completed test group than the failed group (126.5 ± 23.9 vs. 103 ± 15.2, respectively; p = 0.001). In ABGA, the completed test group showed significantly higher P(aO2)/F(iO2) (313.6 ± 229.8 vs. 141.5 ± 131.0, respectively; p = 0.008) and a lower A-a gradient (278.2 ± 209.5 vs. 506.2 ± 173.1, respectively; p = 0.000). In multivariable analysis, low SBP (p = 0.003) and high A-a gradient (p = 0.044) were independent risk factors associated with a failed apnea test. CONCLUSIONS: Although the unexpected adverse events during the apnea test for brain death determination do not occur frequently, they can be fatal. If a brain-dead patient has low SBP and a high A-a gradient, clinicians should pay more attention and prepare for potential complications prior to the apnea test.

The use of modified apnea test in the brain death evaluation / 中华急诊医学杂志

Objective To evaluate the safety and feasibility of the modified apnea test (MAT) for brain death evaluation. Method A prospective, controlled clinical study was carried out. Forty-three patients with suspected brain death underwent a total of 85 MATs. The patient's spontaneous breathing, hemodynamics and oxy genarion were monitored during MAT; arterial blood pH, PaCO2, PaO2 were measured before and after the MAT. Paired t test was used for statistical analysis to determine significant differences in measurements before and after MAT on the same patient. The Wilcoxon Signed-Rank Test was used to determine statistical significance for skew distribution of PaO2 before and after apnea testing. Informed consent was obtained from the kinfolk of all participants and all of the procedures were done in accordance with national and international laws and policies. Results Hemodynamics and oxygenarion were stable in all patients during MAT, and none regained spontaneous respiration. About 89.4% of tests were completed within 4 minutes, and 10.6% within 8 minutes. The mean value of Pa CO2 rise was (23.1 ±4.8), and the average rate of PaCO2 increase was 5.3 mmHg per minute. Conclusions Modified apnea test can be done safely for brain death evaluation and is a useful supplement to the common apnea test.

Improvement of Hypoxemia by Repetitive Alveolar Recruitments in Brain-dead Donor: A case report / 대한마취과학회지

Brain-dead potential donors manifest devastating physiological changes associated with pulmonary edema, profound hemodynamic and metabolic abnormalities. These derangements may be more significant after apnea tests which result in severe hypoxemia and cardiovascular complications. De-recruitment can occur following apnea tests in the brain-dead donor whose ventilator support has been maintained with high positive end-expiratory pressure (PEEP), and recruitment maneuvers are intended to open collapsed lung units. We report a brain-dead potential donor with severe hypoxemia and hemodynamic instability after apnea tests, which improved after multiple alveolar recruitments with adequate vasoactive drugs. Multiple high-pressure recruitment maneuvers will be helpful for expansion of lung collapse with improvement of severe hypoxemia after de-recruitment which could be developed with apnea tests in brain-dead organ donor.

The Apnea Test for the Determination of Brain Death

By the criteria for the determination of brain deathe established in The Korean Medical Association, an appneic patient's PaCO2 must be greater than 50 torr before apnea can be attributed to brain death. Blood gases were analized in 35cases of brain death by the conventional criteria. The data of PaCO2, pH, PaCO2 in the apnea test of the cases were erratic, but a PaCO2 had increased 50 torr in each patient esaily. To perform the apnea test satisfactorily, it is essential to keep oxygen catheter deep into the tracheal tube by at least 10cm for adequate appneic oxygenation, and indwelling arterial catheters were available for rapid, timed blood sampling. And to determine the accuracy of blood gas measurements, duplicate samples drawn less than 4seconds apart were sent to clinical lagoratory in each test. The apneic test is a crucial rapid and safe performance for the determination of brain death. I recognize.