Confounding factors in brain death: cardiogenic ventilator autotriggering and implications for organ transplantation

Cardiac Oscillations Complicating Brain Death Diagnosis

Death by neurologic criteria (DNC) or brain death is a clinical diagnosis. It is often complicated by variations in policies as well as confounders on examination. We discuss here the case of a 27-year-old male who had a cardiac arrest following toxic gaseous exposure. He ultimately progressed to brain death but was identified as having cardiac oscillations during clinical assessments that complicated the diagnosis. We discuss the case as well as the maneuvers used to clarify that the "triggered breaths" on the ventilator were indeed cardiac oscillations.

Computed Tomography Angiography (CTA) in Selected Scenarios with Risk of Possible False-Positive or False-Negative Conclusions in Diagnosing Brain Death

It is widely accepted that brain death (BD) is a diagnosis based on clinical examination. However, false-positive and false-negative evaluation results may be serious limitations. Ancillary tests are used when there is uncertainty about the reliability of the neurologic examination. Computed tomography angiography (CTA) is an ancillary test that tends to have the lowest false-positive rates. However, there are various influencing factors that can have an unfavorable effect on the validity of the examination method. There are inconsistent protocols regarding the evaluation criteria such as scoring systems. Among the most widely used different scoring systems the 4-point CTA-scoring system has been accepted as the most reliable method. Appropriate timing and/or Doppler pre-testing could reduce the number of possible premature examinations and increase the sensitivity of CTA in diagnosing cerebral circulatory arrest (CCA). In some cases of inconclusive CTA, the whole brain computed tomography perfusion (CTP) could be a crucial adjunct. Due to the increasing significance of CTA/CTP in determining BD, the methodology (including benefits and limitations) should also be conveyed via innovative electronic training tools, such as the BRAINDEXweb teaching tool based on an expert system.

Delayed tracheal extubation after cardiac surgery due to cardiogenic ventilator auto-triggering: a case report

Background

Ventilator auto-triggering is associated with poor outcomes. Herein, we present a case of delayed tracheal extubation after cardiac surgery due to cardiogenic auto-triggering.

Case presentation

A 73-year-old male with chronic constrictive pericarditis underwent radical pericardiectomy. After confirming hemodynamic stability, we conducted spontaneous breathing trial (SBT) with a flow-trigger sensitivity of 1 L/min. As his respiratory rate (RR) increased to more than 60 breaths/min and tidal volume decreased to less than 100 mL, this SBT was considered a failure. Next morning, SBT was reperformed and the result was unchanged. However, we noticed that his heart rate and RR were the same and suspected auto-triggering caused by cardiogenic oscillations. We changed ventilator mode from flow triggering to pressure triggering of −2 cmH₂O and he was uneventfully extubated.

Conclusion

We experienced a case of delayed tracheal extubation after cardiac surgery due to cardiogenic auto-triggering. Auto-triggering can be reduced by changing ventilator trigger mode.

Obstacles to obtaining Informed Consent from the Perspective of Transplant Coordinators: A Qualitative Study

Background: The lack of consent to donate body organs leads to an increase in the death rate of patients on the waiting list for transplantation. Unwillingness of families is known as the main obstacle to organ donation, and the media has an essential role in motivating organ donation. Objectives: This study aimed to explore obstacles to obtaining consent for organ donation from transplant coordinators’ perspective throughout Iran. Methods: In this qualitative study, 13 in-depth semi-structured face-to-face interviews were conducted with transplant coordinators from November 2018 to March 2019. The participants were investigated using a purposive sampling method. The participants’ age and work experience ranged between 32 - 49 years and 6 - 25 years, respectively. Open-ended questions were asked from the participants in a private room. An experienced interviewer explained the study’s objectives to the coordinators, and each interview lasted on average 50 minutes. The interview scripts were analyzed using a content analysis method. Results: The findings highlighted the difficulty of obtaining consent from brain-dead patients’ families. The obstacles could be internal or external. External determinants were healthcare providers’ lack of empathy, inadequate consultation from doctors outside the hospital, media content, and uninformed comments from relatives. Internal determinants were hoping for recovery, denial, and disagreement among family members. Conclusions: The healthcare team should have a better connection with families to obtain organ donation consent from them. Therefore, a training program must be developed for the treatment team so that they show more supportive behavior and improve quality of care in hospitals before and after brain death.

Death by neurologic criteria: pathophysiology, definition, diagnostic criteria and tests

Death by neurologic criteria is an irreversible sequence of events culminating in permanent cessation of cerebral functions. In this context, there are no responses arising from the brain, no cranial nerve reflexes nor motor responses to pain stimuli, and no respiratory drive. The diagnosis of death by neurologic criteria implies that there is clinical evidence of the complete and irreversible cessation of brainstem and cerebral functions. The diagnosis, confirmation, and certification of death are core skills for medical practitioners. The aim of this review is to discuss the pathophysiology and definition of death by neurological criteria, describing the clinical assessment, and the use of ancillary tests for the diagnosis of brainstem death.

Patient-ventilator asynchronies: types, outcomes and nursing detection skills

BACKGROUND

Mechanical ventilation is often employed as partial ventilatory support where both the patient and the ventilator work together. The ventilator settings should be adjusted to maintain a harmonious patient-ventilator interaction. However, this balance is often altered by many factors able to generate a patient ventilator asynchrony (PVA). The aims of this review were: to identify PVAs, their typologies and classifications; to describe how and to what extent their occurrence can affect the patients' outcomes; to investigate the levels of nursing skill in detecting PVAs.

METHODS

Literature review performed on Cochrane Library, Medline and CINAHL databases.

RESULTS

1610 records were identified; 43 records were included after double blind screening. PVAs have been classified with respect to the phase of the respiratory cycle or based on the circumstance of occurrence. There is agreement on the existence of 7 types of PVAs: ineffective effort, double trigger, premature cycling, delayed cycling, reverse triggering, flow starvation and auto-cycling. PVAs can be identified through the ventilator graphics monitoring of pressure and flow waveforms.  The influence on patient outcomes varies greatly among studies but PVAs are mostly associated with poorer outcomes. Adequately trained nurses can learn and retain how to correctly detect PVAs.

CONCLUSIONS

Since its challenging interpretation and the potential advantages of its implementation, ventilator graphics monitoring can be classified as an advanced competence for ICU nurses. The knowledge and skills to adequately manage PVAs should be provided by specific post-graduate university courses.

Consciousness and Personhood in Medical Care

Current paradigms in Western medicine often fail to differentiate clearly between consciousness, responsiveness and personhood. The growing number of individuals who exist with sustainable cardiopulmonary systems but who are behaviorally unresponsive has prompted a cultural reconsideration of the relationship between the presence of consciousness and what it means to be a person. This article presents relevant clinical situations that exemplify the different modes in which personhood and consciousness can be associated and dissociated: disorders of consciousness, emergence from anesthesia, and neocortical death. We draw from these examples to call for a reflection on and possible revision of the dominant approach towards unresponsive persons to one in which care providers may work from the default assumption of the existence of an individual’s personhood as part of their therapeutic intervention. Behavior consistent with this assumption aligns with the principle of respect for persons in the face of the uncertainty created by the high rate of misdiagnosis of unconsciousness in unresponsive patients and is most consistent with a therapeutic approach to care considering evidence suggesting that attributing personhood may in fact evoke consciousness in these patients.

Identifying Potential Ventilator Auto-Triggering Among Organ Procurement Organization Referrals

Context:

Ventilator auto-trigger is the delivery of an assisted mechanical ventilated breath over the set ventilator frequency in the absence of a spontaneous inspiratory effort and can be caused by inappropriate ventilator trigger sensitivity. Ventilator auto-trigger can be misinterpreted as a spontaneous breath and has the potential to delay or prevent brain death testing and confuse health-care professionals and/or patient families.

Objective:

To determine the frequency of organ donor referrals from 1 Organ Procurement Organization (OPO) that could benefit from an algorithm designed to assist organ recovery coordinators to identify and correct ventilator auto-triggering.

Design:

This retrospective analysis evaluated documentation of organ donor referrals from 1 OPO in central Texas during the 2013 calendar year that resulted in the withdrawal of care by the patient’s family and the recovery of organs.

Main Outcome Measures:

The frequency of referrals that presented with absent brain stem reflexes except for additional respirations over the set ventilator rate was determined to assess for the need of the proposed algorithm.

Results:

Documentation of 672 organ procurement organization referrals was evaluated. Documentation from 42 referrals that resulted in the withdrawal of care and 21 referrals that resulted in the recovery of organs were identified with absent brain stem reflexes except for spontaneous respirations on the mechanical ventilator. As a result, an algorithm designed to identify and correct ventilator auto-trigger could have been used 63 times during the 2013 calendar year.

Lived Experiences of Iranian Nurses Caring for Brain Death Organ Donor Patients: Caring as "Halo of Ambiguity and Doubt"

Background:

Brain death is a concept in which its criteria have been expressed as documentations in Harvard Committee of Brain Death. The various perceptions of caregiver nurses for brain death patients may have effect on the chance of converting potential donors into actual organ donors.

Objective:

The present study has been conducted in order to perceive the experiences of nurses in care-giving to the brain death of organ donor patients.

Methods:

This qualitative study was carried out by means of Heidegger’s hermeneutic phenomenology. Eight nurses who have been working in ICU were interviewed. The semi-structured interviews were recorded by a tape-recorder and the given texts were transcribed and the analyses were done by Van-Mannen methodology and (thematic) analysis.

Results:

One of the foremost themes extracted from this study included ‘Halo of ambiguity and doubt’ that comprised of two sub-themes of ‘having unreasonable hope’ and ‘Conservative acceptance of brain death’. The unreasonable hope included lack of trust (uncertainty) in diagnosis and verification of brain death, passing through denial wall, and avoidance from explicit and direct disclosure of brain death in patients’ family. In this investigation, the nurses were involved in a type of ambiguity and doubt in care-giving to the potentially brain death of organ donor patients, which were also evident in their interaction with patients’ family and for this reason, they did not definitely announce the brain death and so far they hoped for treatment of the given patient. Such confusion and hesitance both caused annoyance of nurses and strengthening the denial of patients’ family to be exposed to death.

Conclusion:

The results of this study reveal the fundamental perceived care-giving of brain death in organ donor patients and led to developing some strategies to improve care-giving and achievement in donation of the given organ and necessity for presentation of educational and supportive services for nurses might become more evident than ever.

Brain Death: Assessment, Controversy, and Confounding Factors

When brain injury is refractory to aggressive management and is considered nonsurvivable, with loss of consciousness and brain stem reflexes, a brain death protocol may be initiated to determine death according to neurological criteria. Clinical evaluation typically entails 2 consecutive formal neurological examinations to document total loss of consciousness and absence of brain stem reflexes and then apnea testing to evaluate carbon dioxide unresponsiveness within the brain stem. Confounding factors such as use of therapeutic hypothermia, high-dose metabolic suppression, and movements associated with complex spinal reflexes, fasciculations, or cardiogenic ventilator autotriggering may delay initiation or completion of brain death protocols. Neurodiagnostic studies such as 4-vessel cerebral angiography can rapidly document absence of blood flow to the brain and decrease intervals between onset of terminal brain stem herniation and formal declaration of death by neurological criteria. Intracranial pathophysiology leading to brain death must be considered along with clinical assessment, patterns of vital signs, and relevant diagnostic studies.

Ventilator auto-cycling from cardiogenic oscillations: case report and review of literature

BACKGROUND

Brain death is the total loss of all brain and brain stem functions, and its diagnosis is often confirmed by an apnoea test, which relies on disconnecting the patient from the ventilator. Auto-triggering or auto-cycling is defined as a ventilator being triggered in the absence of patient effort, intrinsic respiratory drive or inspiratory muscle activity. Ventilator auto-triggering could delay the diagnosis of brain death leading to unnecessary admission for the patient and false hopes of recovery for the family.

METHODS

We report a case of ventilator auto-triggering associated with cardiogenic oscillations in a female patient.

RESULTS

We confirmed the finding of ventilator auto-triggering by changing the patient's position and reassessing the triggering thresholds. Brain death was then confirmed by apnoea test.

CONCLUSION

This case is presented to arouse the awareness of the medical staff and nurses to this phenomenon, which can mimic an intrinsic respiratory effort in patients allegedly diagnosed with brain death. Along with this case report, we review the English language publications for similar cases.