Benefit of a single recruitment maneuver after an apnea test for the diagnosis of brain death

A Recruitment Maneuver After Apnea Testing Improves Oxygenation and Reduces Atelectasis in Organ Donors After Brain Death

BACKGROUND

Hypoxemia is the main modifiable factor preventing lungs from being transplanted from organ donors after brain death. One major contributor to impaired oxygenation in patients with brain injury is atelectasis. Apnea testing, an integral component of brain death declaration, promotes atelectasis and can worsen hypoxemia. In this study, we tested whether performing a recruitment maneuver (RM) after apnea testing could mitigate hypoxemia and atelectasis.

METHODS

During the study period, an RM (positive end-expiratory pressure of 15 cm H2O for 15 s then 30 cm H2O for 30 s) was performed immediately after apnea testing. We measured partial pressure of oxygen, arterial (PaO2) before and after RM. The primary outcomes were oxygenation (PaO2 to fraction of inspired oxygen [FiO2] ratio) and the severity of radiographic atelectasis (proportion of lung without aeration on computed tomography scans after brain death, quantified using an image analysis algorithm) in those who became organ donors. Outcomes in RM patients were compared with control patients undergoing apnea testing without RM in the previous 2 years.

RESULTS

Recruitment maneuver was performed in 54 patients after apnea testing, with a median immediate increase in PaO2 of 63 mm Hg (interquartile range 0-109, p = 0.07). Eighteen RM cases resulted in hypotension, but none were life-threatening. Of this cohort, 37 patients became organ donors, compared with 37 donors who had apnea testing without RM. The PaO2:FiO2 ratio was higher in the RM group (355 ± 129 vs. 288 ± 127, p = 0.03), and fewer had hypoxemia (PaO2:FiO2 ratio < 300 mm Hg, 22% vs. 57%; p = 0.04) at the start of donor management. The RM group showed less radiographic atelectasis (median 6% vs. 13%, p = 0.045). Although there was no difference in lungs transplanted (35% vs. 24%, p = 0.44), both better oxygenation and less atelectasis were associated with a higher likelihood of lungs being transplanted.

CONCLUSIONS

Recruitment maneuver after apnea testing reduces hypoxemia and atelectasis in organ donors after brain death. This effect may translate into more lungs being transplanted.

Lung donation and donor lung management: a survey among health care professionals in Argentina

OBJECTIVE

To describe health care providers' knowledge about lung donation and donor lung management.

METHODS

A descriptive, cross-sectional study based on an anonymous survey was conducted between March and September 2018 among health care professionals registered to Sociedad Argentina de Terapia Intensiva.

RESULTS

Of the 736 respondents, the mean age was 40.5 years (standard deviation 8.9), and 61.3% were female. Sixty percent were physicians, 21.5% were nurses, and 17.9% were physiotherapists. Seventy-eight percent considered themselves appropriately informed about organ procurement, and 79.8% stated that they knew potential organ donor critical care management. The lung donor criteria were answered correctly by 71.3% of the respondents. However, after the donor's brain death, 51% made no changes to ventilator parameters, 22.9% were not aware of which parameters to reprogram, and 44.5% selected tidal volume of 6 - 8mL/kg and positive end expiratory pressure of 5cmH2O. For 85% of the health care providers, the type of apnea test chosen was disconnection from the ventilator, and only 18.5% used a lung management protocol. The most frequent interventions used in the case of arterial oxygen partial pressure/fractional inspired oxygen < 300 were positive end expiratory pressure titration, closed-circuit endotracheal suctioning, and recruitment maneuvers.

CONCLUSION

Health care professionals surveyed in Argentina correctly answered most of the questions related to lung donor criteria. However, they lacked detailed knowledge about ventilatory settings, ventilatory strategies, and protocols for lung donors. Educational programs are key to optimizing multiorgan donation and should be focused on protecting the donor lungs to increase the numbers of organs available for transplantation.

Apnea Testing for the Determination of Brain Death: A Systematic Scoping Review

Apnea is one of the three cardinal findings in brain death (BD). Apnea testing (AT) is physiologically and practically complex. We sought to review described modifications of AT, safety and complication rates, monitoring techniques, performance of AT on extracorporeal membrane oxygenation (ECMO), and other relevant considerations regarding AT. We conducted a systematic scoping review to answer these questions by searching the literature on AT in English language available in PubMed or EMBASE since 1980. Pediatric or animal studies were excluded. A total of 87 articles matched our inclusion criteria and were qualitatively synthesized in this review. A large body of the literature on AT since its inception addresses a variety of modifications, monitoring techniques, complication rates, ways to perform AT on ECMO, and other considerations such as variability in protocols, lack of uniform awareness, and legal considerations. Only some modifications are widely used, especially methods to maintain oxygenation, and most are not standardized or endorsed by brain death guidelines. Future updates to AT protocols and strive for unification of such protocols are desirable.

Impact of implementing a protocol of respiratory care measures and optimization of mechanical ventilation in potential lung donors

Objective

To describe the results from the implementation of a respiratory care and mechanical ventilation protocol on potential lung donors who met the conditions for procurement. The secondary objective is to compare the results with historical data.

Methods

This was a retrospective, observational study. It included potential donors suitable for procurement of organs who had brain death and were hospitalized in critical care units of the Autonomous City of Buenos Aires from April 2017 to March 2018. Main variables: number of potential lung donors that reached the objective of procurement, rate of lungs procured, and rate of implanted lungs. Values of p < 0.05 were considered significant.

Results

Thirty potential lung donors were included, and 23 (88.5%; 95%CI 69.8 - 97.6) met the oxygenation objective. Twenty potential lung donors donated organs, of whom eight donated lungs, with which four double lung transplants and eight single lung transplants were performed. Seven of 12 lungs were procured and implanted in the preprotocol period, while all 12 were under the protocol (p = 0.38). The implantation rate was 58.3% (7/12) in the historical control period and 100% (12/12) (p = 0.04) in the study period.

Impact of Recruitment Maneuvers to Cover Adverse Effects of Donor Transfer

OBJECTIVES

Our aim was to investigate the negative effects of transferring brain-dead donors to the intensive care unit on the ratio of PaO₂ to inspired oxygen fraction and the benefits of recruitment maneuvers on its reversal.

MATERIALS AND METHODS

In this randomized trial, we assigned 30 brain-dead donors to an intervention group and a control group. After transfer to the intensive care unit, donors in the intervention group received a lung recruitment maneuver according to protocol for 1 hour, whereas the control group did not receive this intervention. Arterial blood gas was drawn before transfer, immediately aftertransfer, and 3 hours after transfer.

RESULTS

Before transfer to immediately after transfer, the PaO₂-to-inspired oxygen fraction ratio decreased from 281.30 ± 100.33 to 225.03 ± 95.72 mm Hg (P < .01). At 3 hours aftertransfer,the PaO₂-to-inspired oxygen fraction ratio in the intervention and control groups was 280.4 ± 120.4 and 213.4 ± 75.5 mm Hg (P = .017), respectively. The absolute difference in PaO₂-to-inspired oxygen fraction ratio from before to 3 hours after transfer was -16.9 ± 44.1 and 51.8 ± 61.4 mm Hg (P < .001), in the intervention and control groups,respectively. Increasing central venous pressure and/or transfer time further potentiated the decrease ofthe PaO₂-to-inspired oxygen fraction ratio.

CONCLUSIONS

The PaO₂-to-inspired oxygen fraction ratio decreased after transfer of brain-dead donors to the intensive care unit. This was partially reversible by standardized recruitment maneuvers.

Identification of Hemodynamic Risk Factors for Apnea Test Failure During Brain Death Determination

OBJECTIVE

An apnea test is essential step for diagnosing brain death and is known to be relatively safe. However, various complications such as hypoxia, arrhythmias, and hypotension could occur. Herein, we identified risk factors of failed apnea test and determined their optimal cutoff values.

METHODS

We retrospectively analyzed 512 patients of apnea test to diagnose brain death and classified them into 2 groups according to success or failure of the test. Demographic characteristics, value of arterial blood gas analysis, and systolic blood pressure (SBP) were collected, and alveolar-arterial gradient (A-a gradient) and Pao₂/fraction of inspired oxygen ratio were calculated to evaluate the respiratory status.

RESULTS

A total of 484 patients completed the apnea test, and the test was aborted in 28 patients because of hypotension or refractory hypoxemia. The SBP, pH, Pao₂, and Pao₂/fraction of inspired oxygen ratio were higher in success group, whereas A-a gradient was lower. In multivariate analysis, low SBP (odds ratio [OR], 0.976; 95% CI, 0.958-0.994; P = .01), low pH (OR, 0.004; 95% CI, 0.000-0.184; P = .005), and elevated A-a gradient (OR, 1.005; 95% CI, 1.003-1.008; P = .001) were associated with apnea test failure. The optimal cutoff values to predict the test failure were 105.0 mm Hg for pretesting SBP, 7.326 for pretesting pH, and 556.4 mm Hg for pretesting A-a gradient.

CONCLUSION

Early recognition and aggressive management for the risk factors are important to reduce failure rates of apnea test and consequently improve outcomes of organ procurement.

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 1-1.5h later CPAP-AT with 100% FiO₂ and CPAP of 10cm H₂O, provided by ventilator in CPAP mode. After pre‑oxygenation with 100% FiO₂ for 10min, 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±128mmHg at T1 to 291±119mmHg at T2 (p=0.004). In subgroup N-H, PaO₂/FiO₂ declined from 355±103 to 321±100mmHg (p=0.008), and in subgroup H, PaO₂/FiO₂ remained almost unchanged. Additionally, in 4 patients from subgroup N-H, PaO₂/FiO₂ decreased below 200mmHg at T2.

CONCLUSIONS

Our study indicates that I-AT may compromise pulmonary function and this may support the recommendation of safer CPAP-AT alternative.

ICU Management of the Potential Organ Donor: State of the Art

End-organ failure is associated with high mortality and morbidity, in addition to increased health care costs. Organ transplantation is the only definitive treatment that can improve survival and quality of life in such patients; however, due to the persistent mismatch between organ supply and demand, waiting lists continue to grow across the world. Careful intensive care management of the potential organ donor with goal-directed therapy has the potential to optimize organ function and improve donation yield.

Organ donation protocols

Organ transplantation improves survival and quality of life in patients with end-organ failure. Waiting lists continue to grow across the world despite remarkable advances in the transplantation process, from the creation of public engagement campaigns to the development of critical pathways for the timely identification, referral, approach, and treatment of the potential organ donor. The pathophysiology of dying triggers systemic changes that are intimately related to organ viability. The intensive care management of the potential organ donor optimizes organ function and improves the donation yield, representing a significant step in reducing the mismatch between organ supply and demand. Different beliefs and cultures reflect diverse legislations and donation practices amongst different countries, creating a challenge to standardized practices. Maintaining public trust is necessary for continued progress in organ donation and transplantation, hence the urge for a joint effort in creating uniform protocols that ensure transparent practices within the medical community.

Novel method of delivery of continuous positive airway pressure for apnea testing during brain death evaluation

Background

There are several methods for apnea testing for the evaluation of neurological death, including oxygen via T-piece, oxygen cannula inserted into the endotracheal tube, and continuous positive airway pressure (CPAP). Lung suitability for transplantation is determined in part by the partial pressure of arterial oxygen (PaO₂) to fraction of inspired oxygen (FiO₂; P:F) ratio. We hypothesized that delivery of CPAP during apnea testing using a novel method would improve post-test P:F ratios.

Methods

A retrospective review was performed at a level I trauma center for all patients undergoing apnea testing from 2010 to 2016. The CPAP system used a flow-inflating bag and was made available in 2012. It was used at the discretion of the clinician. Patients were classified as having an apnea test by CPAP or by non-CPAP method (T-piece, oxygen cannula in endotracheal tube, etc). The two groups were compared for baseline characteristics and the primary outcome of postapnea test P:F ratio.

Results

During the study period, 145 patients underwent apnea testing; 67 patients by the CPAP method and 78 by non-CPAP method. There were no significant differences in demographics, mechanism of brain injury, pneumonia rate, smoking status, or antibiotic usage between the two groups. The pretest P:F ratio was similar between groups, but the CPAP group had significantly higher post-test P:F ratio (304 vs 250, p=0.02). There were no reported complications arising from CPAP use.

Conclusions

We describe a novel method of delivering CPAP by a flow-inflating bag during examination for brain death. This method led to improved oxygenation, P:F ratios, and may decrease barotrauma. The flow-inflating bag was inexpensive, easily implemented, and without adverse effects. Multicentered, prospective trials are needed to elicit significant benefit in lung donation and transplantation.

Level of evidence

Level IV, diagnostic tests.

Efficacy of recruitment maneuver for improving the brain dead marginal lungs to ideal

BACKGROUND

Because of the shortage of lungs for transplantation, finding the suitable lungs in brain-dead donors is an important issue. Recruitment maneuver is a strategy aimed at re-expanding collapsed and edematous lung tissue. The aim of this study was to assess the efficacy of this maneuver on improving marginal lungs for transplantation.

METHODS

From 127 brain-dead potential donor which were evaluated for lung donation in Masih Daneshvari Organ Procurement Unit of Tehran, Iran, 31 (25%) had marginal lungs for transplantation. These donors had normal chest X ray or bilateral infiltration and had PaO2 200-300 mm Hg with FIO2 100%. The recruitment maneuver was performed and arterial blood gas was obtained before and after maneuver. The maneuver lasts for 2 hours with continuous check of O2 saturation and patient's hemodynamic during. Finally, patients with normal bronchoscopy and PaO2/FIO2 >300 mm Hg were considered good candidates for lung transplantation. The frequency (%) and mean ± SD were used for description of variables and the Wilcoxon test was used for comparison between pre- and post-maneuver PaO2 with FIO2 100%.

RESULTS

The mean ± SD of PaO2/FIO2 with 100% FIO2 of patients before and after recruitment were 239 ± 62 and 269 ± 91, respectively. Recruitment maneuver could convert 10 marginal lungs (32%) to appropriate ones (PaO2 > 300) and finally 8 lungs were transplanted.

CONCLUSIONS

Findings of this study showed that recruitment maneuver could convert inappropriate lungs to appropriate ones in one third of brain-dead patients who had marginal lung condition. So, it is recommended that this maneuver is considered in the assessment protocol of lungs for donation.