Design of a flow modulation device to facilitate individualized ventilation in a shared ventilator setup

This study aims to resolve the unmet need for ventilator surge capacity by developing a prototype device that can alter patient-specific flow in a shared ventilator setup. The device is designed to deliver a predictable tidal volume (VT), requiring minimal additional monitoring and workload. The prototyped device was tested in an in vitro bench setup for its performance against the intended use and design criteria. The ventilation parameters: VT and airway pressures, and ventilation profiles: pressure, flow and volume were measured for different ventilator and device settings for a healthy and ARDS simulated lung pathology. We obtained VTs with a linear correlation with valve openings from 10 to 100% across set inspiratory pressures (IPs) of 20 to 30 cmH2O. Airway pressure varied with valve opening and lung elastance but did not exceed set IPs. Performance was consistent in both healthy and ARDS-simulated lung conditions. The ventilation profile diverged from traditional pressure-controlled profiles. We present the design a flow modulator to titrate VTs in a shared ventilator setup. Application of the flow modulator resulted in a characteristic flow profile that differs from pressure- or volume controlled ventilation. The development of the flow modulator enables further validation of the Individualized Shared Ventilation (ISV) technology with individualization of delivered VTs and the development of a clinical protocol facilitating its clinical use during a ventilator surge capacity problem.

In Vitro Model of Prepacked Carbon Dioxide Absorber Use: Development and Testing

BACKGROUND

Carbon dioxide absorbers allow the use of fresh gas flow below minute ventilation (V˙E). Models are developed and tested in vitro to quantify their performance with variable carbon dioxide load (V˙CO2), fresh gas flow, V˙E, end-tidal carbon dioxide (ETco2) fraction, and the type of workstation used.

METHODS

First principles are used to derive a linear relationship between fresh gas flow and fractional canister usage or FCU0.5 (the reciprocal of the time for the inspiratory carbon dioxide fraction to reach 0.5%). This forms the basis for two basic models in which V˙E was measured by spirometry or calculated. These models were extended by multiplying V˙E with an empirical workstation factor. To validate the four models, two hypotheses were tested. To test whether the FCU0.5 intercept varied proportionally with V˙CO2 and was independent of V˙E, FCU was measured for 10 canisters tested with a fixed 0.3 l/min fresh gas flow and a range of V˙CO2 while V˙E was either constant or adjusted to maintain ETco2 fraction. A t test was used to compare the two groups. To confirm whether a change in V˙CO2 accompanied by a change in V˙E to maintain ETco2 fraction would shift the linear fresh gas flow-FCU0.5 relationship in a parallel manner, 19 canisters were tested with different combinations of V˙CO2 and fresh gas flow. These measured FCU values were compared to those predicted by the four models using Varvel's performance criteria.

RESULTS

With 0.3 l/min fresh gas flow, FCU0.5 was proportional with V˙CO2 and independent of whether V˙E was adjusted to maintain ETco2 fraction or not (P = 0.962). The hypothesized parallel shift of the fresh gas flow-FCU0.5 relationship was confirmed. Both extended models are good candidate models.

CONCLUSIONS

The models predict prepacked canister performance in vitro over the range of V˙E, fresh gas flow, and V˙CO2 likely to be encountered in routine clinical practice. In vivo validation is still needed.

EDITOR’S PERSPECTIVE

The effect of anterior quadratus lumborum block on morphine consumption in minimally invasive colorectal surgery: a multicentre, double-blind, prospective randomised placebo-controlled trial

We investigated the efficacy and safety of a bilateral anterior quadratus lumborum block in patients undergoing minimally invasive colorectal surgery. This was a two-centre, double-blind, prospective, randomised, placebo-controlled trial including 150 patients undergoing laparoscopic colorectal surgery (left- or right hemicolectomy, sigmoidectomy) who were enrolled in the institutional abdominal enhanced recovery programme. Before induction of anaesthesia, patients received a bilateral anterior quadratus lumborum block in the left and right lateral decubitus position under ultrasound guidance and were allocated randomly to receive 30 ml of ropivacaine 0.375% (n = 75) or placebo (saline 0.9%) (n = 75) bilaterally. Postoperatively, all patients received multimodal intravenous analgesia including paracetamol, ketorolac and patient-controlled analgesia with morphine. The primary outcome was morphine consumption during the first 24 h after tracheal extubation. Secondary outcomes included severity of pain; presence and extent of sensory block; incidence of postoperative nausea and vomiting; and hospital duration of stay. We also investigated the need for, and dose of, rescue analgesia. Safety outcomes included the incidence of adverse events. Mean (SD) 24-hour morphine consumption was no different between patients allocated to ropivacaine and placebo (28.6 (22.3) mg vs. 28.4 (22.5) mg, p = 0.966, respectively). While a sensory block could be detected in significantly more patients allocated to the ropivacaine group, no differences were detected in pain scores or other secondary or safety endpoints. Patient satisfaction scores were high in both groups. In laparoscopic colorectal surgery, adding a bilateral anterior quadratus lumborum block to a standard multimodal analgesia regimen did not reduce opioid consumption or improve pain scores.

Identification of regional variation in gene expression and inflammatory proteins in donor lung tissue and ex vivo lung perfusate

OBJECTIVE

Diagnosing lung injury is a challenge in lung transplantation. It has been unclear if a single biopsy specimen is truly representative of the entire organ. Our objective was to investigate lung inflammatory biomarkers using human lung tissue biopsies and ex vivo lung perfusion perfusate.

METHODS

Eight human donor lungs declined for transplantation were air inflated, flash frozen, and partitioned from apex to base. Biopsies were then sampled throughout the lung. Perfusate was sampled from 4 lung lobes in 8 additional donor lungs subjected to ex vivo lung perfusion. The levels of interleukin-6, interleukin-8, interleukin-10, and interleukin-1β were measured using quantitative reverse transcription polymerase chain reaction from lung biopsies and enzyme-linked immunosorbent assay from ex vivo lung perfusion perfusate.

RESULTS

The median intra-biopsy equal-variance P value was .50 for messenger RNA biomarkers in tissue biopsies. The median intra-biopsy coefficient of variance was 18%. In donors with no apparent focal injuries, the biopsies in each donor showed no difference in various lung slices, with a coefficient of variance of 20%. The exception was biopsies from the lingula and injured focal areas that demonstrated larger differences. Cytokines in ex vivo lung perfusion perfusate showed minimal variation among different lobes (coefficient of variance = 4.9%).

CONCLUSIONS

Cytokine gene expression in lung biopsies was consistent, and the biopsy analysis reflects the whole lung, except when specimens were collected from the lingula or an area of focal injury. Ex vivo lung perfusion perfusate also provides a representative measurement of lung inflammation from the draining lobe. These results will reassure clinicians that a lung biopsy or an ex vivo lung perfusion perfusate sample can be used to inform donor lung selection.

Intraoperative Red Blood Cell Transfusion and Primary Graft Dysfunction After Lung Transplantation

BACKGROUND

In this international, multicenter study of patients undergoing lung transplantation (LT), we explored the association between the amount of intraoperative packed red blood cell (PRBC) transfusion and occurrence of primary graft dysfunction (PGD) and associated outcomes.

METHODS

The Extracorporeal Life Support in LT Registry includes data on LT recipients from 9 high-volume (>40 transplants/y) transplant centers (2 from Europe, 7 from the United States). Adult patients who underwent bilateral orthotopic lung transplant from January 2016 to January 2020 were included. The primary outcome of interest was the occurrence of grade 3 PGD in the first 72 h after LT.

RESULTS

We included 729 patients who underwent bilateral orthotopic lung transplant between January 2016 and November 2020. LT recipient population tertiles based on the amount of intraoperative PRBC transfusion (0, 1-4, and >4 units) were significantly different in terms of diagnosis, age, gender, body mass index, mean pulmonary artery pressure, lung allocation score, hemoglobin, prior chest surgery, preoperative hospitalization, and extracorporeal membrane oxygenation requirement. Inverse probability treatment weighting logistic regression showed that intraoperative PRBC transfusion of >4 units was significantly ( P  < 0.001) associated with grade 3 PGD within 72 h (odds ratio [95% confidence interval], 2.2 [1.6-3.1]). Inverse probability treatment weighting analysis excluding patients with extracorporeal membrane oxygenation support produced similar findings (odds ratio [95% confidence interval], 2.4 [1.7-3.4], P  < 0.001).

CONCLUSIONS

In this multicenter, international registry study of LT patients, intraoperative transfusion of >4 units of PRBCs was associated with an increased risk of grade 3 PGD within 72 h. Efforts to improve post-LT outcomes should include perioperative blood conservation measures.

Arterial to end-tidal CO2 gradients during isocapnic hyperventilation

Isocapnic hyperventilation (ICHV) is occasionally used to maintain the end-expired CO₂ partial pressure (P_ETCO₂) when the inspired CO₂ (P_ICO₂) rises. Whether maintaining P_ETCO₂ with ICHV during an increase of the P_ICO₂ also maintains arterial PCO₂ (P_aCO₂) remains poorly documented. 12 ASA PS I-II subjects undergoing a robot-assisted radical prostatectomy (RARP) (n = 11) or cystectomy (n = 1) under general endotracheal anesthesia with sevoflurane in O₂/air (40% inspired O₂) were enrolled. P_ICO₂ was sequentially increased from 0 to 0.5, 1.0, 1.5 and 2% by adding CO₂ to the inspiratory limb of the circle system, while increasing ventilation to a target P_ETCO₂ of 4.7-4.9% by adjusting respiratory rate during controlled mechanical ventilation. P_a-ETCO₂ gradients were determined after a 15 min equilibration period at each P_ICO₂ level and compared using ANOVA. Mean (standard deviation) age, height, and weight were 66 (6) years, 171 (6) cm, and 75 (8) kg, respectively. Capnograms were normal and hemodynamic parameters remained stable. P_ETCO₂ could be maintained within 4.7-4.9% in all subjects at all times except in 1 subject with 1.5% P_ICO₂ and 5 subjects with 2.0% P_ICO₂; data from the one subject in whom both 1.5 and 2.0% P_ICO₂ resulted in P_ETCO₂ > 5.1% were excluded from analysis. P_a-ETCO₂ gradients did not change when P_ICO₂ increased. The effect of a modest rise of P_ICO₂ up to 1.5% on P_ETCO₂ during RARP can be readily overcome by increasing ventilation without altering the P_a-ETCO₂ gradients. At higher P_ICO₂, airway pressures may become a limiting factor, which requires further study.

Practice and challenges for organ donation after medical assistance in dying: A scoping review including the results of the first international roundtable in 2021

The procedure combining medical assistance in dying (MAiD) with donations after circulatory determination of death (DCDD) is known as organ donation after euthanasia (ODE). The first international roundtable on ODE was held during the 2021 WONCA family medicine conference as part of a scoping review. It aimed to document practice and related issues to advise patients, professionals, and policymakers, aiding the development of responsible guidelines and helping to navigate the issues. This was achieved through literature searches and national and international stakeholder meetings. Up to 2021, ODE was performed 286 times in Canada, the Netherlands, Spain, and Belgium, including eight cases of ODE from home (ODEH). MAiD was provided 17,217 times (2020) in the eight countries where ODE is permitted. As of 2021, 837 patients (up to 14% of recipients of DCDD donors) had received organs from ODE. ODE raises some important ethical concerns involving patient autonomy, the link between the request for MAiD and the request to donate organs and the increased burden placed on seriously ill MAiD patients.

Memsorb™, a novel CO2 removal device part II: in vivo performance with the Zeus IE®

Memsorb™ (DMF Medical, Halifax, Canada) is a novel device based upon membrane oxygenator technology designed to eliminate CO₂ from exhaled gas when using a circle anesthesia circuit. Exhaled gases pass through semipermeable hollow fibers and sweep gas flowing through these fibers creates a diffusion gradient for CO₂ removal. In vivo Memsorb™ performance was tested during target-controlled closed-circuit anesthesia (TCCCA) with desflurane in O₂/air using a Zeus IE® anesthesia workstation (Dräger, Lübeck, Germany). Clinical care protocols for using this novel device were guided by in vitro performance results from a prior study (submitted simultaneously). After IRB approval, written informed consent was obtained from 10 ASA PS I-III patients undergoing robot-assisted radical prostatectomy. TCCCA targets were 39% inspired O₂ concentration (F_IO₂) and 5.0% end-expired desflurane concentration (F_ETdes). Minute ventilation (MV) was adjusted to maintain 4.5-6.0% F_ETCO₂. The O₂/air (40% O₂) sweep flow into the Memsorb™ was manually adjusted in an attempt to keep inspired CO₂ concentration (F_ICO₂) ≤ 0.8%. The following data were collected: F_IO₂, F_ETdes, F_ICO₂, F_ETCO₂, MV, fresh gas flow (FGF, O₂ and air), sweep flow, and cumulative desflurane usage (Vdes). Vdes of the Zeus IE®-Memsorb™ combination was compared with historical Vdes observed in a previous study when soda lime (DrägerSorb 800 +) was used. Results are reported as median and inter-quartiles. A combination of manually adjusting sweep flow (26 [21,27] L/min) and MV sufficed to maintain F_ICO₂ ≤ 0.8% and F_ETCO₂ ≤ 6.0%, except in one patient in whom the target Zeus IE® FGF had to be increased to 0.7 L/min for 6 min. F_IO₂ and F_ETdes were maintained close to their targets. Zeus IE® FGF after 5 min was 0 [0,0] mL/min. Average Vdes after 50 min was higher with Memsorb™ (20.3 mL) compared to historical soda lime canister data (12.3 mL). During target-controlled closed-circuit anesthesia in patients undergoing robot-assisted radical prostatectomy, the Memsorb™ maintained F_ICO₂ ≤ 0.8% and F_ETCO₂ ≤ 6.0%, and F_IO₂ remained close to target. Modest amounts of desflurane were lost with the use of the Memsorb™. The need for adjustments of sweep flow, minute ventilation, and occasionally Zeus IE® FGF indicates that the Memsorb™ system should preferentially be integrated into an automated closed-loop system.

ESOT Consensus Platform for Organ Transplantation: Setting the Stage for a Rigorous, Regularly Updated Development Process

The European Society for Organ Transplantation (ESOT) has created a platform for the development of rigorous and regularly updated evidence based guidelines for clinical practice in the transplantation field. A dedicated Guideline Taskforce, including ESOT-council members, a representative from the Centre for Evidence in Transplantation, editors of the journal Transplant International has developed transparent procedures to guide the development of guidelines, recommendations, and consensus statements. During ESOT’s first Consensus Conference in November 2022, leading experts will present in-depth evidence based reviews of nine themes and will propose recommendations aimed at reaching a consensus after public discussion and assessment by an independent jury. All recommendations and consensus statements produced for the nine selected topics will be published including the entire evidence-based consensus-finding process. An extensive literature review of each topic was conducted to provide final evidence and/or expert opinion.

The role of transesophageal echocardiography in guiding heart donation after circulatory death

Heart donation after circulatory death (DCD) can significantly expand the heart donor pool, helping to overcome the problem of organ shortage and the increase in waiting list mortality and morbidity. To improve the outcome of DCD heart transplantation, thoraco-abdominal normothermic regional perfusion (TA-NRP) can be performed by selectively restoring circulation followed by in vivo functional heart assessment. Here, we report on the use of periprocedural transoesophageal echocardiography (TOE) as a minimally invasive cardiac assessment tool during different stages of a DCD heart procurement procedure using TA-NRP. We conclude that TOE is a valuable method to assess the donor heart for transplantation eligibility before and after withdrawal of life-sustaining therapy and during subsequent TA-NRP. This article is protected by copyright. All rights reserved.

Donation After Circulatory Death in lung transplantation

The continuing shortage of pulmonary grafts from donors after brain death has led to a resurgence of interest in lung transplantation from donors after circulatory death (DCD). Most lungs from donors after withdrawal from life-sustaining therapy can be recovered rapidly and transplanted directly without ex-vivo assessment in case functional warm ischemic time is limited to 30 to 60 min. The potential of the DCD lung pool is still underutilized and should be maximized in countries with existing legislation. Countries lacking a DCD pathway should be encouraged to develop national ethical, professional, and legal frameworks to address public and professional concerns.

Visualizing in deceased COVID-19 patients how SARS-CoV-2 attacks the respiratory and olfactory mucosae but spares the olfactory bulb

Anosmia, the loss of smell, is a common and often the sole symptom of COVID-19. The onset of the sequence of pathobiological events leading to olfactory dysfunction remains obscure. Here, we have developed a postmortem bedside surgical procedure to harvest endoscopically samples of respiratory and olfactory mucosae and whole olfactory bulbs. Our cohort of 85 cases included COVID-19 patients who died a few days after infection with SARS-CoV-2, enabling us to catch the virus while it was still replicating. We found that sustentacular cells are the major target cell type in the olfactory mucosa. We failed to find evidence for infection of olfactory sensory neurons, and the parenchyma of the olfactory bulb is spared as well. Thus, SARS-CoV-2 does not appear to be a neurotropic virus. We postulate that transient insufficient support from sustentacular cells triggers transient olfactory dysfunction in COVID-19. Olfactory sensory neurons would become affected without getting infected.

Oxygenated machine perfusion at room temperature as an alternative for static cold storage in porcine donor hearts

Background

There is a continued interest in ex situ heart perfusion as an alternative strategy for donor heart preservation. We hypothesize that oxygenated machine perfusion of donor hearts at a temperature that avoids both normothermia and deep hypothermia offers adequate and safe preservation.

Methods

Cardioplegia‐arrested porcine donor hearts were randomly assigned to six hours of preservation using cold storage (CS, n = 5) or machine perfusion using an oxygenated acellular perfusate at 21°C (MP, n = 5). Subsequently, all grafts were evaluated using the Langendorff method for 120 min. Metabolic parameters and histology were analyzed. Systolic function was assessed by contractility and elastance. Diastolic function was assessed by lusitropy and stiffness.

Results

For both groups, in vivo baseline and post‐Langendorff biopsies were comparable, as were lactate difference and myocardial oxygen consumption. Injury markers gradually increased and were comparable. Significant weight gain was seen in MP (p = 0.008). Diastolic function was not impaired in MP, and lusitropy was superior from 30 min up to 90 min of reperfusion. Contractility was superior in MP during the first hour of evaluation.

Conclusion

We conclude that the initial functional outcome of MP‐preserved hearts was transiently superior compared to CS, with no histological injury post‐Langendorff. Our machine perfusion strategy could offer feasible and safe storage of hearts prior to transplantation. Future studies are warranted for further optimization.

Clinical evaluation of a cutaneous zero-heat-flux thermometer during cardiac surgery

We evaluated the disposable non-invasive SpotOn™ thermometer relying on the zero-heat-flux technology. We tested the hypothesis that this technology may accurately estimate the core temperature. The primary objective was to compare cutaneous temperature measurements from this device with blood temperatures measured with the pulmonary artery catheter. Secondary objective was to compare measurements from the zero-heat-flux thermometer indirectly with other routinely used thermometers (nasopharyngeal, bladder, rectal). We included 40 patients electively scheduled for either off-pump coronary artery bypass surgery or pulmonary thromboendarterectomy. Temperatures were measured using zero-heat-flux (SpotOn™), pulmonary artery catheter, nasopharyngeal, rectal, and bladder thermometers. Agreement was assessed using the Bland and Altman random effects method for repeated measures data, and Lin's concordance correlation coefficient. Accuracy was estimated (defined as <0.5° difference with the gold standard), with a 95% confidence interval considering the multiple pairs of measurements per patient. 17 850 sets of temperature measurements were analyzed from 40 patients. The mean overall difference between zero-heat-flux and pulmonary artery catheter thermometer was -0.06 °C (95% limits of agreement of ± 0.89 °C). In addition, 14 968 sets of temperature measurements were analyzed from 34 patients with all thermometers in situ. Results from the zero-heat-flux thermometer showed better agreement with the pulmonary artery catheter than the other secondary core thermometers assessed. In conclusion, the SpotOn™ thermometer reliably assessed core temperature during cardiac surgery. It could be considered an alternative for other secondary thermometers in the assessment of core temperature during general anesthesia.

Perioperative fluid management in esophagectomy for cancer and its relation to postoperative respiratory complications

The optimal perioperative fluid management during esophagectomy is still not clear. Liberal regimens have been associated with higher morbidity and respiratory complications. Restrictive regimens might raise concerns for kidney function and increase the need to associate vasopressors. The aim of this study was to investigate retrospectively the perioperative fluid administration during esophagectomy and to correlate this with postoperative respiratory outcome. All patients who underwent esophagectomy between January and December 2016 were retrospectively analyzed. Patient characteristics, type of surgery and postoperative course were reviewed. Fluid administration and vasopressor use were calculated intraoperatively and during the postoperative stay at the recovery unit. Fluid overload was defined as a positive fluid balance of more than 125 mL/m2/h during the first 24 hours. Patients were divided in 3 groups: GRP0 (no fluid overload/no vasopressors); GRP1 (no fluid overload/need for vasopressors); GRP2 (fluid overload with/without vasopressors). Postoperative complications were prospectively recorded according to Esophagectomy Complications Consensus Group criteria. A total of 103 patients were analyzed: 35 (34%) GRP0, 50 (49%) GRP1 and 18 (17%) GRP2. No significant differences were found for age, treatment (neoadjuvant vs. primary), type of surgery (open/minimally invasive), histology nor comorbidities. There were significant (P ≤ 0.001) differences in fluid balance/m2/h (75 ± 21 mL; 86 ± 22 mL and 144 ± 20 mL) across GRP0, GRP1 and GRP2, respectively. We found differences in respiratory complications (GRP0 (20%) versus GRP1 (42%; P = 0.034) and GRP0 (20%) versus GRP2 (61%; P = 0.002)) and "Comprehensive Complications Index" (GRP0 (20.5) versus GRP1 (34.6; P = 0.015) and GRP0 (20.5) versus GRP2 (35.1; P = 0.009)). Multivariable analysis (binary logistic regression) for "any respiratory complication" was performed. Patients who received fluid overload (GRP2) had a 10.24 times higher risk to develop postoperative respiratory complications. When patients received vasopressors alone (GRP1), the chances of developing these complications were 3.57 times higher compared to GRP0. Among patients undergoing esophagectomy, there is a wide variety in the administration of fluid during the first 24 hours. There was a higher incidence of respiratory complications when patients received higher amounts of fluid or when vasopressors were used. We believe that a personalized and protocolized fluid administration algorithm should be implemented and that individual risk factors should be identified.

Transplantation of donor hearts after circulatory death using normothermic regional perfusion and cold storage preservation

OBJECTIVES

Hearts donated after circulatory determination of death are usually preserved with normothermic machine perfusion prior to transplantation. This type of preservation is costly, requires bench time adding to warm ischaemia, and does not provide a reliable evaluation of the unloaded donor heart. We report on 4 successful donation after circulatory death (category III) hearts transplanted after thoraco-abdominal normothermic regional perfusion (NRP) and static cold storage.

METHODS

After life sustaining therapy was withdrawn and death was declared, perfusion to thoraco-abdominal organs was restored using extracorporeal circulation via cannulas in the femoral artery and vein and clamping of supra-aortic vessels. After weaning from extracorporeal circulation, cardiac function was assessed. Once approved, the heart was retrieved and stored using classic static cold storage. Data are expressed as median [min-max].

RESULTS

Donor and recipient ages were 44 years [12-60] (n = 4) and 53 years [14-64] (n = 4), respectively. Time from the withdrawal of life sustaining therapy to start of NRP was 22 min [18-31]. Cold storage time was 72 min [35-129]. Thirty-day survival was 100% with a left ventricle ejection fraction of 60% [50-60].

CONCLUSIONS

Donation after circulatory death heart transplantation using thoraco-abdominal NRP and subsequent cold storage preservation for up to 129 min was safe for 4 procedures and could be a way to expand the donor heart pool while avoiding costs of machine preservation.

Once daily tacrolimus conversion in lung transplantation: A prospective study on safety and medication adherence

BACKGROUND

Lung transplantation (LTx) requires a calcineurin inhibitor-based immunosuppressive regimen. A once daily (QD) tacrolimus regimen was developed to increase medication adherence. However, data concerning its safety and efficacy in LTx are lacking.

METHODS

In this prospective study, stable LTx patients were consecutively converted from twice daily (BID) tacrolimus to QD tacrolimus on a 1 mg:1 mg basis. Trough level (C_min), renal function, cholesterol, fasting glucose, potassium and lung function were monitored six months before and up to one year after conversion. Adherence and its barriers were assessed by self-reported questionnaires (Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS) and Identification of Medication Adherence Barriers questionnaire (IMAB)) and blood-based assays (mean C_min and coefficient of variation (CV)).

RESULTS

We included 372 patients, in whom we observed a decrease in tacrolimus C_min of 18.5% (p < 0.0001) post-conversion, requiring subsequent daily dose adaptations in both cystic fibrosis (CF) (n = 72) and non-CF patients (n = 300). We observed a small decrease in eGFR one year post-conversion (p = 0.024). No significant changes in blood creatinine, potassium, fasting glucose, cholesterol or rate of lung function decline were observed. In a subgroup of 166 patients, significantly fewer patients missed doses (8.4% vs. 19.3%, p = 0.016) or had irregular intake post-conversion (19.3% vs. 32.5%, p = 0.019). Mean C_min and CV, as well as the total number of barriers, also decreased significantly post-conversion.

CONCLUSIONS

In LTx, conversion from BID to QD tacrolimus (1 mg:1 mg) requires close monitoring of tacrolimus C_min. QD tacrolimus after transplantation is safe with respect to renal function, metabolic parameters and allograft function and improves LTx recipient adherence.

Successful resuscitation after hyperkalemic cardiac arrest during liver transplantation by converting veno-venous bypass to veno-arterial ECMO

INTRODUCTION

Intraoperative cardiac arrest (ICA) is a feared complication during liver transplantation (LTx), typically occurring during reperfusion. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has been used for post-reperfusion cardiac arrest.

CASE REPORT

We present a case of successful resuscitation after hyperkalemic ICA during the pre-anhepatic phase of a second liver transplantation by converting veno-venous bypass (VVB) to VA-ECMO.

DISCUSSION

While this technique has been recommended for ICA during reperfusion, it has never been reported during the pre-anhepatic phase. VA-ECMO can be a lifesaving extension to cardiopulmonary resuscitation for ICA during LTx with beneficial neurological outcome by providing perfusion while the cause of ICA is reversed.

CONCLUSION

Conversion of VVB to VA-ECMO should be considered in all patients who suffer from ICA during LTx with use of VVB. With VVB installed, conversion to VA-ECMO is fast and effective. If VVB is not used, early VA-ECMO should be considered for ICA.

Transmuscular quadratus lumborum (TQL) block for laparoscopic colorectal surgery: study protocol for a double-blind, prospective randomized placebo-controlled trial

BACKGROUND

Thoracic epidural anesthesia is no longer considered the gold standard for perioperative analgesia in laparoscopic colorectal procedures. In the search for alternatives, the efficacy of the transverse abdominal plane (TAP) block and other abdominal wall blocks such as the transmuscular quadratus lumborum (TQL) block continues to be investigated for postoperative pain management. Most of the initial studies on TAP blocks reported positive effects; however, the amount of studies with negative outcomes is increasing, most probably due to the fact that the majority of abdominal wall blocks fail to mitigate visceral pain. The TQL block could prove attractive in the search for better postoperative pain relief after laparoscopic colorectal surgery. In several cadaveric studies of the TQL, a spread of dye into the thoracic paravertebral space, the intercostal spaces, and even the thoracic sympathetic trunk was reported. Given the advantage of possibly reaching the thoracic paravertebral space, the potential to reach nerves transmitting visceral pain, and the possible coverage of dermatomes T4-L1, we hypothesize that the TQL provides superior postoperative analgesia for laparoscopic colorectal surgery as compared to patient-controlled intravenous analgesia with morphine alone.

METHODS AND DESIGN

In this prospective, randomized, double-blind controlled clinical trial, 150 patients undergoing laparoscopic colorectal surgery will be included. Patients will be randomly allocated to two different analgesic strategies: a bilateral TQL with 30 ml ropivacaine 0.375% each on both sides, administered before induction of anesthesia, plus postoperative patient-controlled intravenous analgesia with morphine (TQL group, n = 75), or a bilateral TQL block with 30 ml saline each on both sides plus postoperative patient-controlled intravenous analgesia with morphine (placebo group, n = 75). Our primary outcome parameter will be the morphine consumption during the first 24 h postsurgery. Secondary endpoints include pain intensity as assessed with the numerical rating scale (NRS) for pain, time to return of intestinal function (defined as the time to first flatus and the time to the first postoperative intake of solid food), time to first mobilization, the incidence of postoperative nausea and vomiting during the first 24 h, length of stay on the post anesthesia care unit (PACU) and in the hospital, the extent of sensory block at two time points (admission to and discharge from the PACU), the doses of morphine IV as requested by the patient from the PCA pump, the total dosage of morphine administered IV, the need for and dose of rescue analgesics (ketamine, clonidine), free plasma ropivacaine levels after induction and at discharge from the PACU, and the incidence of adverse events during treatment (in particular, signs of local anesthetic systemic toxicity (LAST)). Epidural analgesia is no longer the standard of care for postoperative analgesia in laparoscopic colorectal surgery. Until now, the most effective analgesic strategy in these patients especially in an enhanced recovery program is still unknown. Several abdominal wall blocks (TAP, fascia transversalis plane block) are known to have an analgesic effect only on somatic pain. Recognizing the importance of procedure-specific pain management, we aim to investigate whether a transmuscular quadratus lumborum block delivers superior pain control in comparison to patient-controlled intravenous analgesia with morphine alone.

TRIAL REGISTRATION

EudraCT identifier 2019-002304-40. Registered on 17 September 2019.