Ignacio Malagon

Validation of Three Postoperative Risk Prediction Models for Intensive Care Unit Mortality after Cardiac Surgery

Background Several cardiac surgery risk prediction models based on postoperative data have been developed. However, unlike preoperative cardiac surgery risk prediction models, postoperative models are rarely externally validated or utilized by clinicians. The objective of this study was to externally validate three postoperative risk prediction models for intensive care unit (ICU) mortality after cardiac surgery. Methods The logistic Cardiac Surgery Scores (logCASUS), Rapid Clinical Evaluation (RACE), and Sequential Organ Failure Assessment (SOFA) scores were calculated over the first 7 postoperative days for consecutive adult cardiac surgery patients between January 2013 and May 2015. Model discrimination was assessed using receiver operating characteristic curve analyses. Calibration was assessed using the Hosmer‐Lemeshow (HL) test, calibration plots, and observed to expected ratios. Recalibration of the models was performed. Results A total of 2255 patients were included with an ICU mortality rate of 1.8%. Discrimination for all three models on each postoperative day was good with areas under the receiver operating characteristic curve of >0.8. Generally, RACE and logCASUS had better discrimination than SOFA. Calibration of the RACE score was better than logCASUS, but ratios of observed to expected mortality for both were generally <0.65. Locally recalibrated SOFA, logCASUS and RACE models all performed well. Conclusion All three models demonstrated good discrimination for the first 7 days after cardiac surgery. After recalibration, logCASUS and RACE scores appear to be most useful for daily risk prediction after cardiac surgery. If appropriately calibrated, postoperative cardiac surgery risk prediction models have the potential to be useful tools after cardiac surgery.

Intra-abdominal hypertension complicating pancreatitis-induced acute respiratory distress syndrome in three patients on extracorporeal membrane oxygenation

BACKGROUND Severe acute pancreatitis is associated with sever multiorgan failure from 15 to 50%, depending on the series. In some of these patients, conventional methods of ventilation and respiratory support will fail, demanding the use of extracorporeal membrane oxygenation (ECMO). Abdominal compartment syndrome is potentially harmful in this cohort of patients. We describe the successful treatment of three patients with severe acute pancreatitis who underwent respiratory ECMO and where intra abdominal pressure was monitored regularly. METHODS Retrospective review of case notes. RESULTS Three patients with severe acute pancreatitis requiring ECMO suffered from increased intra abdominal pressure during their ICU stay. No surgical interventions were taken to relieve abdominal compartment syndrome. Survival to hospital discharge was 100%. CONCLUSIONS Monitoring intraabdominal pressure is a valuable adjunct to decision making while caring for these high-risk critically ill patients.

The KDIGO acute kidney injury guidelines for cardiac surgery patients in critical care: a validation study

BackgroundThe Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury (AKI) guidelines assign the same stage of AKI to patients whether they fulfil urine output criteria, serum creatinine criteria or both criteria for that stage. This study explores the validity of the KDIGO guidelines as a tool to stratify the risk of adverse outcomes in cardiac surgery patients.MethodsProspective data from consecutive adult patients admitted to the cardiac intensive care unit (CICU) following cardiac surgery between January 2013 and May 2015 were analysed. Patients were assigned to groups based on the criteria they met for each stage of AKI according to the KDIGO guidelines. Short and mid-term outcomes were compared between these groups.ResultsA total of 2267 patients were included with 772 meeting criteria for AKI-1 and 222 meeting criteria for AKI-2. After multivariable adjustment, patients meeting both urine output and creatinine criteria for AKI-1 were more likely to experience prolonged CICU stay (OR 4.9, 95%CI 3.3–7.4, p < 0.01) and more likely to require renal replacement therapy (OR 10.5, 95%CI 5.5–21.9, p < 0.01) than those meeting only the AKI-1 urine output criterion. Patients meeting both urine output and creatinine criteria for AKI-1 were at an increased risk of mid-term mortality compared to those diagnosed with AKI-1 by urine output alone (HR 2.8, 95%CI 1.6–4.8, p < 0.01). Patients meeting both urine output and creatinine criteria for AKI-2 were more likely to experience prolonged CICU stay (OR 16.0, 95%CI 3.2–292.0, p < 0.01) or require RRT (OR 11.0, 95%CI 4.2–30.9, p < 0.01) than those meeting only the urine output criterion. Patients meeting both urine output and creatinine criteria for AKI-2 were at a significantly increased risk of mid-term mortality compared to those diagnosed with AKI-2 by urine output alone (HR 3.6, 95%CI 1.4–9.3, p < 0.01).ConclusionsPatients diagnosed with the same stage of AKI by different KDIGO criteria following cardiac surgery have significantly different short and mid-term outcomes. The KDIGO criteria need to be revisited before they can be used to stratify reliably the severity of AKI in cardiac surgery patients. The utility of the criteria also needs to be explored in other settings.

Incidence and outcomes of sepsis after cardiac surgery as defined by the Sepsis-3 guidelines

Background: The Sepsis‐3 guidelines diagnose sepsis based on organ dysfunction in patients with either proven or suspected infection. The objective of this study was to assess the incidence and outcomes of sepsis diagnosed using these guidelines in patients in a cardiac intensive care unit (CICU) after cardiac surgery. Methods: Daily sequential organ failure assessment (SOFA) scores were calculated for 2230 consecutive adult cardiac surgery patients between January 2013 and May 2015. Patients with an increase in SOFA score of ≥2 and suspected or proven infection were identified. The length of CICU stay, 30‐day mortality and 2‐yr survival were compared between groups. Multivariable linear regression, multivariable logistic regression, and Cox proportional hazards regression were used to adjust for possible confounders. Results: Sepsis with suspected or proven infection was diagnosed in 104 (4.7%) and 107 (4.8%) patients, respectively. After adjustment for confounding variables, sepsis with suspected infection was associated with an increased length of CICU stay of 134.1h (95% confidence interval (CI) 99.0–168.2, P<0.01) and increased 30‐day mortality risk (odds ratio 3.7, 95% CI 1.1–10.2, P=0.02). Sepsis with proven infection was associated with an increased length of CICU stay of 266.1h (95% CI 231.6–300.7, P<0.01) and increased 30‐day mortality risk (odds ratio 6.6, 95% CI 2.6–15.7, P<0.01). Conclusions: Approximately half of sepsis diagnoses were based on proven infection and half on suspected infection. Patients diagnosed with sepsis using the Sepsis‐3 guidelines have significantly worse outcomes after cardiac surgery. The Sepsis‐3 guidelines are a potentially useful tool in the management of sepsis following cardiac surgery.

Comparison of traditional microbiological culture and 16S polymerase chain reaction analyses for identification of preoperative airway colonization for patients undergoing lung resection

Purpose: Preoperative airway colonization is associated with increased risk of postoperative respiratory complications following lung resection. This study compares the rates of preoperative lower respiratory tract colonization identified by traditional culture and novel 16S polymerase chain reaction (PCR) tests. Materials and methods: Preoperative sputum and bronchoalveolar lavage (BAL) samples for 49 lung resection patients underwent culture and 16S PCR analyses. Rates of positive test results were determined and relationships between test results and suspected postoperative respiratory tract infection and hospital length of stay (LOS) were investigated. Results: Preoperative BAL cultures were positive for 29 (59.2%) patients (population estimate 95%CI 45.2%–71.8%). 16S PCR tests were positive for 28 (57.1%) patients (population estimate 95%CI 43.3%–70.0%). 17 (34.7%) patients suffered suspected postoperative respiratory tract infection (population estimate 95%CI 22.9%–48.7%). Positive 16S PCR results tended to be associated with longer LOS (median 7.5 days vs 4.0 days for negative, p = 0.08) and increased risk of suspected postoperative respiratory tract infection (46.4% for positive vs 19.0% for negative, p = 0.07). Conclusions: Rates of colonization identified by culture and 16S PCR analyses of BAL samples were similar. Future research should attempt to clarify associations between airway colonization identified by 16S PCR and outcomes. 16S PCR may be useful when stratifying risk of postoperative respiratory complications. HIGHLIGHTSPreoperative lower respiratory tract colonization is linked to poor outcomes.Colonization can be identified by 16S PCR and traditional culture analyses.16S PCR identifies colonization in a similar proportion of patients as culture.As 16S PCR analyses become cheaper and faster they will become more useful.

The use of VV-ECMO in patients with drug dependencies

The purpose of this study is to determine the effect of illicit drug and alcohol dependencies on mortality, length of stay, and complications in patients who have been supported with veno-venous extracorporeal membrane oxygenation (VV-ECMO) following respiratory failure not responsive to conventional methods of ventilation. 584 VV-ECMO referrals received at Wythenshawe Hospital were reviewed for evidence of drug dependency. 13 patients were identified as being drug-dependent and having undergone treatment with VV-ECMO. A matched cohort of 13 non-drug-dependent patients was identified using date of birth, pre-ECMO Murray Score, and primary diagnosis. The outcomes were compared. 19 more complications were found amongst the drug-dependent patients compared with the non-drug-dependent cohort (39 vs 20). A mean difference of 1.46 complications per patient was calculated (p = 0.005). Mortality after 180 days was reported in 4 of the drug-dependent patients, compared with one in the matched cohort. Length of stay on ECMO was increased on average by 1.93 days amongst the drug-dependent patients (p = 0.557); however, the sample size was not great enough to achieve statistical significance. Patients with drug dependencies undergoing VV-ECMO have more complications when compared with a cohort of patients with no proven or suspected drug dependencies. Differences in morbidity and mortality were not statistically significant.

The role of thoracic surgery in extracorporeal membrane oxygenation services

Background Recent evidence surrounding the use of venovenous extracorporeal membrane oxygenation in treating acute respiratory failure has led to the expansion of extracorporeal membrane oxygenation services worldwide. The high rate of complications related to venovenous extracorporeal membrane oxygenation often requires intervention by specialist thoracic surgeons. This study aimed to investigate the role of specialist thoracic surgeons within the multidisciplinary team managing these high-risk patients. Methods We retrospectively reviewed 90 patients who received venovenous extracorporeal membrane oxygenation at our tertiary referral center between December 2011 and May 2015. Four patients who underwent lung transplantation were excluded. Results We found that 29.1% (25/86) of patients on venovenous extracorporeal membrane oxygenation had undergone a thoracic intervention. A total of 82 interventions were performed: 11 thoracotomies, 49 chest drains, 13 rigid bronchoscopies, 4 flexible bronchoscopies, 4 temporary endobronchial blockers, and 1 sternotomy. Of the 11 thoracotomies, 3 were reexplorations. Survival to discharge for patients who underwent thoracic surgical interventions was 72% (18/25). Conclusions Our experience has demonstrated that a large proportion of patients receiving venovenous extracorporeal membrane oxygenation require a thoracic intervention, many of which are major intraoperative procedures. Patients on venovenous extracorporeal membrane oxygenation have benefited from rapid on-site access to thoracic surgical services to manage these challenging life-threatening complications.

The effect of veno-venous ECMO on the pharmacokinetics of Ritonavir, Darunavir, Tenofovir and Lamivudine

Introduction To our knowledge, there is no published data on the pharmacokinetic (PK) profile of antiretroviral (ART) drugs on patients undergoing extracorporeal membrane oxygenation (ECMO) therapy. We present PK analyses of Ritonavir, Darunavir, Lamivudine and Tenofovir in a patient with HIV who required veno‐venous ECMO (VV ECMO). Methods Plasma concentrations for Ritonavir, Darunavir, Tenofovir and Lamivudine were obtained while the patient was on ECMO following pre‐emptive dose adjustments. Published population PK models were used to simulate plasma concentration profiles for the drugs. The population prediction and the observed plasma concentrations were then overlaid with the expected drug profiles using the individual Bayesian post‐hoc parameter estimates. Results Following dose adjustments, the PK profiles of Ritonavir, Darunavir and Tenofovir fell within the expected range and appeared similar to the population prediction, although slightly different for Ritonavir. The observed data for Lamivudine and its PK profile were completely different from the data available in the literature. Conclusions To our knowledge, this is the first study reporting the PK profile of ART drugs during ECMO therapy. Based on our results, dose adjustment of ART drugs while on VV ECMO may be advisable. Further study of the PK profile of Lamivudine is required. HighlightsThis is the first study investigating the PK profile of antiretrovirals during ECMO.Population‐based predications were compared with plasma drug concentrations on ECMO.Ritonavir, Darunavir and Tenofovir were in the expected range after dose adjustments.The observed data for Lamivudine was completely different from predictions.We conclude that dose adjustments of ART drugs while on VV‐ECMO may be advisable.

Randomized Study Comparing the Effect of Carbon Dioxide Insufflation on Veins Using 2 Types of Endoscopic and Open Vein Harvesting

Objective The aim of the study was to assess whether the use of carbon dioxide insufflation has any impact on integrity of long saphenous vein comparing 2 types of endoscopic vein harvesting and traditional open vein harvesting. Methods A total of 301 patients were prospectively randomized into 3 groups. Group 1 control arm of open vein harvesting (n = 101), group 2 closed tunnel (carbon dioxide) endoscopic vein harvesting (n = 100) and Group 3 open tunnel (carbon dioxide) endoscopic vein harvesting (open tunnel endoscopic vein harvesting) (n = 100). Each group was assessed to determine the systemic level of partial arterial carbon dioxide, end-tidal carbon dioxide, and pH. Three blood samples were obtained at baseline, 10 minutes after start of endoscopic vein harvesting, and 10 minutes after the vein was retrieved. Vein samples were taken immediately after vein harvesting without further surgical handling to measure the histological level of endothelial damage. A modified validated endothelial scoring system was used to compare the extent of endothelial stretching and detachment. Results The level of end-tidal carbon dioxide was maintained in the open tunnel endoscopic vein harvesting and open vein harvesting groups but increased significantly in the closed tunnel endoscopic vein harvesting group (P = 0.451, P = 0.385, and P < 0.001). Interestingly, partial arterial carbon dioxide also did not differ over time in the open tunnel endoscopic vein harvesting group (P = 0.241), whereas partial arterial carbon dioxide reduced significantly over time in the open vein harvesting group (P = 0.001). A profound increase in partial arterial carbon dioxide was observed in the closed tunnel endoscopic vein harvesting group (P < 0.001). Consistent with these patterns, only the closed tunnel endoscopic vein harvesting group demonstrated a sudden drop in pH over time (P < 0.001), whereas pH remained stable for both open tunnel endoscopic vein harvesting and open vein harvesting groups (P = 0.105 and P = 0.869, respectively). Endothelial integrity was better preserved in the open vein harvesting group compared with open tunnel endoscopic vein harvesting or closed tunnel endoscopic vein harvesting groups (P = 0.012) and was not affected by changes in carbon dioxide or low pH. Significantly greater stretching of the endothelium was observed in the open tunnel endoscopic open tunnel endoscopic vein harvesting group compared with the other groups (P = 0.003). Conclusions This study demonstrated that the different vein harvesting techniques impact on endothelial integrity; however, this does not seem to be related to the increase in systemic absorption of carbon dioxide or to the pressurized endoscopic tunnel. The open tunnel endoscopic harvesting technique vein had more endothelial stretching compared with the closed tunnel endoscopic technique; this may be due to manual dissection of the vein. Further research is required to evaluate the long-term clinical outcome of these vein grafts.

Chronic mould exposure as a risk factor for severe community acquired pneumonia in a patient requiring extra corporeal membrane oxygenation

A previously fit and well man developed acute respiratory failure due to environmental mould exposure from living in damp rental accommodation. Despite aggressive intensive care management he rapidly deteriorated and required respiratory and cardiac Extracorporeal Membrane Oxygenation. We hypothesize that poor domiciliary conditions may make an underestimated contribution to community respiratory disease. These conditions may present as acute and severe illness with non-typical pathogens identified.