Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

BACKGROUND

Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation.

METHODS

WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109.

FINDINGS

Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0-4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2-6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital.

INTERPRETATION

In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates.

FUNDING

European Society of Intensive Care Medicine, European Respiratory Society.

The dos and do knots of central venous catheterization

Central venous catheterization plays an important role in patients with end-stage renal disease undergoing hemodialysis. Placement of a right subclavian hemodialysis catheter was complicated by looping and entrapment of the guidewire. Computed tomographic and three-dimensional scans were essential in locating and determining that the guidewire was outside the vessel.

Prognostic power of pre- and postoperative B-type natriuretic peptide levels in patients undergoing abdominal aortic surgery

OBJECTIVES

The first aim of the present study was to evaluate the pre- and postoperative B-type natriuretic peptide (BNP) levels in patients undergoing surgery for repair of an infrarenal abdominal aortic aneurysm (AAA) and analyze their power as a predictor of in-hospital cardiac events. The second aim was to evaluate the association among pre- and postoperative BNP levels, postoperative patient complications, and length of hospital stay.

DESIGN

Prospective observational study.

SETTING

A university hospital.

PARTICIPANTS

Forty-five patients undergoing elective surgery for an abdominal aortic aneurysm.

INTERVENTIONS

The plasma BNP level was assessed just before surgery and then on postoperative day 1. Cardiac troponin I levels were measured postoperatively on arrival to the intensive care unit (time 0) and then 12, 48, and 72 hours later.

MEASUREMENTS AND MAIN RESULTS

The preoperative BNP concentration in patients who developed an acute myocardial infarction was 209 (IQR 84-346) pg/mL compared with 74 (IQR 28-142) pg/mL in those who did not. The difference between groups was statistically significant (p = 0.04). The Spearman correlation showed that postoperative BNP levels correlated significantly with preoperative BNP levels (r = 0.73, p = 0.0001), length of hospital stay (r = 0.35, p = 0.04), and troponin I concentration at 0 hour (r = 0.42, p = 0.02), 12 hours (r = 0.51, p = 0.0052), and 48 hours (r = 0.40, p = 0.033). In contrast, preoperative BNP levels correlated with troponin I at only 12 hours (r = 0.34, p = 0.02). Postoperative BNP levels were influenced significantly by transfusions (p = 0.035) and cross-clamping times (p = 0.038).

CONCLUSIONS

The present results confirm the high negative predictive value of preoperative BNP levels; and postoperative BNP levels showed a better correlation with postoperative troponin levels, blood transfusion, and postoperative cardiac events.

Perioperative considerations in HIV-infected liver transplanted patients

The introduction of highly active antiretroviral therapy (HAART) has improved survival in HIV patients, allowing them to undergo liver transplantation (OLT) in cases of end-stage liver disease. HIV patients show a higher incidence of pulmonary hypertension. The aim of this study was to evaluate pulmonary and systemic hemodynamic changes in HIV-infected patients compared with a non-HIV-infected group of patients undergoing OLT.

METHODS

We analyzed 20 HIV-infected patients and 20 non-HIV-infected patients who underwent OLT. We analyzed preoperative cardiovascular status, as well as intra- and postoperative hemodynamic data. Hemodynamic data were recorded at 4 predefined phases during OLT and at 24, 48, and 72 hours after intensive care unit (ICU) admission. We also evaluated the following perioperative aspects: transfusion requirements, postoperative mechanical ventilation time, ventilation time, and length of ICU and of hospital stay.

RESULTS

HIV-positive patients were younger than controls with a greater incidence of coinfection with hepatotropic viruses. One HIV-infected patient died in the ICU. Hemodynamic data showed a higher cardiac index and higher pulmonary vascular resistance index among HIV-infected patients, but without any clinical impact. No significant difference in blood unit transfusions, postoperative time on mechanical ventilation, or length of ICU or hospital stay was observed between the groups.

CONCLUSIONS

Although the number of patients studied is limited, we concluded that HIV-infected patients undergoing OLT showed similar perioperative courses as non-HIV-infected patients.

The liver transplant recipient with cardiac disease

Liver transplantation is a stressful condition for the cardiovascular system of patients with advanced hepatic disease. The underlying hemodynamic and cardiac status of patients with cirrhosis is crucial to determine which patients should became recipients. Generally preoperative cardiovascular testing is performed on potential candidates who are more than 45 years old, or have diabetes mellitus, or peripheral vascular disease, or more than two standard cardiac risk factors. Recent data suggest that the prevalence of coronary artery disease among patients with cirrhosis is much greater than previously believed; it likely mirrors or exceeds the prevalence rate in the healthy population. The morbidity and mortality of patients with coronary artery disease who undergo orthotopic liver transplantation (OLT) without treatment are unacceptably high. In conclusion, accurate preoperative cardiac evaluation according to the new American Heart Association & American College of Cardiology should lead to detect and treat coronary artery disease before liver transplantation. In case of alcohol-related cardiomyopathy, portopulmonary hypertension, and hypertrophic cardiomyopathy, there should be a case-by-case discussion by the hepatologist and cardiologist to consider the patient for liver transplantation. No robust data are available on the impact of decompensated dilated heart failure in this setting. If a recipient with cardiac disease is scheduled for OLT, we strongly suggest advanced intra- and postoperative hemodynamic monitoring plus transesophageal echocardiography.

Arterial pulse cardiac output agreement with thermodilution in patients in hyperdynamic conditions

OBJECTIVE

This study aimed to compare continuous cardiac output (CCO) obtained using the arterial pulse wave (APCO) measurement with a simultaneous measurement of the intermittent cardiac output (ICO) and CCO obtained with a pulmonary artery catheter (PAC) in liver transplant patients.

DESIGN

A prospective, single-center evaluation.

SETTING

A university hospital intensive care unit.

PATIENTS

Eighteen patients after liver transplantation.

INTERVENTIONS

Pulmonary artery catheters were placed in all patients, and ICO and CCO were determined using thermodilution. APCO measurements were made with the Vigileo System (Edwards Lifesciences, Irvine, CA).

MEASUREMENTS AND MAIN RESULTS

The authors obtained 126 data pairs of ICO and APCO and 864 pairs of CCO and APCO. ICO data were collected after intensive care unit admission and every 8 hours until the 48th postoperative hour. CCO and APCO data were collected every hour from admission until the 48th postoperative hour. Bias and precision were 0.95 +/- 1.41 L/min for ICO versus APCO and 1.29 +/- 1.28 L/min for CCO and APCO. Bias and precision for cardiac output (CO) data pairs less than 8 L/min were 0.32 +/- 1.14 L/min between ICO and APCO and 0.71 +/- 0.98 L/min between CCO and APCO. For CO data pairs higher than 8 L/min, bias and precision were 1.79 +/- 1.54 L/min between ICO and APCO and 2.25 +/- 1.14 L/min between CCO and APCO.

CONCLUSIONS

APCO enables the assessment of CO with clinically acceptable bias and precision. At higher CO levels, APCO underestimates PAC measurements and it is not as reliable as thermodilution in hyperdynamic liver transplant patients.

Hemodynamics During Liver Transplantation

Assessing the optimal volemia in the perioperative course of liver transplantation is a challenge for the anesthesiologist. Traditional estimates of intravascular volume status, such as pulmonary artery occlusion pressure (PAOP), have been widely shown to poorly correlate with changes in cardiac output among critically ill patients. Hence, there has been recent interest in alternative, catheter-related, bedside device volume estimates using thermodilution. Continuous end diastolic volume (CEDVI) showed better correlations with cardiac performance than cardiac filling pressures in studies performed in critically ill patients. When compared with conventional pressure-derived data, preload monitoring estimated as intrathoracic blood volume index (ITBVI) with the PiCCO system based on an integrated transpulmonary thermodilution technique better reflected left ventricular filling both in critically ill patients and those who underwent liver transplantation. Moreover, in liver transplantation, the use of transoesophageal echocardiography (TEE) has been increasing for it provides rapid visualization of the dimension and function of heart chambers as well as the left ventricular end diastolic area index (EDAI) that seem to correlate with graded acute hypovolemia, although its validity as on preload index is still under discussion.

Sedation in the critically ill patient

Critically ill patients who require intensive care need effective analgesia and sedation to control potentially unpleasant symptoms, such as pain and anxiety. Analgesics and sedatives are also used to allow patients to tolerate nursing procedures and tracheal intubation as well as to aid mechanical ventilation. Metabolism of traditional opioids is dependent on organ function, which is abnormal among critically ill patients. The use of a score system to ensure sufficient but not excessive sedation should be mandatory. Sufentanil and remifentanil are more predictable opioids that are suitable for either sedation or analgesia in critically ill patients to achieve an adequate Ramsay score from 2 to 4.

Analgesia in PACU: nonsteroidal anti-inflammatory drugs

Control and abolition of pain during and after surgical procedures is crucial point in the practice of anaesthesiology. In the last years the concept of multimodal analgesia (the use of different analgesic and techniques to relieve pain), has developed and non-steroidal anti-inflammatory drugs (NSAIDs) have a major role in it, because they have an opioid sparing effect. Moreover, they are very effective on somatic and breakthrough pain. NSAIDs can be divided functionally in four classes: salicylates, acetaminophen, non-specific inhibitors (i.e. ibuprofen, ketorolac, etc.) and cyclooxygenase2-inhibitors (coxibs). The target of action of these drugs is the different isozymes of the Prostaglandin G/H synthase, called Cyclooxygenases (COX). At least three different types of COX have been identified, which are probably organ specific. These isozymes play a crucial role in the developing of the inflammatory cascade, and in the genesis of various pain mediators released from tissue injury. Their most important side effects affect mainly gastrointestinal system, the kidney and the coagulation system. Less important are the effects on the liver and the immunologic system (asthma). The analgesic nephropathy and the coagulopathy must be taken into account in the surgical patient, for the possibility of increase perioperative morbidity. Very recently the newest class of coxibs, although they reduce g.i. bleeding and coagulopathy, have proved to increase the risk of cardiovascular accidents both in long term therapy than postoperatively in cardiac surgical patients. Many data are needed, but in patients at high risk of cardiac disease other NSAIDs should be considered.

Long-Term Results of In Situ Split-Liver Transplantation

BACKGROUND

Split-liver transplantation (SLT) offers immediate expansion of the cadaver donor pool. The principal beneficiaries have been adult and pediatric recipients with excellent outcomes. This study analyzed a single-center experience of adult to adult in situ SLT in adult recipients.

PATIENTS AND METHODS

Fourteen consecutive adult-to-adult in situ SLT have been performed at our institution since 1998. The extended right lobe comprising segment 1 was transplanted in to adult patients, the left lateral segment, for pediatric transplants.

RESULTS

Donors of SLT were significantly younger (P = .03) than those of whole liver transplants. Survival rates of patients receiving a split liver were 83%, 73%, and 73% at 1, 3, and 5 years after the transplant respectively and grafts of 73%, 73%, and 73% for SLT and 76%, 70%, and 66% for whole liver transplants (P = .44). The rate of biliary complication after SLT was 21%, which was comparable to that after whole organ transplantation (17%). The incidence of hepatic artery thrombosis and primary nonfunction was not significantly different between split liver and whole organ transplantation performed during the same time period (7% versus 4.6% P = .67 and 7% versus 2.6% P = .32, respectively).

CONCLUSION

This limited single-center experience confirmed that both early and long-term results of SLT are comparable to those of traditional whole liver organ transplantation.

Secondary migration of a central venous catheter. A case report

A case of central venous catheter (CVC) secondary migration in a patient with Hodgkin's lymphoma is reported. The catheter was inserted in the right internal jugular vein with anterior approach. The correct position of the catheter tip in the superior vena cava was confirmed by X-ray. Secondary migration to the right subclavian vein, without displacement at the point of insertion, was reported 8 days later by a chest X-ray performed for worsening of the respiratory condition. CVC was removed and reinserted with the same procedure. The correct position of the catheter tip was confirmed by thoracic radiography till 10 days later. Epidemiological data present in the literature and secondary migration predisposing factors are reported.

Circadian variations in cyclosporine C2 concentrations during the first 2 weeks after liver transplantation

The strategies currently used to monitor concentrations of cyclosporine (CsA) in transplanted patients include whole blood trough (C0), total or abbreviated area under the curve (AUC) concentration and population pharmacokinetic approaches. Recently, a single blood concentration measurement at 2 hours (C2) after CsA administration has been shown to be helpful to predict clinical effects during the first weeks after transplantation of liver and kidney grafts. However, this approach has raised multiple questions about pharmacokinetic variability, analytical methods, and organizational requirements. From a pharmacokinetic point of view, the variability of CsA blood concentrations may relate to circadian variations. The present study sought to characterize the circadian variation in C0 and C2 CsA levels among 20 liver transplant recipients during the first 2 weeks posttransplant. All patients received two equal oral doses of CsA microemulsion formulation every 12 hours. Blood samples were collected before and 2 hours after CsA administration in the morning (AM) and in the evening (PM). Whole blood concentrations of CsA were assayed using the monoclonal fluorescence polarization immunoassay system. During the first 2 weeks posttransplant, C2 AM mean levels were significantly higher than C2 PM levels (542 +/- 241 vs 383 +/- 182 ng/mL, P =.005), while the C0 AM mean level was not statistically different from the C0 PM (285 +/- 174 vs 223 +/- 124 ng/mL, P =.367). Our results suggest that morning CsA blood samples may afford a better approach to optimize the CsA dosage, especially based on C2 values.

Elective transumbilical compared with standard laparoscopic cholecystectomy

OBJECTIVE

To compare the transumbilical technique of laparoscopic cholecystectomy with standard laparoscopic cholecystectomy.

DESIGN

Randomised open study.

SETTING

Teaching hospital, Italy.

SUBJECTS

90 patients who required elective cholecystectomy under general anaesthesia.

INTERVENTIONS

Standard laparoscopic cholecystectomy through 4 ports or transumbilical cholecystectomy through 2 ports.

MAIN OUTCOME MEASURES

Amount of pain and analgesia, cost, side effects, and cosmesis.

RESULTS

25 patients were excluded from analysis (8 in the standard group because relevant data were not recorded; and 17 in the transumbilical group in 4 of whom relevant data were not recorded, and 13 for technical reasons). 32 patients who had standard, and 25 who had transumbilical cholecystectomy had operative cholangiograms. There were no complications, no side effects, and no conversions to open cholecystectomy. Those who had transumbilical cholecystectomy had significantly lower pain scores (p<0.05) and required significantly less analgesia during the first 24 hours (p<0.05) than those who had standard laparoscopic cholecystectomy.

CONCLUSION

Once the learning curve has been completed, transumbilical cholecystectomy is possible without some of difficulties associated with standard laparoscopic cholecystectomy.

[Postoperative epidural analgesia]

Epidural analgesia with local anesthetics and opioids is one of the most effective methods for postoperative pain control. In critical patients it seems to improve outcome as well as pain control. This technique works better when started in the intraoperative time. Epidural analgesia is safe on surgical wards if nursing staff is trained in managing epidural catheters and in early detection and treatment of major and minor side effects. Nursing staff cooperates with the Acute Pain Service doctors and nurses who are on call on a 24 hour basis. Many perspective and retrospective studies showed a very low incidence of major side effects with epidurals. So we can consider it safe and effective even if we consider its invasiveness.