Year in review in Intensive Care Medicine, 2006. II. Infections and sepsis, haemodynamics, elderly, invasive and noninvasive mechanical ventilation, weaning, ARDS

Weaning from mechanical ventilation: a cross-sectional study of reference values and the discriminative validity of aging

[Purpose] To evaluate pre-extubation variables and check the discriminative validity of age as well as its correlation with weaning failure in elderly patients. [Subjects and Methods] Two hundred thirty-nine consecutive patients (48% female) who were on mechanical ventilation and had undergone orotracheal intubation were divided into four subgroups according to their age: <59 years, 60-69 years, 70-79 years, and >80 years old. The expiratory volume (VE), respiratory frequency (f), tidal volume (VT), and respiratory frequency/tidal volume ratio (f/VT) were used to examine differences in weaning parameters between the four subgroups, and age was correlated with weaning failure. [Results] The rate of weaning failure was 27.8% in patients aged >80 years and 22.1% in patients aged <60 years old. Elderly patients presented higher f/VT and f values and lower VT values. The areas under the receiver operating characteristic curves for f/VT ratio were smaller than those published previously. [Conclusion] Our results indicate that aging influences weaning criteria without causing an increase in weaning failure.

A TLR4-interacting SPA4 peptide inhibits LPS-induced lung inflammation

The interaction between surfactant protein-A (SP-A) and TLR4 is important for host defense. We have recently identified an SPA4 peptide region from the interface of SP-A-TLR4 complex. Here, we studied the involvement of the SPA4 peptide region in SP-A-TLR4 interaction using a two-hybrid system, and biological effects of SPA4 peptide in cell systems and a mouse model. HEK293 cells were transfected with plasmid DNAs encoding SP-A or a SP-A-mutant lacking SPA4 peptide region and TLR4. Luciferase activity was measured as the end-point of SP-A-TLR4 interaction. NF-κB activity was also assessed simultaneously. Next, the dendritic cells or mice were challenged with Escherichia coli-derived LPS and treated with SPA4 peptide. Endotoxic shock-like symptoms and inflammatory parameters (TNF-α, NF-κB, leukocyte influx) were assessed. Our results reveal that the SPA4 peptide region contributes to the SP-A-TLR4 interaction and inhibits the LPS-induced NF-κB activity and TNF-α. We also observed that the SPA4 peptide inhibits LPS-induced expression of TNF-α, nuclear localization of NF-κB-p65 and cell influx, and alleviates the endotoxic shock-like symptoms in a mouse model. Our results suggest that the anti-inflammatory activity of the SPA4 peptide through its binding to TLR4 can be of therapeutic benefit.

Statins in prevention and treatment of severe sepsis and septic shock

Severe sepsis is an infection-induced inflammatory syndrome that can lead to multi-organ dysfunction and continues to be a major cause of morbidity and mortality worldwide. Because numerous cascades are triggered during sepsis, selective blocking of inflammatory mediators may be insufficient to arrest this process, and recent therapeutic approaches have proven controversial. Statins are the most commonly prescribed agents for hypercholesterolaemia and dominate the area of cardiovascular risk reduction. Moreover, these drugs have a variety of actions that are independent of their lipid lowering effect. Such anti-inflammatory, antioxidant, immunomodulatory, and antiapoptotic features have been collectively referred to as pleiotropic effects. By virtue of their pleiotropic effects, statins have also emerged as potentially useful in various critical care areas such as bacteraemia, the early phases of sepsis and septic shock, as well as the management of serious infections. This review outlines current evidence on the use of statins for preventing and treating sepsis.

Cost-consequence analysis of remifentanil-based analgo-sedation vs. conventional analgesia and sedation for patients on mechanical ventilation in the Netherlands

INTRODUCTION

Hospitals are increasingly forced to consider the economics of technology use. We estimated the incremental cost-consequences of remifentanil-based analgo-sedation (RS) vs. conventional analgesia and sedation (CS) in patients requiring mechanical ventilation (MV) in the intensive care unit (ICU), using a modelling approach.

METHODS

A Markov model was developed to describe patient flow in the ICU. The hourly probabilities to move from one state to another were derived from UltiSAFE, a Dutch clinical study involving ICU patients with an expected MV-time of two to three days requiring analgesia and sedation. Study medication was either: CS (morphine or fentanyl combined with propofol, midazolam or lorazepam) or: RS (remifentanil, combined with propofol when required). Study drug costs were derived from the trial, whereas all other ICU costs were estimated separately in a Dutch micro-costing study. All costs were measured from the hospital perspective (price level of 2006). Patients were followed in the model for 28 days. We also studied the sub-population where weaning had started within 72 hours.

RESULTS

The average total 28-day costs were €15,626 with RS versus €17,100 with CS, meaning a difference in costs of €1474 (95% CI -2163, 5110). The average length-of-stay (LOS) in the ICU was 7.6 days in the RS group versus 8.5 days in the CS group (difference 1.0, 95% CI -0.7, 2.6), while the average MV time was 5.0 days for RS versus 6.0 days for CS. Similar differences were found in the subgroup analysis.

CONCLUSIONS

Compared to CS, RS significantly decreases the overall costs in the ICU.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00158873.

Genetic variants in the angiopoietin-2 gene are associated with increased risk of ARDS

OBJECTIVE

Angiopoietin-2 (Ang-2) is a potent regulator of vascular permeability and inflammation in acute lung injury and acute respiratory distress syndrome (ARDS). Genetic variants in the Ang-2 gene may lead to altered activities of Ang-2 (or ANGPT2) gene. The aim of this study was to assess if genetic variants of Ang-2 are associated with the risk of ARDS.

DESIGN

Unmatched, case-control study nested within a prospectively enrolled cohort.

SETTING

Intensive care units (ICU) of an academic medical center.

PATIENTS

About 1,529 critically ill patients with risk factors for ARDS consecutively admitted to the ICUs from 1999 to 2006. Cases were 449 patients who developed ARDS and controls were 1,080 subjects who did not developed ARDS.

INTERVENTION

None.

MEASUREMENTS AND RESULTS

Nine tagging SNPs (tSNPs) spanning the entire Ang-2 gene were genotyped in all patients. The results were analyzed using logistic regression models, adjusting for covariates. The variant T allele of one tSNP (rs2515475) was significantly associated with increased risk of ARDS (OR(adjusted) = 1.28; P = 0.042). This association was stronger in subjects with extrapulmonary injuries (OR(adjusted) = 1.79; P = 0.004). Haplotype TT in block 2 containing the T allele of the rs2515475 was also significantly associated with higher risk of ARDS (OR(adjusted) = 1.42; P = 0.009), particularly in subjects with extrapulmonary injuries (OR(adjusted) = 1.90; P = 0.004).

CONCLUSION

Common genetic variation in the Ang-2 gene may be associated with increased risk of ARDS, especially among patients with extrapulmonary injuries.

Application of ultrasound-guided pigtail catheter for drainage of pleural effusions in the ICU

BACKGROUND

Little is known about the effectiveness of the pigtail catheter for drainage of pleural effusions in the intensive care unit (ICU).

METHODS

We conducted a retrospective review of adult patients (>/=18 years) who underwent ultrasound-guided pigtail catheter drainage of pleural effusions in the ICUs from January 2005 to July 2007 in a university hospital.

RESULTS

Among the 133 enrolled patients, there were 93 (70%) males and 40 (30%) females, with a mean age of 63.7 +/- 15.4 years old. The reasons for pigtail drainage were as follows: thoracic empyema (n = 59, 44%), massive transudative pleural effusions (n = 33, 25%), postoperative pleural effusion (n = 29, 15%), malignant pleural effusion (n = 18, 14%) and traumatic hemothorax (n = 3, 2%). In comparing the total amount of fluids drained, the duration of drainage, success rate and complication rate among these different causes of pleural effusion, pigtail drainage for massive transudative pleural effusion yielded the largest amount of pleural fluids (5,382 +/- 4,844 ml), provided the longest duration of drainage (9 +/- 7 days), and had the highest complication rate (18%). The success rate was highest when used to treat traumatic hemothorax (100%) and postoperative pleural effusions (85%); drains inserted for empyema were more likely to fail (overall success rate, 42%). No significant insertion complications, such as hollow organ perforation, were caused by this procedure.

CONCLUSION

The ultrasound-guided pigtail catheter inserted by intensivists is a well-tolerated and effective method of draining all kinds of pleural effusions in critically ill patients. We suggest that pigtail catheter drainage be considered as the initial treatment of choice in the ICU.

Pediatric intestinal and multivisceral transplantation: a new challenge for the pediatric intensivist

Introduction

With increasing survival rates, intestinal transplantation (ITx) and multivisceral transplantation have reached the mainstream of medical care. Pediatric candidates for ITx often suffer from severe multisystem impairments that pose challenges to the medical team. These patients frequently require intensive care preoperatively and have unique intensive care needs postoperatively.

Methods

We reviewed the literature on intensive care of pediatric intestinal transplantation as well as our own experience. This review is not aimed only at pediatric intensivists from ITx centers; these patients frequently require ICU care at other institutions.

Results

Preoperative management focuses on optimization of organ function, minimizing ventilator-induced lung injury, preventing excessive edema yet maintaining adequate organ perfusion, preventing and controlling sepsis and bleeding from varices at enterocutaneous interfaces, and optimizing nutritional support. The goal is to extend life in stable condition to the point of transplantation. Postoperative care focuses on optimizing perfusion of the mesenteric circulation by maintaining intravascular volume, minimizing hypercoagulability, and providing adequate oxygen delivery. Careful monitoring of the stoma and its output and correction of electrolyte imbalances that may require renal replacement therapy is critical, as are monitoring for and aggressively treating infections, which often present with only subtle clinical clues. Signs of intestinal rejection may be non-specific, and early differentiation from other causes of intestinal dysfunction is important. Understanding of the expanding armamentarium of immunosuppressive agents and their side-effects is required.

Conclusions

As outcomes of ITx improve, transplant teams accept patients with higher pre-operative morbidity and at higher risk for complications. Many ITx patients would benefit from earlier referral for transplant evaluation before severe liver disease, recurrent central venous catheter-related sepsis and venous thromboses develop.

Statins and sepsis

Severe sepsis and septic shock is common and frequently fatal. Over the last few years, the primary treatments demonstrated to improve outcome from several major clinical trials have finally emerged. However, translating these recent therapeutic advances to routine clinical practice has proven controversial, and new approaches of additional strategies are continued to be developed. Given their pleiotropic effects related to many pathophysiological determinants of sepsis, statin therapy could be the next step in the search for adjuvant therapy. A future challenge may be to test both the efficacy and the safety by large randomized controlled clinical trials ascertaining the effects of statins administered at the onset of sepsis and in patients with severe sepsis or septic shock admitted into intensive care units.

ARDS and knowledge translation

Knowledge translation is an important step for translational research. In this issue of Intensive Care Medicine, a new mini-series of basic research-related reviews is published. Three invited reviews focus on the role of extracellular matrix in ventilator-induced lung injury and mechanotransduction. The major challenges in the diagnosis and management of acute respiratory distress syndrome are discussed, which promote further awareness of knowledge translation in intensive care.

Advances in mechanisms of repair and remodelling in acute lung injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) is the most severe manifestation of acute lung injury (ALI). In patients who survive the acute injury the process of repair and remodelling may be an independent risk factor determining morbidity and mortality. This review explores recent advances in the field of fibroproliferative ARDS/ALI, with a special emphasis on (a) the primary contributing factors with a focus on cellular and soluble factors, and (b) mechanisms involved in repair and remodelling as they pertain to the importance of cell death, re-population, and matrix deposition.

DISCUSSION

Factors influencing progression to fibroproliferative ARDS vs. resolution and reconstitution of the normal pulmonary parenchymal architecture are poorly understood. Determinants of persistent injury and abnormal repair and remodelling may be profoundly affected by both environmental and genetic factors. Moreover, cumulative evidence suggests that acute inflammation and fibrosis may be in part independent and interactive processes that are autonomously regulated and thus amenable to individual and specific therapy.

CONCLUSIONS

Although our current understanding of these processes is limited by the inability to accurately replicate the complex human physiology in laboratory settings, it has recently become apparent that the process of repair and remodelling begins early in the course of ARDS/ALI and may be determined by the type of pulmonary injury. Understanding the mechanisms leading to and regulating fibroproliferative changes may contribute to the development of novel early therapeutic interventions in ARDS/ALI patients.