Evaluation of ferritin and the ferritin index as prognostic biomarkers in septic shock

BACKGROUND

Ferritin, an acute phase reactant, and the ferritin index (FI = observed ferritin level/upper limit of normal level for age and sex) may be prognostic biomarkers in septic shock and cardiac surgery patients.

OBJECTIVE

The purpose of this exploratory study is to assess the outcome associations of ferritin and FI levels in septic shock compared to post-cardiac surgery patients.

DESIGN

This was a prospective, double-centre, observational study.

SETTING

The study setting involved two adult intensive care units (ICUs) in Victoria, Australia.

PARTICIPANTS

Sixty-one septic shock and 30 post-cardiac surgery patients participated in this study.

MAIN OUTCOME MEASURES

We measured ferritin and FI on ICU admission (T1) and 24 h later (T2) to assess its correlation with mortality, illness severity, and hospital length of stay (LOS).

RESULTS

The baseline characteristics of patients in the septic shock group and cardiac surgery group were similar apart from illness severity scores (APACHE III and modified SOFA score). Septic shock patients had more physiological derangements as well as greater use and higher doses of norepinephrine at both T1 and T2. Septic shock patients had significantly higher median ferritin levels (372 μg/L versus 198 μg/L; p < 0.001 at T1, 457 μg/L versus 264 μg/L; p = 0.001 at T2) than post-cardiac surgery patients. Ferritin levels, however, did not have a linear correlation with illness severity or hospital mortality. Instead, there was an association between high ferritin levels at T2 and longer ICU (p = 0.017) and hospital LOS (p = 0.013). Females with septic shock had significantly higher FI (p < 0.001 at T1, p = 0.004 at T2) than males.

CONCLUSION

In septic shock patients, ferritin levels and FI were twice the level compared to post-cardiac surgery patients. Both had no association with mortality, but levels above the median at 24 h were associated with longer ICU and hospital LOS.

Mild Hypercapnia or Normocapnia after Out-of-Hospital Cardiac Arrest

BACKGROUND

Guidelines recommend normocapnia for adults with coma who are resuscitated after out-of-hospital cardiac arrest. However, mild hypercapnia increases cerebral blood flow and may improve neurologic outcomes.

METHODS

We randomly assigned adults with coma who had been resuscitated after out-of-hospital cardiac arrest of presumed cardiac or unknown cause and admitted to the intensive care unit (ICU) in a 1:1 ratio to either 24 hours of mild hypercapnia (target partial pressure of arterial carbon dioxide [Paco₂], 50 to 55 mm Hg) or normocapnia (target Paco₂, 35 to 45 mm Hg). The primary outcome was a favorable neurologic outcome, defined as a score of 5 (indicating lower moderate disability) or higher, as assessed with the use of the Glasgow Outcome Scale-Extended (range, 1 [death] to 8, with higher scores indicating better neurologic outcome) at 6 months. Secondary outcomes included death within 6 months.

RESULTS

A total of 1700 patients from 63 ICUs in 17 countries were recruited, with 847 patients assigned to targeted mild hypercapnia and 853 to targeted normocapnia. A favorable neurologic outcome at 6 months occurred in 332 of 764 patients (43.5%) in the mild hypercapnia group and in 350 of 784 (44.6%) in the normocapnia group (relative risk, 0.98; 95% confidence interval [CI], 0.87 to 1.11; P = 0.76). Death within 6 months after randomization occurred in 393 of 816 patients (48.2%) in the mild hypercapnia group and in 382 of 832 (45.9%) in the normocapnia group (relative risk, 1.05; 95% CI, 0.94 to 1.16). The incidence of adverse events did not differ significantly between groups.

CONCLUSIONS

In patients with coma who were resuscitated after out-of-hospital cardiac arrest, targeted mild hypercapnia did not lead to better neurologic outcomes at 6 months than targeted normocapnia. (Funded by the National Health and Medical Research Council of Australia and others; TAME ClinicalTrials.gov number, NCT03114033.).

Accuracy of non-invasive body temperature measurement methods in critically ill patients: a prospective, bicentric, observational study

Objective: The accuracy of different non-invasive body temperature measurement methods in intensive care unit (ICU) patients is uncertain. We aimed to study the accuracy of three commonly used methods. Design: Prospective observational study. Setting: ICUs of two tertiary Australian hospitals. Participants: Critically ill patients admitted to the ICU. Interventions: Invasive (intravascular and intra-urinary bladder catheter) and non-invasive (axillary chemical dot, tympanic infrared, and temporal scanner) body temperature measurements were taken at study inclusion and every 4 hours for the following 72 hours. Main outcome measures: Accuracy of non-invasive body temperature measurement methods was assessed by the Bland-Altman approach, accounting for repeated measurements and significant explanatory variables that were identified by regression analysis. Clinical adequacy was set at limits of agreement (LoA) of 1°C compared with core temperature. Results: We studied 50 consecutive critically ill patients who were mainly admitted to the ICU after cardiac surgery. From over 375 observations, invasive core temperature (mostly pulmonary artery catheter) ranged from 33.9°C to 39°C. On average, the LoA between invasive and non-invasive measurements methods were about 3°C. The temporal scanner showed the worst performance in estimating core temperature (bias, 0.66°C; LoA, -1.23°C, +2.55°C), followed by tympanic infrared (bias, 0.44°C; LoA, -1.73°C, +2.61°C) and axillary chemical dot methods (bias, 0.32°C; LoA, -1.64°C, +2.28°C). No methods achieved clinical adequacy even accounting for significant explanatory variables. Conclusions: The axillary chemical dot, tympanic infrared and temporal scanner methods are inaccurate measures of core temperature in ICU patients. These non-invasive methods appeared unreliable for use in ICU patients.

Cytokine and lipid metabolome effects of low-dose acetylsalicylic acid in critically ill patients with systemic inflammation: a pilot, feasibility, multicentre, randomised, placebo-controlled trial

OBJECTIVE

The systemic inflammatory response syndrome (SIRS) is a dysregulated response that contributes to critical illness. Adjunctive acetylsalicylic acid (ASA) treatment may offer beneficial effects by increasing the synthesis of specialised proresolving mediators (a subset of polyunsaturated fatty acid-derived lipid mediators).

DESIGN

Pilot, feasibility, multicentre, double-blind, randomised, placebo-controlled trial.

SETTING

Four interdisciplinary intensive care units (ICUs) in Australia.

PARTICIPANTS

Critically ill patients with SIRS.

INTERVENTIONS

ASA 100 mg 12-hourly or placebo, administered within 24 hours of ICU admission and continued until ICU day 7, discharge or death, whichever came first.

MAIN OUTCOME MEASURES

Interleukin-6 (IL-6) serum concentration at 48 hours after randomisation and, in a prespecified subgroup of patients, serum lipid mediator concentrations measured by mass spectrometry.

RESULTS

The trial was discontinued in December 2017 due to slow recruitment and after the inclusion of 48 patients. Compared with placebo, ASA did not decrease IL-6 serum concentration at 48 hours. In the 32 patients with analysis of lipid mediators, low-dose ASA increased the concentration of 15-hydroxyeicosatetraenoic acid, a proresolving precursor of lipoxin A4, and reduced the concentration of the proinflammatory cytochrome P-dependent mediators 17-HETE (hydroxyeicosatetraenoic acid), 18-HETE and 20-HETE. In the eicosapentaenoic acid pathway, ASA significantly increased the concentration of the anti-inflammatory mediators 17,18-DiHETE (dihydroxyeicosatetraenoic acid) and 14,15-DiHETE.

CONCLUSIONS

In ICU patients with SIRS, low-dose ASA did not significantly alter serum IL-6 concentrations, but it did affect plasma concentrations of certain lipid mediators. The ability to measure lipid mediators in clinical samples and to monitor the effect of ASA on their levels unlocks a potential area of biological investigation in critical care.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN 12614001165673).

Cytokine and lipid metabolome effects of low-dose acetylsalicylic acid in critically ill patients with systemic inflammation: a pilot, feasibility, multicentre, randomised, placebo-controlled trial

OBJECTIVE

The systemic inflammatory response syndrome (SIRS) is a dysregulated response that contributes to critical illness. Adjunctive acetylsalicylic acid (ASA) treatment may offer beneficial effects by increasing the synthesis of specialised proresolving mediators (a subset of polyunsaturated fatty acid-derived lipid mediators).

DESIGN

Pilot, feasibility, multicentre, double-blind, randomised, placebo-controlled trial.

SETTING

Four interdisciplinary intensive care units (ICUs) in Australia.

PARTICIPANTS

Critically ill patients with SIRS.

INTERVENTIONS

ASA 100 mg 12-hourly or placebo, administered within 24 hours of ICU admission and continued until ICU day 7, discharge or death, whichever came first.

MAIN OUTCOME MEASURES

Interleukin-6 (IL-6) serum concentration at 48 hours after randomisation and, in a prespecified subgroup of patients, serum lipid mediator concentrations measured by mass spectrometry.

RESULTS

The trial was discontinued in December 2017 due to slow recruitment and after the inclusion of 48 patients. Compared with placebo, ASA did not decrease IL-6 serum concentration at 48 hours. In the 32 patients with analysis of lipid mediators, low-dose ASA increased the concentration of 15-hydroxyeicosatetraenoic acid, a proresolving precursor of lipoxin A4, and reduced the concentration of the proinflammatory cytochrome P-dependent mediators 17-HETE (hydroxyeicosatetraenoic acid), 18-HETE and 20-HETE. In the eicosapentaenoic acid pathway, ASA significantly increased the concentration of the anti-inflammatory mediators 17,18-DiHETE (dihydroxyeicosatetraenoic acid) and 14,15-DiHETE.

CONCLUSIONS

In ICU patients with SIRS, low-dose ASA did not significantly alter serum IL-6 concentrations, but it did affect plasma concentrations of certain lipid mediators. The ability to measure lipid mediators in clinical samples and to monitor the effect of ASA on their levels unlocks a potential area of biological investigation in critical care.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN 12614001165673).

The effect of dexmedetomidine on vasopressor requirements in patients with septic shock: a subgroup analysis of the Sedation Practice in Intensive Care Evaluation [SPICE III] Trial

BACKGROUND

Septic shock is associated with decreased vasopressor responsiveness. Experimental data suggest that central alpha2-agonists like dexmedetomidine (DEX) increase vasopressor responsiveness and reduce catecholamine requirements in septic shock. However, DEX may also cause hypotension and bradycardia. Thus, it remains unclear whether DEX is hemodynamically safe or helpful in this setting.

METHODS

In this post hoc subgroup analysis of the Sedation Practice in Intensive Care Evaluation (SPICE III) trial, an international randomized trial comparing early sedation with dexmedetomidine to usual care in critically patients receiving mechanical ventilation, we studied patients with septic shock admitted to two tertiary ICUs in Australia and Switzerland. The primary outcome was vasopressor requirements in the first 48 h after randomization, expressed as noradrenaline equivalent dose (NEq [μg/kg/min] = noradrenaline + adrenaline + vasopressin/0.4).

RESULTS

Between November 2013 and February 2018, 417 patients were recruited into the SPICE III trial at both sites. Eighty-three patients with septic shock were included in this subgroup analysis. Of these, 44 (53%) received DEX and 39 (47%) usual care. Vasopressor requirements in the first 48 h were similar between the two groups. Median NEq dose was 0.03 [0.01, 0.07] μg/kg/min in the DEX group and 0.04 [0.01, 0.16] μg/kg/min in the usual care group (p = 0.17). However, patients in the DEX group had a lower NEq/MAP ratio, indicating lower vasopressor requirements to maintain the target MAP. Moreover, on adjusted multivariable analysis, higher dexmedetomidine dose was associated with a lower NEq/MAP ratio.

CONCLUSIONS

In critically ill patients with septic shock, patients in the DEX group received similar vasopressor doses in the first 48 h compared to the usual care group. On multivariable adjusted analysis, dexmedetomidine appeared to be associated with lower vasopressor requirements to maintain the target MAP.

TRIAL REGISTRATION

The SPICE III trial was registered at ClinicalTrials.gov ( NCT01728558 ).

Continuous Magnesium Infusion to Prevent Atrial Fibrillation After Cardiac Surgery: A Sequential Matched Case-Controlled Pilot Study

OBJECTIVE

The authors aimed to test whether a bolus of magnesium followed by continuous intravenous infusion might prevent the development of atrial fibrillation (AF) after cardiac surgery.

DESIGN

Sequential, matched, case-controlled pilot study.

SETTING

Tertiary university hospital.

PARTICIPANTS

Matched cohort of 99 patients before and intervention cohort of 99 consecutive patients after the introduction of a continuous magnesium infusion protocol.

INTERVENTIONS

The magnesium infusion protocol consisted of a 10 mmol loading dose of magnesium sulphate followed by a continuous infusion of 3 mmol/h over a maximum duration of 96 hours or until intensive care unit discharge.

MEASUREMENTS AND MAIN RESULTS

The study groups were balanced except for a lower cardiac index in the intervention cohort. The mean duration of magnesium infusion was 27.93 hours (95% confidence interval [CI]: 24.10-31.76 hours). The intervention group had greater serum peak magnesium levels: 1.72 mmol/L ± 0.34 on day 1, 1.32 ± 0.36 on day 2 versus 1.01 ± 1.14 and 0.97 ± 0.13, respectively, in the control group (p < 0.01). Atrial fibrillation occurred in 25 patients (25.3%) in the intervention group and 40 patients (40.4%) in the control group (odds ratio 0.49, 95% CI, 0.27-0.92; p = 0.023). On a multivariate Cox proportional hazards model, the hazard ratio for the development of AF was significantly less in the intervention group (hazard ratio 0.45, 95% CI, 0.26-0.77; p = 0.004).

CONCLUSION

The magnesium delivery strategy was associated with a decreased incidence of postoperative AF in cardiac surgery patients. These findings provide a rationale and preliminary data for the design of future randomized controlled trials.

9 The ‘Colchester Older Persons’ Evaluation for Surgery (COPES)’ Clinic: A Multidisciplinary Approach to Preoperative Management of Frail, Older Patients

Introduction

In 2014-15, 2.5 million patients over 75 years old underwent surgery compared to 1.5 million in 2006-7. The population is aging with increasing numbers of comorbidities, and associated frailty.1 The Royal College of Anaesthetists recommends that preoperative assessment for these complex older patients takes a “cross-specialty approach.”2 In Colchester the COPES clinic has been introduced in which selected high-risk patients are seen by a Consultant Anaesthetist and Consultant Geriatrician. This aims to medically optimise patients prior to surgery and to facilitate shared decision making.

Methods

The new clinic was introduced in October 2018. The following data was collected from COPES clinic letters from October to February 2018-19 (n=46):Patient/ surgery characteristics: age, comorbidities, frailty score and any cognitive impairmentInterventions: changes to medication, specialty referral, intravenous iron, diabetes optimisation, otherOutcomes of surgery following the COPES clinic

Patients were asked to complete feedback forms to evaluate the service.

Results

52% of patients had 4-6, and 28% had 7-9 comorbidities. The majority had Rockwood frailty scores of 4 or 5. 28% of patients had medications changed, 48% had specialty referrals, 17% received intravenous iron, 8.7% required diabetes optimisation and 28% of patients had investigations including echocardiograms, MRI and CT scans. 12/46 patients had surgery deemed unlikely to go ahead after shared decision making with patients in conjunction with the multidisciplinary team involved in their care. 2 patients died of their comorbidities after deciding not to proceed with surgery. 12/46 patients underwent surgery; 4 developed post-operative complications, none died and the mean length of stay was 3.38 days. The remaining 22/46 patients are awaiting surgery. Patient feedback questionnaires (n=10) were overwhelmingly positive. Everyone felt that they were treated with respect and that their fears were addressed and they were clear in the next steps in management.

Conclusions

The introduction of the ‘COPES’ clinic has helped address frailty and multiple comorbidities by optimising patients’ medical conditions and allowing alternatives to surgery to be considered. Patients were very satisfied with the COPES clinic and felt it has prepared them for upcoming surgery.

References

1. Lin H. Frailty and post-operative outcomes in older surgical patients: a systematic review. BMC Geriatrics, 2016.

2. RCoA. Guidelines for the Provision of Anaesthesia Services. www.pre-op.org/sites/default/files/GPAS%202016.pdf

Hospital-acquired complications in intensive care unit patients with diabetes: A before-and-after study of a conventional versus liberal glucose control protocol

BACKGROUND

Critically ill patients with diabetes mellitus (DM) are at increased risk of in-hospital complications and the optimal glycemic target for such patients remains unclear. A more liberal approach to glucose control has recently been suggested for patients with DM, but uncertainty remains regarding its impact on complications.

METHODS

We aimed to test the hypothesis that complications would be more common with a liberal glycemic target in ICU patients with DM. Thus, we compared hospital-acquired complications in the first 400 critically ill patients with DM included in a sequential before-and-after trial of liberal (glucose target: 10-14 mmol/L) vs conventional (glucose target: 6-10 mmol/L) glucose control.

RESULTS

Of the 400 patients studied, 165 (82.5%) patients in the liberal and 177 (88.5%) in the conventional-control group were coded for at least one hospital-acquired complication (P = 0.09). When comparing clinically relevant complications diagnosed between ICU admission and hospital discharge, we found no difference in the odds for infectious (adjusted odds ratio [aOR] for liberal-control: 1.15 [95% CI: 0.68-1.96], P = 0.60), cardiovascular (aOR 1.40 [95% CI: 0.63-3.12], P = 0.41) or neurological complications (aOR: 1.07 [95% CI: 0.61-1.86], P = 0.81), acute kidney injury (aOR 0.83 [95% CI: 0.43-1.58], P = 0.56) or hospital mortality (aOR: 1.09 [95% CI: 0.59-2.02], P = 0.77) between the liberal and the conventional-control group.

CONCLUSION

In this prospective before-and-after study, liberal glucose control was not associated with an increased risk of hospital-acquired infectious, cardiovascular, renal or neurological complications in critically ill patients with diabetes.

Sepsis uncouples serum C-peptide and insulin levels in critically ill patients with type 2 diabetes mellitus

OBJECTIVE

To assess the effects of sepsis and exogenous insulin on C-peptide levels and C-peptide to insulin ratios in intensive care unit (ICU) patients with type 2 diabetes mellitus (T2DM).

DESIGN, SETTING AND PARTICIPANTS

In this prospective, observational, single-centre study, we enrolled 31 ICU-admitted adults with T2DM. We measured serum C-peptide and insulin levels during the first 3 days of ICU stay and recorded characteristics of exogenous insulin therapy. Patients were compared on the basis of the presence of sepsis, and their exposure to exogenous insulin therapy. C-peptide levels were also measured in eight healthy subjects.

MAIN OUTCOME MEASURES

Serum insulin and C-peptide levels during the first 3 days in ICU.

RESULTS

Median C-peptide levels were higher in the ICU population compared with healthy subjects (10.9 [IQR, 8.2 -14.1] v 4.8 [IQR, 4.6-5.1] nmol/L, P < 0.01). Sepsis was present in 25 ICU patients (81%). Among ICU patients unexposed to exogenous insulin, the 11 patients with sepsis had higher median C-peptide levels compared with the six non-septic patients (2.5 [IQR, 1.8-3.7] v 1.7 [IQR, 0.8-2.2] nmol/L, P = 0.04), and a threefold higher C-peptide to insulin ratio (45 [IQR, 37-62] v 13 [IQR, 11-17], P = 0.03). However, septic patients exposed to exogenous insulin had lower median C-peptide levels (1.2 [IQR, 0.7-2.3] nmol/L, P = 0.01) and C-peptide to insulin ratios (5 [IQR, 2-10], P < 0.01) compared with insulin-free septic patients. The C-peptide to insulin ratio was significantly associated with white cell count and severity of illness in insulin-free septic patients.

CONCLUSION

C-peptide levels were elevated in critically ill patients with T2DM. In this population, sepsis increased C-peptide levels and uncoupled serum C-peptide and insulin levels. Exogenous insulin decreased both C-peptide levels and C-peptide to insulin ratios.

Conservative versus conventional oxygen therapy for cardiac surgical patients: A before-and-after study

Avoiding hypoxaemia is considered crucial in cardiac surgery patients admitted to the intensive care unit (ICU). However, avoiding hyperoxaemia may also be important. A conservative approach to oxygen therapy may reduce exposure to hyperoxaemia without increasing the risk of hypoxaemia. Using a before-and-after design, we evaluated the introduction of conservative oxygen therapy (target SpO₂ 88%-92% using the lowest FiO₂) for cardiac surgical patients admitted to the ICU. We studied 9041 arterial blood gas (ABG) datasets: 4298 ABGs from 245 'conventional' and 4743 ABGs from 298 'conservative' oxygen therapy patients. During mechanical ventilation (MV) and while in the ICU, compared to the conventional group, conservative group patients had significantly lower FiO₂ exposure and PaO₂ values ( P < 0.001 for each). Accordingly, using the mean PaO₂ during MV, more conservative group patients were classified as normoxaemic (226 versus 62 patients, P < 0.01), fewer as hyperoxaemic (66 versus 178 patients, P < 0.01) and no patient in either group as hypoxaemic or severely hypoxaemic. Moreover, more ABG samples were hyperoxaemic or severely hyperoxaemic during conventional treatment ( P < 0.001). Finally, there was no difference in ICU or hospital length of stay, ICU or hospital mortality or 30-day mortality between the groups. Our findings support the feasibility and physiological safety of conservative oxygen therapy in patients admitted to ICU after cardiac surgery.

Rapid response team review of hemodynamically unstable ward patients: The accuracy of cardiac index assessment

PURPOSE

Intensive care doctors commonly attend rapid response team (RRT) reviews of hospital-ward patients with hemodynamic instability and estimate the patient's likely cardiac index (CI). We aimed to non-invasively measure the CI of such patients and assess the level of agreement between such measurements and clinically estimated CI categories (low <2L/min/m2, normal 2-2.99L/min/m2 or high ≥3L/min/m2).

MATERIALS AND METHODS

A prospective, observational study of non-invasive measurement and clinical estimation of CI categories in 50 adult hospital-ward patients who activated the RRT for 'hemodynamic instability' (tachycardia > 100BPM or hypotension < 90mmHg or both).

RESULTS

The CI was measured in 47/50(94%) patients and the mean CI was 3.5(95% CI 3.2-3.7) L/min/m2. Overall, 30(64%) patients had a high CI, 13(28%) and 4(9%) had a normal and a low CI, respectively. The level of agreement between measured and clinically estimated CI categories was low(19.2%). Sensitivity and positive predictive values of clinical estimation were low(0% and 3.3% for high CI, and 0% and 50% for low CI, respectively).

CONCLUSIONS

Non-invasive CI measurement was possible in almost all hospital-ward patients triggering RRT review for hemodynamic instability. In such patients, the CI was high, and intensive care clinicians were unable to identify a low or a high CI state.

Intravenous fluid bolus therapy: a bi-national survey of critical care nurses' self-reported practice

Knowledge of critical care nurses' intravenous fluid bolus therapy (FBT) practice remains underexplored. Using a multi-choice online survey conducted between September and October 2014, we sought to describe the self-reported practice of critical care nurses located in Australia and New Zealand. Two hundred and ninety-five critical care nurses responded to the survey with most practising in adult ICUs. Overall, 0.9% saline solution was the preferred solution for FBT. However, more Australian than New Zealand respondents preferred 'albumin 4%' (31% versus 3.6%, P <0.01) for FBT. In contrast, more New Zealand respondents preferred 'Plasma-Lyte®' (33.3% versus 6.4%, P <0.01). Half of the respondents defined FBT as 250 ml administered as quickly as possible. However, FBT volumes ranged from 100 ml to >1000 ml and administration duration from as quickly as possible to 60 minutes. In response to FBT, almost half of the respondents expected an increase in mean arterial pressure of between 11 to 20 mmHg. Similarly, >40% expected a central venous pressure increase >3 mmHg, >70% expected a urinary output increase of 0.5 to 1.0 ml/kg/hr, and >60% expected a decrease in heart rate of >11 /min. Overall, 0.9% saline remains the most common solution for FBT, but there are significant national differences in the preference for albumin and Plasma-Lyte. A volume of 250 ml defines a fluid bolus, with a range from 100 ml to >1000 ml, and speed of delivery from stat to 60 minutes. Most nurses expect substantial physiological effects with FBT.

Urinary neutrophil gelatinase-associated lipocalin to hepcidin ratio as a biomarker of acute kidney injury in intensive care unit patients

BACKGROUND

Labile iron is important in the pathogenesis of acute kidney injury (AKI). Neutrophil gelatinase-associated lipocalin (NGAL) and hepcidin control iron metabolism and are upregulated during renal stress. However, higher levels of urinary NGAL are associated with AKI severity whereas higher urinary hepcidin levels are associated with absence of AKI. We aimed to investigate the value of combining both biomarkers to estimate the severity and progression of AKI in intensive care unit (ICU) patients.

METHODS

Urinary NGAL and hepcidin were quantified within 48 hours of ICU admission in patients with the systemic inflammatory response syndrome and early kidney dysfunction (oliguria for ≥ 2 hours and/or a 25 µmol/L creatinine rise from baseline). Diagnostic and prognostic characteristics were assessed by logistic regression and receiver operating characteristics (ROC) analysis.

RESULTS

Of 102 patients, 26 had mild AKI and 28 patients had severe AKI on admission. Sepsis (21%), cardiac surgery (17%) and liver failure (9%) were primary admission diagnoses. NGAL increased (P=0.03) whereas hepcidin decreased (P=0.01) with increasing AKI severity. The value of NGAL/hepcidin ratio to detect severe AKI was higher than when NGAL and hepcidin were used individually and persisted after adjusting for potential confounders (adjusted OR 2.40, 95% CI 1.20-4.78). The ROC areas for predicting worsening AKI were 0.50, 0.52 and 0.48 for NGAL, 1/hepcidin and the NGAL/hepcidin ratio.

CONCLUSION

The NGAL/hepcidin ratio is more strongly associated with severe AKI than the single biomarkers alone. NGAL and hepcidin, alone or combined as a ratio, were unable to predict progressive AKI in this selected ICU cohort.

Intensive care nurses' self-reported practice of intravenous fluid bolus therapy

OBJECTIVE

To describe self-reported practice of fluid bolus therapy by intensive care nurses.

RESEARCH METHODOLOGY

Multi-choice questionnaire of intensive care nurses conducted in July, 2014.

SETTING

Major university tertiary referral centre.

FINDINGS

141 (64%) intensive care nurses responded. The majority of respondents identified 4% albumin as the commonest fluid bolus type and stated a fluid bolus was 250ml; however fluid bolus volume varied from 100ml to 1000ml. Hypotension was identified as the primary physiological trigger for a fluid bolus. In the hour following a fluid bolus for hypotension almost half of respondents expected an 'increase in mean arterial pressure of 0-10mmHg'; for oliguria, >60% expected an 'increase in urinary output of '0.5-1ml/kg/hour'; for low CVP, 50% expected 'an increase in CVP of 3-4mmHg'; and, for tachycardia, 45% expected a 'decrease in heart rate of 11-20beats/minute'. Finally, 7-10% of respondents were 'unsure' about the physiological response to a fluid bolus.

CONCLUSION

Most respondents identified fluid bolus therapy to be at least 250ml of 4% albumin given as quickly as possible; however, volumes from 100 to 1000ml were also accepted. There was much uncertainty about the expected physiological response to fluid bolus therapy according to indication.

Bioelectrical impedance vector analysis in critically ill patients: a prospective, clinician-blinded investigation

Introduction

Assessment of fluid status in critically ill patients is challenging. We aimed to assess the feasibility and validity of bioelectrical impedance vector analysis (BIVA) as a measure of hydration in critically ill patients.

Methods

We performed twice-daily BIVA measurements and fluid balance calculations and recorded physiological variables in mechanically ventilated patients within 24 h of intensive care unit (ICU) admission for up to 5 days. Treating clinicians were blinded to BIVA results.

Results

We performed 344 BIVA measurements in 61 patients. According to BIVA, 14 patients (23 %) were dehydrated, 22 (36 %) were normally hydrated and 25 (41 %) were overhydrated upon ICU admission. Patients with normal BIVA hydration were less sick, had fewer comorbidities and had less deranged physiology than patients found to be dehydrated or overhydrated with BIVA. Cumulative fluid balance increased in patients found to be dehydrated with BIVA by a mean of 3.4±2.2 L, whereas in patients found to be overhydrated with BIVA, it decreased by a mean of 4.5±6.9 L. In patients found to be normally hydrated with BIVA, fluid balance remained unchanged. BIVA-defined hydration increased with 1 L (median change 1.5 %, P =0.09) or 2 L (median change 0.7 %, P =0.09) of calculated fluid gains. BIVA-defined hydration decreased (median change −0.8 %, P =0.02) with a negative cumulative fluid balance of >2 L. BIVA-defined hydration between first and last measurement correlated with the corresponding change in fluid balance (ρ =0.25, P =0.05).

Conclusions

BIVA is feasible in critically ill patients. Its validity is supported by the observed characteristics of patients with different degrees of BIVA hydration upon admission and by different fluid management of such patients by blinded clinicians. The sensitivity of repeated BIVA hydration measurements to detect fluid accumulation or fluid balance changes <2 L was low, however. These contradictory findings provide the rational basis for studies of BIVA-assisted fluid management in ICU patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1009-3) contains supplementary material, which is available to authorized users.

Neutrophil gelatinase-associated lipocalin after off pump versus on pump coronary artery surgery

CONTEXT

Cardiac surgery.

OBJECTIVE

To compare plasma and urinary neutrophil gelatinase-associated lipocalin (P-/U-NGAL) in on-pump (n = 43) versus off-pump (n = 40) surgery.

MATERIALS AND METHODS

We obtained perioperative P-/U-NGAL and outcome data.

RESULTS

P-/U-NGAL increased after surgery. P-NGAL was higher post-surgery in on pump patients (139 versus 67 µg L(-1); p < 0.001), but not at 24 h. There were no differences in U-NGAL. Correlation between P-/U-NGAL and plasma creatinine was weak.

DISCUSSION

P-NGAL acts like a neutrophil activation biomarker and U-NGAL like a tubular injury marker.

CONCLUSION

On-pump patients had greater neutrophil activation. On- versus off-pump surgery had similar impact on tubular cells.

Extended normothermic extracorporeal perfusion of isolated human liver after warm ischaemia: a preliminary report

BACKGROUND

Donation after circulatory death (DCD) livers are at markedly increased risk of primary graft dysfunction and biliary tract ischaemia. Normothermic extracorporeal liver perfusion (NELP) may increase the ability to transplant DCD livers and may allow their use for artificial extracorporeal liver support of patients with fulminant liver failure.

OBJECTIVE

We conducted two proof-of-concept experiments using human livers after DCD to assess the feasibility and functional efficacy of NELP over an extended period.

METHODS

We applied extracorporeal membrane oxygenation, parenteral nutrition, separate hepatic artery and portal vein perfusion and physiological perfusion pressures to two livers obtained after DCD.

RESULTS

We achieved NELP and evidence of liver function (bile production, paracetamol removal and maintenance of normal lactate levels) in both livers; one for 24 hours and the other for 43 hours. Histological examination showed areas of patchy ischaemia but preserved biliary ducts and canaliculi.

CONCLUSIONS

Our experiments justify further investigations of the feasibility and efficacy of extended DCD liver preservation by ex-vivo perfusion.

High cut-off hemofiltration versus standard hemofiltration: a pilot assessment of effects on indices of apoptosis

OBJECTIVES

To measure plasma pro-apoptotic and pro-necrotic activity in severe acute kidney injury (AKI) patients within a randomized controlled trial of continuous veno-venous hemofiltration with high cut-off filters (CVVH-HCO) versus standard filters (CVVH-Std).

METHODS

We measured pro-apoptotic and pro-necrotic plasma activity by trypan blue exclusion cell viability assay, detection of DNA fragmentation, and by determination of caspase-3 activity and annexin V-based apoptosis and necrosis detection assay.

RESULTS

Compared to no apoptosis or necrosis after incubation with healthy plasma, 14-18% of cells showed apoptosis and 4-8% showed necrosis after incubation with plasma from AKI patients. When comparing different measures of pro-apoptotic or pro-necrotic activity, CVVH-HCO and CVVH-Std showed no differential effects on such activity, which remained high over the first 3 days of treatment. However, using annexin V-FITC, there was a significant drop in pro-apoptotic activity across the filter for the CVVH-HCO group (p = 0.043) but not for the CVVH-Std group (p = 0.327) and a significant difference between the two groups (CVVH-HCO vs. CVVH-Std p = 0.006).

CONCLUSIONS

Patients with severe AKI have increased pro-apoptotic and pro-necrotic activity. Although on single-pass effect assessment, CVVH-HCO was superior to CVVH-Std in decreasing annexin V-FITC-assessed pro-apoptotic activity, there was no overall attenuation of such activity during the first 3 days of treatment.

Intensive care clinicians' opinion of conservative oxygen therapy (SpO₂ 90-92%) for mechanically ventilated patients

BACKGROUND

In the ICU, SpO2≥96% are regularly targeted implying that more oxygen may be given than desirable. To reduce exposure to hyperoxia a conservative oxygen therapy protocol (targeted SpO2 90-92% using lowest FiO2) for mechanically ventilated patients was introduced in a single tertiary ICU in September 2012.

OBJECTIVES

To describe intensive care clinicians' opinion of conservative oxygen therapy for mechanically ventilated adult patients.

METHODS

A structured multi-choice questionnaire of intensive care clinicians was conducted between February and March 2013.

RESULTS

Responses were received from 90 staff members: 81 intensive care nurses and 9 medical doctors. A majority of respondents (60.7%) considered oxygen related lung injury as 'a major concern'. Most respondents (81/89; 91.1%) felt conservative oxygen therapy was easy to perform and few respondents (6/88; 8%) considered performing conservative oxygen therapy to be stressful. Most respondents (58%) reported not performing more arterial blood gases to monitor PaO2 during conservative oxygen therapy and 90% (81/90) of respondents indicated a desire to continue conservative oxygen therapy. Free text comments indicated adoption of this protocol was a paradigm shift yet more education and research to elucidate the benefits/harm of lower oxygen saturation targeting is needed.

CONCLUSIONS

Intensive care clinicians readily accepted the introduction of a conservative oxygen therapy protocol into their practice. Most respondents found conservative oxygen therapy easy and not stressful to perform. Further evaluation the administration of oxygen therapy, its management by intensive care clinicians and possible impact on outcome for mechanically ventilated patients appears well accepted by clinical staff.

The nature and discriminatory value of urinary neutrophil gelatinase-associated lipocalin in critically ill patients at risk of acute kidney injury

BACKGROUND

Different molecular forms of urinary neutrophil gelatinase-associated lipocalin (NGAL) have recently been discovered. We aimed to explore the nature, source and discriminatory value of urinary NGAL in intensive care unit (ICU) patients.

METHODS

We simultaneously measured plasma NGAL (pNGAL), urinary NGAL (uNGAL), and estimated monomeric and homodimeric uNGAL contribution using Western blotting-validated enzyme-linked immunosorbent assays [uNGAL(E1) and uNGAL(E2)] and their calculated ratio in 102 patients with the systemic inflammatory response syndrome and oliguria, and/or a creatinine rise of >25 μmol/L.

MEASUREMENTS AND MAIN RESULTS

Bland-Altman analysis demonstrated that, despite correlating well (r = 0.988), uNGAL and uNGAL(E1) were clinically distinct, lacking both accuracy and precision (bias: 266.23; 95% CI 82.03-450.44 ng/mg creatinine; limits of agreement: -1,573.86 to 2,106.32 ng/mg creatinine). At best, urinary forms of NGAL are fair (area under the receiver operating characteristic [AUROC] ≤0.799) predictors of renal or patient outcome; most perform significantly worse. The 44 patients with a primarily monomeric source of uNGAL had higher pNGAL (118.5 ng/ml vs. 72.5 ng/ml; p < 0.001), remaining significant following Bonferroni correction.

CONCLUSIONS

uNGAL is not a useful predictor of outcome in this ICU population. uNGAL patterns may predict distinct clinical phenotypes. The nature and source of uNGAL are complex and challenge the utility of NGAL as a uniform biomarker.

Safety evaluation of a trial of lipocalin-directed sodium bicarbonate infusion for renal protection in at-risk critically ill patients

BACKGROUND

Urine alkalinisation with sodium bicarbonate decreases renal oxidative stress and might attenuate sepsisassociated acute kidney injury (s-AKI). The safety and feasibility of urine alkalinisation in patients at risk of s-AKI has never been tested.

METHODS

We randomly assigned patients at risk of s-AKI (those with systemic inflammatory response syndrome [SIRS], oliguria and elevated [≥150 µg/L] serum neutrophil gelatinase-associated lipocalin [sNGAL] concentration) to receive sodium bicarbonate (treatment group) or sodium chloride (placebo group) in a 0.5 mmol/kg bolus followed by an infusion of 0.2 mmol/kg/hour.

RESULTS

Among 50 patients with SIRS and oliguria, 25 (50%) had an elevated sNGAL concentration. Of these, 13 were randomised to receive sodium bicarbonate and 12 to receive sodium chloride infusion. Study drugs were infused for a mean period of 25.9 hours (SD, 10 hours). Severe electrolyte abnormalities occurred in seven patients (28%) (four [30.8%] in the treatment group and three [25%] in the placebo group). These abnormalities resulted in early protocol cessation in six patients (24%) and study drug suspension in one patient (4%). This adverse event rate was judged to be unacceptable and the study was terminated early. There was no difference between the two groups in sNGAL or urinary NGAL concentrations over time, occurrence of acute kidney injury, requirement for renal replacement therapy, hospital length-of-stay or mortality.

CONCLUSION

Administration of sodium bicarbonate and sodium chloride solutions to patients at risk of s-AKI was associated with frequent major electrolyte abnormalities and early protocol cessation. The tested protocol does not appear safe or feasible.

A questionnaire survey of critical care nurses' attitudes to delirium assessment before and after introduction of the CAM-ICU

BACKGROUND

Nurses are usually the first to identify delirium in ICU patients. We aimed to assess the attitudes of Australian critical care nurses when we introduced the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU).

METHODS

We surveyed all 174 nurses in our ICU using two questionnaires: first after a one-month period of mandated but unstructured delirium assessments, and then following one month of CAM-ICU assessments. We also quantified antipsychotic medication usage by inspecting pharmacy records.

FINDINGS

The first survey response rate was 65/174 (37%). Most nurses (73%) thought active delirium assessment was important, and 93% thought their assessments were worth the time required. These assessments were largely unstructured, as only 20% knew a formal delirium test, and only 7% sometimes used one. The second survey response rate was 45/174 (26%). Most (89%) still thought delirium assessment was important, but only 75% thought the CAM-ICU worth the time required (p=0.01 compared to unstructured assessments). Similar proportions (75% and 73%) were confident in the accuracy of their assessments. Many (33%) found the CAM-ICU 'quite' or 'very' hard to perform, but despite this, 82% wanted to continue to use it. Free-text answers suggested this was because medical staff paid more attention to the CAM-ICU. Supporting this, prescriptions of antipsychotic medications increased significantly in the CAM-ICU period.

CONCLUSION

Critical care nurses in our Australian ICU who responded to our survey think delirium assessment is important. Although they find unstructured assessments easier to perform, they wanted to persist with the CAM-ICU, in part because it facilitated more appropriate pharmacological treatment of delirium for their patients. We recommend the CAM-ICU as a tool to improve communication between nurses and physicians in the management of delirium.

Routine use of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) by bedside nurses may underdiagnose delirium

BACKGROUND

The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) is emerging as the most frequently used tool for identifying delirium among critically ill patients.

OBJECTIVE

To determine whether the number of patients and nursing shifts in which delirium was diagnosed would increase after the introduction of the CAM-ICU in our unit.

DESIGN

Before-and-after study. In a 30-day Phase 1, we asked bedside nurses to assess their ICU patients for delirium each shift. We then conducted intensive education on the CAM-ICU for 30 days, including lectures, bedside tutorials, and supervised practice. In Phase 2, for 30 days we asked bedside nurses to record the results of their CAM-ICU assessments.

SETTING

20-bed mixed medical and surgical ICU at the Austin Hospital, Melbourne.

PARTICIPANTS

All patients admitted to the ICU during each phase.

MAIN OUTCOME MEASURES

Diagnosis of delirium by bedside nurses using either the CAM-ICU or an unstructured clinical assessment, by patient and nursing shift.

RESULTS

Compared with unstructured assessments, the CAM-ICU identified a significantly lower proportion of patients (36.7% v 21.3%; P = 0.004) and a significantly lower proportion of shifts (14.7% v 6.4% of shifts, P = 0.002) with delirium. When adjusted for differences in age, sex, Acute Physiology and Chronic Health Evaluation III risk of death and total length of stay between the two periods, assessment type remained a significant predictor of the diagnosis of delirium.

CONCLUSIONS

In our hospital, the CAM-ICU detected delirium less often than unstructured delirium assessments made by qualified intensive care nurses.

Critical care nurses' opinion and self-reported practice of oxygen therapy: a survey

BACKGROUND

Critical care nurses frequently and independently manage oxygen therapy. Despite the importance of oxygen therapy, there is limited evidence to inform or support critical care nurses' oxygen therapy practices.

AIM

To establish if there is variability in oxygen therapy practices of critical care nurses and examine the degree of variability.

METHOD

On-line questionnaire of ACCCN members between April and June 2010.

RESULTS

The response rate was 36% (542/1523 critical care nurses). Overall, 378 (70%) respondents practiced in metropolitan critical care units; 278 (51%) had ≥14 years of specialty practice. In response to falling SpO(2), 8.9% of nurses would never escalate oxygen therapy without a doctor's request, and 51% of nurses would not routinely escalate oxygen therapy in the absence of medical orders. Only 56% of nurses reported always increasing FiO(2) prior to endotracheal suctioning. In mechanically ventilated patients, 33% of nurses believed oxygen toxicity was a greater threat to lung injury than barotrauma. More than >60% of respondents reported a tolerance for a stable SpO(2) of 90%. Nurses in rural critical care units were less likely to independently titrate oxygen to their own target SpO(2), but more likely to independently treat a falling SpO(2) with higher FiO(2).

CONCLUSION

Critical care nurses varied in their self-reported oxygen therapy practices justifying observational and interventional studies aimed at improving oxygen therapy for critically ill patients.

Intensivists' opinion and self-reported practice of oxygen therapy

Intensivists frequently prescribe oxygen therapy for critically ill patients, however little is known about how intensivists manage oxygen therapy, or what factors influence their decisions. We surveyed intensivists listed on the Australian and New Zealand Intensive Care Society Clinical Trials Group database to investigate how intensivists report their approach to the monitoring, prescription and management of risks associated with oxygen therapy. The response rate was 60.4% (99/164 intensivists). Overall 81 (83.5%) respondents practised in metropolitan units and 50 (50.5%) had > or =14 years of intensive care unit specialty practice. All respondents reported using pulse oximetry and > 93% reported having access to a blood gas machine within their intensive care unit. Sixty-one percent of respondents (60/98) reported assessing other indices of tissue oxygenation (pH, lactate, MvO2). Twelve respondents (12.8%) believed that oxygen toxicity was a greater threat to lung injury than barotrauma when commencing mechanical ventilation. A significantly (P = 0.016) greater proportion of regional (5/16) than metropolitan (7/70) respondents were concerned that a high FiO2 is a greater threat to the lungs than barotrauma. For a ventilated acute respiratory distress syndrome patient, 36.8% (36/98 respondents) would not allow an SaO2 of < 85% for < or =15 minutes, and 27.6% (27/96 respondents) would not allow an SaO2 < 90% for > 24 hours. Respondents with < or = 14 years of specialty practice were more likely to specify the oxygen delivery device to be used (P = 0.014). Recognising the factors that currently influence oxygen administration decisions is a necessary prelude to the potential conduct of interventional studies, as well as for the development of better guidance for oxygen therapy in critical care.

Oxygen administration and monitoring for ward adult patients in a teaching hospital

AIM

The aims of this study were to describe oxygen administration and respiratory monitoring of ward patients in a tertiary teaching hospital, and to assess differences in characteristics and outcomes between patients who are receiving versus are not receiving oxygen.

METHODS

Prospective clinical audit of all non-ventilated adult ward patients in a tertiary teaching hospital in Melbourne, Victoria on 26 August 2009.

RESULTS

All 323 eligible patients were audited (medical 218, surgical 105). At assessment, 76 patients (24%) were on oxygen therapy and of these, 57 patients (74%) received oxygen by nasal prongs. Overall, oxygen saturation was documented in 301 (93.2%) patients and respiratory rate (RR) documented in 283 patients (87.6%). Patients receiving oxygen had a lower median SpO(2) (94% vs 96%, P < 0.0001), higher median RR (20/min vs 18/min, P < 0.0005); and were older (68.8 v 63.1 years, P= 0.0094). The in-hospital mortality of patients receiving oxygen therapy was 15.8% compared with 5.3% for those not on oxygen (P < 0.0056).

CONCLUSION

Oxygen is administered to one-quarter of ward patients in our hospital. Oxygen saturation and RR are not documented in approximately 10% of patients. Oxygen therapy in ward patients identifies individuals with increased mortality. Continuing educational interventions to increase awareness of the high-risk status of these patients and strategies to detect patients at risk of hypoxaemia are needed.

Barriers to targeted HIV testing on an acute admissions unit: evaluation of the UK guideline

BACKGROUND

One-quarter of people living with human immunodeficiency virus (HIV) in the UK are unaware of their infection, leading to late presentation with consequent increased morbidity and mortality, as well as ongoing transmission of infection. Recent UK guidelines advise HIV testing of patients with 'indicator diseases' in secondary care. There are limited seroprevalence data to support this recommendation, and acute medical settings present operational difficulties that may limit its feasibility.

METHODS

We conducted an audit of HIV testing rates over a 3-month period in an inner London acute admissions unit.

RESULTS

Lower respiratory tract infection and fever were the most frequent indicator diseases. A total of 14% were known to be HIV positive on admission, indicating a high prevalence of HIV infection among patients presenting with indicator diseases. Of the remaining 56 patients, 29% were tested for HIV infection, with one new positive diagnosis.

CONCLUSION

Longer hospital admission and infectious disease consult were associated with testing. Introduction of an HIV testing protocol based on the UK recommendations had no impact on testing rates. Given the high prevalence of HIV infection in these acute hospital settings, more intensive strategies are needed to facilitate testing.

Emergence of permanent teeth and dental age in a series of Finns

The emergence of permanent teeth was studied in 187 Finnish children who had longitudinal records of the emergence of all permanent teeth except third molars. Exact emergence dates were known for about one third of the teeth. Emergence ages of the remaining teeth were based on their presence and absence at clinical examinations. We calculated ages at clinical eruption of permanent teeth and tooth counts at half year intervals. Ages corresponding to counts of permanent teeth from 1 to 27 are also given. The schedules presented, which slow means, standard deviations, and percentage distributions, are expected to serve as useful references in clinical dentistry, pediatrics, forensics, and research. The mandibular central incisor emerged before the first molar of the same jaw in 68% of the children. A change in the emergence order of these teeth in Finns seems to have occurred in the 1960s. A visual comparison of dental maturity curves based on tooth counts with curves based on tooth mineralization in a previous Finnish radiographic study showed that the mean curves had roughly the same form, whereas the forms of standard deviation curves differed distinctly. It appears that the two methods to assess dental maturity are not interchangeable in practice. Tooth counts can be used in maturity estimations up to about 13 years of age, whereas the radiographic method works best to about 11 years.