Anaemia among intensive care unit survivors and association with days alive and at home: an observational study.

Anaemia is highly prevalent at the time of intensive care unit discharge and is persistent for a high proportion of intensive care unit survivors. Whether anaemia is a driver of impaired recovery after critical illness is uncertain. The aim of this study was to test the hypothesis that, in adult intensive care survivors, anaemia at the time of intensive care unit discharge independently predicts decreased days at home-90. This retrospective cohort study was conducted in a tertiary intensive care unit in Perth, Western Australia. All patients aged ≥ 16 years, discharged alive from their index intensive care unit admission and without documented treatment limitations were included. Median (IQR [range]) age of the 6358 participants was 61 (46-72 [16-95]) years and included 3385 (53.2%) unplanned admissions. Intensive care unit discharge with a haemoglobin concentration < 100 g.l-1 occurred in 2886 (45.4%) patients, a threshold that identified a cohort with significantly lower days at home-90 (median (IQR [range]) 80 (64-85 [0-90]) days vs. 85 (77-88 [0-90]) days (median difference 5 days, 95%CI 4.4-5.5, p < 0.0001). The association followed a severity-response relationship with more severe anaemia predicting lower days at home-90. When accounting for prespecified covariates including admission haemoglobin concentration and red blood cell transfusion, anaemia at intensive care unit discharge remained a significant predictor of decreased days at home-90, relative risk 0.96 (0.93-0.98), p < 0.002. These findings support the need for interventional trials investigating whether this risk is modifiable.

The feasibility and reliability of actigraphy to monitor sleep in intensive care patients: an observational study.

BACKGROUND: Sleep amongst intensive care patients is reduced and highly fragmented which may adversely impact on recovery. The current challenge for Intensive Care clinicians is identifying feasible and accurate assessments of sleep that can be widely implemented. The objective of this study was to investigate the feasibility and reliability of a minimally invasive sleep monitoring technique compared to the gold standard, polysomnography, for sleep monitoring. METHODS: Prospective observational study employing a within subject design in adult patients admitted to an Intensive Care Unit. Sleep monitoring was undertaken amongst minimally sedated patients via concurrent polysomnography and actigraphy monitoring over a 24-h duration to assess agreement between the two methods; total sleep time and wake time. RESULTS: We recruited 80 patients who were mechanically ventilated (24%) and non-ventilated (76%) within the intensive care unit. Sleep was found to be highly fragmented, composed of numerous sleep bouts and characterized by abnormal sleep architecture. Actigraphy was found to have a moderate level of overall agreement in identifying sleep and wake states with polysomnography (69.4%; K = 0.386, p < 0.05) in an epoch by epoch analysis, with a moderate level of sensitivity (65.5%) and specificity (76.1%). Monitoring accuracy via actigraphy was improved amongst non-ventilated patients (specificity 83.7%; sensitivity 56.7%). Actigraphy was found to have a moderate correlation with polysomnography reported total sleep time (r = 0.359, p < 0.05) and wakefulness (r = 0.371, p < 0.05). Bland-Altman plots indicated that sleep was underestimated by actigraphy, with wakeful states overestimated. CONCLUSIONS: Actigraphy was easy and safe to use, provided moderate level of agreement with polysomnography in distinguishing between sleep and wakeful states, and may be a reasonable alternative to measure sleep in intensive care patients. Clinical Trial Registration number ACTRN12615000945527 (Registered 9/9/2015).

Primary prevention in the intensive care unit: a prospective single-centre study of the risk factors for invasive pneumococcal disease.

Invasive pneumococcal disease is a significant health burden in Australia, with immunisation recommended for children and at-risk adults. Health benefits of immunisation are clear, but less effective when immunisation rates are low, as in Western Australia. We hypothesised that patients admitted unplanned to the intensive care unit (ICU) would have high eligibility for pneumococcal immunisation, but low rates of recorded vaccine administration. We performed a prospective observational study of 119 emergency admissions to Royal Perth ICU, a 20-bed mixed ICU at a tertiary teaching hospital in Western Australia. Each admission was screened for vaccine eligibility (age and risk factors as per Australian Technical Advisory Group of Immunisation guidelines), with patients' health records examined and primary care providers contacted after ICU discharge. Risk factors for invasive pneumococcal disease were common, with 52% of the study population having one or more. Fifty-four of 119 admitted patients (45%) were assessed as eligible for immunisation after ICU discharge. ICU survivors represent a high-risk population for which intervention against modifiable targets, such as invasive pneumococcal disease, may reduce both their chronic health burden and future health expenditure. Future efforts should concentrate on assessing the feasibility of a screening program for modifiable factors in ICU survivors, and the logistics of delivering these interventions in a timely manner during their hospital stay.

Can femoral venous pressure be used as an estimate for standard vesical intra-abdominal pressure measurement?

Intra-abdominal hypertension (IAH) is highly prevalent in critically ill patients admitted to the intensive care unit and is associated with an increased morbidity and mortality. The present study investigated whether femoral venous pressure (FVP) can be used as a surrogate parameter for intra-abdominal pressure (IAP) measured via the bladder in IAH grade II (IAP <20 mmHg) or grade III (IAP ≥20 mmHg). This was a single-centre prospective study carried out in a tertiary adult intensive care unit. IAP was measured via the bladder with a urinary catheter with simultaneous recording of the FVP via a femoral central line. If the IAP was <20 mmHg external weight to a maximum of 10 kg was applied to the abdomen with subsequent measurements of IAP and FVP. Eleven patients were enrolled into the study. IAH (IAP >12 mmHg) was identified in five patients (42%) and abdominal compartment syndrome (ACS, IAP >20 mmHg with new onset organ failure) in two (18%) with all-cause study mortality of 18%. The mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 21 ± 5, Simplified Acute Physiology (SAPS 2) score 49 ± 8, and Sequential Organ Failure Assessment (SOFA) score 9 ± 3. At baseline the bias between IAP and FVP was 3.2 with a precision of 3.63 mmHg (limits of agreement [LA] -4.1, 10.4). At 5 kg and 10 kg, the bias was 2.5 with a precision of 3.92 mmHg (LA -5.4, 10.3) and 2.26 mmHg (LA -2.1, 7.0) respectively. A receiver operating characteristic analysis for FVP to predict IAH showed an area under the curve of 0.87 (95% confidence interval 0.74-0.94, P=0.0001). FVP cannot be recommended as a surrogate measure for IAP even at IAP values above 20 mmHg. However, an elevated FVP was a good predictor of IAH.

Iron-restricted erythropoiesis and risk of red blood cell transfusion in the intensive care unit: a prospective observational study.

Intravenous (IV) iron can decrease transfusion requirements in selected patients with low, normal and moderately elevated ferritin. Whether the syndrome of iron-restricted erythropoiesis (IRE), diagnosed by iron studies, identifies critically ill patients at risk for subsequent red blood cell (RBC) transfusion, and hence, provides a simple method to determine response to IV iron therapy, is uncertain. We aimed to describe the characteristics of patients with IRE on admission to intensive care and determine the optimal variables to identify patients at risk of RBC transfusion who may benefit from early administration of IV iron. The study included 201 consecutive ICU admissions from a single 23-bed combined medical/surgical ICU. The prevalence of IRE on admission to ICU, defined according to ferritin <300 µg/l and transferrin saturation <20%, was 26.2% (95% CI 19.9 to 32.4). The proportion of patients with IRE subsequently receiving RBC transfusion was significantly lower than the proportion of patients without IRE receiving RBC transfusion (absolute mean difference 18.9% [95% CI 4.7 to 33.1, P <0.001]). IRE was not independently associated with risk of transfusion on multivariate analysis, however, a prognostic model with three risk factors (RBC transfusion prior to ICU admission, Hb <100 g/l and ICU length of stay >3 days), had good discrimination and calibration for predicting transfusion (receiver operator curve area under the curve 0.87 [95% CI 0.79 to 0.94, P=0.88], Hosmer-Lemeshow 6.21; P=0.1). Excluding iron overload and using simple prognostic criteria to identify patients at high risk of RBC transfusion may be a preferable strategy for identifying critically ill patients who may benefit from IV iron.

Central venous-to-arterial carbon dioxide gradient as a marker of occult tissue hypoperfusion after major surgery.

The central venous-arterial carbon dioxide tension gradient ('CO2gap') has been shown to correlate with cardiac output and tissue perfusion in septic shock. Compared to central venous oxygen saturation (SCVO2), the CO2gap is less susceptible to the effect of hyperoxia and may be particularly useful as an adjunctive haemodynamic target in the perioperative period. This study investigated whether a high CO2gap was associated with an increased systemic oxygen extraction (O2ER >0.3) or occult tissue hypoperfusion in 201 patients in the immediate postoperative period. The median CO2gap of all patients was 8 mmHg (IQR 6 to 9), and a large CO2gap was very common (> 6mmHg in 139 patients [69%], 95% CI 63 to 75; >5 mmHg in 170 patients [85%], 95% CI 79 to 89). A CO2 gap >5 mmHg had a higher sensitivity (93%) and negative predictive value (74%) than a CO2gap >6 mmHg in excluding occult tissue hypoperfusion. Of the four variables that were predictive of an increased O2ER in the multivariate analysis-CO2gap, arterial pH, haemoglobin and arterial lactate concentrations-the CO2gap (odds ratio 4.41 per mmHg increment, 95% CI 1.7 to 11.2, P=0.002) was most important and explained about 34% of the variability in the risk of occult tissue hypoperfusion. In conclusion, a normal CO2 gap (<5 mmHg) had a high sensitivity and negative predictive value in excluding inadequate systemic oxygen delivery and may be useful as an adjunct to other haemodynamic targets in avoiding occult tissue hypoperfusion in the perioperative setting when high inspired oxygen concentrations are used.

Clinical predictors of a low central venous oxygen saturation after major surgery: a prospective prevalence study.

Optimising perioperative haemodynamic status may reduce postoperative complications. In this prospective prevalence study, we investigated the associations between standard haemodynamic parameters and a low central venous oxygen saturation (ScvO2) in patients after major surgery. A total of 201 patients requiring continuous arterial and central venous pressure monitoring after major surgery were recruited. Simultaneous arterial and central venous blood gases, haemodynamic and biochemical data and perfusion index were obtained from patients at a single time-point within 24 hours of surgery. A low ScvO2 (<70%) was observed in 109 patients (54%). Use of mechanical ventilation, mean arterial pressure, central venous pressure, haemoglobin concentrations, arterial pH and lactate concentrations, arterial oxygen (PaO2) and carbon dioxide tensions (PaCO2) were all associated with a low ScvO2 in the univariate analyses. In the multivariate analysis, only a higher perfusion index (odds ratio [OR] 0.87, 95% confidence interval [CI] 0.78 to 0.98), PaO2 (OR 0.98 per mmHg increment, 95% CI 0.97 to 0.99) and PaCO2 (OR 0.88 per mmHg increment, 95% CI 0.82 to 0.95) and a lower central venous pressure (OR 1.14 per mmHg increment, 95% CI 1.04 to 1.25) were significantly associated with a reduced risk of a low ScvO2, all in a linear fashion. In conclusion, PaO2, PaCO2, perfusion index and central venous pressure were significant predictors of a low ScvO2 in patients after major surgery including cardiac surgery.

Assessment of the plethysmographic variability index as a predictor of fluid responsiveness in critically ill patients: a pilot study.

Optimising intravascular volume in patients with hypotension requiring vasopressor support is a key challenge of critical care medicine. The optimal haemodynamic parameter to assess fluid responsiveness in critically ill patients, particularly those requiring a noradrenaline infusion and mechanical ventilation, remains uncertain. This pilot study assessed the accuracy of the plethysmographic variability index (PVI), (Radical-7 pulse co-oximeter, Masimo®, Irvine, CA, USA) in predicting fluid responsiveness in 25 patients who required noradrenaline infusion to maintain mean arterial pressure over 65 mmHg and were mechanically ventilated with a 'lung-protective' strategy, and whether administering a fluid bolus was associated with a change in PVI (Δ PVI). In this study, fluid responsiveness was defined as an increase in stroke volume of greater than 15% after a 500 ml bolus of colloid infusion over 20 minutes. Of the 25 patients included in the study, only 12 (48%) were considered fluid responders. As static haemodynamic parameters, PVI, central venous pressure and inferior vena cava distensibility index were all inaccurate at predicting volume responsiveness with PVI being the least accurate (area under the receiver operating characteristic curve=0.41, 95% confidence interval 0.18 to 0.65). However, fluid responsiveness was associated with a change in PVI, but not a change in heart rate or central venous pressure. This association between Δ PVI and fluid responsiveness may be a surrogate marker of improved cardiac output following a fluid bolus and warrants further investigation.

Prophylactic intraaortic balloon counterpulsation in high-risk cardiac surgery: a survey of opinion and current practice.

INTRODUCTION: Patients undergoing cardiac surgery increasingly have greater comorbidities and subsequently are at higher risk of adverse postoperative outcomes. Despite some evidence suggests that prophylactic intraaortic balloon counterpulsation reduces mortality in selected high-risk patients, its use remains low. The aim of this study was to investigate reported management strategies of high-risk patients and attitudes towards further research in this area. METHODS: A 22-question survey was developed and distributed electronically to all practicing cardiothoracic fellows through the email list of the Australian and New Zealand Society of Cardiac and Thoracic Surgeons. RESULTS: The response rate was 28% (n=31). Reported use of prophylactic intraaortic balloon counterpulsation varied depending on the specified preoperative indication. Prophylactic intraaortic balloon counterpulsation was used occasionally or never by the majority of respondents for their patients with characteristics similar to those of previous trials. The most frequent reason given for not using prophylactic intraaortic balloon counterpulsation was lack of data (42.9%), with a willingness to consider participation in an randomised controlled trial of prophylactic intraaortic balloon counterpulsation by a large majority of respondents (79.3%). CONCLUSIONS: The majority of surgeons who responded to this survey do not routinely use prophylactic intraaortic balloon counterpulsation for high-risk patients. Further prospective data is warranted to ascertain whether potential barriers to a randomised control trial of prophylactic intraaortic balloon counterpulsation, such as adequate patient numbers and clear selection criteria, can be overcome.

Effect of hyperoxia and vascular occlusion on tissue oxygenation measured by near infra-red spectroscopy (InSpectra™): a volunteer study.

Standard cardiorespiratory monitoring may fail to detect occult tissue ischaemia. This study assessed whether a near infra-red spectroscopy tissue oxygen saturation monitor (InSpectra™) could detect progressive peripheral tissue ischaemia and whether hyperoxia may confound tissue oxygen saturation measurement. Tissue oxygen and arterial oxygen saturations were measured continuously in 30 healthy volunteers, first during a period of progressive increase in inspired oxygen concentration and subsequently during two periods of low- and high-pressure limb ischaemia. Increasing inspired oxygen concentration was associated with a small increase in mean (SD) tissue oxygen saturation of 5.3 (7.1) %, reaching a plateau between 30% and 40% inspired oxygen. The rate and magnitude of decreases in tissue oxygen saturations were greater during high- than low-pressure ischaemia with a mean (SD) desaturation rate of 3.3 (0.9) vs 1.8 (0.8) %.min(-1) (p<0.01). The dose-related association and lack of confounding by hyperoxia suggest that tissue oxygen saturation monitoring may be a useful adjunct to detect occult ischaemia.

The PiCCO monitor: a review.

Advanced haemodynamic monitoring remains a cornerstone in the management of the critically ill. While rates of pulmonary artery catheter use have been declining, there has been an increase in the number of alternatives for monitoring cardiac output as well as greater understanding of the methods and criteria with which to compare devices. The PiCCO (Pulse index Continuous Cardiac Output) device is one such alternative, integrating a wide array of both static and dynamic haemodynamic data through a combination of trans-cardiopulmonary thermodilution and pulse contour analysis. The requirement for intra-arterial and central venous catheterisation limits the use of PiCCO to those with evolving critical illness or at high risk of complex and severe haemodynamic derangement. While the accuracy of trans-cardiopulmonary thermodilution as a measure of cardiac output is well established, several other PiCCO measurements require further validation within the context of their intended clinical use. As with all advanced haemodynamic monitoring systems, efficacy in improving patient-centred outcomes has yet to be conclusively demonstrated. The challenge with PiCCO is in improving the understanding of the many variables that can be measured and integrating those that are clinically relevant and adequately validated with appropriate therapeutic interventions.

The PATRIARCH Study. Using outcome measures for league tables: can a North American prediction of admission score be used in a United Kingdom children's emergency department? PRISA And Triage In A Regional Children's Hospital.

OBJECTIVES: The use of league tables has become predominant in the healthcare culture of the United Kingdom. These tables are often based on measures that are viewed with scepticism by clinicians. This study was designed to test the validity of a North American risk of admission score, the PRISA, for use in a United Kingdom population of accident and emergency (A&E) attendees. METHODS: All attendees to a children's A&E department were scored using the PRISA for a single calendar month (November 2000) RESULTS: 701 children were studied in total. The results show that the PRISA applied to this population gives an area under the receiver operator curve of 0.76. Of the 701 patients studied, 206 (29.4%) were admitted. The PRISA predicted a total of 206.10 admissions. Of the 50 patients discharged with the highest PRISA scores (that is, with the highest likelihood of admission), none were admitted in the 48 hours after their original attendance. CONCLUSIONS: These results show that the PRISA is suitable as a measure of paediatric A&E department performance in the United Kingdom and it is highly promising as a future measure of quality.