Recruitment-to-inflation Ratio Assessed through Sequential End-expiratory Lung Volume Measurement in Acute Respiratory Distress Syndrome

BACKGROUND

Positive end-expiratory pressure (PEEP) benefits in acute respiratory distress syndrome are driven by lung dynamic strain reduction. This depends on the variable extent of alveolar recruitment. The recruitment-to-inflation ratio estimates recruitability across a 10-cm H2O PEEP range through a simplified maneuver. Whether recruitability is uniform or not across this range is unknown. The hypotheses of this study are that the recruitment-to-inflation ratio represents an accurate estimate of PEEP-induced changes in dynamic strain, but may show nonuniform behavior across the conventionally tested PEEP range (15 to 5 cm H2O).

METHODS

Twenty patients with moderate-to-severe COVID-19 acute respiratory distress syndrome underwent a decremental PEEP trial (PEEP 15 to 13 to 10 to 8 to 5 cm H2O). Respiratory mechanics and end-expiratory lung volume by nitrogen dilution were measured the end of each step. Gas exchange, recruited volume, recruitment-to-inflation ratio, and changes in dynamic, static, and total strain were computed between 15 and 5 cm H2O (global recruitment-to-inflation ratio) and within narrower PEEP ranges (granular recruitment-to-inflation ratio).

RESULTS

Between 15 and 5 cm H2O, median [interquartile range] global recruitment-to-inflation ratio was 1.27 [0.40 to 1.69] and displayed a linear correlation with PEEP-induced dynamic strain reduction (r = -0.94; P < 0.001). Intraindividual recruitment-to-inflation ratio variability within the narrower ranges was high (85% [70 to 109]). The relationship between granular recruitment-to-inflation ratio and PEEP was mathematically described by a nonlinear, quadratic equation (R2 = 0.96). Granular recruitment-to-inflation ratio across the narrower PEEP ranges itself had a linear correlation with PEEP-induced reduction in dynamic strain (r = -0.89; P < 0.001).

CONCLUSIONS

Both global and granular recruitment-to-inflation ratio accurately estimate PEEP-induced changes in lung dynamic strain. However, the effect of 10 cm H2O of PEEP on lung strain may be nonuniform. Granular recruitment-to-inflation ratio assessment within narrower PEEP ranges guided by end-expiratory lung volume measurement may aid more precise PEEP selection, especially when the recruitment-to-inflation ratio obtained with the simplified maneuver between PEEP 15 and 5 cm H2O yields intermediate values that are difficult to interpret for a proper choice between a high and low PEEP strategy.

EDITOR’S PERSPECTIVE

Physiological effects of awake prone position in acute hypoxemic respiratory failure

BACKGROUND

The effects of awake prone position on the breathing pattern of hypoxemic patients need to be better understood. We conducted a crossover trial to assess the physiological effects of awake prone position in patients with acute hypoxemic respiratory failure.

METHODS

Fifteen patients with acute hypoxemic respiratory failure and PaO2/FiO2 < 200 mmHg underwent high-flow nasal oxygen for 1 h in supine position and 2 h in prone position, followed by a final 1-h supine phase. At the end of each study phase, the following parameters were measured: arterial blood gases, inspiratory effort (ΔPES), transpulmonary driving pressure (ΔPL), respiratory rate and esophageal pressure simplified pressure-time product per minute (sPTPES) by esophageal manometry, tidal volume (VT), end-expiratory lung impedance (EELI), lung compliance, airway resistance, time constant, dynamic strain (VT/EELI) and pendelluft extent through electrical impedance tomography.

RESULTS

Compared to supine position, prone position increased PaO2/FiO2 (median [Interquartile range] 104 mmHg [76-129] vs. 74 [69-93], p < 0.001), reduced respiratory rate (24 breaths/min [22-26] vs. 27 [26-30], p = 0.05) and increased ΔPES (12 cmH2O [11-13] vs. 9 [8-12], p = 0.04) with similar sPTPES (131 [75-154] cmH2O s min-1 vs. 105 [81-129], p > 0.99) and ΔPL (9 [7-11] cmH2O vs. 8 [5-9], p = 0.17). Airway resistance and time constant were higher in prone vs. supine position (9 cmH2O s arbitrary units-3 [4-11] vs. 6 [4-9], p = 0.05; 0.53 s [0.32-61] vs. 0.40 [0.37-0.44], p = 0.03). Prone position increased EELI (3887 arbitrary units [3414-8547] vs. 1456 [959-2420], p = 0.002) and promoted VT distribution towards dorsal lung regions without affecting VT size and lung compliance: this generated lower dynamic strain (0.21 [0.16-0.24] vs. 0.38 [0.30-0.49], p = 0.004). The magnitude of pendelluft phenomenon was not different between study phases (55% [7-57] of VT in prone vs. 31% [14-55] in supine position, p > 0.99).

CONCLUSIONS

Prone position improves oxygenation, increases EELI and promotes VT distribution towards dependent lung regions without affecting VT size, ΔPL, lung compliance and pendelluft magnitude. Prone position reduces respiratory rate and increases ΔPES because of positional increases in airway resistance and prolonged expiratory time. Because high ΔPES is the main mechanistic determinant of self-inflicted lung injury, caution may be needed in using awake prone position in patients exhibiting intense ΔPES. Clinical trail registeration: The study was registered on clinicaltrials.gov (NCT03095300) on March 29, 2017.

Long-term outcome of COVID-19 patients treated with helmet noninvasive ventilation vs. high-flow nasal oxygen: a randomized trial

BACKGROUND

Long-term outcomes of patients treated with helmet noninvasive ventilation (NIV) are unknown: safety concerns regarding the risk of patient self-inflicted lung injury and delayed intubation exist when NIV is applied in hypoxemic patients. We assessed the 6-month outcome of patients who received helmet NIV or high-flow nasal oxygen for COVID-19 hypoxemic respiratory failure.

METHODS

In this prespecified analysis of a randomized trial of helmet NIV versus high-flow nasal oxygen (HENIVOT), clinical status, physical performance (6-min-walking-test and 30-s chair stand test), respiratory function and quality of life (EuroQoL five dimensions five levels questionnaire, EuroQoL VAS, SF36 and Post-Traumatic Stress Disorder Checklist for the DSM) were evaluated 6 months after the enrollment.

RESULTS

Among 80 patients who were alive, 71 (89%) completed the follow-up: 35 had received helmet NIV, 36 high-flow oxygen. There was no inter-group difference in any item concerning vital signs (N = 4), physical performance (N = 18), respiratory function (N = 27), quality of life (N = 21) and laboratory tests (N = 15). Arthralgia was significantly lower in the helmet group (16% vs. 55%, p = 0.002). Fifty-two percent of patients in helmet group vs. 63% of patients in high-flow group had diffusing capacity of the lungs for carbon monoxide < 80% of predicted (p = 0.44); 13% vs. 22% had forced vital capacity < 80% of predicted (p = 0.51). Both groups reported similar degree of pain (p = 0.81) and anxiety (p = 0.81) at the EQ-5D-5L test; the EQ-VAS score was similar in the two groups (p = 0.27). Compared to patients who successfully avoided invasive mechanical ventilation (54/71, 76%), intubated patients (17/71, 24%) had significantly worse pulmonary function (median diffusing capacity of the lungs for carbon monoxide 66% [Interquartile range: 47-77] of predicted vs. 80% [71-88], p = 0.005) and decreased quality of life (EQ-VAS: 70 [53-70] vs. 80 [70-83], p = 0.01).

CONCLUSIONS

In patients with COVID-19 hypoxemic respiratory failure, treatment with helmet NIV or high-flow oxygen yielded similar quality of life and functional outcome at 6 months. The need for invasive mechanical ventilation was associated with worse outcomes. These data indicate that helmet NIV, as applied in the HENIVOT trial, can be safely used in hypoxemic patients. Trial registration Registered on clinicaltrials.gov NCT04502576 on August 6, 2020.

Respective Effects of Helmet Pressure Support, Continuous Positive Airway Pressure, and Nasal High-Flow in Hypoxemic Respiratory Failure: A Randomized Crossover Clinical Trial

Rationale: The respective effects of positive end-expiratory pressure (PEEP) and pressure support delivered through the helmet interface in patients with hypoxemia need to be better understood. Objectives: To assess the respective effects of helmet pressure support (noninvasive ventilation [NIV]) and continuous positive airway pressure (CPAP) compared with high-flow nasal oxygen (HFNO) on effort to breathe, lung inflation, and gas exchange in patients with hypoxemia (PaO2/FiO2 ⩽ 200). Methods: Fifteen patients underwent 1-hour phases (constant FiO2) of HFNO (60 L/min), helmet NIV (PEEP = 14 cm H2O, pressure support = 12 cm H2O), and CPAP (PEEP = 14 cm H2O) in randomized sequence. Measurements and Main Results: Inspiratory esophageal (ΔPES) and transpulmonary pressure (ΔPL) swings were used as surrogates for inspiratory effort and lung distension, respectively. Tidal Volume (Vt) and end-expiratory lung volume were assessed with electrical impedance tomography. ΔPES was lower during NIV versus CPAP and HFNO (median [interquartile range], 5 [3-9] cm H2O vs. 13 [10-19] cm H2O vs. 10 [8-13] cm H2O; P = 0.001 and P = 0.01). ΔPL was not statistically different between treatments. PaO2/FiO2 ratio was significantly higher during NIV and CPAP versus HFNO (166 [136-215] and 175 [158-281] vs. 120 [107-149]; P = 0.002 and P = 0.001). NIV and CPAP similarly increased Vt versus HFNO (mean change, 70% [95% confidence interval (CI), 17-122%], P = 0.02; 93% [95% CI, 30-155%], P = 0.002) and end-expiratory lung volume (mean change, 198% [95% CI, 67-330%], P = 0.001; 263% [95% CI, 121-407%], P = 0.001), mostly due to increased aeration/ventilation in dorsal lung regions. During HFNO, 14 of 15 patients had pendelluft involving >10% of Vt; pendelluft was mitigated by CPAP and further by NIV. Conclusions: Compared with HFNO, helmet NIV, but not CPAP, reduced ΔPES. CPAP and NIV similarly increased oxygenation, end-expiratory lung volume, and Vt, without affecting ΔPL. NIV, and to a lesser extent CPAP, mitigated pendelluft. Clinical trial registered with clinicaltrials.gov (NCT04241861).

Treatment of severe infections caused by ESBL or carbapenemases-producing Enterobacteriaceae

Enterobacteriaceae are the most frequent pathogens in the Intensive Care Unit. Due to their safety and activity, β-Lactams (BL) and carbapenems represented the most common strategy adopted against these germs. The increasing exposure to these molecules led to the development of several types of antimicrobial resistance as the expression of extended-spectrum β-lactamases (ESBLs) and carbapenemases. Great molecular variability exists among these enzymes, with significant clinical impact. To limit morbidity and mortality, old antibiotics were tested and represent viable alternatives for specific types of infections, or once the spectrum of susceptibility of each germ has been determined. Alongside, new molecules have been specifically designed but enzyme molecular variability prevents the existence of one single antibiotic which fits for all. Therefore, a quicker identification of the molecular identity of each germ, together with the knowledge of the activity spectrum of each antibiotic is crucial to tailor the therapy and make it effective.

Effects of changes in inspired oxygen fraction on urinary oxygen tension measurements

BACKGROUND

Continuous measurement of urinary PO₂ (PuO₂) is being applied to indirectly monitor renal medullary PO₂. However, when applied to critically ill patients with shock, its measurement may be affected by changes in FiO₂ and PaO₂ and potential associated O₂ diffusion between urine and ureteric or bladder tissue. We aimed to investigate PuO₂ measurements in septic shock patients with a fiberoptic luminescence optode inserted into the urinary catheter lumen in relation to episodes of FiO₂ change. We also evaluated medullary and urinary oxygen tension values in Merino ewes at two different FiO₂ levels.

RESULTS

In 10 human patients, there were 32 FiO₂ decreases and 31 increases in FiO₂. Median pre-decrease FiO₂ was 0.36 [0.30, 0.39] and median post-decrease FiO₂ was 0.30 [0.23, 0.30], p = 0.006. PaO₂ levels decreased from 83 mmHg [77, 94] to 72 [62, 80] mmHg, p = 0.009. However, PuO₂ was 23.2 mmHg [20.5, 29.0] before and 24.2 mmHg [20.6, 26.3] after the intervention (p = 0.56). The median pre-increase FiO₂ was 0.30 [0.21, 0.30] and median post-increase FiO₂ was 0.35 [0.30, 0.40], p = 0.008. PaO₂ levels increased from 64 mmHg [58, 72 mmHg] to 71 mmHg [70, 100], p = 0.04. However, PuO₂ was 25.0 mmHg [IQR: 20.7, 26.8] before and 24.3 mmHg [IQR: 20.7, 26.3] after the intervention (p = 0.65). A mixed linear regression model showed a weak correlation between the variation in PaO₂ and the variation in PuO₂ values. In 9 Merino ewes, when comparing oxygen tension levels between FiO₂ of 0.21 and 0.40, medullary values did not differ (25.1 ± 13.4 mmHg vs. 27.9 ± 15.4 mmHg, respectively, p = 0.6766) and this was similar to urinary oxygen values (27.1 ± 6.17 mmHg vs. 29.7 ± 4.41 mmHg, respectively, p = 0.3192).

CONCLUSIONS

Changes in FiO₂ and PaO₂ within the context of usual care did not affect PuO₂. Our findings were supported by experimental data and suggest that PuO₂ can be used as biomarker of medullary oxygenation irrespective of FiO₂.

Vitamin D Status and Potential Therapeutic Options in Critically Ill Patients: A Narrative Review of the Clinical Evidence

Vitamin D covers roles of paramount importance in the regulation of multiple physiological pathways of the organism. The metabolism of vitamin D involves kidney-liver crosstalk and requires an adequate function of these organs, where vitamin D is progressively turned into active forms. Vitamin D deficiency has been widely reported in patients living in the community, being prevalent among the most vulnerable subjects. It has been also documented in many critically ill patients upon admission to the intensive care unit. In this context, vitamin D deficiency may represent a risk factor for the development of life-threatening clinical conditions (e.g., infection and sepsis) and worse clinical outcomes. Several researchers have investigated the impact of vitamin D supplementation showing its feasibility, safety, and effectiveness, although conflicting results have put into question its real benefit in critically ill patients. The existing studies included heterogeneous critically ill populations and used slightly different protocols of vitamin D supplementation. For these reasons, pooling up the results is difficult and not conclusive. In this narrative review, we described vitamin D physiology and the pathophysiology of vitamin D depletion with a specific focus on critically ill patients with liver dysfunction, acute kidney injury, acute respiratory failure, and sepsis.

Helmet noninvasive support for acute hypoxemic respiratory failure: rationale, mechanism of action and bedside application

Introduction

Helmet noninvasive support may provide advantages over other noninvasive oxygenation strategies in the management of acute hypoxemic respiratory failure. In this narrative review based on a systematic search of the literature, we summarize the rationale, mechanism of action and technicalities for helmet support in hypoxemic patients.

Main results

In hypoxemic patients, helmet can facilitate noninvasive application of continuous positive-airway pressure or pressure-support ventilation via a hood interface that seals at the neck and is secured by straps under the arms. Helmet use requires specific settings. Continuous positive-airway pressure is delivered through a high-flow generator or a Venturi system connected to the inspiratory port of the interface, and a positive end-expiratory pressure valve place at the expiratory port of the helmet;  alternatively, pressure-support ventilation is delivered by connecting the helmet to a mechanical ventilator through a bi-tube circuit. The helmet interface allows continuous treatments with high positive end-expiratory pressure with good patient comfort. Preliminary data suggest that helmet noninvasive ventilation (NIV) may provide physiological benefits compared to other noninvasive oxygenation strategies (conventional oxygen, facemask NIV, high-flow nasal oxygen) in non-hypercapnic patients with moderate-to-severe hypoxemia (PaO₂/FiO₂ ≤ 200 mmHg), possibly because higher positive end-expiratory pressure (10–15 cmH₂O) can be applied for prolonged periods with good tolerability. This improves oxygenation, limits ventilator inhomogeneities, and may attenuate the potential harm of lung and diaphragm injury caused by vigorous inspiratory effort. The potential superiority of helmet support for reducing the risk of intubation has been hypothesized in small, pilot randomized trials and in a network metanalysis.

Conclusions

Helmet noninvasive support represents a promising tool for the initial management of patients with severe hypoxemic respiratory failure. Currently, the lack of confidence with this and technique and the absence of conclusive data regarding its efficacy render helmet use limited to specific settings, with expert and trained personnel. As per other noninvasive oxygenation strategies, careful clinical and physiological monitoring during the treatment is essential to early identify treatment failure and avoid delays in intubation.

COMBED: Rapid non-invasive Cardiac Output Monitoring Baseline assessment in adult Emergency Department patients with haemodynamic instability

OBJECTIVE

The application of rapid, non-operator-dependent, non-invasive cardiac output monitoring (COM) may provide early physiological information in ED patients with haemodynamic instability (HI). Our primary objective was to assess the feasibility of measuring pre-intervention (baseline) cardiac index (CI) and associated haemodynamic parameters.

METHODS

We performed a prospective observational study of adults shortly after presentation to the ED of a large university hospital with tachycardia or hypotension or both. We applied non-invasive COM for 5 min and recorded CI, mean arterial pressure (MAP), stroke volume index (SVI) and systemic vascular resistance index (SVRI). We assessed for differences between those presenting with hypotension or hypotension and tachycardia with tachycardia alone and between those with or without suspected infection.

RESULTS

We obtained haemodynamic parameters in 46 of 49 patients. In patients with hypotension or hypotension and tachycardia (n = 15) rather than tachycardia alone (n = 31), we observed a lower MAP (60.8 vs 87.7, P < 0.0001), CI (2.8 vs 3.9, P = 0.0167) and heart rate (85.5 vs 115.4, P < 0.0001). There was no difference in SVI (33.7 vs 33.4, P = 0.93) or SVRI (1970 vs 2088, P = 0.67). Patients with suspected infection had similar haemodynamic values except for a lower SVRI (1706 vs 2237, P = 0.011).

CONCLUSIONS

Rapid, non-operator-dependent, non-invasive COM was possible in >90% of ED patients presenting with HI. Compared with tachycardia alone, patients with hypotension had lower CI, MAP and heart rate, while those with suspected infection had a lower SVRI. This technology provides novel insights into the early state of the circulation in ED patients with HI.

Dyspnoea and clinical outcome in critically ill patients receiving noninvasive support for COVID-19 respiratory failure: post hoc analysis of a randomised clinical trial

In non-COVID-19 acute hypoxaemic respiratory failure, the entity of dyspnoea has been associated with severity of hypoxaemia, and represents a factor predicting noninvasive ventilation (NIV) failure, the need for endotracheal intubation and mortality [1].

In #COVID19 patients, presence of moderate-to-severe dyspnoea is a marker of disease severity correlated to clinical outcomeshttps://bit.ly/3Bp2G1b

Rapid 500 mL albumin bolus versus rapid 200 mL bolus followed by slower continuous infusion in post-cardiac surgery patients: a pilot before-and-after study

Objective: To evaluate the haemodynamic effects of rapid fluid bolus therapy (FBT) (500 mL of 4% albumin over several minutes) versus combined FBT (rapid 200 mL FBT followed by a 300 mL infusion over 30 minutes). Design: Single centre, prospective, before-and-after trial. Setting: A tertiary intensive care unit in Australia. Participants: Fifty mechanically ventilated post-cardiac surgery patients. Interventions: Rapid 4% albumin FBT versus combined FBT. Main outcome measures: We recorded haemodynamic parameters from before FBT to 30 minutes after FBT. A mean arterial pressure (MAP) response was defined by a MAP increase > 10%, and a cardiac index (CI) response was defined by a CI increase > 15%. Results: Immediately after rapid FBT versus combined FBT, there was a CI response in 13 patients (52%) compared with five patients (20%) respectively (P = 0.038), and a MAP response in 11 patients (44%) in each group. However, from FBT administration to 30 minutes, there was a time and group interaction such that MAP was higher in the rapid FBT group (P = 0.003), as was the case for central venous pressure (P = 0.002) and mean pulmonary artery pressure (P < 0.001). Body temperature fell immediately and was lower with rapid FBT but became warmer than with combined FBT later (P < 0.001). At 30 minutes, a MAP response was seen in ten patients (40%) compared with nine patients (36%) (P < 0.99) and a CI response was present in eight patients (32%) compared with 11 patients (44%) (P = 0.56) in the rapid versus combined FBT groups respectively. Conclusion: Rapid FBT was superior to combined FBT in terms of mean MAP levels and immediate CI response. However, the number of MAP responders or CI responders was similar at 30 minutes.

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.

A comparison of the hemodynamic effects of fluid bolus therapy with crystalloids vs. 4% albumin and vs. 20% albumin in patients after cardiac surgery

BACKGROUND

Crystalloids, 4% albumin and 20% albumin are used for fluid bolus therapy (FBT) in patients after cardiac surgery. However, their detailed early (30 min) hemodynamic effects remain unstudied.

METHODS

In a comparative prospective observational trial of 120 ventilated, we studied post cardiac surgery patients who received crystalloid 500 ml FBT, 4% albumin 500 ml FBT or 20% albumin 100 ml FBT (40 per group). We recorded second-by-second hemodynamic parameters and 15-minutely cardiac index (CI) data before and for 30 min after FBT. We compared the crystalloid group (reference) vs. the 4% albumin group, and vs. the 20% albumin group.

RESULTS

Immediately after FBT, the mean (standard deviation) CI increase was 0.4 (0.4) L/min/m² with crystalloids, 0.4 (0.5) L/min/m² with 4% albumin and 0.3 (0.4) L/min/m² with 20% albumin, despite the much smaller FBT volume with 20% albumin. Mean arterial pressure (MAP) increase was 11 (10), 12 (9) and 9 (6) mm Hg, respectively. There was no group effect or interaction for changes in CI. However, there were time-group interactions for MAP changes such that crystalloid FBT had faster MAP reduction than 4% (p<0.001) or 20% albumin (p < 0.001). Moreover, patients treated with crystalloid FBT showed a faster decline in central venous pressure, perfusion pressure than the two groups. Finally, 20% albumin attenuated the fall in temperature induced by FBT.

CONCLUSION

In postoperative cardiac surgery patients, after a similar initial CI and MAP response, the MAP effect of crystalloid FBT dissipates faster than that of 4% or 20% albumin FBT. These findings can be used to inform clinical practice.

Radiologically and clinically diagnosed acute pulmonary oedema in critically ill patients: prevalence, patient characteristics, treatments and outcomes

Background: Acute pulmonary oedema is a life-threatening syndrome diagnosed based on radiological and clinical findings. However, to our knowledge, no studies have investigated this syndrome in critically ill patients. Objective: To describe the prevalence of radiologically and clinically diagnosed pulmonary oedema (RCDPO) in critically ill patients, characteristics of diagnosed patients, and treatments and outcomes in this patient population. Methods: We conducted a retrospective study using natural language processing to identify all radiological reports of pulmonary oedema among patients who had been admitted to single tertiary intensive care unit (ICU) over a 1-year period (January 2015 to January 2016). We reviewed clinical data, discharge diagnosis, treatment and outcomes for such patients, and used multivariable logistic regression analysis to identify the association of RCDPO with various outcomes. Results: Out of 2001 ICU patients, we identified 238 patients (11.9%) with RCDPO. Patients with RCDPO were more acutely ill, had more chronic liver disease and had more chronic renal failure than critically ill patients who did not have RCDPO. They were typically admitted with acute cardiovascular disease; were more likely to receive invasive mechanical ventilation and continuous renal replacement therapy; had longer duration of ICU and hospital stay; were more likely to die in hospital; and, if discharged alive, were more likely to be admitted to a chronic care facility. In total, 46 RCDPO patients (19.3%) died in hospital. On multivariable analysis, only age and continuous renal replacement therapy were independently associated with mortality. In contrast, invasive mechanical ventilation was associated with a 2.5 times greater odds of radiological resolution. Conclusion: RCDPO affected about one in eight ICU patients. Such patients were sicker and had more comorbidities. The presence of RCDPO was independently associated with higher risk of death. Invasive mechanical ventilation was the only intervention independently associated with greater odds of radiological resolution.

The hemodynamic effects of warm versus room-temperature crystalloid fluid bolus therapy in post-cardiac surgery patients

INTRODUCTION

The contribution of fluid temperature to the effect of crystalloid fluid bolus therapy (FBT) in post-cardiac surgery patients is unknown. We evaluated the hemodynamic effects of FBT with fluid warmed to 40°C (warm FBT) versus room-temperature fluid.

METHODS

In this single centre prospective before-and-after study, we evaluated the effects of 500 ml of warm versus room-temperature compound sodium lactate administered over <30 minutes, in 50 cardiac surgery patients admitted to ICU. We recorded hemodynamics continuous before and for 30 minutes after the first FBT. We defined CI responsiveness (CI-R) as an CI increase >15% of baseline immediately after FBT and effect dissipation if the CI returned to <5% of baseline and MAP responsiveness as >10% increase and dissipation as return to <3 mmHg of baseline.

RESULTS

Hypotension (56%) and low CI (40%) typically triggered FBT. Temperature decreased >0.3°C in 13 (52%) patients after room-temperature FBT versus 0 (0%) after warm FBT (p < 0.01). CI and MAP responsiveness was similar (16 [64%] versus 11 [44%], p = 0.15 and 15 [60%] versus 17 [68%], p = 0.77, respectively). Among CI responders, CI increased more with room-temperature FBT (+0.6 [IQR, 0.5-1.1] versus +0.5 [IQR, 0.4-0.6] L/min/m², p = 0.01). However, dissipation was more common after room-temperature versus warm FBT (9/16 [56%] versus 1/11 [9%], p = 0.02).

CONCLUSION

In postoperative cardiac surgery patients, warm FBT preserved core temperature and induced smaller but more sustained CI increases among responders. Fluid temperature appears to impact both core temperature and the duration of CI response.

Effect of Helmet Noninvasive Ventilation vs High-Flow Nasal Oxygen on Days Free of Respiratory Support in Patients With COVID-19 and Moderate to Severe Hypoxemic Respiratory Failure: The HENIVOT Randomized Clinical Trial

IMPORTANCE

High-flow nasal oxygen is recommended as initial treatment for acute hypoxemic respiratory failure and is widely applied in patients with COVID-19.

OBJECTIVE

To assess whether helmet noninvasive ventilation can increase the days free of respiratory support in patients with COVID-19 compared with high-flow nasal oxygen alone.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter randomized clinical trial in 4 intensive care units (ICUs) in Italy between October and December 2020, end of follow-up February 11, 2021, including 109 patients with COVID-19 and moderate to severe hypoxemic respiratory failure (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen ≤200).

INTERVENTIONS

Participants were randomly assigned to receive continuous treatment with helmet noninvasive ventilation (positive end-expiratory pressure, 10-12 cm H2O; pressure support, 10-12 cm H2O) for at least 48 hours eventually followed by high-flow nasal oxygen (n = 54) or high-flow oxygen alone (60 L/min) (n = 55).

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of days free of respiratory support within 28 days after enrollment. Secondary outcomes included the proportion of patients who required endotracheal intubation within 28 days from study enrollment, the number of days free of invasive mechanical ventilation at day 28, the number of days free of invasive mechanical ventilation at day 60, in-ICU mortality, in-hospital mortality, 28-day mortality, 60-day mortality, ICU length of stay, and hospital length of stay.

RESULTS

Among 110 patients who were randomized, 109 (99%) completed the trial (median age, 65 years [interquartile range {IQR}, 55-70]; 21 women [19%]). The median days free of respiratory support within 28 days after randomization were 20 (IQR, 0-25) in the helmet group and 18 (IQR, 0-22) in the high-flow nasal oxygen group, a difference that was not statistically significant (mean difference, 2 days [95% CI, -2 to 6]; P = .26). Of 9 prespecified secondary outcomes reported, 7 showed no significant difference. The rate of endotracheal intubation was significantly lower in the helmet group than in the high-flow nasal oxygen group (30% vs 51%; difference, -21% [95% CI, -38% to -3%]; P = .03). The median number of days free of invasive mechanical ventilation within 28 days was significantly higher in the helmet group than in the high-flow nasal oxygen group (28 [IQR, 13-28] vs 25 [IQR 4-28]; mean difference, 3 days [95% CI, 0-7]; P = .04). The rate of in-hospital mortality was 24% in the helmet group and 25% in the high-flow nasal oxygen group (absolute difference, -1% [95% CI, -17% to 15%]; P > .99).

CONCLUSIONS AND RELEVANCE

Among patients with COVID-19 and moderate to severe hypoxemia, treatment with helmet noninvasive ventilation, compared with high-flow nasal oxygen, resulted in no significant difference in the number of days free of respiratory support within 28 days. Further research is warranted to determine effects on other outcomes, including the need for endotracheal intubation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04502576.

Accuracy of non-invasive body temperature measurement methods in adult patients admitted to the intensive care unit: a systematic review and meta-analysis

Objective: Non-invasive thermometers are widely used in both clinical practice and trials to estimate core temperature. We aimed to investigate their accuracy and precision in patients admitted to the intensive care unit (ICU). Study design: Systematic review and meta-analysis. Data sources: We searched MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials to identify all relevant studies from 1966 to 2017. We selected published trials that reported the accuracy and precision of non-invasive peripheral thermometers (index test) in ICU patients compared with intravascular temperature measurement (reference test). The extracted data included the study design and setting, authors, study population, devices, and body temperature measurements. Methods: Two reviewers performed the initial search, selected studies, and extracted data. Study quality was assessed using the QUADAS-2 tool. Pooled estimates of the mean bias between index and reference tests and the standard deviation of mean bias were synthesised using DerSimonian and Laird random effects meta-analyses. Results: We included 13 cohort studies (632 patients, 105 375 measurements). Axillary, tympanic infrared and zero heat flux thermometers all underestimated intravascular temperature. Only oesophageal measurements showed clinically acceptable accuracy. We found an insufficient number of studies to assess precision for any technique. Study heterogeneity was high (99-100%). Risk of bias for the index test was unclear, mostly because of no device calibration or control for confounders. Conclusions: Compared with the gold standard of intravascular temperature measurement, non-invasive peripheral thermometers have low accuracy. This makes their clinical and trial-related use in ICU patients unreliable and potentially misleading.

Temperature and haemodynamic effects of a 100 mL bolus of 20% albumin at room versus body temperature in cardiac surgery patients

Objective: To study the temperature and haemodynamic effects of room versus body temperature 20% albumin fluid bolus therapy (FBT). Design: Single-centre, prospective, before-after trial. Setting: A tertiary intensive care unit (ICU) in Australia. Participants: Sixty ventilated post-cardiac surgery patients. Intervention: Room versus body temperature 100 mL 20% albumin FBT. Main outcome measures: We recorded haemodynamic data from FBT start to 30 minutes after FBT. The cardiac index (CI) response was defined by a CI increase > 15%, and the mean arterial pressure (MAP) response was defined by a MAP increase > 10%. Outcomes: Immediately after FBT, median blood temperature decreased by -0.1°C (interquartile range [IQR], -0.1 to 0.0°C) with room temperature albumin versus 0.0°C (IQR, -0.1 to 0.0°C) with body temperature albumin (P < 0.001). The CI or MAP responses were similar. There was, however, a time and study group interaction for blood temperature (P < 0.001) for absolute and relative changes. In addition, mean pulmonary arterial pressure (PAP) (P = 0.002) increased more with body temperature albumin and remained higher for most of the observation period. Conclusion: Compared with room temperature albumin FBT, body temperature 20% albumin FBT prevents FBT-associated blood temperature fall and increases mean PAP. However, CI and MAP changes were the similar between the two groups, implying that fluid temperature has limited haemodynamic effects in these patients.

Thromboelastography clot strength profiles and effect of systemic anticoagulation in COVID-19 acute respiratory distress syndrome: a prospective, observational study

OBJECTIVE

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection may yield a hypercoagulable state with fibrinolysis impairment. We conducted a single-center observational study with the aim of analyzing the coagulation patterns of intensive care unit (ICU) COVID-19 patients with both standard laboratory and viscoelastic tests. The presence of coagulopathy at the onset of the infection and after seven days of systemic anticoagulant therapy was investigated.

PATIENTS AND METHODS

Forty consecutive SARS-CoV-2 patients, admitted to the ICU of a University hospital in Italy between 29th February and 30th March 2020 were enrolled in the study, providing they fulfilled the acute respiratory distress syndrome criteria. They received full-dose anticoagulation, including Enoxaparin 0.5 mg·kg-1 subcutaneously twice a day, unfractionated Heparin 7500 units subcutaneously three times daily, or low-intensity Heparin infusion. Thromboelastographic (TEG) and laboratory parameters were measured at admission and after seven days.

RESULTS

At baseline, patients showed elevated fibrinogen activity [rTEG-Ang 80.5° (78.7 to 81.5); TEG-ACT 78.5 sec (69.2 to 87.9)] and an increase in the maximum amplitude of clot strength [FF-MA 42.2 mm (30.9 to 49.2)]. No alterations in time of the enzymatic phase of coagulation [CKH-K and CKH-R, 1.1 min (0.85 to 1.3) and 6.6 min (5.2 to 7.5), respectively] were observed. Absent lysis of the clot at 30 minutes (LY30) was observed in all the studied population. Standard coagulation parameters were within the physiological range: [INR 1.09 (1.01 to 1.20), aPTT 34.5 sec (29.7 to 42.2), antithrombin 97.5% (89.5 to 115)]. However, plasma fibrinogen [512.5 mg·dl-1 (303.5 to 605)], and D-dimer levels [1752.5 ng·ml-1 (698.5 to 4434.5)], were persistently increased above the reference range. After seven days of full-dose anticoagulation, average TEG parameters were not different from baseline (rTEG-Ang p = 0.13, TEG-ACT p = 0.58, FF-MA p = 0.24, CK-R p = 0.19, CKH-R p  = 0.35), and a persistent increase in white blood cell count, platelet count and D-dimer was observed (white blood cell count p < 0.01, neutrophil count p = 0.02, lymphocyte count p < 0.01, platelet count p = 0.13 < 0.01, D-dimer levels p= 0.02).

CONCLUSIONS

SARS-CoV-2 patients with acute respiratory distress syndrome show elevated fibrinogen activity, high D-dimer levels and maximum amplitude of clot strength. Platelet count, fibrinogen, and standard coagulation tests do not indicate a disseminated intravascular coagulation. At seven days, thromboelastographic abnormalities persist despite full-dose anticoagulation.

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).

Comparison of the Hemodynamic and Temperature Effects of a 500-mL Bolus of 4% Albumin at Room Versus Body Temperature in Cardiac Surgery Patients

OBJECTIVE

To compare the hemodynamic effect of room temperature (cold) 4% albumin fluid bolus therapy (FBT) with body temperature (warm) albumin FBT.

DESIGN

Prospective, before-after trial.

SETTING

A tertiary intensive care unit (ICU).

PARTICIPANTS

Sixty ventilated, post-cardiac surgery patients prescribed with 4% albumin FBT.

INTERVENTION

Cold or warm 4% albumin 500 ml FBT.

MEASUREMENTS AND MAIN RESULTS

We recorded hemodynamic parameters before and for 30 minutes after FBT. Cardiac index (CI) and mean arterial pressure (MAP) responses were defined by a CI increase >15% and a MAP increase >10%, respectively. Immediately after FBT, median [interquartile range] core temperature changed by -0.3 [-0.4; -0.3] °C with cold albumin vs. 0.0 [0.0; 0.1]°C with warm albumin (P<0.001). The median CI increase was 0.3 [0.0; 0.5] L/min/m2 with 14 CI-responders (47%) in both groups (P>0.99). The median immediate MAP increase was 9 [3; 15] mmHg with cold albumin vs. 11 [5; 13] mmHg with warm albumin (P=0.79), with a MAP-response in 16 vs. 17 patients (P=0.99). There was an interaction between group and time for MAP (P=0.002), mean pulmonary artery pressure (PAP) (P=0.002) and core temperature (P<0.001). In the cold albumin group, after the initial response, MAP and mean PAP decreased more slowly than with warm albumin and, after the initial fall, core temperature increased toward baseline.

CONCLUSION

In postoperative cardiac surgery patients, warm albumin FBT prevents the decrease in core temperature and, after an initial similar increase, is associated with a faster return of MAP and mean PAP toward baseline.

Risk prediction for severe acute kidney injury by integration of urine output, glomerular filtration, and urinary cell cycle arrest biomarkers

BACKGROUND

Frequent assessment of urine output (UO), serum creatinine (sCr) and urinary cell cycle arrest biomarkers (CCAB) may improve acute kidney injury (AKI) prediction.

OBJECTIVE

To study the performance of UO, short term sCr changes and urinary CCAB to predict severe AKI.

METHODS

We measured 6 hours of UO, 6-hourly sCr changes, and urinary CCABs in all critically ill patients with cardiovascular or respiratory failure or early signs of renal stress between February and October 2018. We studied the association of such measurements, and their combination, with the development of AKI Stage 2 or 3 of the Kidney Disease: Improving Global Outcomes (KDIGO) definition at 12 hours. We evaluated predictive performance with logistic regression, area under the receiver operating characteristic (AUROC) curve, and net reclassification indices. We computed an optimal cut-off value for each biomarker.

RESULTS

We assessed 622 patients and, as per the exclusion criteria, we enrolled 105 critically ill patients. After 12 hours of enrolment, AKI occurred in 32 patients (30%). UO, sCr change over 6 hours and CCABs were significantly associated with severe AKI at 12 hours, with all variables achieving an AUROC > 0.7 after adjustment. Combination of any of the two or three variables achieved an AUROC > 0.7 for subsequent severe AKI at 12 hours. The optimal predictive high specificity cut-off values were ≤ 0.4 mL/kg/h for UO, variation of +15 μmol/L over 6 hours in sCr, and ≥ 1.5 (ng/mL)2/1000 for CCABs.

CONCLUSION

In this prospective study, an integrative approach using UO, short term sCr change and/or urinary CCABs showed a satisfactory performance for the prediction of severe AKI development at 12 hours.

Risk prediction for severe acute kidney injury by integration of urine output, glomerular filtration, and urinary cell cycle arrest biomarkers

BACKGROUND: Frequent assessment of urine output (UO), serum creatinine (sCr) and urinary cell cycle arrest biomarkers (CCAB) may improve acute kidney injury (AKI) prediction. OBJECTIVE: To study the performance of UO, short term sCr changes and urinary CCAB to predict severe AKI. METHODS: We measured 6 hours of UO, 6-hourly sCr changes, and urinary CCABs in all critically ill patients with cardiovascular or respiratory failure or early signs of renal stress between February and October 2018. We studied the association of such measurements, and their combination, with the development of AKI Stage 2 or 3 of the Kidney Disease: Improving Global Outcomes (KDIGO) definition at 12 hours. We evaluated predictive performance with logistic regression, area under the receiver operating characteristic (AUROC) curve, and net reclassification indices. We computed an optimal cut-off value for each biomarker. RESULTS: We assessed 622 patients and, as per the exclusion criteria, we enrolled 105 critically ill patients. After 12 hours of enrolment, AKI occurred in 32 patients (30%). UO, sCr change over 6 hours and CCABs were significantly associated with severe AKI at 12 hours, with all variables achieving an AUROC > 0.7 after adjustment. Combination of any of the two or three variables achieved an AUROC > 0.7 for subsequent severe AKI at 12 hours. The optimal predictive high specificity cut-off values were ≤ 0.4 mL/kg/h for UO, variation of +15 μmol/L over 6 hours in sCr, and ≥ 1.5 (ng/mL)2/1000 for CCABs. CONCLUSION: In this prospective study, an integrative approach using UO, short term sCr change and/or urinary CCABs showed a satisfactory performance for the prediction of severe AKI development at 12 hours.

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.

Haemodynamic effect of a 20% albumin fluid bolus in post-cardiac surgery patients

Objective: To study the cardiovascular effect over 30 minutes following the end of fluid bolus therapy (FBT) with 20% albumin in patients after cardiac surgery. Design: Prospective observational study. Setting: Intensive care unit of a tertiary university-affiliated hospital. Participants: Twenty post-cardiac surgery mechanically ventilated patients with a clinical decision to administer FBT. Intervention: FBT with a 100 mL bolus of 20% albumin. Main outcome measures: Cardiac index (CI) response was defined by a  15% increase, while mean arterial pressure (MAP) response was defined by a  10% increase. Results: The most common indication for FBT was hypotension (40%). Median duration of infusion was 7 minutes (interquartile range [IQR], 3–9 min). At the end of FBT, five patients (25%) showed a CI response, which increased to almost half in the following 30 minutes and dissipated in one patient. MAP response occurred in 11 patients (55%) and dissipated in five patients (45%) by a median of 6 minutes (IQR, 6–10 min). CI and MAP responses coexisted in four patients (20%). An intrabolus MAP response occurred in 17 patients (85%) but dissipated in 11 patients (65%) within a median of 7 minutes (IQR, 2–11 min). On regression analysis, faster fluid bolus administration predicted MAP increase at the end of the bolus. Conclusion: In post-cardiac surgery patients, CI response to 20% albumin FBT was not congruous with MAP response over 30 minutes. Although hypotension was the main indication for FBT and a MAP response occurred in most of patients, such response was maximal during the bolus, dissipated in a few minutes, and was dissociated from the CI response.

Haemodynamic effect of a 20% albumin fluid bolus in post-cardiac surgery patients

OBJECTIVE

To study the cardiovascular effect over 30 minutes following the end of fluid bolus therapy (FBT) with 20% albumin in patients after cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Intensive care unit of a tertiary university-affiliated hospital.

PARTICIPANTS

Twenty post-cardiac surgery mechanically ventilated patients with a clinical decision to administer FBT.

INTERVENTION

FBT with a 100 mL bolus of 20% albumin.

MAIN OUTCOME MEASURES

Cardiac index (CI) response was defined by a ≥ 15% increase, while mean arterial pressure (MAP) response was defined by a ≥ 10% increase.

RESULTS

The most common indication for FBT was hypotension (40%). Median duration of infusion was 7 minutes (interquartile range [IQR], 3-9 min). At the end of FBT, five patients (25%) showed a CI response, which increased to almost half in the following 30 minutes and dissipated in one patient. MAP response occurred in 11 patients (55%) and dissipated in five patients (45%) by a median of 6 minutes (IQR, 6-10 min). CI and MAP responses coexisted in four patients (20%). An intrabolus MAP response occurred in 17 patients (85%) but dissipated in 11 patients (65%) within a median of 7 minutes (IQR, 2-11 min). On regression analysis, faster fluid bolus administration predicted MAP increase at the end of the bolus.

CONCLUSION

In post-cardiac surgery patients, CI response to 20% albumin FBT was not congruous with MAP response over 30 minutes. Although hypotension was the main indication for FBT and a MAP response occurred in most of patients, such response was maximal during the bolus, dissipated in a few minutes, and was dissociated from the CI response.

Duplex Doppler evidence of high hepatic artery resistive index after liver transplantation: Role of portal hypertension and clinical impact

BACKGROUND

Early increase of hepatic artery resistive index (HARI) is frequently observed after liver transplant (LTx).

AIM

We aimed to investigate contributing factors and prognostic relevance of high HARI after LTx from deceased donor.

METHODS

We conducted a retrospective analysis of prospectively collected data from January 2017 and February 2019. According to the Duplex Doppler HARI values (3^d post-operative day), patients were grouped in normal (0.55-0.80) and high (>0.80-1) HARI groups.

RESULTS

Among 81 LTx, 36 had a high HARI and 45 a normal HARI. Patients developing high HARI were older, exhibited lower platelet, hemoglobin, platelet count/spleen diameter ratio, higher serum creatinine, and a more pronounced spleen enlargement (median values 170 versus 120 mm). At multivariate analysis, PLT/spleen diameter ratio (OR 0.994, p < 0.001) creatinine levels (OR 2.418, p = 0.029), and recipient age (OR 1.157, p = 0.004) significantly predicted the occurrence of high HARI. Patients with high or normal HARI had similar vascular complications, rejection rate and 90-day mortality. In most cases, HARI recovered to normal without any clinical effect.

CONCLUSIONS

HARI rises in presence of several surrogate markers of portal hypertension. The increase is mostly transitory, and it may result from the hepatic artery spasm due to the high portal blood flow.

A pilot randomised controlled trial evaluating the pharmacodynamic effects of furosemide versus acetazolamide in critically ill patients

OBJECTIVE

To compare the physiological and biochemical effects of a single intravenous dose of furosemide or acetazolamide in critically ill patients.

DESIGN

Single centre, pilot randomised controlled trial.

SETTING

Large tertiary adult intensive care unit (ICU).

PARTICIPANTS

Twenty-six adult ICU patients deemed to require diuretic therapy.

INTERVENTION

Single dose of intravenous 40 mg furosemide or 500 mg acetazolamide.

MAIN OUTCOME MEASURES

Data were collected on urine output, cumulative fluid balance, and serum and urine biochemistry for 6 hours before and 6 hours after diuretic administration.

RESULTS

Study patients had a median age of 55 years (IQR, 50-66) and median APACHE III score of 44 (IQR, 37-52). Furosemide caused a much greater increase in-urine output and much greater median mass chloride excretion (121.7 mmol [IQR, 81.1-144.6] v 23.3 mmol [IQR, 20.4-57.3]; P < 0.01) than acetazolamide. Furosemide also resulted in a progressively more negative fluid balance while acetazolamide resulted in greater alkalinisation of the urine (change in median urinary pH, +2 [IQR, 1.75-2.12] v 0 [IQR, 0-0.5]; P = 0.02). In keeping with this effect, furosemide alkalinised and acetazolamide acidified plasma (change in median serum pH, +0.03 [IQR, 0.01-0.04] v -0.01 [IQR, -0.04 to 0]; P = 0.01; change in median serum HCO₃-, +1.5 mmol/L [IQR, 0.75-2] v -2 mmol/L [IQR, -3 to 0]; P < 0.01).

CONCLUSIONS

Furosemide is a more potent diuretic and chloriuretic agent than acetazolamide in critically ill patients, and achieves a threefold greater negative fluid balance. Compared with acetazolamide, furosemide acidifies urine and alkalinises plasma. Our findings imply that combination therapy might be a more physiological approach to diuresis in critically ill patients.

High-Flow Nasal Cannula Versus Standard Oxygen Therapy After Extubation in Liver Transplantation: A Matched Controlled Study

BACKGROUND

High-flow nasal cannula (HFNC) is a key component of oxygen therapy and has largely been used in patients with acute respiratory failure. We conducted a matched controlled study with the aim to compare the preventive use of oxygen therapy delivered by HFNC versus via air-entrainment mask (standard O₂) after extubation in adult subjects with liver transplantation for reducing postextubation hypoxemia.

METHODS

Twenty-nine subjects with liver transplantation who received HFNC after extubation (HFNC group) were matched 1:1 with 29 controls (standard O₂ group) chosen from an historical group of 90 subjects admitted to the ICU during the previous 36 months. The primary outcome of the study was the incidence of hypoxemia at 1 h and 24 h after extubation. Secondary outcomes were the rate of weaning failure, ICU length of stay, and 28-d mortality.

RESULTS

The incidence of hypoxemia was not significantly different between the HFNC and standard O₂ groups at 1 h and 24 h after extubation. In the HFNC group, there was a trend toward a lower rate of weaning failure compared with the standard O₂ group. ICU length of stay and 28-d mortality were similar in both groups.

CONCLUSIONS

Early application of HFNC in the subjects with liver transplantation did not reduce the incidence of hypoxemia after extubation compared with standard O₂ and did not modify the incidence of weaning failure, ICU length of stay, and 28-d mortality in this high-risk population of subjects. (ClinicalTrials.gov registration NCT03441854.).

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.

Furosemide reverses medullary tissue hypoxia in ovine septic acute kidney injury

In experimental sepsis, the rapid development of renal medullary hypoxia precedes the development of acute kidney injury (AKI) and may contribute to its pathogenesis. We investigated whether inhibiting active sodium transport and oxygen consumption in the medullary thick ascending limb with furosemide attenuates the medullary hypoxia in experimental septic AKI. Sheep were instrumented with flow probes on the pulmonary and renal arteries and fiber optic probes to measure renal cortical and medullary perfusion and oxygen tension (Po₂). Sepsis and AKI were induced by infusion of live Escherichia coli. At 24 h of sepsis there were significant decreases in renal medullary tissue perfusion (1,332 ± 233 to 698 ± 159 blood perfusion units) and Po₂ (44 ± 6 to 19 ± 6 mmHg) (both P < 0.05). By 5 min after intravenous administration of furosemide (20 mg), renal medullary Po₂ increased to 43 ± 6 mmHg and remained at this normal level for 8 h. Furosemide caused transient increases in fractional excretion of sodium and creatinine clearance, but medullary perfusion, renal blood flow, and renal oxygen delivery were unchanged. Urinary F₂-isoprostanes, an index of oxidative stress, were not significantly changed at 24 h of sepsis but tended to transiently decrease after furosemide treatment. In septic AKI, furosemide rapidly restored medullary Po₂ to preseptic levels. This effect was not accompanied by changes in medullary perfusion or renal oxygen delivery but was accompanied by a transient increase in fractional sodium excretion, implying decreased oxygen consumption as a mechanism.

Modern technology-derived normative values for cerebral tissue oxygen saturation in adults

Modern near-infrared spectroscopy technology is increasingly adopted to measure cerebral tissue oxygen saturation. However, the normal range of cerebral tissue oxygen saturation in adults with such technology is unknown. We sought to measure cerebral tissue oxygen saturation in healthy volunteers using the novel O3 Regional Oximetry® device (Masimo Corporation, Irvine, CA, USA) and assess its relationship with key physical and haemodynamic characteristics. For ≥5 minutes, we continuously recorded cerebral tissue oxygen saturation, pulse oximetry, cardiac index and mean arterial pressure. We assessed for differences in cerebral tissue oxygen saturation between hemispheres, sex, skin type, comorbidity or smoking status, and for associations between cerebral tissue oxygen saturation and age, height, weight, SpO₂and haemodynamic parameters. We recorded >32,000 observations in 98 volunteers aged 22 to 60 years, including 41 (42%) males. One-fifth had one or more co morbidities ( n=22, 22.5%), one-tenth were either current or former-smokers ( n=13, 13%), and most had a Fitzpatrick skin type of 3 or lower ( n=84, 86%). The mean combined average cerebral tissue oxygen saturation was 67.6% (95% confidence interval 66.8%-68.6%). We found statistically significant differences in cerebral tissue oxygen saturation according to hemisphere and an association between cerebral tissue oxygen saturation and mean arterial pressure and cardiac index. The combined average cerebral tissue oxygen saturation in 98 healthy volunteers was 67.6% with a narrow confidence interval and no combined average cerebral tissue oxygen saturation was below 56%. We also observed statistically significant yet quantitatively small cerebral tissue oxygen saturation differences between hemispheres, and an association between cerebral tissue oxygen saturation and mean arterial pressure and cardiac index.

Body temperature measurement methods and targets in Australian and New Zealand intensive care units

OBJECTIVE

In Australian and New Zealand (ANZ) intensive care units (ICUs), the preferred measurement methods and targets for temperature remain uncertain, but are crucial for future interventional studies. We aimed to investigate the reported use of temperature measurement methods and targets in ANZ ICUs.

DESIGN, SETTINGS AND PARTICIPANTS

Structured online questionnaire delivered via the email list of the Australian and New Zealand Intensive Care Society Clinical Trials Group.

MAIN OUTCOME MEASURES

Measurements methods and targets for temperature in ANZ ICUs.

RESULTS

Of 209 respondents, 130 were nurses (62.2%) and 79 were doctors (37.8%). Only 21.5% of the respondents reported having a unit protocol for measuring body temperature. However, invasive temperature measurement methods were preferred by doctors (69.8% v 55.3%) and non-invasive methods by nurses (29.9% v 44.2%). Moreover, among non-invasive methods, tympanic measurement was preferred by doctors (66.0% v 26.9%) and axillary by nurses (11.7% v 51.9%). Both professions reported a wide range of temperature thresholds that they believed required cooling interventions, but 16.7% of doctors and 42.4% of nurses reported that, in patients with cardiac arrest, they would actively cool patients only if the temperature was ≥ 38°C.

CONCLUSION

In ANZ ICUs, preferred temperature measurement methods and targets are typically not governed by protocol, vary greatly and differ between doctors and nurses. Targeted temperature management after cardiac arrest is not fully established. Future studies of the comparative accuracy of non-invasive temperature measurements methods and practice in patients with cardiac arrest appear important.

Magnesium sulfate therapy after cardiac surgery: a before-and-after study comparing strategies involving bolus and continuous infusion

BACKGROUND

Magnesium therapy may reduce the risk of atrial fibrillation after cardiac surgery. However, studies are heterogeneous in relation to dosage and method of delivery and no studies have directly compared the biochemical effect of different delivery strategies.

AIMS

We conducted a before-and-after study to compare the effects of two strategies of magnesium delivery after cardiac surgery.

METHODS

We conducted a prospective interventional before-and-after study. We enrolled patients admitted to the intensive care unit (ICU) after cardiac surgery and with no history of renal failure. The before period consisted of a single 20 mmol of magnesium sulfate bolus administered over one hour. The after period comprised a 10 mmol magnesium loading dose over one hour followed by a continuous infusion at 3 mmol/h for 12 hours. We measured serum and urine magnesium levels at baseline (T0), at the end of loading dose (T1), 6 (T2) and 12 hours after the intervention (T3).

RESULTS

We enrolled 60 patients (30 in each group) with similar baseline characteristics. In the before period, patients had a higher peak serum magnesium level at T1 (1.88 ± 0.06 v 1.59 ± 0.04 mmo/L; P < 0.001) compared with the after period. However, at 6 hours, patients in the after period had a significantly higher magnesium level (1.61 ± 0.04 v 1.29 ± 0.26 mmol/L; P < 0.001) and this level remained higher at 12 hours (1.70 ± 0.05 v 1.17 ± 0.02; P < 0.001), leading to increased time-weighted magnesaemia (P < 0.001). These changes occurred despite a significantly increased urinary magnesium concentration, fractional excretion of magnesium, and magnesium clearance, which paralleled changes in magnesaemia (P < 0.001).

CONCLUSIONS

The strategy of a 10 mmol magnesium bolus followed by a continuous infusion over 12 hours achieved a more sustained and moderately elevated magnesium concentration in comparison to a single 20 mmol bolus, despite increased urinary losses of magnesium. Further studies are required to assess a more extended continuous infusion.

Repeated sensor use for regional cerebral oxygenation measurements by near-infrared spectroscopy: a technical report

OBJECTIVE

Near-infrared spectroscopy (NIRS) has been used in clinical practice to assess regional cerebral tissue oxygen saturation (StcO₂). There is no evidence whether repeated use of the same sensor affects StcO₂ measurements. We aimed to assess whether there was a significant systematic decrease or increase in StcO₂ when NIRS sensors were reused.

DESIGN

Participants were divided into three groups (A, B and C). StcO₂ was recorded over 5 minutes daily for 5 days in Groups A and B ("new-sensor" [NS] period; sensor age, 1-5 days) and in Groups A and C, with the sensor previously used for A ("extended-use" [EU] period; sensor age, 6-10 days).

SETTING

Single-centre, university hospital, intensive care unit.

PARTICIPANTS

Healthy volunteers.

MAIN OUTCOME MEASURES

StcO₂ change within and between study periods.

RESULTS

In 13 participants (9 male; median age, 30 years), the range of median StcO₂ values per day was 65-72%. In the NS period, there were no changes in right-sided StcO₂, and left-sided StcO₂ showed no systematic or progressive patterns of increase or decrease when comparing Day 1 with subsequent days. There were no differences when comparing Day 1 with subsequent days (up to Day 10) in the EU period or between the NS and EU periods for left or right StcO₂.

CONCLUSIONS

Repeated use of NIRS sensors measured StcO₂ in different individuals for up to 10 days. There were no significant, systematic, persistent or progressive changes in StcO₂ with extended use over time. Our findings suggest that StcO₂ does not change with sensor reuse for up to 10 days.

Prognostic value of the reactive oxygen species in severe sepsis and septic shock patients: a pilot study

BACKGROUND

Reactive oxygen species (ROS) have been shown to play a role in the pathophysiology of sepsis. The aim of this study was to investigate ROS production over time in critically ill with sepsis patients and its correlation with outcome.

METHODS

This was a pilot single-centre prospective, observational study of patients consecutively admitted to our 18-general ICU. Over a period of 6 months all the consecutive patients with recent-onset of severe sepsis or septic shock were enrolled. Clinical and demographic characteristics of all patients were recorded. ROMs (ROS metabolites), reduced sulfhydryl groups (SH) and plasmatic lactate levels were collected at enrollment in the study and then every 5-7 days over 28 days or until sepsis resolution or death during sepsis. ROMs were analysed spectrophotometrically by the d-ROMs test (Diacron-Italia). SH were assayed in plasma by Ellman's reaction by spectrophotometric method. Septic shock-related mortality was defined as death that occurred during the follow up period, when the signs of shock remained, and death could not be attributed to causes other than septic shock by the attending physician.

RESULTS

Twenty-five patients were studied. The SOFA score and the plasmatic lactate levels significantly correlated with the ROMs plasmatic levels. The mortality rate was higher in patients whose ROMs plasmatic levels decreased during septic shock evolution.

CONCLUSIONS

Serial measurements of the ROMs plasmatic levels together with the SOFA score and lactate levels could help to identify septic shock patients with a very high probability of death.

Clinical and microbiological outcome in septic patients with extremely low 25-hydroxyvitamin D levels at initiation of critical care

A relationship between vitamin D status and mortality in patients in intensive care units (ICU) has been documented. The present study aims to describe the clinical profile and sepsis-related outcome of critically ill septic patients with extremely low (<7 ng/mL) vitamin D levels at ICU admission. We conducted an observational study in the ICU of a teaching hospital including all patients admitted with severe sepsis/septic shock and undergoing 25-hydroxyvitamin D (25(OH)D) testing within the first 24 hours from admission. We studied 107 patients over 12 months. At ICU admission vitamin D deficiency (≤20 ng/mL) was observed in 93.5% of the patients: 57 (53.3%) showed levels <7 ng/mL. As primary outcome, sepsis-related mortality rate was higher in patients with vitamin D levels <7 ng/mL (50.9% versus 26%). Multivariate regression analysis showed that vitamin D concentration <7 ng/mL on ICU admission (p 0.01) and higher mean SAPS II (p <0.01) score were independent predictors of sepsis-related mortality. Patients with very low vitamin D levels suffered higher rate of microbiologically confirmed infections but a lower percentage of microbiological eradication with respect to patients whose values were >7 ng/mL (80.7% versus 58%, p 0.02; 35.3% versus 68%; p 0.03, respectively). Post hoc analysis showed that, in the extremely low vitamin D group, the 52 patients with pneumonia showed a longer duration of mechanical ventilation (9 days (3.75-12.5 days) versus 4 days (2-9 days), p 0.04) and the 66 with septic shock needed vasopressor support for a longer period of time (7 days (4-10 days) versus 4 days (2-7.25 days), p 0.02). Our results suggest that in critical septic patients extremely low vitamin D levels on admission may be a major determinant of clinical outcome. Benefits of vitamin D replacement therapy in this population should be elucidated.