Haemodynamic changes during prone versus supine position in patients with COVID-19 acute respiratory distress syndrome

BACKGROUND

Prone positioning improves oxygenation in patients with acute respiratory distress syndrome (ARDS) secondary to COVID-19. However, its haemodynamic effects are poorly understood.

OBJECTIVES

The objective of this study was to investigate the acute haemodynamic changes associated with prone position in mechanically ventilated patients with COVID-19 ARDS. The primary objective was to describe changes in cardiac index with prone position. The secondary objectives were to describe changes in mean arterial pressure, FiO2, PaO2/FiO2 ratio, and oxygen delivery (DO2) with prone position.

METHODS

We performed this cohort-embedded study in an Australian intensive care unit, between September and November 2021. We included adult patients with severe COVID-19 ARDS, requiring mechanical ventilation and prone positioning for respiratory failure. We placed patients in the prone position for 16 h per session. Using pulse contour technology, we collected haemodynamic data every 5 min for 2 h in the supine position and for 2 h in the prone position consecutively.

RESULTS

We studied 18 patients. Cardiac index, stroke volume index, and mean arterial pressure increased significantly in the prone position compared to supine position. The mean cardiac index was higher in the prone group than in the supine group by 0.44 L/min/m2 (95% confidence interval, 0.24 to 0.63) (P < 0.001). FiO2 requirement decreased significantly in the prone position (P < 0.001), with a significant increase in PaO2/FiO2 ratio (P < 0.001). DO2 also increased significantly in the prone position, from a median DO2 of 597 mls O2/min (interquartile range, 504 to 931) in the supine position to 743 mls O2/min (interquartile range, 604 to 1075) in the prone position (P < 0.001).

CONCLUSION

Prone position increased the cardiac index, mean arterial pressure, and DO2 in invasively ventilated patients with COVID-19 ARDS. These changes may contribute to improved tissue oxygenation and improved outcomes observed in trials of prone positioning.

Evaluating an inquiry-based learning program

Inquiry-based learning (IBL) is a promising educational framework that is understudied in graduate medical education. To determine participant satisfaction and engagement with phases of an IBL postgraduate education program, a mixed-methods study collected data via survey statements and open-ended responses. The authors included participants attending an intensive care medicine (ICM) IBL program from May to November 2020. Quantitative outcomes included participants' satisfaction with the IBL format and impact of engagement with IBL on the learning experience. Qualitative outcomes explored determinants of engagement with IBL phases and the impact on the learning experience. Of 378 attendees, 167 submitted survey responses (44.2%). There was strong agreement relating to overall satisfaction (93.4%). Responses indicated engagement with "orientation" (94.6%), "conceptualization" (97.3%), "discussion" (91.1%), and "conclusion" (91.0%) but limited engagement with the "investigation" phase (48.1%). Greater engagement with IBL phases had positive impacts, with repeat attenders having clearer learning objectives (79.1% vs. 56.6%, P < 0.05) and enhanced learning through collaborative discussion (65.9% vs. 48.7%, P < 0.05). Qualitative analysis showed that ICM learners value active learning principles, clear objectives, and a safe environment to expand their "knowledge base." Sessions facilitated "clinically relevant learning," with application of theoretical knowledge. Learners transformed and "reframed their understanding," using the input of others' experiences. ICM learners were highly satisfied with the IBL format and reported valuable learning. Participants engaged strongly with all IBL phases except the investigation phase during the sessions. IBL facilitated learners' active construction of meaning, facilitating a constructivist approach to learning.NEW & NOTEWORTHY An inquiry-based learning (IBL) program was launched as part of a novel binational intensive care medicine education program. Postgraduate intensive care medicine practitioners participated in this education intervention, where facilitated group discussions explored core intensive care medicine concepts. Survey responses indicated overall satisfaction, engagement with the IBL format, and a constructivist approach to learning. This study provided new insights into the benefits and challenges of an IBL program in the context of practicing clinicians.

Mega-dose sodium ascorbate: a pilot, single-dose, physiological effect, double-blind, randomized, controlled trial

BACKGROUND

Mega-dose sodium ascorbate (NaAscorbate) appears beneficial in experimental sepsis. However, its physiological effects in patients with septic shock are unknown.

METHODS

We conducted a pilot, single-dose, double-blind, randomized controlled trial. We enrolled patients with septic shock within 24 h of diagnosis. We randomly assigned them to receive a single mega-dose of NaAscorbate (30 g over 1 h followed by 30 g over 5 h) or placebo (vehicle). The primary outcome was the total 24 h urine output (UO) from the beginning of the study treatment. Secondary outcomes included the time course of the progressive cumulative UO, vasopressor dose, and sequential organ failure assessment (SOFA) score.

RESULTS

We enrolled 30 patients (15 patients in each arm). The mean (95% confidence interval) total 24-h UO was 2056 (1520-2593) ml with placebo and 2948 (2181-3715) ml with NaAscorbate (mean difference 891.5, 95% confidence interval [- 2.1 to 1785.2], P = 0.051). Moreover, the progressive cumulative UO was greater over time on linear mixed modelling with NaAscorbate (P < 0.001). Vasopressor dose and SOFA score changes over time showed faster reductions with NaAscorbate (P < 0.001 and P = 0.042). The sodium level, however, increased more over time with NaAscorbate (P < 0.001). There was no statistical difference in other clinical outcomes.

CONCLUSION

In patients with septic shock, mega-dose NaAscorbate did not significantly increase cumulative 24-h UO. However, it induced a significantly greater increase in UO and a greater reduction in vasopressor dose and SOFA score over time. One episode of hypernatremia and one of hemolysis were observed in the NaAscorbate group. These findings support further cautious investigation of this novel intervention. Trial registration Australian New Zealand Clinical Trial Registry (ACTRN12620000651987), Date registered June/5/2020.

Subsegmental pulmonary embolism and anticoagulant therapy: the impact of clinical context

BACKGROUND

Anticoagulation for subsegmental pulmonary embolism (SSPE) is controversial.

AIM

To assess the impact of clinical context on anticoagulation and outcomes of SSPE.

METHODS

We electronically searched computed tomography pulmonary angiogram reports to identify SSPE. We extracted demographic, risk factor, investigations and outcome data from the electronic medical record. We stratified patients according to anticoagulation and no anticoagulation.

RESULTS

From 1 January 2017 to 31 December 2019, we identified 166 patients with SSPE in 5827 pulmonary angiogram reports. Of these, 123 (74%) received anticoagulation. Compared with non-anticoagulated patients, such patients had a different clinical context: higher rates of previous venous thromboembolism (11% vs 0%; P = 0.019), more recent surgery (26% vs 9%; P = 0.015), more elevated serum D-dimer (22% vs 5%; P = 0.004), more lung parenchymal abnormalities (76% vs 61%; P = 0.037) and were almost twice as likely to require inpatient care (76% vs 42%; P < 0.001). Such patients also had twice the all-cause mortality at 1 year (32% vs 16%).

CONCLUSIONS

SSPE is diagnosed in almost 3% of pulmonary angiograms and is associated with high mortality, regardless of anticoagulation, due to coexistent disease processes rather than SSPE. Anticoagulation appears dominant but markedly affected by the clinical context of risk factors, alternative indications and illness severity. Thus, the controversy is partly artificial because anticoagulation after SSPE is clinically contextual with SSPE as only one of several factors.

Changes in SedLine-derived processed electroencephalographic parameters during hypothermia in patients undergoing cardiac surgery with cardiopulmonary bypass

Objective

Processed electroencephalography (pEEG) is used to monitor depth-of-anesthesia during cardiopulmonary bypass (CPB). The SedLine device has been recently introduced for pEEG monitoring. However, the effect of hypothermia on its parameters during CPB is unknown. Accordingly, we aimed to investigate temperature-induced changes in SedLine-derived pEEG parameters during CPB.

Design

Prospective observational study.

Setting

Cardiac surgery operating theatre.

Participants

28 patients undergoing elective cardiac surgery with CPB.

Interventions

We continuously measured patient state index (PSI), suppression ratio (SR), bilateral spectral edge frequency (SEF) and temperature. We used linear mixed modelling with fixed and random effects to study the interactions between pEEG parameters and core temperature.

Measurements and main results

During CPB maintenance, the median temperature was 32.1°C [interquartile range (IQR): 29.8-33.6] at the end of cooling and 32.8°C (IQR: 30.1-34.0) at rewarming initiation. For each degree Celsius change in temperature during cooling and rewarming the PSI either decreased by 0.8 points [95% confidence interval (CI): 0.7-1.0; p < 0.001] or increased by 0.7 points (95% CI: 0.6-0.8; p < 0.001). The SR increased by 2.9 (95% CI: 2.3-3.4); p < 0.001) during cooling and decreased by 2.2 (95% CI: 1.7-2.7; p < 0.001) during rewarming. Changes in the SEF were not related to changes in temperature.

Conclusions

During hypothermic CPB, temperature changes led to concordant changes in the PSI. The SR increased during cooling and decreased during rewarming. Clinicians using SedLine for depth-of-anesthesia monitoring should be aware of these effects when interpreting the PSI and SR values.

Sodium glucose co-transporter-2 inhibitors in intensive care unit patients with type 2 diabetes: a pilot case control study

BACKGROUND

Sodium glucose co-transporter-2 (SGLT2) inhibitors improve long-term cardiovascular and renal outcomes in individuals with type 2 diabetes. However, the safety of SGLT2 inhibitors in ICU patients with type 2 diabetes is uncertain. We aimed to perform a pilot study to assess the relationship between empagliflozin therapy and biochemical, and clinical outcomes in such patients.

METHODS

We included 18 ICU patients with type 2 diabetes receiving empagliflozin (10 mg daily) and insulin to target glucose range of 10-14 mmol/l according to our liberal glucose control protocol for patients with diabetes (treatment group). Treatment group patients were matched on age, glycated hemoglobin A1c, and ICU duration with 72 ICU patients with type 2 diabetes exposed to the same target glucose range but who did not receive empagliflozin (control group). We compared changes in electrolyte and acid-base parameters, hypoglycemia, ketoacidosis, worsening kidney function, urine culture findings, and hospital mortality between the groups.

RESULTS

Median (IQR) maximum increase in sodium and chloride levels were 3 (1-10) mmol/l and 3 (2-8) mmol/l in the control group and 9 (3-12) mmol/l and 8 (3-10) mmol/l in the treatment group (P = 0.045 for sodium, P = 0.059 for chloride). We observed no differences in strong ion difference, pH or base excess. Overall, 6% developed hypoglycemia in each group. No patient in the treatment group and one patient in the control group developed ketoacidosis. Worsening kidney function occurred in 18% and 29% of treatment and control group patients, respectively (P = 0.54). Urine cultures were positive in 22% of treatment group patients and 13% of control group patients (P = 0.28). Overall, 17% of treatment group patients and 19% of control group patients died in hospital (P = 0.79).

CONCLUSIONS

In our pilot study of ICU patients with type 2 diabetes, empagliflozin therapy was associated with increases in sodium and chloride levels but was not significantly associated with acid-base changes, hypoglycemia, ketoacidosis, worsening kidney function, bacteriuria, or mortality.

Glycemic control and blood gas sampling frequency during continuous glucose monitoring in the intensive care unit: A before-and-after study

BACKGROUND

Whether subcutaneous continuous glucose monitoring (CGM) can safely replace intermittent arterial blood gas glucose analyses in intensive care unit (ICU) patients remains uncertain. We aimed to compare CGM to blood gas glucose values and assess whether CGM use reduces blood gas sampling frequency and glucose variability in ICU patients with type 2 diabetes managed with liberal glucose control.

METHODS

We used the FreeStyle Libre CGM in 15 ICU patients and compared their blood glucose metrics with a pre-CGM control population of 105 ICU patients with type 2 diabetes. Both groups received insulin to target glucose range of 10-14 mmol/L. We used linear regression analysis adjusted for illness severity to assess the association of CGM use with blood gas sampling frequency and glucose variability. We used mean absolute relative difference (MARD) and Clarke error grid analysis to assess accuracy of matched CGM-blood glucose values overall, across glucose stata (<10, 10-14, >14 mmol/L), and over time (≤48, 48-96, >96 h).

RESULTS

We analyzed 483 matched glucose values. Overall MARD was 11.5 (95% CI, 10.7-12.3)% with 99% of readings in Clarke zones A and B. MARD was 15.5% for glucose values <10 mmol/L, 11.1% at 10-14 mmol/L, and 11.4% >14 mmol/L. MARD was 13.8% in the first 48 h, 10.9% at 48-96 h, and 8.9% beyond 96 h. CGM use was associated with 30% reduction in blood gas sampling frequency. CGM use was not associated with glucose variability as determined by glycemic lability index or standard deviation of blood glucose.

CONCLUSIONS

In our cohort of ICU patients with type 2 diabetes receiving liberal glycemic control, CGM showed acceptable accuracy and was associated with a reduction in blood gas sampling frequency without compromising glucose control. Lowest accuracy was observed at glucose values below 10 mmol/L and during the first 48 h of CGM use.

Trajectory of plasma syndecan-1 and heparan sulphate during major surgery: A retrospective observational study

BACKGROUND

Surgical trauma-induced inflammation during major surgery may disrupt endothelial integrity and affect plasma concentrations of glycocalyx constituents, such as syndecan-1 and heparan sulphate. To date, no studies have focused on their perioperative temporal changes.

METHODS

As part of a trial, we obtained plasma and urine specimens sampled during the perioperative period in 72 patients undergoing major abdominal surgery. The plasma concentration of syndecan-1 and heparan sulphate was measured on five occasions, from baseline to the second postoperative day. Plasma and urinary creatinine and urinary syndecan-1 concentrations were measured before surgery and on the first postoperative morning.

RESULTS

We observed three different temporal patterns of plasma syndecan-1 concentration. Group 1 'low' (64% of patients) showed only minor changes from baseline despite a median heparan sulphate increase of 67% (p < .005). Group 2 'increase' (21% of patients) showed a marked increase in median plasma syndecan-1 from 27 μg/L to 118 μg/L during the first postoperative day (p < .001) with a substantial (+670%; p < .005) increase in median plasma heparan sulphate from 279 to 2196 μg/L. Group 3 'high' (14% of patients) showed a constant elevation of plasma syndecan-1 to >100 μg/L, but low heparan sulphate levels. The plasma C-reactive protein concentration did not differ across the three groups and 90% of colon surgeries occurred in Group 1. Treatment with dexamethasone was similar across the three groups. Surgical blood loss, duration of surgery and liver resection were greatest in Group 2.

CONCLUSION

Changes in syndecan-1 and heparan sulphate after surgery appear to show three different patterns, with the greatest increases in those patients with greater blood loss, more liver surgery and longer operations. These observations suggest that increases in syndecan-1 and heparan sulphate reflect the degree of surgical injury.

Characteristics and outcomes of surgical patients admitted to an overnight intensive recovery unit: A retrospective observational study

Postoperative 'enhanced care' models that sit between critical care and ward-based care may allow for more cost-effective and efficient utilisation of resources for high-risk surgical patients. In this retrospective observational study, we describe an overnight intensive recovery model in a tertiary hospital, termed 'recovery high dependency unit', and the characteristics, treatment, disposition at discharge and in-hospital outcomes of patients admitted to this unit. We included all adult patients (≥18 years) admitted to the recovery high dependency unit for at least one hour between July 2017 and June 2020. Over this three-year period, 1257 patients were included in the study. The median length of stay in the recovery high dependency unit was 12.6 (interquartile range 9.1-15.9) hours and the median length of hospital stay was 8.3 (interquartile range 5.0-17.3) days. Hospital discharge data showed that 1027 (81.7%) patients were discharged home and that 37 (2.9%) patients died. Non-invasive ventilation was delivered to 59 (4.7%) patients and 290 (23.1%) required vasopressor support. A total of 164 patients (13.0%) were admitted to the intensive care unit following their recovery high dependency unit admission. Of the 1093 patients who were discharged to the ward, 70 patients (6.4%) had a medical emergency team call within 24 hours of discharge from the recovery high dependency unit. In this study of a recovery high dependency unit patient cohort, there was a relatively low need for intensive care unit admission postoperatively and a very low incidence of medical emergency team calls post-discharge to the ward. Other institutions may consider the introduction and evaluation of this model in the care of their higher risk surgical patients.

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.

A pilot study of the pharmacokinetics of continuous magnesium infusion in critically ill patients

Objective: The pharmacokinetics and haemodynamic effect of continuous magnesium infusion in non-cardiac intensive care unit (ICU) patients are poorly understood. We aimed to measure serum and urine magnesium levels during bolus and continuous infusion in critically ill adults, compare serum levels with those of a control population, and assess its haemodynamic effect. Design: Pharmacokinetic study Setting: A single tertiary adult ICU. Participants: Mechanically ventilated adults requiring vasopressor support. Intervention: A 10 mmol bolus of magnesium sulfate followed by 1.5-3 mmol/h infusion for 24 hours. Main outcome measures: The primary outcome was the change in total serum magnesium concentration. The main secondary outcome was mean arterial pressure (MAP)- adjusted vasopressor dose. Results: We matched 31 treated patients with 93 controls. Serum total magnesium concentration increased from a median 0.94 mmol/L (interquartile range [IQR], 0.83-1.10 mmol/L) to 1.38 mmol/L (IQR, 1.25-1.69 mmol/L; P < 0.001) and stabilised between a median 1.64 mmol/L (IQR, 1.38-1.88 mmol/L) at 7 hours and 1.77 mmol/L (IQR, 1.53-1.85 mmol/L) at 25 hours. This was significantly greater than in the control group (P < 0.001). The MAP-adjusted vasopressor dose decreased during magnesium infusion (P < 0.001). Conclusion: In critically ill patients, a magnesium sulfate bolus followed by continuous infusion achieved moderately elevated levels of total serum magnesium with a decrease in MAP-adjusted vasopressor dose. Trial registration number: ACTRN12619000925145.

Serum Creatinine Levels and Nephrocheck® Values With and Without Correction for Urine Dilution-A Multicenter Observational Study

Background

The Nephrocheck® test is a single-use cartridge designed to measure the concentrations of two novel cell-cycle arrest biomarkers of acute kidney injury, namely tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7). Correlations of serum creatine values and TIMP-2 and IGFBP7 with and without correction for urine dilution have not been previously undertaken in patients undergoing major abdominal surgery. We hypothesized that the Nephrocheck® values would be significantly different with and without correction for urine dilution in patients with elevated creatinine values post major abdominal surgery.

Methods

We performed a post hoc analysis of serum and urine specimens sampled preoperatively and postoperatively in 72 patients undergoing major abdominal surgery. Thirty samples were measured from patients with the greatest decrease and the greatest increase in postoperative serum creatinine values. Urine was analyzed with the Nephrocheck to predict the risk of acute kidney injury (AKIRisk™). We then examined the relationship between serum creatinine and the urinary excretion of TIMP-2 and IGFBP7 as measured by the Nephrocheck test. The AKIRisk between the groups with and without correction for urine dilution was assessed.

Results

The median perioperative change in serum creatinine in the two groups was −19% and +57%, respectively. The uncorrected median baseline AKIRisk decreased from 0.70 (25th−75th percentiles, 0.09–1.98) to 0.35 (0.19–0.57) (mg/L)² in the first group and rose from 0.57 (0.22–1.53) to 0.85 (0.67–2.20) (mg/L)² in the second group. However, when corrected for the squared urine dilution, the AKIRisk™ in patients with postoperative increases in serum creatinine was not indicative of kidney injury; the corrected AKIRisk was 8.0 (3.2–11.7) μg²/mmol² before surgery vs.6.9 (5.3–11.0) μg²/mmol² after the surgery (P = 0.69).

Conclusion

In the setting of major abdominal surgery, after correction of TIMP-2 and IGFBP7 for urine dilution, the Nephrocheck AKIRisk scores were significantly different from the uncorrected values. These finding imply that the AKIRisk index is a function of urine flow in addition to an increased release of the biomarkers.

A pilot, feasibility, randomised controlled trial of midodrine as adjunctive vasopressor for low-dose vasopressor-dependent hypotension in intensive care patients: The MAVERIC study

PURPOSE

To assess the feasibility and physiological efficacy of adjunctive midodrine in patients with vasopressor-dependent hypotension.

MATERIALS AND METHODS

This was a pilot, open label, randomised controlled trial. Patients were enrolled from two tertiary intensive care units on low dose intravenous vasopressor therapy for more than 24 h. We randomly assigned patients to receive either adjunctive midodrine (10 mg every 8 h) or usual care. The primary efficacy outcome was time to cessation of intravenous vasopressor therapy. Secondary outcomes included protocol compliance, ICU and hospital length of stay.

RESULTS

We screened 381 patients over 22-months and enrolled 62 (32 in midodrine group, 30 in usual care group). Median time to cessation of vasopressor infusion was 16.5 h for midodrine vs 19 h for usual care (p = 0.22). Time in ICU (50 [25.50, 74.00] hours for midodrine v 59 [38.50, 93.25] hours for usual care, p = 0.14) and hospital length of stay (9 days vs. 7.5 days, p = 0.92) were similar. Protocol compliance was 96.9%. One patient ceased midodrine early due to symptomatic bradycardia.

CONCLUSIONS

Adjunctive midodrine therapy was feasible with acceptable compliance, duration of therapy, and safety profile. However, at the chosen dose, there was no evidence of physiological or clinical efficacy.

Effect of adjunctive vitamin C, glucocorticoids, and vitamin B1 on longer-term mortality in adults with sepsis or septic shock: a systematic review and a component network meta-analysis

We aimed to compare the effects of vitamin C, glucocorticoids, vitamin B1, combinations of these drugs, and placebo or usual care on longer-term mortality in adults with sepsis or septic shock. MEDLINE, Embase, CENTRAL, ClinicalTrials.gov and WHO-ICTRP were searched. The final search was carried out on September 3rd, 2021. Multiple reviewers independently selected randomized controlled trials (RCTs) comparing very-high-dose vitamin C (≥ 12 g/day), high-dose vitamin C (< 12, ≥ 6 g/day), vitamin C (< 6 g/day), glucocorticoid (< 400 mg/day of hydrocortisone), vitamin B1, combinations of these drugs, and placebo/usual care. We performed random-effects network meta-analysis and, where applicable, a random-effects component network meta-analysis. We used the Confidence in Network Meta-Analysis framework to assess the degree of treatment effect certainty. The primary outcome was longer-term mortality (90-days to 1-year). Secondary outcomes were severity of organ dysfunction over 72 h, time to cessation of vasopressor therapy, and length of stay in intensive care unit (ICU). Forty-three RCTs (10,257 patients) were eligible. There were no significant differences in longer-term mortality between treatments and placebo/usual care or between treatments (10 RCTs, 7,096 patients, moderate to very-low-certainty). We did not find any evidence that vitamin C or B1 affect organ dysfunction or ICU length of stay. Adding glucocorticoid to other treatments shortened duration of vasopressor therapy (incremental mean difference, - 29.8 h [95% CI - 44.1 to - 15.5]) and ICU stay (incremental mean difference, - 1.3 days [95% CI - 2.2 to - 0.3]). Metabolic resuscitation with vitamin C, glucocorticoids, vitamin B1, or combinations of these drugs was not significantly associated with a decrease in longer-term mortality.

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.

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.

A multicenter randomized clinical trial of pharmacological vitamin B1 administration to critically ill patients who develop hypophosphatemia during enteral nutrition (The THIAMINE 4 HYPOPHOSPHATEMIA trial)

BACKGROUND

Hypophosphatemia may be a useful biomarker to identify thiamine deficiency in critically ill enterally-fed patients. The objective was to determine whether intravenous thiamine affects blood lactate, biochemical and clinical outcomes in this group.

METHOD

This randomized clinical trial was conducted across 5 Intensive Care Units. Ninety critically ill adult patients with a serum phosphate ≤0.65 mmol/L within 72 h of commencing enteral nutrition were randomized to intravenous thiamine (200 mg every 12 h for up to 14 doses) or usual care (control). The primary outcome was blood lactate over time and data are median [IQR] unless specified.

RESULTS

Baseline variables were well balanced (thiamine: lactate 1.2 [1.0, 1.6] mmol/L, phosphate 0.56 [0.44, 0.64] mmol/L vs. control: lactate 1.0 [0.8, 1.3], phosphate 0.54 [0.44, 0.61]). Patients randomized to the intervention received a median of 11 [7.5, 13.5] doses for a total of 2200 [1500, 2700] mg of thiamine. Blood lactate over the entire 7 days of treatment was similar between groups (mean difference = -0.1 (95 % CI -0.2 to 0.1) mmol/L; P = 0.55). The percentage change from lactate pre-randomization to T = 24 h was not statistically different (thiamine: -32 (-39, -26) vs. control: -24 (-31, -16) percent, P = 0.09). Clinical outcomes were not statistically different (days of vasopressor administration: thiamine 2 [1, 4] vs. control 2 [0, 5.5] days; P = 0.37, and deaths 9 (21 %) vs. 5 (11 %); P = 0.25).

CONCLUSIONS

In critically ill enterally-fed patients who developed hypophosphatemia, intravenous thiamine did not cause measurable differences in blood lactate or clinical outcomes.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry (ACTRN12619000121167).

Efficacy and Safety of Parenteral High-Dose Vitamin C Therapy in Pediatric Patients: A Scoping Review

OBJECTIVES

Recently, several adult trials have investigated the potential benefit of high-dose vitamin C therapy in critically ill patients. In pediatric patients, little is known on the efficacy, safety, and risk of high-dose vitamin C therapy. We aimed to review the efficacy and potential harm associated with high-dose vitamin C treatment.

DATA SOURCES

We searched MEDLINE, EMBASE, Cochrane Library, and National Institute of Health Clinical Trials Register.

STUDY SELECTION

We included studies in neonatal and pediatric patients who received IV or intra-arterial high-dose vitamin C (ascorbic acid) defined as greater than or equal to 75 mg/kg/d.

DATA EXTRACTION

Two independent investigators screened articles and extracted data.

DATA SYNTHESIS

We found 1,364 articles, assessed 193 full texts for eligibility, and identified 12 eligible studies. These studies included 855 patients, with 194 receiving high-dose vitamin C. The age of patients who received high-dose vitamin C ranged from 2 hours after delivery to 8.4 years (median 2.4 yr), and the vitamin C dose ranged from 100 to 1,500 mg/kg/d (median 260.5 mg/kg/d). Four studies were double-blind randomized controlled trials, and no clinical efficacy outcome was reported in favor of or against vitamin C. Furthermore, no adverse event or signal of harm was reported with high-dose vitamin C.

CONCLUSIONS

In 12 studies with 194 children treated with parenteral high-dose vitamin C, there was no evidence of clinical efficacy or inferior clinical outcomes in double-blind randomized controlled trials, and no reported harmful effects. These findings justify further investigations of this treatment in children.

Early net ultrafiltration rate and mortality in critically ill patients receiving continuous renal replacement therapy

BACKGROUND

In patients treated with continuous renal replacement therapy (CRRT), early net ultrafiltration (NUF) rates may be associated with differential outcomes. We tested whether higher early NUF rates are associated with increased mortality in CRRT patients.

METHODS

We performed a retrospective, observational study of all patients treated with CRRT within 14 days of intensive care unit admission. We defined the early (first 48 h) NUF rate as the volume of fluid removed per hour adjusted for patient body weight and analysed as a categorical variable (>1.75, 1.01-1.75 and <1.01 mL/kg/h). The primary outcome was 28-day mortality. To deal with competing risk, we also compared different time epochs.

RESULTS

We studied 347 patients {median age 64 [interquartile range (IQR) 53-71] years and Acute Physiology and Chronic Health Evaluation III score 73 [IQR 54-90]}. Compared with NUF rates <1.01 mL/kg/h, NUF rates >1.75 mL/kg/h were associated with greater mortality rates in each epoch: Days 0-5, adjusted hazard ratio (aHR) 1.27 [95% confidence interval (CI) 1.21-1.33]; Days 6-10, aHR 1.62 (95% CI 1.55-1.68); Days 11-15, aHR 1.87 (95% CI 1.79-1.94); Days 16-26, aHR 1.92 (95% CI 1.84-2.01) and Days 27-28, aHR 4.18 (95% CI 3.98-4.40). For every 0.5 mL/kg/h NUF rate increase, mortality similarly increased during these epochs.

CONCLUSION

Compared with early NUF rates <1.01 mL/kg/h, NUF rates >1.75 mL/kg/h are associated with increased mortality. These observations provide the rationale for clinical trials to confirm or refute these findings.

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.

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.

Reversal of the Pathophysiological Responses to Gram-Negative Sepsis by Megadose Vitamin C

OBJECTIVES

Oxidative stress appears to initiate organ failure in sepsis, justifying treatment with antioxidants such as vitamin C at megadoses. We have therefore investigated the safety and efficacy of megadose sodium ascorbate in sepsis.

DESIGN

Interventional study.

SETTING

Research Institute.

SUBJECTS

Adult Merino ewes.

INTERVENTIONS

Sheep were instrumented with pulmonary and renal artery flow-probes, and laser-Doppler and oxygen-sensing probes in the kidney. Conscious sheep received an infusion of live Escherichia coli for 31 hours. At 23.5 hours of sepsis, sheep received fluid resuscitation (30 mL/kg, Hartmann solution) and were randomized to IV sodium ascorbate (0.5 g/kg over 0.5 hr + 0.5 g/kg/hr for 6.5 hr; n = 5) or vehicle (n = 5). Norepinephrine was titrated to restore mean arterial pressure to baseline values (~80 mm Hg).

MEASUREMENTS AND MAIN RESULTS

Sepsis-induced fever (41.4 ± 0.2°C; mean ± se), tachycardia (141 ± 2 beats/min), and a marked deterioration in clinical condition in all cases. Mean arterial pressure (86 ± 1 to 67 ± 2 mm Hg), arterial Po2 (102.1 ± 3.3 to 80.5 ± 3.4 mm Hg), and renal medullary tissue Po2 (41 ± 5 to 24 ± 2 mm Hg) decreased, and plasma creatinine doubled (71 ± 2 to 144 ± 15 µmol/L) (all p < 0.01). Direct observation indicated that in all animals, sodium ascorbate dramatically improved the clinical state, from malaise and lethargy to a responsive, alert state within 3 hours. Body temperature (39.3 ± 0.3°C), heart rate (99.7 ± 3 beats/min), and plasma creatinine (32.6 ± 5.8 µmol/L) all decreased. Arterial (96.5 ± 2.5 mm Hg) and renal medullary Po2 (48 ± 5 mm Hg) increased. The norepinephrine dose was decreased, to zero in four of five sheep, whereas mean arterial pressure increased (to 83 ± 2 mm Hg). We confirmed these physiologic findings in a coronavirus disease 2019 patient with shock by compassionate use of 60 g of sodium ascorbate over 7 hours.

CONCLUSIONS

IV megadose sodium ascorbate reversed the pathophysiological and behavioral responses to Gram-negative sepsis without adverse side effects. Clinical studies are required to determine if such a dose has similar benefits in septic patients.

NephroCheck® Quality Test

BACKGROUND

The acute kidney injury (AKI) risk score helps detect moderate and severe AKI in the next 12-24 h. However, inappropriate urine collection may impact its results.

AIM

The aim of this study was to evaluate the stability of NephroCheck® after urine storage at different temperatures.

METHODS

The urine sample was centrifuged and split into 3 tubes. One was tested as soon as possible by the laboratory. The other 2 samples were frozen at -20 and -80°C, and the NephroCheck® test was performed 8 weeks later.

RESULTS

The mean values of the AKI risk score were 1.19 ± 0.93, 1.15 ± 1.14, and 1.20 ± 1.11 (ng/mL)2/1,000 for fresh urine, -20, and -80°C, respectively (p = 0.70). Spearman's rank correlation for -20 and -80°C versus immediate processing was strong with a rho of 0.82 and 0.98, respectively.

CONCLUSION

The AKI risk score was relatively stable. Urine could be collected without dry ice or liquid nitrogen and kept for up to 8 weeks with either -20 or -80°C freezing with stable NephroCheck® results.

Extracorporeal Ammonia Clearance for Hyperammonemia in Critically Ill Patients: A Scoping Review

INTRODUCTION

Hyperammonemia is a life-threatening condition. However, clearance of ammonia via extracorporeal treatment has not been systematically evaluated.

METHODS

We searched EMBASE and MEDLINE databases. We included all publications reporting ammonia clearance by extracorporeal treatment in adult and pediatric patients with clearance estimated by direct dialysate ammonia measurement or calculated by formula. Two reviewers screened and extracted data independently.

RESULTS

We found 1,770 articles with 312 appropriate for assessment and 28 studies meeting eligibility criteria. Most of the studies were case reports. Hyperammonemia was typically secondary to inborn errors of metabolisms in children and to liver failure in adult patients. Ammonia clearance was most commonly reported during continuous renal replacement therapy (CRRT) and appeared to vary markedly from <5 mL/min/m2 to >250 mL/min/m2. When measured during intermittent hemodialysis (IHD), clearance was highest and correlated with blood flow rate (R2 = 0.853; p < 0.001). When measured during CRRT, ammonia clearance could be substantial and correlated with effluent flow rate (EFR; R2 = 0.584; p < 0.001). Neither correlated with ammonia reduction. Peritoneal dialysis (PD) achieved minimal clearance, and other extracorporeal techniques were rarely studied.

CONCLUSIONS

Extracorporeal ammonia clearance varies widely with sometimes implausible values. Treatment modality, blood flow, and EFR, however, appear to affect such clearance with IHD achieving the highest values, PD achieving minimal values, and CRRT achieving substantial values especially at high EFRs. The role of other techniques remains unclear. These findings can help inform practice and future studies.

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.

P1460MEDIATORS OF THE IMPACT OF HOURLY NET ULTRAFILTRATION RATE ON MORTALITY IN CRITICALLY ILL PATIENTS RECEIVING CONTINUOUS RENAL REPLACEMENT THERAPY

Background and Aims

During continuous renal replacement therapy (CRRT), a high net ultrafiltration (NUF) rate is associated with increased mortality. However, it is unknown what might mediate its putative effect on mortality. This study aims to investigate whether the relationship between early (first 48h) NUF and mortality is mediated by fluid balance (FB), hemodynamic instability or low potassium or phosphate blood levels.

Method

We performed a retrospective, observational study in patients treated with CRRT within 14 days of ICU admission who survived &gt;48 hours. The primary outcome was hospital mortality. We applied multiple mediation analysis to identify possible mediators of NUF’s putative impact on mortality.

Results

We studied 347 patients [median (interquartile range) age: 64 (53–71) years and Acute Physiology and Chronic Health Evaluation (APACHE) III score: 73 (54–90)]. After adjustment for confounders, compared with a NUF&lt;1.01 ml/kg/h, a NUF rate &gt; 1.75 mL/kg/h was associated with significantly greater mortality (adjusted odds ratio [aOR], 1.15 [95%CI, 1.03 to 1.29]; p = 0.011). Adjusted univariable mediation analysis found no suggestion of a causal mediation effect for blood pressure, vasopressor therapy, or potassium levels, but identified a possible effect for FB (average causal mediation effect (ACME), 0.95 [95%CI, 0.90 to 0.99]; p = 0.062) and percentage of phosphate measurements with hypophosphatemia (ACME, 0.96 [95%CI, 0.92 to 1.00]; p = 0.055). However, on multiple mediator analysis, such variables lost any suggestion of a significant effect. In contrast, NUF rate remained associated with mortality even in their presence (average direct effect, 1.24 [95%CI, 1.11 to 1.40]; p &lt; 0.001).

Conclusion

An early NUF greater than 1.75 mL/kg/h was independently associated with increased hospital mortality. Its putative effect was not mediated by FB, low blood pressure, vasopressor use, hypokalemia or hypophosphatemia.

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.

Early net ultrafiltration rate and mortality in critically ill patients receiving continuous renal replacement therapy

BACKGROUND

In patients treated with continuous renal replacement therapy (CRRT), early net ultrafiltration (NUF) rates may be associated with differential outcomes. We tested whether higher early NUF rates are associated with increased mortality in CRRT patients.

METHODS

We performed a retrospective, observational study of all patients treated with CRRT within 14 days of intensive care unit admission. We defined the early (first 48 h) NUF rate as the volume of fluid removed per hour adjusted for patient body weight and analysed as a categorical variable (>1.75, 1.01-1.75 and <1.01 mL/kg/h). The primary outcome was 28-day mortality. To deal with competing risk, we also compared different time epochs.

RESULTS

We studied 347 patients {median age 64 [interquartile range (IQR) 53-71] years and Acute Physiology and Chronic Health Evaluation III score 73 [IQR 54-90]}. Compared with NUF rates <1.01 mL/kg/h, NUF rates >1.75 mL/kg/h were associated with greater mortality rates in each epoch: Days 0-5, adjusted hazard ratio (aHR) 1.27 [95% confidence interval (CI) 1.21-1.33]; Days 6-10, aHR 1.62 (95% CI 1.55-1.68); Days 11-15, aHR 1.87 (95% CI 1.79-1.94); Days 16-26, aHR 1.92 (95% CI 1.84-2.01) and Days 27-28, aHR 4.18 (95% CI 3.98-4.40). For every 0.5 mL/kg/h NUF rate increase, mortality similarly increased during these epochs.

CONCLUSION

Compared with early NUF rates <1.01 mL/kg/h, NUF rates >1.75 mL/kg/h are associated with increased mortality. These observations provide the rationale for clinical trials to confirm or refute these findings.

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.

Effect of Vitamin C, Hydrocortisone, and Thiamine vs Hydrocortisone Alone on Time Alive and Free of Vasopressor Support Among Patients With Septic Shock: The VITAMINS Randomized Clinical Trial

IMPORTANCE

It is unclear whether vitamin C, hydrocortisone, and thiamine are more effective than hydrocortisone alone in expediting resolution of septic shock.

OBJECTIVE

To determine whether the combination of vitamin C, hydrocortisone, and thiamine, compared with hydrocortisone alone, improves the duration of time alive and free of vasopressor administration in patients with septic shock.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, open-label, randomized clinical trial conducted in 10 intensive care units in Australia, New Zealand, and Brazil that recruited 216 patients fulfilling the Sepsis-3 definition of septic shock. The first patient was enrolled on May 8, 2018, and the last on July 9, 2019. The final date of follow-up was October 6, 2019.

INTERVENTIONS

Patients were randomized to the intervention group (n = 109), consisting of intravenous vitamin C (1.5 g every 6 hours), hydrocortisone (50 mg every 6 hours), and thiamine (200 mg every 12 hours), or to the control group (n = 107), consisting of intravenous hydrocortisone (50 mg every 6 hours) alone until shock resolution or up to 10 days.

MAIN OUTCOMES AND MEASURES

The primary trial outcome was duration of time alive and free of vasopressor administration up to day 7. Ten secondary outcomes were prespecified, including 90-day mortality.

RESULTS

Among 216 patients who were randomized, 211 provided consent and completed the primary outcome measurement (mean age, 61.7 years [SD, 15.0]; 133 men [63%]). Time alive and vasopressor free up to day 7 was 122.1 hours (interquartile range [IQR], 76.3-145.4 hours) in the intervention group and 124.6 hours (IQR, 82.1-147.0 hours) in the control group; the median of all paired differences was -0.6 hours (95% CI, -8.3 to 7.2 hours; P = .83). Of 10 prespecified secondary outcomes, 9 showed no statistically significant difference. Ninety-day mortality was 30/105 (28.6%) in the intervention group and 25/102 (24.5%) in the control group (hazard ratio, 1.18; 95% CI, 0.69-2.00). No serious adverse events were reported.

CONCLUSIONS AND RELEVANCE

In patients with septic shock, treatment with intravenous vitamin C, hydrocortisone, and thiamine, compared with intravenous hydrocortisone alone, did not significantly improve the duration of time alive and free of vasopressor administration over 7 days. The finding suggests that treatment with intravenous vitamin C, hydrocortisone, and thiamine does not lead to a more rapid resolution of septic shock compared with intravenous hydrocortisone alone.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03333278.

Hourly Fluid Balance in Patients Receiving Continuous Renal Replacement Therapy

INTRODUCTION

Little is known about early (first 48 h) hourly and cumulative fluid balance (FB) during continuous renal replacement therapy (CRRT).

OBJECTIVES

To study the characteristics and outcome associations of early hourly and cumulative FB.

METHODS

We studied FB in CRRT patients (2016-2018).

RESULTS

Among 350 patients, mean hourly FB became negative after 20 CRRT hours, but within 6 CRRT hours in patients with baseline fluid overload. A negative early FB was never achieved in patients receiving vasopressor therapy (p < 0.001). Mortality was 31%. The percentage of hourly negative FB was independently associated with decreased ICU mortality. A time-weighted hourly FB between 18.5 and -33 mL/h was also significantly and independently associated with decreased mortality.

CONCLUSIONS

In CRRT patients, an early FB conservative approach is possible, modulated by patient characteristics, and associated with a low mortality. Moreover, avoidance of an early positive FB is associated with decreased mortality.

Pharmacokinetic data support 6-hourly dosing of intravenous vitamin C to critically ill patients with septic shock

OBJECTIVES

To study vitamin C pharmacokinetics in septic shock.

DESIGN

Prospective pharmacokinetic study.

SETTING

Two intensive care units.

PARTICIPANTS

Twenty-one patients with septic shock enrolled in a randomised trial of high dose vitamin C therapy in septic shock.

INTERVENTION

Patients received 1.5 g intravenous vitamin C every 6 hours. Plasma samples were obtained before and at 1, 4 and 6 hours after drug administration, and vitamin C concentrations were measured by high performance liquid chromatography.

MAIN OUTCOME MEASURES

Clearance, volume of distribution, and half-life were calculated using noncompartmental analysis. Data are presented as median (interquartile range [IQR]).

RESULTS

Of the 11 participants who had plasma collected before any intravenous vitamin C administration, two (18%) were deficient (concentrations < 11 μmol/L) and three (27%) had hypovitaminosis C (concentrations between 11 and 23 μmol/L), with a median concentration 28 μmol/L (IQR, 11-44 μmol/L). Volume of distribution was 23.3 L (IQR, 21.9-27.8 L), clearance 5.2 L/h (IQR, 3.3-5.4 L/h), and half-life 4.3 h (IQR, 2.6-7.5 h). For the participants who had received at least one dose of intravenous vitamin C before sampling, T0 concentration was 258 μmol/L (IQR, 162- 301 μmol/L). Pharmacokinetic parameters for subsequent doses were a median volume of distribution 39.9 L (IQR, 31.4-44.4 L), clearance 3.6 L/h (IQR, 2.6-6.5 L/h), and half-life 6.9 h (IQR, 5.7-8.5 h).

CONCLUSION

Intravenous vitamin C (1.5 g every 6 hours) corrects vitamin C deficiency and hypovitaminosis C and provides an appropriate dosing schedule to achieve and maintain normal or elevated vitamin C levels in septic shock.

Large volume infusions of hydroxyethyl starch during cardiothoracic surgery may be associated with postoperative kidney injury: propensity-matched analysis

Background

The safety of intraoperative administration of hydroxyethyl starch (HES) has been debated. We hypothesized that intraoperative use of HES is associated with postoperative acute kidney injury (AKI) following cardiopulmonary bypass (CPB).

Materials and methods

Patients who underwent cardiothoracic surgery using CPB between 2007 and 2014 were retrospectively reviewed. The incidence of AKI within 7 days after surgery, defined by the Kidney Disease Improving Global Outcome criteria, was compared for patients who did or did not receive 6% (70/0.5) or 6% (130/0.4) HES for anesthesia management before or after CPB. Multivariable logistic regression and propensity matching analysis were performed to examine whether use of HES is associated with postoperative AKI. Outcomes comparing patients receiving HES ≥ 1000 mL and < 1000 mL were also compared.

Results

Data from 1976 patients were reviewed. All patients received 70/0.5 HES as a part of the priming solution for CPB. The incidence of postoperative AKI was 28.2% in patients who received HES and 26.0% in patients who did not (p = 0.33). In multivariable analysis, there was no correlation between the use of HES and the incidence of AKI (odds ratio 0.87, 95% CI 0.30–2.58, p = 0.81). Propensity matching showed that the incidence of AKI was not significantly different between 481 patients administered with HES and 962 patients (26.6% vs. 26.9%, p = 0.95) who did not receive HES for anesthesia management. However, peak creatinine levels, needed for renal replacement therapy, and in-hospital mortality were higher, and 28-day hospital-free days were lower in patients receiving HES ≥ 1000 mL than those receiving HES < 1000 mL (p < 0.05).

Conclusions

Intraoperative use of HES was not associated with postoperative AKI following CPB. However, administration of large volumes of HES may be associated with kidney-related adverse clinical outcomes.

Angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use prior to medical intensive care unit admission and in-hospital mortality: propensity score-matched cohort study

BACKGROUND

The aim of this study was to evaluate whether angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker (ACEI/ARB) use prior to medical intensive care unit (ICU) admission was associated with in-hospital mortality and length of ICU stay.

METHODS

A propensity score-matched cohort study was conducted at single center from 2004 to 2016. We included all adult patients who were admitted to the ICU due to internal medicine-related conditions. We compared patients who had used ACEIs/ARBs prior to ICU admission to patients who had not. Our primary and secondary outcomes were in-hospital mortality and length of stay among survivors and the deceased. Propensity scores were calculated via logistic regression analyses with forward stepwise selection. An odds ratio (OR) for primary outcome was calculated via logistic regression. Sensitivity analyses were performed using conditional logistic regression models including different sets of covariates to confirm our results.

RESULTS

3095 patients were admitted to the ICU. Overall, 693 patients were identified via matching, 231 of whom had used ACEIs/ARBs and 462 of whom had not. None of the baseline characteristics differed significantly between groups. Among them, 131 (18.9%) died. Those who had used ACEIs/ARBs had a lower rate of mortality (p < 0.01). Length of ICU stay did not differ significantly between those with ACEIs/ARBs and those without among survivors (p = 0.43) and the deceased (p = 0.14). The OR for mortality was 0.51 (95% confidence interval 0.32-0.79). The results of the sensitivity analyses confirmed the results (ORs 0.4 6-0.53; all were statistically significant).

CONCLUSION

Prior ACEI/ARB use may be related to in-hospital mortality among medical ICU patients.

[Two Cases of Large Gynecological Tumor Complicated by Preoperative Deep Vein Thromboembolism and Pulmonary Thromboembolism-Should We Use Inferior Vena Cava Filters ?-]

We experienced two cases of large gynecological tumor resection with co-existing deep vein thrombo- embolism (VTE) and pulmonary thromboembolism (PTE). Despite perioperative anticoagulation, one of the two patients developed dyspnea with massive PTE postoperatively, although the other patient did not have any postoperative complications. To prevent fatal mas- sive PTE, temporary inferior vena cava (IVC) filter might have been effective during perioperative period in these cases. Since there are wide variations among institutes regarding the perioperative application of temporary IVC filters for patients with co-existing VTE and/or PTE before surgery, guidelines or recom- mendations for appropriate usage of perioperative IVC filter are necessary.

Low prevalence of active cytomegalovirus infection in a cardiovascular intensive care unit

Active cytomegalovirus infection is not uncommon in critically ill non-immunosuppressed patients. We conducted a preliminary observational study to determine the prevalence of active cytomegalovirus infection in cardiovascular surgical patients. One hundred patients admitted to the intensive care unit following cardiovascular surgery were enrolled between January 2010 and May 2010. Four patients (4%) were positive for serum pp65 antigens, though cytomegalovirus-positive serology (immunoglobulin G, IgG) was found in 98 patients (98%) including those four patients. Active cardiac diseases and their operative procedures including cardiopulmonary bypass may not be significant risk factors for active cytomegalovirus infection unless systemic derangements are also present.

Ischemic heart disease due to compression of the coronary arteries by malignant lymphoma

A 76-year-old man presented with a two-month history of angina pectoris. Computed tomography (CT) revealed a serial enlargement of the supraclavicular and mediastinal lymph nodes compressing the heart, pulmonary artery and aorta. CT angiography (CTA) showed stenosis of the coronary arteries as a result of compression by the enlarged lymph nodes. First-pass contrast-enhanced cardiac magnetic resonance imaging (MRI) at rest revealed a perfusion defect, thus indicating myocardial ischemia. Diffuse large B-cell lymphoma was diagnosed and multidrug combination chemotherapy led to prompt improvement of the symptoms. Relief of the stenosis in the coronary arteries and improvements in myocardial perfusion were noted on follow-up CTA and MRI.

Frequent recovery of triplet mutations in UVB-exposed skin epidermis of Xpc-knockout mice

Mutations of the Xpc gene cause a deficiency in global genome repair, a subpathway of nucleotide excision repair (NER), in mammalian cells. We used transgenic mice harboring the lambda-phage-based lacZ mutational reporter gene to study the effect of an Xpc null mutation (Xpc-/-) on damage induction, repair and mutagenesis in mouse skin epidermis after UVB irradiation. UVB induced equal amounts of cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidone photoproducts (64PPs) in mouse skin epidermis of Xpc-/- and wild-type mice. CPDs were not significantly removed in either of the mouse genotypes by 12h after irradiation, whereas removal of 64PPs was observed in the wild-type. Irradiation with 300 and 400J/m2 UVB increased the lacZ mutant frequency in the Xpc-/- epidermis to at least twice as high as in the wild-type. Ninety-nine lacZ mutants isolated from the UVB-exposed epidermis of Xpc(-/-)mice were analyzed and compared with mutant sequences from irradiated wild-type mice. The spectra of the mutations in the two genotypes were both highly UV-specific and similar in the dominance of C-->T transitions at dipyrimidine sites; however, Xpc-/- mice had a higher frequency of two-base tandem substitutions, including CC-->TT mutations, three-base tandem substitutions and double base substitutions that were separated by one unchanged base in a three-base sequence (alternating mutations). These tandem/alternating mutations included a remarkably large number of triplet mutations, a recently reported, novel type of UV-specific mutation, characterized by multiple base substitutions or frameshifts within a three-nucleotide sequence containing a dipyrimidine. We concluded that the triplet mutation is a UV-specific mutation that preferably occurs in NER deficient genetic backgrounds.

Mutation spectrum in UVB-exposed skin epidermis of Xpa-knockout mice: frequent recovery of triplet mutations

Knockout mutations in both alleles of the Xpa gene give rise to a complete deficiency in nucleotide excision repair (NER) in mammalian cells. We used transgenic mice harboring the lambda-phage-based lacZ mutational reporter gene to study the effect of Xpa null mutation (Xpa(-/-)) on damage induction, repair, and mutagenesis in mouse skin epidermis after UVB irradiation. UVB induced equal amounts of cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidone photoproducts (64PPs) in mouse skin epidermis of Xpa(-/-) and wild-type mice. Neither photolesion was removed in the Xpa(-/-) epidermis by 12 hr after irradiation whereas removal of 64PPs was observed in the epidermis of wild-type mice. Irradiation with 200 and 300 J/m(2) UVB increased the lacZ mutant frequency in the epidermis of Xpa(-/-) mice, but the induced mutant frequencies were not significantly different from those previously determined for wild-type mice. One-hundred lacZ mutants isolated from the UVB-exposed epidermis of Xpa(-/-) mice were analyzed and compared with mutant sequences previously determined for irradiated wild-type mice. The distribution of the mutations along the lacZ transgene and the preferred dipyrimidine context of the UV-specific mutations were similar in mutants from the Xpa(-/-) and wild-type mice. The spectra of the mutations in the two genotypes were both highly UV-specific and similar in a dominance of C --> T transitions at dipyrimidine sites; however, Xpa(-/-) mice had a higher frequency than wild-type mice of two-base tandem substitutions, including CC --> TT mutations, three-base tandem mutations and double base substitutions that were separated by one unchanged base in a three-base sequence (alternating mutations). These tandem/alternating mutations included a remarkably large number of triplet mutations, a recently reported, novel type of UV-specific mutation, characterized by multiple base substitutions or frameshifts within a three-nucleotide sequence containing a dipyrimidine. We conclude that the triplet mutation is a UV-specific mutation that preferably occurs in NER-deficient genetic backgrounds.