1. Role of mean arterial patient (MAP) in prevention of need of renal replacement therapy
(RRT) in septic shock patients admitted with acute kidney injury (AKI) to an intensive
care unit (ITU)
Anumakonda Vikram and Hassan Hawa; Critical care unit (CCU), BSUH Foundation trust,
Brighton, U.K
Aim of study: To investigate, role of MAP in mitigating risk of CVVH in septic shock patient with AKI. Primary end point of the study was prevention of renal replacement therapy in patient admitted to ITU and secondary end point is length of dependence on level 3 care. Although RRT for refractory fluid overload, as well as electrolyte and acid-base imbalance, is recommended by the Surviving Sepsis Campaign, issues related to when and how to perform RRT are not addressed.
Methods: All septic shock admitted to ITU directly following a septic shock from 2010 to 2012 at Royal Sussex county hospital, Brighton and Sussex University hospitals NHS trust, UK. A total of one hundred and thirteen patients were included in the study. Data collected included age, sex, heart rate, lactate, blood pressures, temperature, lactate, differential diagnosis, white cell count (WBC), level of organ support, length of stay, use of vasopressors, routine investigations and renal replacement therapy requirement.
Inclusion criteria included any septic shock patient admitted with a MAP of <60 mm Hg, systolic blood pressure <90mm Hg or SBP Drop >40 mm Hg of normal, temperature >38°Celsius (C) (100.4°Farenheit (F)) or < 36°C (96.8°F), heart rate > 90 per minute, respiratory rate > 20 per minute or PaCO2 < 32 mm Hg, > 12,000/cubic millimetre (m3), < 4,000/mm3, age>16 years, signs of organ dysfunction, hypotension, or hypoperfusion with admission serum lactate >4mmol/litre and evidence of ≥ 2 Organs failing. All patients were vasoplegic, treated with noradrenaline at time of admission to ITU. All those treated with other vasopressors except noradrenaline and dialysis dependent patients, age <16 were exclusion criteria for the study.
Data were collected prospectively using Metavision electronic patient records. Data was collected retrospectively using Microsoft excel and integrated into a SQL database using patient hospital number-time unique datasets. SPSS 21 was used for statistical analysis.
Results: A total of eight patients (7%) of 113 needed renal replacement therapy. 11.5% needed level 2 and rest level 3 organ support care. Dependence of level 3 respiratory organ support for those dependent on Continuous veno-venous haemofiltration (CVVH) and not on CVVH were 8.25, 6.74 days respectively. Average serum lactates were 8.15 and 5.7 mmol /litre respectively in those needing RRT to those not started on RRT. Average ages of male and female in years were 67.3 and 68.7 respectively. Patient not requiring CVVH has significantly higher average MAP than those requiring CVVH. However, this difference was reversed on day 2, but not significant statistically (Table: 1). Higher mean arterial pressures in the septic group have significant impact on minimising RRT requirement in this high risk cohort (p value- 0.04). Creatinine amongst those requiring RRT was higher during first three days of admission to ITU (Table: 2). Average SOFA scores were 12.
 Area under curve for MAP on day of admission was (Fig: 1). The positive likelihood ratio (LR+) for not requiring CVVH at MAP70, 75 mm Hg was 1.65 and 1.64 respectively. However, at MAP 65mm Hg, a negative likelihood ratio
(LR-ve) for avoiding CVVH was 1.07.
Table1:Mean arterial pressures over 7 days across both groups.
Average MAP day1 ( in mm Hg)
Average MAP day2
Average MAP day3
Average MAP day4
Average MAP day5
Average MAP day6
Average MAP day7
Not on CVVH
85.41
84.60
CVVH
79.02
77.95
Table2: Average creatinine over 7 days across both groups.
Avg. Creatinine (Cr) on admission
day2
day3
day4
day5
day6
day7
Not on CVVH
225.4
216.57
209.32
187.14
174.31
161.82
169.02
CVVH
305.77
232.75
231.75
207.56
156.88
178.5
149.6
Fig: 1-ROC curve: MAP day1 Vs Patients not requiring RRT(AUC= 0.623)
 Discussion: Septic AKI exerts an important and independent increase in the risk for hospital death. In survivors, septic AKI is associated with prolonged ICU and hospital stays but also a trend toward greater recovery of kidney function (5, 6). In our cohort, patients who had higher MAP were found to have lower creatinine values on first four days after their admission to ITU. Higher MAP within 24 hours of their admission has some renal protection and minimises need for RRT. Contrary to typical septic patients, our cohort had higher lactate levels. However, all vasoplegic septic patients could benefit with higher MAP especially during their first 24 hours. Interestingly, our study did not show any significant adverse effects associated with high doses of noradrenaline. We postulate higher MAP could preserve renal functions in septic patients with AKI. Interestingly, CVVH as a mode of RRT has significant impact on resources and morbidity (7).
Conclusion: Higher MAP>70mm Hg have role in avoiding RRT. Future warrants a multicentre randomised control trails to establish renal protective effect of higher MAP in this high risk cohort.
References
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