Vasoactive drugs and the kidney

Treatment of Patients with Cardiac Surgery Associated-Acute Kidney Injury

Members of the Acute Dialysis Quality Initiative (ADQI) participated in a 3-day conference in Vicenza in May 2007 to evaluate the available literature on this topic and draft consensus recommendations for research studies in this area. This report summarizes the available evidence and describes the key questions that will need to be addressed with the goal of standardizing the care of patients with cardiac surgery-associated acute kidney injury (CSA-AKI) and improving outcomes.

Intraoperative management and early postoperative outcomes of pediatric renal transplants

INTRODUCTION

Smaller children are presenting for renal transplantation as the treatment of choice for end-stage renal disease. Adult donor organs are more successful than pediatric deceased donor organs. An adult kidney may sequester ~75% of the circulating volume of a 5 year-old child and requires significantly increased cardiac output to maintain renal perfusion. Treatment includes volume, inotropic or vasopressor agents, or central neuroaxial blockade for sympatholysis. We describe the perioperative anesthestic management as a guide to clinical outcomes.

METHODS

A retrospective chart review of renal transplant patients between 2006 and 2014 was performed. We recorded patient demographics, surgical and anesthetic factors and postoperative outcome.

RESULTS

One hundred and fifty-six children underwent renal transplantation, of which 38% were from living donors. There were 99/156 (63.5%) males. Median age was 10 years (range 1-17 years) and the mean weight was 36.2 kg (sd 20.6 kg; range 7.6-109.6 kg). There were 36 children ≤5 years of age and 14 children ≤2 years of age. One hundred and nineteen (77%) were dialysis dependent. Pharmacological support to increase renal perfusion included mannitol in 95%, and dopamine in 83%. Furosemide was used in 82% of cases. Inotropic therapy continued into the postoperative period in 34%. Radiological pulmonary edema was diagnosed in 33% and clinical pulmonary edema in 7%. Intraoperative use of dopamine delayed the time to creatinine nadir in all grafts (9.5 days vs 6.5 days, P = 0.04) and in deceased donor grafts (12.9 vs 7.4 days, P = 0.007). Patients who received dopamine had no significant difference in central venous pressure (CVP) preclamp removal, 14 mmHg vs 11.5 mmHg (P = 0.12) but a higher CVP after clamp removal, 14.3 mmHg vs 11.8 mmHg (P = 0.003).

CONCLUSION

Dopamine use was common and was an independent risk factor for delayed time to creatinine nadir. Many different agents were used to enhance renal perfusion. The 'supra-physiological' hemodynamics resulted in pulmonary edema in 33% of patients.

From Pre-Existing Renal Failure to Perioperative Renal Protection: The Anesthesiologist's Dilemmas

CONTEXT

Pre-existing renal dysfunction presents specific features that anesthesiologists must deal with. Anesthesia and renal function are connected and can interfere with each other. Induced hypotension anesthesia and the toxic effects of anesthetic drugs can further deteriorate renal function.

EVIDENCE ACQUISITION

Decreased renal function can prolong anesthetic drug effects by decreased elimination of these drugs. Anesthesia can deteriorate renal function and decreased renal function can interfere with drug elimination leading to their prolonged effect. The anesthesiologist must understand all the physiological aspects of the patient, renal protection, and the relationships between anesthetic drugs and renal function. This review article aims to summarize these aspects.

RESULTS

Perioperative renal failure and renal protection is a crucial moment in clinical practice of every anesthesiologist.

CONCLUSIONS

Good knowledges for renal function remain a hallmark of daily practice of the anesthesiologist, considering renal function as an important determinant factor in anesthesia practice.

Extracorporeal cardiopulmonary resuscitation for adult patients who underwent post-cardiac surgery

Background

Refractory cardiac arrest (CA) occasionally develops in patients after cardiac surgery.

Objective

To examine the clinical outcomes of extracorporeal cardiopulmonary resuscitation (ECPR) in adult patients with post-cardiotomy CA.

Methods

This was a retrospective study of the 9-year experience (from January 2004 to May 2012) of the Beijing Anzhen Hospital with ECPR in adult patients with post-cardiotomy CA. At this hospital, a dedicated ECPR team is available 24/7 for emergency cases requiring ECPR. Demographic data, biochemical data, survival, morbidity, and complications were examined before, during, and after ECPR. Outcomes were compared between survivors and non-survivors.

Results

Twenty-four adult patients (19 men and 5 women; mean age: 59.3 ± 11.9 years) received ECPR support for post-cardiotomy CA. The cardiac surgery procedures included coronary artery bypass grafting (n = 20, 83.3 %), valvular surgery alone (n = 2, 8.3 %), and correction of congenital heart defects (n = 2, 8.3 %). The mean extracorporeal membrane oxygenation (ECMO) duration was 115.23 ± 70.17 h. Twenty-one patients received ECPR after intra-aortic balloon pump, and three patients received ECPR directly. The main cause of mortality was multiple system organ failure (n = 12, 50.0 %). Approximately one-half of non-survivors had severe neurologic impairments. Among 16 patients who were weaned off ECMO support, eight patients survived to hospital discharge.

Conclusions

ECPR can be effective for partial cardiopulmonary support to resuscitate adult patients suffering from refractory CA after cardiac surgery. Improvement in outcomes of patients who received ECPR requires a multidisciplinary approach to protect organ function and limit organ injury before and during cardiac support.

Augmented renal clearance implies a need for increased amoxicillin-clavulanic acid dosing in critically ill children

There is little data available to guide amoxicillin-clavulanic acid dosing in critically ill children. The primary objective of this study was to investigate the pharmacokinetics of both compounds in this pediatric subpopulation. Patients admitted to the pediatric intensive care unit (ICU) in whom intravenous amoxicillin-clavulanic acid was indicated (25 to 35 mg/kg of body weight every 6 h) were enrolled. Population pharmacokinetic analysis was conducted, and the clinical outcome was documented. A total of 325 and 151 blood samples were collected from 50 patients (median age, 2.58 years; age range, 1 month to 15 years) treated with amoxicillin and clavulanic acid, respectively. A three-compartment model for amoxicillin and a two-compartment model for clavulanic acid best described the data, in which allometric weight scaling and maturation functions were added a priori to scale for size and age. In addition, plasma cystatin C and concomitant treatment with vasopressors were identified to have a significant influence on amoxicillin clearance. The typical population values of clearance for amoxicillin and clavulanic acid were 17.97 liters/h/70 kg and 12.20 liters/h/70 kg, respectively. In 32% of the treated patients, amoxicillin-clavulanic acid therapy was stopped prematurely due to clinical failure, and the patient was switched to broader-spectrum antibiotic treatment. Monte Carlo simulations demonstrated that four-hourly dosing of 25 mg/kg was required to achieve the therapeutic target for both amoxicillin and clavulanic acid. For patients with augmented renal function, a 1-h infusion was preferable to bolus dosing. Current published dosing regimens result in subtherapeutic concentrations in the early period of sepsis due to augmented renal clearance, which risks clinical failure in critically ill children, and therefore need to be updated. (This study has been registered at Clinicaltrials.gov as an observational study [NCT02456974].).

Renal failure: emergency evaluation and management

Patients with altered renal function are frequently encountered in the emergency department (ED) and emergency physicians often play an important role in the evaluation and management of renal disease. Early recognition, diagnosis, prevention of further iatrogenic injury, and management of renal disease have important implications for long-term morbidity and mortality. This article reviews basic renal physiology, discusses the differential diagnosis and approach to therapy, as well as strategies to prevent further renal injury, for adult patients who present to the ED with renal injury or failure.

Influence of non-ventilatory options on postoperative outcome

Perioperative patient handling should urgently be updated according to current evidence and, if none is available, at least according to physiological knowledge. To prevent pulmonary aspiration, preoperative fasting for 2 h (clear fluids) and 6 h (solid food) and abdication of 20 min for smoking is sufficient. Beta-blockage requires an indication. Bowel preparation should be abandoned and minimal invasive surgery as well as local and regional anaesthesia should be used where possible. Fluid therapy should be rational and requirement-adapted, and hypothermia, postoperative nausea and vomiting, unnecessary drains, tubes and catheters avoided. A multi-modal opioid-sparing pain therapy, sufficient oxygenation as well as early nutrition and mobilisation all play an important role for patient outcome. Recent studies have postulated that combining single-modality evidence-based care principles into a multi-modal effort to enhance postoperative recovery has improved patient outcome. Henrik Kehlet termed such a principle the 'fast-track concept', comprehending the entire perioperative phase starting with preoperative preparation, over atraumatic surgical and anaesthesiological techniques reducing the neuroendocrine stress response and also comprising the postoperative treatment. This strategy has been shown to positively influence organ function, homeostasis, morbidity, need for hospitalisation and convalescence and, therefore, to reduce costs. Despite these promising results, general implementation of evidence-based measures leaves a lot to be desired. Further development of surgical minimally invasive techniques and ongoing evaluation of procedure-specific strategies is urgently warranted.

An Official ATS/ERS/ESICM/SCCM/SRLF Statement: Prevention and Management of Acute Renal Failure in the ICU Patient: an international consensus conference in intensive care medicine

OBJECTIVES

To address the issues of Prevention and Management of Acute Renal Failure in the ICU Patient, using the format of an International Consensus Conference.

METHODS AND QUESTIONS

Five main questions formulated by scientific advisors were addressed by experts during a 2-day symposium and a Jury summarized the available evidence: (1) Identification and definition of acute kidney insufficiency (AKI), this terminology being selected by the Jury; (2) Prevention of AKI during routine ICU Care; (3) Prevention in specific diseases, including liver failure, lung Injury, cardiac surgery, tumor lysis syndrome, rhabdomyolysis and elevated intraabdominal pressure; (4) Management of AKI, including nutrition, anticoagulation, and dialysate composition; (5) Impact of renal replacement therapy on mortality and recovery.

RESULTS AND CONCLUSIONS

The Jury recommended the use of newly described definitions. AKI significantly contributes to the morbidity and mortality of critically ill patients, and adequate volume repletion is of major importance for its prevention, though correction of fluid deficit will not always prevent renal failure. Fluid resuscitation with crystalloids is effective and safe, and hyperoncotic solutions are not recommended because of their renal risk. Renal replacement therapy is a life-sustaining intervention that can provide a bridge to renal recovery; no method has proven to be superior, but careful management is essential for improving outcome.

Blood volume is normal after pre-operative overnight fasting

BACKGROUND

Pre-operative fasting is assumed to cause a deficit in intravascular blood volume (BV), as a result of ongoing urine production and insensible perspiration. Standard regimes consist of volume loading prior or simultaneous to any anaesthetic procedure to minimise the risk of hypotension. However, fluid overload in the context of major abdominal surgery has been shown to deteriorate patient outcome. Our study aimed to quantify total intravascular BV after fasting by direct measurements and to compare it with calculated normal values in comparable non-fasted patients.

METHODS

After 10 h of fasting, total plasma volume (PV) and red cell volume (RCV) were measured via the double-label technique (indocyanine green dilution and erythrocytes labelled with fluorescein, respectively) following induction of general anaesthesia in 53 gynaecological patients suffering from malignoma of the cervix. The corresponding normal values were calculated individually from age, body height and body weight.

RESULTS

Measured BV, RCV and PV after fasting were 4123+/-589, 1244+/-196 and 2879+/-496 ml, respectively. The differences to the corresponding calculated normal values were not significant (3882+/-366, 1474+/-134 and 2413+/-232 ml, respectively). The measured haematocrit reflected a slight anaemic state (0.35+/-0.03).

CONCLUSION

Our data suggest that even after prolonged pre-operative fasting, cardio-pulmonary healthy patients remain intravascularly normovolaemic. Therefore, hypotension associated with induction of general or neuraxial anaesthesia should perhaps be treated with moderate doses of vasopressors rather than with undifferentiated volume loading.

Determinanten des insensiblen Flüssigkeitsverlustes

Accurate perioperative fluid balance is the basis of a targeted infusion regimen. However, neither the initial status nor perioperative changes of the fluid compartments can be reliably measured in daily routine. In particular, insensible losses are not consistently assessed, so that substitution therapy is generally empirical. The object of this paper is to communicate the scientific data on this topic. Preoperative fasting (10 h) does not per se cause intravascular hypovolemia. In adults, total basal evaporation by way of the skin and airways and of any wounds during major abdominal interventions is usually less than 1 ml/kg/h. An inconstant fluid and protein shift towards the interstitial space perioperatively seems to be associated with hypervolemia, which suggests it should be preventable. The decisive factor in this context seems to be deterioration of the endothelial glycocalyx, whose further patho-physiological impact is currently only partially known. Clinical studies have revealed a link between fluid restriction and improved outcome after major abdominal surgery.

Cardiovascular impact of dobutamine in neonates with myocardial dysfunction

OBJECTIVE

To study effects of dobutamine on cardiac functional parameters, cerebral, mesenteric and renal blood flow in preterm neonates with myocardial dysfunction.

STUDY DESIGN

Prospective evaluation of Doppler sonographically measured left ventricular systolic time intervals, stroke volume (SV), cardiac output (CO), and blood flow parameters of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal arteries (RA), before, after 20 min and 8-10 h of dobutamine treatment in 20 neonates (gestational age 29.6+/-4.4 weeks, birth weight 1450+/-609 g and postnatal age 2+/-2.1 days). Dobutamine was given in a mean dosage of 9.1+/-1.1 microg/kg.

RESULTS

After 20 min SV increased from 1.71+/-0.5 ml to 2.12+0.57 ml/kg, CO from 223+/-76 to 290 ml/kg/min. A shortening of left ventricular pre ejection period from 86+/-12 to 66+/-13 ms and of the ratio of pre-ejection period/ejection time from 0.52+/-0.12 to 0.40+/-0.11 were observed. Blood flow velocities of ACA increased after 8-10 h: peak systolic flow velocity (PSV) from 19.0+/-6 to 29.6+/-7.1 ms, end diastolic velocity (EDV) from 2.9+/-2.6 to 12.7+/-11.3 ms. PSV of SMA increased from 32.5+/-4.7 to 49.7+/-7.8 ms after 8-10 h, EDV from 8.9+/-8 ms to 20.6+/-6.1 ms. PSV of RA increased from 18.2+/-6.1 ms to 39.9+/-4.8 ms, EDV from 2.2+/-1.2 to 8.2+/-2.1 ms after 8-10 h. The pulsatility indices decreased significantly after 8-10 h: ACA from 2.3+/-0.6 to 1.4+/-0.5, SMA from 1.7 to 1.2 and RA from 2.57 to 1.57.

CONCLUSION

Dobutamine improves the cardiac functional parameters already after 20 min and has an influence on the blood flow parameters of ACA, SMA and RA 8-10 h after administration in neonates with myocardial dysfunction.

Influence of S(+)-ketamine analgesia in renal intraoperative ischemia: histological study in rats

PURPOSE: To study in rats the effect of S(+)ketamine on the renal histology after intraoperative hemorrhage. METHODS: Twenty male Wistar rats, anesthetized with sodium pentobarbital, were randomly divided in 2 groups: G1 - control (n=l0) and G2 - S(+)-ketamine (n=10), both submitted to arterial hemorrhage of 30% of volemia in 3 moments (10% each 10 min) 60 min after anesthesia. G2 received S(+)-ketamine, 15 mg. kg-1, i.m., 5 min after anesthesia and 55 min before the 1st hemorrhage moment (Ml). Medium arterial pressure (MAP), rectal temperature (T) and heart rate were monitored. The animals were sacrificed in M4, 30 min after the 3rd hemorrhage moment (M3) and the kidneys and blood collected from hemorrhage were utilized for histological study and hematocrit (Ht) determination. RESULTS: There were significant reduction of MAP, T, and Ht. The histological study verified G1 = G2 for tubular dilation, congestion, and necrosis. The total score addition were significant1y different and G2 > G 1. CONCLUSION: Hemorrhage and hypotension determined changes in kidney histology. The rise in catecholamine blood concentration probably was the cause of S(+)-ketamine-induced higher score of histological changes.

Renal failure secondary to acute tubular necrosis: epidemiology, diagnosis, and management

Acute tubular necrosis (ATN) is a form of acute renal failure (ARF) that is common in hospitalized patients. In critical care units, it accounts for about 76% of cases of ARF. Despite the introduction of hemodialysis > 30 years ago, the mortality rates from ATN in hospitalized and ICU patients are about 37.1% and 78.6%, respectively. The purpose of this review is to discuss briefly the cause, diagnosis, and epidemiology of ARF, and to review in depth the clinical trials performed to date that have examined the influence of growth factors, hormones, antioxidants, diuretics, and dialysis. In particular, the role of the dialysis modality, dialyzer characteristics, and dosing strategies are discussed.