Children Post Cardiac Surgery Research Articles

Antipyrexial effects of paracetamol in postcardiac surgery children

<h3>Objective</h3> To determine the pharmacodynamic effects of paracetamol on pyrexia after cardiac surgery in children. To investigate if there was a dose-effect relationship. To investigate if formulation or route of administration had an effect on the antipyrexial effects. <h3>Methods</h3> Data was collected both prospectively (over a 3 month period between June and August 2010) and retrospectively over a 12 month period between June 2009 and June 2010. Data was collected for patients on both PICU and the paediatric cardiac ward. Data was obtained from the patients medical notes, nursing notes and prescription chart. Since the reason for prescribing paracetamol (pain or pyrexia) is often not stated in the notes or prescription chart, the inclusion criteria were simplified to include all patients who had an elevated temperature, receiving paracetamol who had a core temperature recorded prior to and after paracetamol administration. Temperature was recorded hourly following paracetamol administration. All data was entered onto an Excel spreadsheet for analysis. Mean, SD and the range of uncorrected and baseline corrected temperatures post dosing were determined. <h3>Results</h3> In total, data from 52 patients were collected (8 prospective, 44 retrospective). However, the final analysis was limited to 35 patients in whom temperature ≥ 38°C was recorded and who did not receive concomitant NSAIDs. Only one patient received intravenous paracetamol, and in the remaining subjects it was not possible to distinguish whether the oral or rectal route was used from the prescription chart. The mean age was 3 years 2 months (range 2 months–16 years 9 months), mean weight was 14.1 kg (range 3.9–71 kg), mean dose of paracetamol was 15.8 mg/kg (range 12.7–20.3 mg/kg). The ratio male/female was 1.69. The onset of antipyrexial effect of paracetamol was 1 h after PO/PR administration. The mean time to maximum antipyresis was 4.3 (range 1–6) h. The overall mean maximum decline in temperature was 1.5 (range 0.1–4.4)^°C. The relationship between dose and maximum temperature decline was analysed by categorising dose into Group 1 ≤ 16 mg/kg and Group 2 ≥ 16 mg/kg. The results revealed that the higher dose group achieved a greater temperature reduction; 1.2 versus 1.9°C (p=0.03). In 13 patients (37%), hypothermia (temperature &lt; 36.5°C) was observed after administration of paracetamol. Although this could be interpreted as an adverse effect, the effect could not be attributed directly to paracetamol, and other factors such as environmental temperature may have influenced the findings. <h3>Conclusion</h3> The pharmacodynamic effects of paracetamol were assessed using easily accessible clinical records. Enterally administered paracetamol is shown to reduce temperature effectively; however the time to maximum antipyrexial effect is delayed and may reflect delayed gastric empyting. A greater temperature decline (and perhaps more rapid) maybe achieved with higher doses. A prospective study is required to investigate whether formulation affects the pharmacodynamic response.

Monitoring of protein catabolism in neonates and young infants post-cardiac surgery

To evaluate cell catabolism by balance of nitrogen and phosphate, and creatinine excretion in children post-cardiac surgery; to establish protein and energy requirements to minimize catabolism; and to assess nutritional therapy by following these parameters and serial anthropometric measurements. A prospective observational study of children with congenital heart disease undergoing cardiac surgery. Blood samples and 24-h urine collections were obtained postoperatively for creatinine measurement and nitrogen and phosphate balance. Anthropometric measurements (weight, mid-arm muscle circumference and triceps skinfold thickness) were obtained preoperatively and at paediatric intensive care unit and hospital discharge. Eleven children were studied for 3-10 postoperative days. Anabolism was associated with higher protein and energy intakes compared to catabolism (1.1 vs. 0.1 g/kg/day and 54 vs. 17 kcal/kg/day, respectively). On days with anabolism, phosphate balance was greater compared with that on days with catabolism. Daily creatinine excretion did not correlate with protein balance. Anthropometric measurements did not change significantly over time. Children with congenital heart disease undergoing cardiac surgery achieved anabolism with >55 kcal/kg/day and >1 g/kg/day of protein. Balance of phosphate was useful to monitor cell breakdown. Anthropometric measurements were not valuable to evaluate nutritional therapy in this population.

Defining acute kidney injury: playing hide-and-seek with the unknown man?

Acute kidney injury (AKI) occurs frequently in hospitalized patients, especially at the intensive care unit (ICU), and is associated with a high morbidity, mortality and cost [1,2]. The disappointing quest for a golden bullet to treat or prevent AKI during the 1990s has been replaced by a crusade to develop (early) biomarkers of AKI [3]. The underlying reasoning for this change in research perspective is that the single-shot therapies that worked so well in the rat models do not work in humans because we lag behind with accurate, early diagnosis. As a result, several biomarkers have been identified and tested over the last decade in an attempt to diagnose AKI earlier. In a recent issue of Kidney International, Endre et al. [4] report the negative results of a trial using biomarkers to guide administration of rHuEPO to prevent or attenuate AKI. Most of the interest in this study is that the biomarkers used were not at all able to establish an accurate diagnosis of AKI, although they have been claimed previously to be accurate [5]. History seems to repeat itself: whereas some of these biomarkers seem to work properly in well-controlled conditions and restricted populations, such as in children postcardiac surgery [6], their performance decreases in mixed or more complex populations [3], and confidence intervals for sensitivity and specificity become wide [7]. Although Endre et al. [4] have to be congratulated for their courage in setting up this study, it is exemplary for the difficulties faced by all initiatives in the field of AKI: as long as a coherent and meaningful definition of AKI is lacking, all attempts for early diagnosis, prevention or treatment are bound to fail. The several initiatives undertaken over the last years to harmonize the definition of AKI [8–10] must be greatly credited for having brought the problem of AKI to the attention of non-nephrologists. However, although the principles of RIFLE and AKIN are well accepted, most papers use a ‘convenience’ format of RIFLE or AKIN in real practice. Also, the boundaries of the diagnostic criteria, especially in relation to the baseline value of creatinine, seem to change continuously [8,11,12]. Most attempts to come up with one definition neglect the simple truth that ‘the’ AKI as a single entity does not exist. For the clinician, AKI is the reduction in glomerular filtration rate, when most likely the kidney has already been damaged substantially, while for the experimental physiologist, harm to even a few tubular cells as evidenced by biomarkers is enough to establish the diagnosis. AKI is a multifaceted condition, in terms of severity, underlying disease and circumstances, and sequence of events. By creating stages of AKI, both RIFLE [10] and AKIN [9] tried to tackle this problem. It has been demonstrated that these stages correlate with outcome [13,14]. This has been accepted as validation of these definitions. But here loom a number of conceptual problems. First, in order to define a change in creatinine, a baseline value is needed, changing the problem of definition of AKI into a problem of defining a baseline value of creatinine, which might lead to different classifications [15]. In the study of Endre et al. [4], although all patients complied with one definition of AKI based on baseline creatinine, this ‘baseline’ creatinine was defined according to a pre-specified algorithm, consisting of five different definitions, de facto resulting in five different types of AKI. It has been demonstrated that the selection of baseline creatinine influences the categorization of AKI [15]. Second, besides the difference between a baseline and a second value, also the further kinetics of the evolution of serum creatinine should be taken into account. The current definitions of RIFLE and AKIN take into account neither the kinetics of creatinine nor the duration of an increase. When a patient with an established normal kidney function comes in with acute dehydration, his creatinine on admission might be several folds his baseline value, but will decrease rapidly by rehydration. This is cardinal for the concept of ‘fluid responsiveness’ [16], and the best marker to be followed here is the rise in urinary output, a neglected parameter in many studies. In a septic patient, declining urinary output despite fluid loading is often the first sign of impending AKI, but creatinine will only rise slowly in the beginning. The distinction between renal and pre-renal, from the therapeutic viewpoint the most crucial distinction to be made, can only be made by evaluating fluid responsiveness or the effect of increasing renal perfusion, not by a definition based on single changes from baseline in serum creatinine or a biomarker [17]. Third, relative risk rather than predictive value is used to indicate the increase

Comparison of two red-cell transfusion strategies after pediatric cardiac surgery: A subgroup analysis

To determine the impact of a restrictive vs. a liberal transfusion strategy on new or progressive multiple organ dysfunction syndrome in children post cardiac surgery. The optimal transfusion threshold after cardiac surgery in children is unknown. Randomized, controlled trial. Tertiary pediatric intensive care units. Participants are a subgroup of pediatric patients post cardiac surgery from the TRIPICU (Transfusion Requirements in Pediatric Intensive Care Units) study. Exclusion criteria specific to the cardiac surgery subgroup included: age <28 days and patients remaining cyanotic. Critically ill children with a hemoglobin < or = 95 g/L within 7 days of pediatric intensive care unit admission were randomized to receive prestorage leukocyte-reduced red-cell transfusion if their hemoglobin dropped either <70 g/L (restrictive) or 95 g/L (liberal). Postoperative cardiac patients (n = 125) from seven centers were enrolled. The restrictive (n = 63) and liberal (n = 62) groups were similar at baseline in age (mean +/- standard deviation = 31.4 +/- 38.1 mos vs. 26.4 +/- 39.1 mos), surgical procedure, severity of illness (Pediatric Risk of Mortality score = 3.4 +/- 3.2 vs. 3.2 +/- 3.2), multiple organ dysfunction syndrome (46% vs. 44%), mechanical ventilation (62% vs. 60%), and hemoglobin (83 vs. 80 g/L). Mean hemoglobin remained 21 g/L lower in the restrictive group after randomization. No significant difference was found in new or progressive multiple organ dysfunction syndrome (primary outcome) in the restrictive group vs. liberal group (12.7% vs. 6.5%; p = .36), pediatric intensive care unit length of stay (7.0 +/- 5.0 days vs. 7.4 +/- 6.4 days) or 28-day mortality (3.2% vs. 3.2%). In this subgroup analysis of cardiac surgery patients, a restrictive red-cell transfusion strategy, as compared with a liberal one, was not associated with any significant difference in new or progressive multiple organ dysfunction syndrome, but this evidence is not definitive.

Nosocomial infections in pediatric cardiovascular surgery patients: A 4-year survey

To determine the prevalence, characteristics, and risk factors for nosocomial infections (NIs) in children postcardiac surgery and hospitalized in a pediatric intensive care unit (PICU). Case control study. PICU of a tertiary care university-affiliated medical center. Between January 1, 1999 and December 31, 2002, 356 children underwent cardiac surgery and were admitted to the PICU (381 admissions). There were 146 episodes (91 patients) of NI according to the Centers for Disease Control and Prevention criteria. The control group (92 patients) was drawn as a random sample from admissions with no evidence of NI. Data retrieved from medical records included demographic information, type of operation, complexity score, extrinsic risk factors (invasive devices, postoperative complications, etc.), specific pathogens, therapeutic interventions, and outcome. There were 146 episodes of NI during 381 admissions, yielding a nosocomial infection ratio of 38.3%, and a prevalence of PICU-acquired infection of 24.4% (93 admissions with NI out of a total of 381 admissions). The most common NI sites were the bloodstream and the lower respiratory tract (65.8% and 16.4%, respectively). The main causative organisms were Coagulase negative Staphylococcus, Klebsiella pneumonia, and Candida spp. (18.8%, 16.7%, and 15%, respectively). Multivariate analysis revealed the following risk factors for NI: age < 2 months, congenital malformations, post operative complications, and open-chest procedure. The crude mortality rate for patients with NI was 23.7%, compared with 2.2% for patients without NI (p < 0.001). Predictors for mortality in patients with NI were post operative complications, open-chest procedure, sepsis, and urinary tract infection. Our results draw attention to the importance of NI and their influence on survival in pediatric patients undergoing cardiac surgery. Prevention and control measures may reduce these infections and subsequently reduce morbidity and mortality in this vulnerable population.

Lack of agreement between arterial and central venous blood glucose measurement in critically ill children

Dear Sir, We were interested to read the article by Critchell et al. [1] highlighting concerns about the accuracy of bedside capillary blood glucose measurements in critically ill patients. We would agree that the importance of sampling site for blood glucose measurement has been under-emphasized in the published studies on hyperglycaemia and tight glycaemic control. The majority of studies linking hyperglycaemia with adverse clinical outcome have not provided data on the site of sampling. We would like to share preliminary data regarding the use of central venous blood sampling for glucose measurement in critically ill children. The objective of this preliminary study was to compare blood glucose concentrations in simultaneously drawn arterial and central venous blood glucose samples taken for clinical purposes. Paired arterial and central venous blood gas samples were taken to obtain information about oxygen extraction and the results were prospectively documented. Blood glucose was measured on a blood gas analyzer (Bayer Rapidlab; electrochemical biosensor), which is subject to strict quality control by the Clinical Chemistry department. No glucose containing solution was infused into either the arterial or the central venous sampling lines. A total of 245 paired arterial and central venous blood samples were obtained from 71 children, age range 5 days–14 years, between January and October 2006. The majority of cases were children post cardiac surgery, reflecting a group of patients in whom regular assessment of oxygen extraction is undertaken. The median number of samples per patient was 2 (range 1–22). The samples included a wide range of arterial blood glucose values, from 2.4 to 23 mmol/l. There was poor agreement between arterial and central venous blood glucose (Fig. 1). The central venous blood glucose was frequently higher than the arterial blood glucose (median 0.4 mmol/l, CI 0.3–0.5, P \ 0.001 Wilcoxon Signed Rank test). On occasions, the difference exceeded 5 mmol/l. The implications of these findings for titration of insulin therapy are obvious. Inappropriate adjustments to insulin therapy could be made and, importantly, hypoglycaemia could go undetected if central venous sampling is used to monitor blood glucose in this population of critically ill children. It is common for a child to be managed without an arterial line once their cardio-respiratory condition has stabilized, and for bloods to be taken through a central line, if present, to avoid the need for venepuncture. In contrast with our findings, a recent study by Evron et al. [2] found no difference between arterial and central venous blood glucose concentration in adult patients undergoing major orthopaedic or colon surgery though these patients were all studied in the context of general anaesthesia and surgery and were not critically ill. It is possible that glucose containing fluids infused into a vein peripheral to the central venous line or infused via one of the other central venous line lumens could have contaminated the central venous sample that was taken. As this was an opportunistic study performed under uncontrolled conditions information about glucose infusions was not collected, other than confirmation that no glucose containing fluid was infused into either the arterial or central venous sampling lines. However, alternative explanations are possible in that glucose may be generated in peripheral tissues, most notably in muscle, during critical illness and released into the venous system [3, 4]. 0 5 10 15 20 25

34th Annual Scientific Meeting of the Association of Paediatric Anaesthetists of Great Britain and Ireland, 8?10 March 2007, Manchester. Paediatric propofol pharmacokinetics: a multicentre study

Introduction: Schuttler and Imhsens propofol pharmacokinetic (PK) model (1) based on pooled adult and paediatric data lacked information for the smallest patients. We conducted a pooled population analysis of available neonatal and paediatric propofol PK data. The variable clinical circumstances of the individual studies allowed us to explore health status as a PK model covariate. Methods: We combined raw propofol blood/plasma concentration vs time data, dosing information and demographic data from eight paediatric studies conducted by six research groups, with our data (2,3). The pooled data set comprised 197 individuals (2315 observations), aged 0.02–12.25 years (2.75–60.5 kg, median 15 kg). In this preliminary population PK analysis using NONMEM, the basic model structure was established before all model parameters were allometrically scaled to body weight. The influence of health status on paediatric propofol PK was explored. Results: In this 3-compartment preliminary model, postcardiac surgery patients have significantly reduced metabolic clearance rates (31–45% less when compared with healthy children or noncardiac PICU patients). The volume of the deep peripheral compartment in critically ill and postcardiac surgery children is 319% and 205% larger, respectively, than in healthy children, see Table 1. Table 1. PK values for a child weighing 15 kg Parameter Typical Value 95% Confidence Interval CL (l·min-1) Healthy 0.614 0.563–0.665 PICU 0.767 0.628–0.906 PICU cardiac 0.421 0.366–0.476 Q2 (l·min-1) 0.839 0.703–0.975 Q3 (l·min-1) 0.252 0.221–0.283 V1 (l) 7.76 6.33–9.19 V2 (l) 14.4 12.8–16.0 V3 (l) Healthy 83.9 61.4–106 PICU 268 183–353 PICU cardiac 172 117–227

Capillary refill and core-peripheral temperature gap as indicators of haemodynamic status in paediatric intensive care patients.

Capillary refill time is an important diagnostic adjunct in the acute resuscitation phase of the shocked child. This study assesses its relation to commonly measured haemodynamic parameters in the postresuscitation phase when the child has reached the intensive care unit, and compares this with core-peripheral temperature gap. Ninety standardised measurements of capillary refill time were made on 55 patients, who were divided into postcardiac surgery (n = 27), and general (n = 28), most of whom had septic shock (n = 24). A normal capillary refill time was defined as < or = 2 seconds. Measured haemodynamic variables included: cardiac index, central venous pressure, systemic vascular resistance index, stroke volume index (SVI), and blood lactate. Seventy measurements were made on patients while being treated with inotropes or vasodilators. Capillary refill time and temperature gap both correlated poorly with all haemodynamic variables among post-cardiac surgery children. For general patients, capillary refill time was related to SVI and lactate; temperature gap correlated poorly with all variables. General patients with a prolonged capillary refill time had a lower median SVI (28 v 38 ml/m2) but not a higher lactate (1.7 v 1.1 mmol/l). A capillary refill time of > or = 6 seconds had the best predictive value for a reduced SVI. Among ventilated, general intensive care patients, capillary refill time is related weakly to blood lactate and SVI. A normal value for capillary refill time of < or = 2 seconds has little predictive value and might be too conservative for this population; septic shock.

Preliminary data: PIM and Prism in infants and children post cardiac surgery in a UK PICU

Preliminary data: PIM and Prism in infants and children post cardiac surgery in a UK PICU

Chest physiotherapy following paediatric cardiac surgery: The influence of mode of treatment on oxygen saturation and haemodynamic stability

Chest physiotherapy is widely used after open heart surgery to prevent secondary pathology in the lungs. Yet chest physiotherapy has been reported to cause hypoxaemia. In order to investigate the relationship between specific chest physiotherapy techniques and oxygen saturation in children post-cardiac surgery, a prospective clinical study was undertaken. Sixty-seven ventilated children below 4 years of age completed the study. Their oxygen saturation, heart rate and blood pressure were recorded before, during and after chest physiotherapy, which included endotracheal suctioning. Exploratory data analysis on the eight resulting treatment groups showed that maximum falls in oxygen saturation varied from less than 1% (vibrations and bag squeezing) to almost 6% (percussion, vibrations and position change). Analysis of covariance revealed that the treatment ‘package’ given to the child was the main determinant of the maximum fall in oxygen saturation (P<0.001) and that younger children demonstrated greater fa...

208 POSTOPERATIVE JUNCTIONAL TACHYCARDIA IN PEDIATRIC PATIENTS

We determined the incidence of cardiac arrhythmias in children post cardiac surgery, the cardiac malformations associated with specific arrhythmias and the ECG characteristics of the arrhythmias. Continuous 2-lead ECG's were recorded in 26 consecutive patients (ages 2 mos-13 yrs) during the first 24 hours after open heart surgery. The most frequent non-sinus arrhythmia was atrioventricular junctional tachycardia (JT) which occurred in 9 patients (39%). Ventricular, junctional and atrial premature depolarizations were infrequent ( the duration of the basic cardiac cycle (i.e., occurring as accelerated junctional escape); the second occurred when sinus tachycardia supplanted normal sinus rhythm and then was overdriven by an accelerated junctional focus. The second type of onset is consistent with reentry or triggered activity; the first, with an automatic focus. Both JT had similar QRS morphologies and axes and appeared unrelated to perioperative medication and acid-base and electrolyte status. The high incidence of JT after open heart surgery is of interest because of its infrequency in the general pediatric population. It may result from surgical manipulation of the AV junction and it appears that more than one mechanism is responsible for its initiation.