Augusto Pérez

Jugular venous oxygen saturation or arteriovenous difference of lactate content and outcome in children with severe traumatic brain injury.

Objective To assess the association between neurologic outcome and the alterations of jugular venous oxygen saturation (Sjvo2) or the increase in arteriovenous difference of lactate content (AVDL) in children with severe traumatic brain injury. Design Observational prospective cohort study. Setting Multidisciplinary pediatric intensive care unit of a university hospital. Patients A total of 27 pediatric patients with severe traumatic brain injury, with a Glasgow Coma Scale after resuscitation of <9, who were admitted to the pediatric intensive care unit within 36 hrs after injury. Interventions Intermittent measurement of Sjvo2 and AVDL. Measurements and Main Results Sjvo2 and AVDL were assessed simultaneously every 6 hrs. The primary dependent variable measured was assessed independently 3 months after trauma according to the Pediatric Cerebral Performance Category. Patients were classified into two groups: group 1 (favorable outcome, Pediatric Cerebral Performance Category 1–3) and group 2 (unfavorable outcome, Pediatric Cerebral Performance Category 4–6); 81% were included in group 1 and 19% in group 2. A total of 354 measurements of Sjvo2 and AVDL were made, with a mean of 13.1 ± 7.9 per patient. The number of abnormal measurements of Sjvo2 and increased AVDL used to predict the neurologic outcome was selected according to the area under the receiver operating characteristic curve. Mortality was 15% (four patients). The strongest association was found between a poor neurologic outcome and two or more pathologic AVDL measurements (higher than −0.37 mmol/L; relative risk, 17.6; 95% confidence interval, 2.5–112.5;p = .001). The presence of two or more measurements of Sjvo2 of ≤55% was significantly associated with a poor neurologic outcome (relative risk, 6.6; 95% confidence interval, 1.5–29.7;p = .003). The frequency of measurements of Sjvo2 of ≥75% was not different between groups 1 and 2. Conclusion In children with severe traumatic brain injury, two or more measurements of Sjvo2 of ≤55% or two or more pathologic AVDL measurements were associated with a poor neurologic outcome. Further studies are needed to recommend the use of these variables as a guideline to optimize treatment.

Validation of pediatric index of mortality 2 (PIM2) in a single pediatric intensive care unit of Argentina.

Objective: Pediatric Index of Mortality 2 (PIM2) is an up-to-date mortality prediction model in the public domain that has not yet been widely validated. We aimed to evaluate this score in the population of patients admitted to our pediatric intensive care unit. Design: Prospective cohort study. Setting: Multidisciplinary pediatric intensive care unit in a general university hospital in Buenos Aires, Argentina. Patients: All consecutive patients admitted between January 1, 2004, and December 31, 2005. Interventions: None. Measurements and Main Results: There were 1,574 patients included in the study. We observed 41 (2.6%) deaths, and PIM2 estimated 48.1 (3.06) deaths. Discrimination assessed by the area under the receiver operating characteristic curve was 0.9 (95% confidence interval, 0.89–0.92). Calibration across five conventional mortality risk intervals assessed by the Hosmer–Lemeshow goodness-of-fit test showed &khgr;2(5) = 12.2 (p = .0348). The standardized mortality ratio for the whole population was 0.85 (95% confidence interval, 0.6–1.1). Conclusions: PIM2 showed an adequate discrimination between death and survival and a poor calibration assessed by the Hosmer–Lemeshow goodness-of-fit test. The standardized mortality ratio and clinical analysis of the Hosmer–Lemeshow table make us consider that PIM2 reasonably predicted the outcome of our patients.

Hospital-acquired hyponatremia in postoperative pediatric patients: Prospective observational study*

Objective: To establish the incidence and factors associated with hospital-acquired hyponatremia in pediatric surgical patients who received hypotonic saline (sodium 40 mmol/L plus potassium 20 mmol/L) at the rate suggested by the Holliday and Segar’s formula for calculations of maintenance fluids. Design: Prospective, observational, cohort study. Setting: Pediatric intensive care unit. Patients: Eighty-one postoperative patients. Interventions: None. Measurements and Main Results: Incidence and factors associated with hyponatremia (sodium ≤135 mmol/L). Univariate analysis was conducted post surgery at 12 hrs and at 24 hrs. Mean values were compared with independent t test samples. Receiver operating characteristics curve analysis was performed in variables with a p <.05, and relative risks were calculated. Eighty-one patients were included in the study. The incidence of hyponatremia at 12 hrs was 17 (21%) of 81 (95% confidence interval, 3.7–38.3); at 24 hrs, it was was 15 (31%) of 48 (95% confidence interval, 11.4–50.6). Univariate analysis at 12 hrs showed that hyponatremic patients had a higher sodium loss (0.62 mmol/kg/hr vs. 0.34 mmol/kg/hr, p = .0001), a more negative sodium balance (0.39 mmol/kg/hr vs. 0.13 mmol/kg/hr, p < .0001), and a higher diuresis (3.08 mL/kg/hr vs. 2.2 mL/kg/hr, p = .0026); relative risks were 11.55 (95% confidence interval, 2.99–44.63; p = .0004) for a sodium loss >0.5 mmol/kg/hr; 10 (95% confidence interval, 2.55–39.15; p = .0009) for a negative sodium balance >0.3 mmol/kg/hr; and 4.25 (95% confidence interval, 1.99–9.08; p = .0002) for a diuresis >3.4 mL/kg/hr. At 24 hrs, hyponatremic patients were in more positive fluid balance (0.65 mL/kg/hr vs. 0.10 mL/kg/hr, p = .0396); relative risk was 3.25 (95% confidence interval, 1.2–8.77; p = .0201), for a positive fluid balance >0.2 mL/kg/hr. Conclusions: The incidence of hyponatremia in this population was high and progressive over time. Negative sodium balance in the first 12 postoperative hours and then a positive fluid balance could be associated with the development of postoperative hyponatremia.

The value of gastric intramucosal pH in the postoperative period of cardiac surgery in pediatric patients.

Objective: To examine the usefulness of gastric intramucosal pH (pHi) to predict adverse events during the postoperative period after cardiac surgery in pediatric patients. Design: Prospective, observational clinical study. Setting: Multidisciplinary pediatric intensive care unit, university hospital. Patients: A total of 70 patients who had elective cardiac surgery and cardiopulmonary bypass; mean age, 4.0 yrs. Interventions: Gastric tonometry. Measurements and Main Results: In all cases, the pHi was determined within the first 2 hrs and again within the first 12 hrs of the postoperative period after cardiac surgery. The following adverse events were considered: mortality, multiple organ failure (MOF), and infectious complications. Patients were divided into three groups: Group A, patients having the two pHi measurements ≤7.32 (n = 15); Group B, patients having the two pHi determinations >7.32 (n = 28); and Group C, patients having one pHi determination ≤7.32 and the other >7.32 (n = 27). Of the total sample, 5 (7.1%) patients died; 4 (5.7%) had MOF, and 13 (18.5%) had infectious complications. When the rate of adverse events was analyzed in the three groups, significant differences were found in mortality (p < .035) and MOF (p < .029). This was not the case for infectious complications (p = .071). In Group A, three patients died and three had MOF. The standardized chi‐square values were 1.87 and 2.31 respectively, causing the authors to consider that this group accounted for the differences found in the global analysis. Conclusions: Two pHi determinations ≤7.32, one at admission and one at 12 hrs of the postoperative period after cardiac surgery and cardiopulmonary bypass, were associated with a higher rate of mortality and MOF, but not with a higher rate of infectious complications. It is not yet possible to recommend the use of this finding as a treatment objective to guide hemodynamic optimization in this group of patients.

Adequate agreement between venous oxygen saturation in right atrium and pulmonary artery in critically ill children.

Objective: To determine the agreement between venous oxygen saturation in right atrium (Srao2) and pulmonary artery (Svo2) in critically ill pediatric patients. Design: Retrospective, observational study. Setting: Multidisciplinary pediatric intensive care unit from a general university hospital. Patients: Thirty critically ill children in whom a pulmonary artery catheter (PAC) was inserted for catecholamine refractory shock (septic and cardiogenic, n = 18) and postoperative management (liver and cardiac transplant, n = 12). Measurements and Main Results: Ninety measurements of Srao2 and Svo2 were obtained after placement of PAC and every 6 hrs for the first 12 hrs of pediatric intensive care unit admission. The agreement between Srao2 and Svo2 was determined through Bland and Altman methodology, concordance correlation coefficient, and the frequency of differences between Srao2 and Svo2. The frequency of differences between both saturations was evaluated in three categories: ±1%–5%, ±6%–9%, and higher than ±10%. The first category was the threshold to consider both variables interchangeable. Changes of Srao2 related to clinically significant (>5%) increases and drops of Svo2 were analyzed. Srao2 and Svo2 were not significantly different: median (interquartile range) 83% (75%–86%) and 81% (75%–85%), respectively (p = 0.23). The frequency of differences between Srao2 and Svo2 was ±1%–5%, 71 (79%); ±6%–9%, 14 (15.5%); and higher than ±10%, 5 (5.5%). Bland and Altman analysis showed a 2% bias with a 95% limits of agreement of −6.9% to 10.9%. The concordance correlation coefficient was 0.90. Svo2 increased in 11/90 measurements and Srao2 followed it 82% of the times. Svo2 decreased in 7/90 measurements and Srao2 followed it 100% of the times. Conclusion: The concordance analysis performed allows to conclude that there is an appropriate agreement between Svo2 and Srao2. This finding may become clinically relevant considering the difficulties associated to the use of PAC in children.

Internal mammary artery injury after central venous catheterization.

Objective: We describe an infrequent but potentially lethal complication: an iatrogenic injury of the internal mammary artery after central venous catheterization. Design: Report of cases. Setting: Pediatric intensive care unit. Patients: The first patient we report on is a 3-yr-old girl who was severely neurologically damaged and was admitted to the pediatric intensive care unit for aspiration pneumonia and septic shock. Immediately after vein cannulation on the left internal jugular vein, the patient suffered hypotension and cardiac arrest, secondary to an adequately drained massive hemothorax. Restoration of spontaneous circulation was initially achieved, and the patient was transferred to the angiographic suite. Selective angiography during cardiopulmonary resuscitation for a second cardiac arrest revealed a laceration of the internal mammary artery. Resuscitation was not successful, and the patient died. The second case reported is a 7-yr-old girl admitted for bone marrow transplantation. She was electively taken to the angiographic suite for central venous insertion. An infraclavicular approach of the right subclavian vein was attempted, but radioscopy showed the guidewire inside the pleural space. Soon thereafter, the patient became hypotensive and was in shock. Radioscopy showed a large pleural effusion and a massive hemothorax was drained. Selective angiography demonstrated an injured internal mammary artery was embolized. Hemodynamics improved, and the patient was transferred to the pediatric intensive care unit, where she was extubated 12 hrs later. Interventions: None. Conclusions: Central venous catheter placement in the intrathoracic vein may cause potentially lethal complications in the form of an injury to the internal mammary artery. Hypotension during or immediately after the procedure should be a warning of a serious adverse event, such as massive hemothorax, that may compromise life. Adequate drainage of the pleural cavity may not completely relieve vascular compression if some of the bleeding from an injured internal mammary artery is extrapleural. Early diagnosis and treatment by selective embolization of the injured vessel in interventional radiology is the first therapeutic choice and may be life saving.

Limitation in paediatric logistic organ dysfunction score

In their letter about the paediatric logistic organ dysfunction (PELOD) score (March 18, p 897), the authors of the original report describe a limitation in their previous calibration of the score against mortality. That is, the points given to each criterion of the score (0, 1, 10, or 20) cannot add up to a sum with predicted risk of mortality between 5% and 15% when using the equation: probability of death = 1/(1 + exp[7·64–0·30*PELOD score]). Despite this problem, the authors still consider the PELOD score a good measure of severity of illness. There seems to be another anomaly in the PELOD score: the score is not a continuous variable. Between zero and 71 (the minimum and maximum scores) the only possible scores are 0–4, 10–14, 20–24, 30–34, 40–43, 50–53, 60–62, 70 and 71. When incorporated into the probability-ofdeath equation, there is no mortality prediction between 3·1% and 16·2% because it is not possible to have scores between 14 and 20. However, there is another gap in the score between 24 and 30, which means that there is also no risk-of-mortality prediction between 40% and 80% (fi gure). The PELOD score was developed as a measurement of severity of illness to be used in clinical trials. We believe that many factors now invalidate its use: the score is discontinuous and provides no data for patients with moderate (5–15%) or severe (40–80%) risk of mortality, its calibration is poor, and the relation with mortality is nonlinear. So, a 2-point increase in PELOD score could refer to a 0·1% or a 10% change in risk of mortality (score 1–3 or 20–22, respectively). Alternatively, if we are interested in a change in risk of mortality, then the gaps in the curve (5–15% and 40–80%) are problematic. We declare that we have no confl ict of interest.

Transpyloric feeding tube placement by gastric air insufflation technique in pediatric intensive care patients

INTRODUCTION The aim of the study was to evaluate the success rate of transpyloric tube (TPT) placement using air gastric insufflation technique in patients hospitalized in the Pediatric Intensive Care Unit. POPULATION, MATERIALS AND METHODS: The data were collected retrospectively from a prospective filled database. TPT positioning was defined as successful by evaluation of its distal end in the abdominal X-ray. Demographic information, success rate, duration of the procedure were registered. Descriptive statistics was used to analyze the data. RESULTS There were 37 procedures in 33 patients and 84% of them were on mechanical ventilation. The percentage of success in TPT placement was 89% (33/37) and the mean duration of the procedure was 12.8 min +/- 5.3. No complications were registered. CONCLUSION TPT placement through the insufflation of air in the stomach is a short, simple, effective, and well tolerated procedure that can be done at bedside.

Balance de fluidos y duración de la ventilación mecánica en niños internados en una Unidad de Terapia Intensiva Pediátrica

INTRODUCTION Associations between cumulative fluid balance and a prolonged duration of assisted mechanical ventilation have been described in adults. The aim of this study was to evaluate whether fluid balance in the first 48 hours of assisted mechanical ventilation initiation was associated with a prolonged duration of this process among children in the Pediatric Intensive Care Unit (PICU). METHODS Retrospective cohort of patients in the PICU o, Hospital Italiano de Buenos Aires, between 1/1/2010 and 6/30/2012. Balance was calculated in percentage of body weight; prolonged mechanical ventilation was defined as >7 days, and confounders were registered. Univariate and multivariate analyses were performed. RESULTS Two hundred and forty-nine patients were mechanically ventilated for over 48 hours; 163 were included in the study. Balance during the first 48 hours of mechanical ventilation was 5.7% ± 5.86; 82 patients (50.3%) were on mechanical ventilation for more than 7 days. Age 〈 4 years old (OR 3.21, 95% CI 1.38-7.48, p 0.007), respiratory disease (OR 4.94, 95% CI 1.51-16.10, p 0.008), septic shock (OR 4.66, 95% CI 1.10-19.65, p 0.036), Pediatric Logistic Organ Dysfunction (PELOD) 〉 10 (OR 2.44, 95% CI 1.234.85, p 0.011), and positive balance 〉 13% (OR 4.02, 95% CI 1.08-15.02, p 0.038) were associated with prolonged mechanical ventilation. The multivariate model resulted in an OR 2.58, 95% CI: 1.17-5.58, p= 0.018 for PELOD 〉 10, and an OR 3.7, 95% CI: 0.91-14.94, p= 0.066 for positive balance 〉 13%. CONCLUSIONS Regarding prolonged mechanical ventilation, the multivariate model showed an independent association with organ dysfunction (PELOD 〉 10) and a trend towards an association with positive balance 〉 13%.