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 < or = 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.

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.

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 chi5 = 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.

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.

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 out-come 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 < or = 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 > or = 75% was not different between groups 1 and 2. CONCLUSION: In children with severe traumatic brain injury, two or more measurements of SjvO2 of < or = 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.