Lung recruitment maneuvers are frequently used in the treatment of children with lung injury. Here we describe a pilot study to compare the acute effects of 2 commonly used lung recruitment maneuvers ...on lung volume, gas exchange, and hemodynamic profiles in children with acute lung injury.
In a prospective, non-randomized, crossover pilot study, 10 intubated pediatric subjects with lung injury sequentially underwent: a period of observation; a sustained inflation (SI) maneuver of 40 cm H2O for 40 seconds and open-lung ventilation; a staircase recruitment strategy (SRS) (which utilized 5 cm H2O increments in airway pressure, from a starting plateau pressure of 30 cm H2O and PEEP of 15 cm H2O); a downwards PEEP titration; and a 1 hour period of observation with PEEP set 2 cm H2O above closing PEEP.
Arterial blood gases, lung mechanics, hemodynamics, and functional residual capacity were recorded following each step of the study and following each increment of the SRS. Both SI and SRS were effective in raising PaO2 and functional residual capacity. During the SRS maneuver we noted significant increases in dead-space ventilation, a decrease in carbon dioxide elimination, an increase in PaCO2, and a decrease in compliance of the respiratory system. Lung recruitment was not sustained following the decremental PEEP titration.
SRS is effective in opening the lung in children with early acute lung injury, and is hemodynamically well tolerated. However, attention must be paid to PaCO2 during the SRS. Even minutes following lung recruitment, lungs may derecruit when PEEP is lowered beyond the closing pressure.
To determine the relationship between estimated free, measured free, and measured total phenytoin levels in critically ill pediatric patients, assess the utility of the Sheiner-Tozer equation in ...predicting free phenytoin levels, and identify comedications that may influence phenytoin binding or confound attempts to maintain therapeutic concentrations.
Retrospective chart review.
Twenty-four-bed medical-surgical pediatric intensive care unit.
Sixty critically ill pediatric patients receiving phenytoin for treatment of seizures in a large multidisciplinary intensive care unit.
The linear correlation between free and total phenytoin concentrations was moderate (r = .795), but the mean difference between actual free concentrations and those estimated from total concentrations using the Sheiner-Tozer equation was -0.31 +/- 0.5 microg/mL (95% confidence interval, -1.3 to 0.7). This difference was of concern, as 10% of patients had toxic free levels (>2 microg/mL) when simultaneously measured total levels were therapeutic (<20 microg/mL). The mean free/total phenytoin ratio was 0.13 +/- 0.07 (range, 0.06-0.42) and varied considerably among patients. Free fractions were particularly elevated in children whose serum albumin concentrations were <2.5 g/dL (0.22, p < .001). However, the relationship between free phenytoin and serum albumin concentration appeared to be nonlinear. Coadministration of valproic acid and cefazolin also increased free fraction (p < .001).
Measured total phenytoin concentrations are unreliable for directing therapy in critically ill children. In part, this is because phenytoin binding shows greater variability in this population than has been reported in adults. This phenomenon is exacerbated by coadministration of other highly protein-bound drugs. Instead, free phenytoin concentrations should be routinely measured in critically ill children to prevent possible intoxications and ensure therapeutic dosing. Corrections using the Sheiner-Tozer equation were unreliable.
Regional lung overdistension occurring during high frequency oscillatory ventilation (HFOV) and partial liquid ventilation (PLV) was investigated in a prospective animal trial using 18 mechanically ...ventilated Yorkshire swine under general anesthesia. Lung injury was induced with saline lavage and augmented using large tidal volumes. Electrical impedance tomography (EIT) and regional lung histopathology were used to identify regional lung overdistension during HFOV. Lung injury was quantified using a histopathologic lung injury score. The animals were randomized to three groups (n = 6 animals in each group): a control group and two dose groups of perfluorooctyl bromide (PFOB) (PFOB-Lo 1.5 ml kg(-1) and PFOB-Hi 3 ml kg(-1)). The animals were transitioned from conventional ventilation to HFOV, and a slow inflation-deflation maneuver was performed by changing mean airway pressure (Paw) by 5 cmH(2)O every 15 min to a maximum Paw of 40 cmH(2)O. In dependent lung areas, the PFOB-Hi (3 ml kg(-1)) group, in comparison with the control group, was associated with significantly greater alveolar overdistension seen on lung histopathology (P < 0.001 compared to control), a decreased mean impedance (P < 0.05 compared to the control group) and a decreased ventilation-induced impedance change during HFOV (P < 0.05 compared to the control group). We conclude that treatment with PFOB-Hi during HFOV compared to a control group in an animal model of lung injury led to regional overdistension of dependent lung areas, as evidenced by increased alveolar overdistension on lung histopathology, decreased mean lung impedance and decreased HFOV-induced regional lung volume changes as measured by EIT.
The placement of nasal or oral gastric tubes is one of the most frequently performed procedures in critically ill children; tube malposition, particularly in the trachea, is an important ...complication. Neurally adjusted ventilatory assist (NAVA) ventilation (available only on the Servo-i ventilator, Maquet Critical Care, Solna, Sweden) requires a proprietary-design catheter (Maquet Critical Care, Solna, Sweden) with embedded electrodes that detect the electrical activity of the diaphragm (EA(di)). The EA(di) catheter has the potential benefit of confirming proper positioning of a gastric catheter, based on and the EA(di) waveforms.
In a case series study, our multidisciplinary team used EA(di) guidance for immediate, real-time confirmation of proper nasal or oral gastric tube placement in 20 mechanically ventilated pediatric patients who underwent 23 oral or nasal gastric tube placements. The catheters were placed with our standard practice, with the addition of a team member monitoring the EA(di) waveforms. As the tube passes down the esophagus and posterior to the heart, a characteristic EA(di) pattern is identified and the position of the atrial signal confirms correct placement of the gastric tube. If the EA(di) waveforms indicate incorrect placement, the tube is repositioned until the proper EA(di) waveform pattern is obtained. Then proper tube placement is reconfirmed via auscultation over the stomach while air is injected into the catheter, checking the pH of fluid suctioned from the catheter (gastric pH indicates correct positioning), and/or radiograph.
The group's median age was 3 years (range 4 d to 16 y). All 20 patients had successful gastric catheter placement. The EA(di) catheter provided characteristic patterns for correctly placed tubes, tubes malpositioned above or below the gastroesophageal junction, and curled tubes. Proper catheter position was confirmed via radiograph and/or gastric pH in all 20 patients.
EA(di) guidance helps confirm proper gastric catheter position, is equivalent to our standard practice for confirming gastric catheter placement, and may reduce the need for radiographs and improve patient safety by avoiding catheter malpositions.
To review articles relevant to the field of pediatric respiratory disease that were published after the 2008 Rogers' Textbook of Pediatric Intensive Care.
The authors searched the PubMed database ...(http://www.ncbi.nlm.nih.gov/sites/entrez) from the National Library of Medicine for citations from the pediatric and adult literature relevant to pediatric status asthmaticus, bronchiolitis, pneumonia, acute lung injury, acute respiratory distress syndrome, and neonatal respiratory failure. The authors also searched the reference lists of key primary publications and recent review articles, and queried the National Institutes of Health's ClinicalTrials.gov Web site (www.clinicaltrials.gov) to obtain information about ongoing clinical trials for acute lung injury. The authors had knowledge of new publications in the field of respiratory monitoring, which were considered for inclusion in the review.
The authors reviewed the promising articles and the decision to include any article in the review was based on its potential to inform pediatric intensive care practice or future research.
Articles in six categories were selected for inclusion: status asthmaticus, bronchiolitis, pneumonia, acute lung injury/acute respiratory distress syndrome, respiratory monitoring, and neonatal respiratory failure.
There have been important new developments relevant to the pathogenesis and management of pediatric respiratory diseases. In particular, new insights into the causal pathways of respiratory syncytial virus-induced airways disease can potentially lead to novel therapies. Computed tomography imaging of the injured lung during mechanical ventilation has opened new avenues for future research directed at testing new treatments in acute lung injury subpopulations defined according to lung mechanics. Promising new monitoring techniques may play a supporting role in the conduct of these studies. Finally, evidence from the neonatal literature recently has shown how the course and future consequences of respiratory failure in this population may be modified through more widespread use of noninvasive support.
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