Tag Archives: Anoxia

Accuracy of Pulse Oximeters Intended for Hypoxemic Pediatric Patients.

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Harris BU, et al. Accuracy of Pulse Oximeters Intended for Hypoxemic Pediatric Patients.Pediatr Crit Care Med. 2016 Feb 24. [Epub ahead of print]

OBJECTIVES: Prior studies have shown inaccuracies in pulse oximetry readings at saturations less than 85%; however, no large studies have evaluated new sensors marketed for these low saturations. This study’s purpose was to evaluate two sensors with claims of improved accuracy in children with saturations less than 85%.

DESIGN: Prospective observational study.

SETTING: Single institution; cardiac catheterization laboratory, and operating room.

PATIENTS: Fifty patients weighing 3-20 kg with baseline saturations less than 90% undergoing surgical or catheterization procedure.

MEASUREMENTS AND MAIN RESULTS: Data collected included demographics, diagnosis, continuous saturations from three different pulse oximeters (Masimo LNCS [Masimo, Irvine, CA], Masimo Blue [Masimo], and Nellcor Max-I [Medtronic, Dublin, reland]) and up to four blood samples for co-oximetry as the gold-standard arterial oxygen saturation. Analysis included scatter plots, smoothed regression estimates of mean continuous saturation levels plotted against corresponding arterial oxygen saturation values, and Bland-Altman plots. Bland-Altman analysis indicated increasing levels of bias and variability for decreasing arterial oxygen saturation levels for all three sensors, with a statistically significant increase in mean difference observed for decreasing arterial oxygen saturation level. The Masimo Blue sensor had the lowest mean difference, SD and Bland-Altman limits in patients with saturations less than or equal to 85%. At saturation range of less than or equal to 85% and greater than 75%, 14% of the samples obtained from Masimo Blue, 24% of the readings from the Nellcor, and 31% from the Masimo Standard sensors were greater than or equal to 5% points difference. All three sensors had a further increase in these differences for arterial oxygen saturation values less than 75%.

CONCLUSIONS: The Masimo Blue sensor has improved accuracy at saturations 75-85% versus the Nellcor and Masimo Standard sensors. The accuracy of peripheral capillary oxygen saturation of the Masimo Blue sensor was within 5% points of the arterial oxygen saturation the majority of the time. Currently, at saturations less than or equal to 85%, pulse oximetry alone should not be relied on in making clinical decisions.

Pediatric calfactant in acute respiratory distress syndrome trial. (Dugan)

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Willson DF, Thomas NJ, Tamburro R, Truemper E, Truwit J, Conaway M, Traul C, Egan EE; Pediatric Acute Lung and Sepsis Investigators Network. Pediatric Calfactant in Acute Respiratory Distress Syndrome Trial*. Pediatr Crit Care Med. 2013 Sep;14(7):657-665.

RATIONALE: Our previous studies in children with acute lung injury/acute respiratory distress syndrome demonstrated improved outcomes with exogenous surfactant (calfactant) administration. Sample sizes in those studies were small, however, and the subject populations heterogeneous, thus making recommendations tenuous.

OBJECTIVE: To investigate the efficacy of surfactant administration in a larger, more homogenous population of children with lung injury/acute respiratory distress syndrome due to direct lung injury.

DESIGN AND SETTING: Masked, randomized, placebo-controlled trial in 24 children’s hospitals in six different countries.

PATIENTS AND METHODS: Children 37 weeks postconception to 18 years old with lung injury/acute respiratory distress syndrome due to direct lung injury were randomized to receive up to three doses of 30 mg/cm height of surfactant (calfactant) versus placebo (air) within 48 hours of intubation and initiation of mechanical ventilation. The primary outcome was mortality at 90 days. Ventilator-free days, changes in oxygenation, and adverse events were also assessed.

RESULTS: The study was stopped at the sponsor’s request after the second interim analysis for presumed futility. A total of 110 subjects were enrolled, with consent withdrawn from one whose data are unavailable. There were no significant differences between groups except in hospital-free days (10.4 ± 7.8 placebo vs 6.4 ± 7.8 surfactant; p = 0.01). Overall 90-day mortality was 11% (seven surfactant, five placebo). No immediate improvement in oxygenation was associated with surfactant administration.

CONCLUSIONS: Surfactant did not improve outcomes relative to placebo in this trial of children with direct lung injury/acute respiratory distress syndrome. Differences in concentration of the surfactant, failure to recruit the lung during surfactant administration, or using two rather than four position changes during administration are possible explanations for the difference from previous studies. Exogenous surfactant cannot be recommended at this time for children with direct lung injury/acute respiratory distress syndrome.

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Inhaled epoprostenol vs inhaled nitric oxide for refractory hypoxemia in critically ill patients. (Stockwell)

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J Crit Care. 2013 May 14. pii: S0883-9441(13)00067-1. PMID: 23683572

PURPOSE: The purpose of this is to compare efficacy, safety, and cost outcomes inpatients who have received either inhaled epoprostenol (iEPO) or inhaled nitric oxide (iNO) for hypoxic respiratory failure.

MATERIALS AND METHODS: This is a retrospective, single-center analysis of adult, mechanically ventilated patients receiving iNO or iEPO for improvement in oxygenation.

RESULTS: We evaluated 105 mechanically ventilated patients who received iEPO (52patients) or iNO (53 patients) between January 2009 and October 2010. Most patientsreceived therapy for acute respiratory distress syndrome (iNO 58.5% vs iEPO 61.5%; P = .84). There was no difference in the change in the partial pressure of arterial O2/fraction of inspired O2 ratio after 1 hour of therapy (20.58 ± 91.54 vs 33.04 ± 36.19 [P = .36]) in the iNO and iEPO groups, respectively. No difference was observed in duration of therapy (P = .63), mechanical ventilation (P = .07), intensive care unit (P = .67), and hospital lengths of stay (P = .26) comparing the iNO and iEPO groups. No adverse events were attributed to either therapy. Inhaled nitric oxide was 4.5 to 17 times more expensive than iEPO depending on contract pricing.

CONCLUSIONS: We found no difference in efficacy and safety outcomes when comparing iNO and iEPO in hypoxic, critically ill patients. Inhaled epoprostenol is associated with less drug expenditure than iNO.

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Early oxygenation and ventilation measurements after pediatric cardiac arrest: lack of association with outcome. (Dugan)

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Crit Care Med. 2013 Jun;41(6):1534-1542. PMID: 23552509

OBJECTIVES: To explore oxygenation and ventilation status early after cardiac arrest in infants and children. We hypothesize that hyperoxia is common and associated with worse outcome after pediatric cardiac arrest.

DESIGN: Retrospective cohort study.

SETTING: Fifteen hospitals within the Pediatric Emergency Care Applied Research Network.

PATIENTS: Children who suffered a cardiac arrest event and survived for at least 6 hoursafter return of circulation.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Analysis of 195 events revealed that abnormalities in oxygenation andventilation are common during the initial 6 hours after pediatric cardiac arrest. Hyperoxia was frequent, affecting 54% of patients. Normoxia was documented in 34% and hypoxia in 22% of patients. These percentages account for a 10% overlap of patients who had both hyperoxia and hypoxia. Ventilation status was more evenly distributed with hyperventilation observed in 38%, normoventilation in 29%, and hypoventilation in 46%, with a 13% overlap of patients who had both hyperventilation and hypoventilation. Derangements in bothoxygenation and ventilation were common early after cardiac arrest such that both normoxia and normocarbia were documented in only 25 patients (13%). Neitheroxygenation nor ventilation status was associated with outcome. After controlling for potential confounders, arrest location and rhythm were significantly associated with worse outcome; however, hyperoxia was not (odds ratio for good outcome, 1.02 [0.46, 2.84]; p = 0.96).

CONCLUSIONS: Despite recent resuscitation guidelines that advocate maintenance of normoxia and normoventilation after pediatric cardiac arrest, this is uncommonly achieved in practice. Although we did not demonstrate an associationbetween hyperoxia and worse outcome, the small proportion of patients kept within normal ranges limited our power. Preclinical data suggesting potential harm with hyperoxia remain compelling, and further investigation, including prospective, large studies involving robust recording of physiological derangements, is necessary to further advance our understanding of this important topic.

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