Exposure of red blood cells to oxidants increases production of methemoglobin (MHb) resulting in impaired oxygen delivery to tissues. There are no reliable estimates of methemoglobinemia in low ...resource clinical settings. Our objectives were to: i) evaluate risk factors for methemoglobinemia in Ugandan children hospitalized with fever (study 1); and ii) investigate MHb responses in critically ill Ugandan children with severe malaria treated with inhaled nitric oxide (iNO), an oxidant that induces MHb in a dose-dependent manner (study 2).
Two prospective studies were conducted at Jinja Regional Referral Hospital in Uganda between 2011 and 2013. Study 1, a prospective cohort study of children admitted to hospital with fever (fever cohort, n = 2089 children 2 months to 5 years). Study 2, a randomized double-blind placebo-controlled parallel arm trial of room air placebo vs. 80 ppm iNO as an adjunctive therapy for children with severe malaria (RCT, n = 180 children 1-10 years receiving intravenous artesunate and 72 h of study gas). The primary outcomes were: i) masimo pulse co-oximetry elevated MHb levels at admission (>2 %, fever cohort); ii) four hourly MHb levels in the RCT.
In the fever cohort, 34 % of children admitted with fever had elevated MHb at admission. Children with a history of vomiting, delayed capillary refill, elevated lactate, severe anemia, malaria, or hemoglobinopathies had increased odds of methemoglobinemia (p < 0.05 in a multivariate model). MHb levels at admission were higher in children who died (n = 89) compared to those who survived (n = 1964), p = 0.008. Among children enrolled in the iNO RCT, MHb levels typically plateaued within 12-24 h of starting study gas. MHb levels were higher in children receiving iNO compared to placebo, and MHb > 10 % occurred in 5.7 % of children receiving iNO. There were no differences in rates of study gas discontinuation between trial arms.
Hospitalized children with evidence of impaired oxygen delivery, metabolic acidosis, anemia, or malaria were at risk of methemoglobinemia. However, we demonstrated high-dose iNO could be safely administered to critically ill children with severe malaria with appropriate MHb monitoring.
ClinicalTrials.gov Identifier: NCT01255215 (Date registered: December 5, 2010).
Muscle vascular dysfunction, a hallmark of chronic diseases such as heart failure and diabetes, impairs the matching of blood flow (
Q
˙
m
) to O
2 utilization (
V
˙
O
2
m
) following exercise onset. ...One recently described consequence of this behavior is that arterial–venous O
2 difference
(
a
−
v
)
O
2
, the mirror image of muscle vascular oxygenation transiently overshoots the subsequent steady-state and, in so doing, may provide important information regarding
Q
˙
m
versus
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O
2
m
dynamics. Using computer simulations, we tested the hypothesis that key parameters of the
(
a
−
v
)
O
2
overshoot – peak response, downward time constant (
τ
D), and total area – would relate quantitatively to
Q
˙
m
kinetics. Our results demonstrated significant proportionality (all
p
<
0.01) between
Q
˙
m
mean response time and peak (
r
2
=
0.56),
τ
D (
r
2
=
72) and total area (
r
2
=
0.97) of
(
a
−
v
)
O
2
overshoot. These results suggest that analysis of
(
a
−
v
)
O
2
or its proxy, muscle vascular oxygenation measured using near-infrared spectroscopy or phosphorescence quenching, provides valuable information regarding blood flow and vascular function particularly in reference to
V
˙
O
2
m
kinetics.
Introduction: The management of sepsis essentially relies on effective resuscitation with fluids and vasopressors, appropriate and adequate antimicrobial therapy, and organ support. Any of these ...interventions can have beneficial but also harmful effects.
Areas covered: We focus on the key hemodynamic signs of sepsis and discuss the potential safety risks associated with the management of each of them, including optimizing arterial pressure, cardiac output and oxygen delivery. We also underline the importance of the timing of interventions.
Expert opinion: Patients with septic shock are heterogeneous, making it particularly difficult to provide therapeutic recommendations that are safe and effective for all. A personalized medicine approach should be used with treatment decisions carefully considered and the risks and benefits of each intervention balanced in each individual patient.
Preterm infants, especially those with extremely low birth weight (ELBW) are exposed to frequent blood draws as part of their care in the neonatal intensive care unit. ELBW infants develop the anemia ...of prematurity (AOP), a hypo-proliferative anemia marked by inadequate production of erythropoietin (Epo). Treatment of AOP includes red blood cell transfusions, which are given to preterm infants based on indications and guidelines (hematocrit/hemoglobin levels, ventilation and oxygen need, apneas and bradycardias, poor weight gain) that are relatively non-specific. In this article we review recent studies evaluating transfusion guidelines, discuss ways to decrease phlebotomy losses and examine the use of red cell growth factors such as Epo in preventing and treating anemia in preterm infants.
To determine the relationship between tissue oxygen saturation (StO2) and oxygen delivery ( D.O2) during hypoxemia and hyperoxemia.
Prospective, randomized study.
Eight purpose-bred Beagle dogs.
Dogs ...were anesthetized with isoflurane, ventilated to eucapnia, and instrumented for thermodilution cardiac output, invasive mean arterial pressure (MAP), sartorius muscle StO2 and airway gas monitoring. Dogs were administered rocuronium to facilitate mechanical ventilation and esmolol to minimize anesthetic effects on cardiac output. Instrumentation and baseline data collection were at 0.21 fractional inspired oxygen (FIO2). Dogs were evaluated at high (0.40 then 0.95) and low (0.15 then 0.10) FIO2 sequences in random order with a 60 minute rest period at FIO2 0.21 between sequences. Target FIO2 was achieved by manipulating nitrogen and oxygen flow rates. Data collected at each FIO2, after a 10 minute period of stabilization, included heart rate (HR), MAP, cardiac index (CI) and StO2. Arterial oxygen content (CaO2) and oxygen delivery index ( D.O2I) were calculated at each FIO2. Data analysis included Pearson’s correlation analysis and mixed-model anova (p < 0.05).
There were no significant differences in HR, MAP or CI across all FIO2 values. Significant decreases occurred in mean ± standard deviation StO2 (90 ± 4% to 69 ± 18%; p = 0.0001), D.O2I (458 ± 70 to 281 ± 100 mL minute−1 m−2; p = 0.0008) and CaO2 (13.2 ± 1.53 to 8.4 ± 2.05 mL dL−1; p = 0.0001) from FIO2 0.21 to 0.10, but not at remaining FIO2 values. The correlation between StO2 and D.O2I across all FIO2 values was strong (r = 0.97; p = 0.0013) and linear.
In this model of hypoxemia and hyperoxemia, the strong correlation between StO2 and D.O2I suggests that StO2 can be used to estimate D.O2.
OBJECTIVES:To establish whether perioperative low-dose dopexamine infusion (≤1 μg/kg/min) is associated with a reduction in mortality and duration of hospital stay following major surgery.
DATA ...SOURCE:Medline, EMBASE, CINAHL, Cochrane Library, Google Scholar, and reference lists.
STUDY SELECTION:Two reviewers independently screened studies for inclusion, assessed trial quality, and extracted data. Eligible trials were randomized controlled trials comparing dopexamine infusion to control treatment. Data are reported as odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals.
DATA EXTRACTION:Systematic review and meta-regression analysis of individual patient data.
DATA SYNTHESIS:Five studies fulfilled the inclusion criteria. Analysis of pooled data from high- and low-dose dopexamine groups identified a reduction in duration of hospital stay (median 14 vs. 15 days; HR 0.85 0.73–0.91; p = .03) but no improvement in mortality (9.1% vs. 12.3%; OR 0.78 0.31–1.99; p = .61). However, low-dose dopexamine was associated with a 50% reduction in 28-day mortality (6.3% vs. 12.3%; OR 0.50 0.28–0.88; p = .016) as well as a reduced duration of stay (median 13 vs. 15 days; HR 0.75 0.64–0.88; p = .0005). When high-dose dopexamine groups were compared with controls, there was no difference in either mortality (OR 1.06 0.60–1.87; p = .85) or duration of stay (HR 1.04 0.94–1.16; p = .36).
CONCLUSIONS:For pooled data describing perioperative dopexamine infusion at all doses, there was an improvement in duration of hospital stay but no survival benefit. However, at low doses, dopexamine was associated with improved survival and reduced duration of stay. Further clinical trials are warranted to confirm this observation.
Heat‐induced hyperventilation may reduce PaCO2 and thereby cerebral perfusion and oxygenation and in turn exercise performance. To test this hypothesis, eight volunteers completed three incremental ...exercise tests to exhaustion: (a) 18 °C ambient temperature (CON); (b) 38 °C (HEAT); and (c) 38 °C with addition of CO2 to inspiration to prevent the hyperventilation‐induced reduction in PaCO2 (HEAT + CO2). In HEAT and HEAT + CO2, rectal temperature was elevated prior to the exercise tests by means of hot water submersion and was higher (P < 0.05) than in CON. Compared with CON, ventilation was elevated (P < 0.01), and hence, PaCO2 reduced in HEAT. This caused a reduction (P < 0.05) in mean cerebral artery velocity (MCAvmean) from 68.6 ± 15.5 to 53.9 ± 10.0 cm/s, which was completely restored in HEAT + CO2 (68.8 ± 5.8 cm/s). Cerebral oxygenation followed a similar pattern.
V
˙
O
2
m
a
x
was 4.6 ± 0.1 L/min in CON and decreased (P < 0.05) to 4.1 ± 0.2 L/min in HEAT and remained reduced in HEAT + CO2 (4.1 ± 0.2 L/min). Despite normalization of MCAvmean and cerebral oxygenation in HEAT + CO2, this did not improve exercise performance, and thus, the reduced MCAvmean in HEAT does not seem to limit exercise performance.
The aim of this article is to study the overview of pathophysiology and clinical application of central venous oxygen saturation monitoring in critically ill patients and during the perioperative ...period.
There are several clinical studies and animal experiments evaluating the effects of goal-directed hemodynamic stabilization on critically ill patients. Recent systematic reviews and meta-analyses found that advanced hemodynamic endpoints-targeted management has a positive effect on outcome in high-risk surgical patients. As all interventions aim to improve tissue oxygenation, it is of utmost importance to monitor the balance between oxygen delivery and consumption. For this purpose, central venous blood gas analysis provides an easily available tool in the everyday clinical practice. The adequate interpretation of central venous oxygen saturation renders the need of careful evaluation of several physiological and pathophysiological circumstances. When appropriately evaluated, central venous oxygen saturation can be a valuable component of a multimodal individualized approach, in which components of oxygen delivery are put in the context of the patients' individual oxygen consumption. In addition to guide therapy, central venous oxygen saturation may also serve as an early warning sign of inadequate oxygen delivery, which would otherwise remain hidden from the attending physician.
With the incorporation of central venous oxygen saturation in the everyday clinical routine, treatment could be better tailored for the patients' actual needs; hence, it may also improve outcome.
Pathophysiology of hemorragic shock Copotoiu, R; Cinca, E; Collange, O ...
Transfusion clinique et biologique : journal de la Societe francaise de transfusion sanguine,
11/2016, Letnik:
23, Številka:
4
Journal Article
Recenzirano
This review addresses the pathophysiology of hemorrhagic shock, a condition produced by rapid and significant loss of intravascular volume, which may lead to hemodynamic instability, decreases in ...oxygen delivery, decreased tissue perfusion, cellular hypoxia, organ damage, and death. The initial neuroendocrine response is mainly a sympathetic activation. Haemorrhagic shock is associated altered microcirculatory permeability and visceral injury. It is also responsible for a complex inflammatory response associated with hemostasis alteration.
Using perioperative goal-directed therapy (GDT) or peroperative hemodynamic optimization significantly reduces postoperative complications and risk of death in patients undergoing noncardiac major ...surgeries. In this review, we discuss the main changes in the field of perioperative optimization over the last few years.
One of the key aspects that has changed in the last decade is the shift from invasive monitoring with pulmonary artery catheters (PACs) to less or minimally invasive monitoring systems. The evaluation of intravascular fluid volume deficits has also changed dramatically from the use of static indices to the assessment of fluid responsiveness using either dynamic indices or functional hemodynamic. Finally, attention has been directed toward more restrictive strategies of crystalloids as maintenance fluids.
GDT is safe and more likely to tailor the amount of fluids given to the amount of fluids actually needed. This approach includes assessment of fluid responsiveness and, if necessary, the use of inotropes; moreover, this approach can be coupled with a restrictive strategy for maintenance fluids. These strategies have been increasingly incorporated into protocols for perioperative hemodynamic optimization in high-risk patients undergoing major surgery, resulting in more appropriate use of fluids, vasopressors, and inotropes.
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