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Anesthesia and Analgesia May 2022The American Society of Anesthesiologists' (ASA) Task Force on Management of the Difficult Airway has developed a decision tree tool that uses inductive assessments to...
The American Society of Anesthesiologists' (ASA) Task Force on Management of the Difficult Airway has developed a decision tree tool that uses inductive assessments to guide the anesthesiologist's choice of pathway in the ASA's Difficult Airway Algorithm. The tool prompts the anesthesiologist to consider the risk of difficulty with laryngoscopy (direct or indirect) and tracheal intubation, facemask or supraglottic ventilation, gastric contents aspiration, and rapid oxyhemoglobin desaturation. For every airway management event, the approach integrates the anesthesiologist's unique combination of experience, expertise, patient anatomy and disease, equipment availability, and other contextual conditions into the decision process. Entry into the awake intubation pathway is encouraged when the patient is judged at risk of difficult tracheal intubation and one or more of the following: difficult ventilation, significant aspiration risk, and/or rapid oxyhemoglobin desaturation. The decision tree tool is anticipated to improve communication between anesthesiologists and others by clearly identifying those factors of concern and how decision-making is affected by those concerns.
Topics: Airway Management; Algorithms; Anesthesiologists; Decision Trees; Humans; Intubation, Intratracheal; Laryngoscopy; Oxyhemoglobins
PubMed: 35171880
DOI: 10.1213/ANE.0000000000005930 -
PloS One 2021A new method for hemoglobin (Hb) deoxygenation, in suspension or within red blood cells (RBCs) is described using the commercial enzyme product, EC-Oxyrase®. The...
A new method for hemoglobin (Hb) deoxygenation, in suspension or within red blood cells (RBCs) is described using the commercial enzyme product, EC-Oxyrase®. The enzymatic deoxygenation method has several advantages over established deoxygenation methodologies, such as avoiding side reactions that produce methemoglobin (metHb), thus eliminating the need for an inert deoxygenation gas and airtight vessel, and facilitates easy re-oxygenation of Hb/RBCs by washing with a buffer that contains dissolved oxygen (DO). The UV-visible spectra of deoxyHb and metHb purified from human RBCs using three different preparation methods (sodium dithionite [to produce deoxyHb], sodium nitrite [to produce metHb], and EC-Oxyrase® [to produce deoxyHb]) show the high purity of deoxyHb prepared using EC-Oxyrase® (with little to no metHb or hemichrome production from side reactions). The oxyHb deoxygenation time course of EC-Oxyrase® follows first order reaction kinetics. The paramagnetic characteristics of intracellular Hb in RBCs were compared using Cell Tracking Velocimetry (CTV) for healthy and sickle cell disease (SCD) donors and oxygen equilibrium curves show that the function of healthy RBCs is unchanged after EC-Oxyrase® treatment. The results confirm that this enzymatic approach to deoxygenation produces pure deoxyHb, can be re-oxygenated easily, prepared aerobically and has similar paramagnetic mobility to existing methods of producing deoxyHb and metHb.
Topics: Anemia, Sickle Cell; Female; Hemoglobins; Humans; Magnetics; Male; Methemoglobin; Oxygen; Oxyhemoglobins; Tissue Donors
PubMed: 34478473
DOI: 10.1371/journal.pone.0257061 -
The Journal of Physiology Mar 2021
Topics: Oxygen; Oxyhemoglobins
PubMed: 33719049
DOI: 10.1113/JP281213 -
Scientific Reports May 2014Photoacoustic microscopy (PAM) is emerging as a powerful technique for imaging microvasculature at depths beyond the ~1 mm depth limit associated with confocal...
Photoacoustic microscopy (PAM) is emerging as a powerful technique for imaging microvasculature at depths beyond the ~1 mm depth limit associated with confocal microscopy, two-photon microscopy and optical coherence tomography. PAM, however, is currently qualitative in nature and cannot quantitatively measure important functional parameters including oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), oxygen saturation (sO2), blood flow (BF) and rate of oxygen metabolism (MRO2). Here we describe a new photoacoustic microscopic method, termed photoacoustic computed microscopy (PACM) that combines current PAM technique with a model-based inverse reconstruction algorithm. We evaluate the PACM approach using tissue-mimicking phantoms and demonstrate its in vivo imaging ability of quantifying HbO2, HbR, sO2, cerebral BF and cerebral MRO2 at the small vessel level in a rodent model. This new technique provides a unique tool for neuroscience research and for visualizing microvasculature dynamics involved in tumor angiogenesis and in inflammatory joint diseases.
Topics: Animals; Cerebrovascular Circulation; Hemoglobins; Microscopy; Microscopy, Acoustic; Microvessels; Oxygen; Oxyhemoglobins; Photoacoustic Techniques; Rats
PubMed: 24828539
DOI: 10.1038/srep04960 -
Journal of Applied Physiology... Oct 2017Humans ascending to high altitude (HA) experience a reduction in arterial oxyhemoglobin saturation and, as a result, arterial O content ([Formula: see text]). As HA... (Review)
Review
Humans ascending to high altitude (HA) experience a reduction in arterial oxyhemoglobin saturation and, as a result, arterial O content ([Formula: see text]). As HA exposure extends, this reduction in [Formula: see text] is counteracted by an increase in arterial hemoglobin concentration. Initially, hemoconcentration is exclusively related to a reduction in plasma volume (PV), whereas after several weeks a progressive expansion in total red blood cell volume (RCV) contributes, although often to a modest extent. Since the decrease in PV is more rapid and usually more pronounced than the expansion in RCV, at least during the first weeks of exposure, a reduction in circulating blood volume is common at HA. Although the regulation of hematological responses to HA has been investigated for decades, it remains incompletely understood. This is not only related to the large number of mechanisms that could be involved and the complexity of their interplay but also to the difficulty of conducting comprehensive experiments in the often secluded HA environment. In this review, we present our understanding of the kinetics, the mechanisms and the physiological relevance of the HA-induced reduction in PV and expansion in RCV.
Topics: Acclimatization; Altitude; Blood Volume; Erythropoietin; Humans; Hypoxia; Oxygen; Oxyhemoglobins
PubMed: 28572493
DOI: 10.1152/japplphysiol.00118.2017 -
Advances in Physiology Education Sep 2022Pulse oximetry has become the standard of care in operating rooms, intensive care units, and hospitals worldwide. A pulse oximeter continuously and noninvasively...
Pulse oximetry has become the standard of care in operating rooms, intensive care units, and hospitals worldwide. A pulse oximeter continuously and noninvasively monitors the functional oxygen saturation of hemoglobin in arterial blood ([Formula: see text]). [Formula: see text] is so important in medical care that it is often regarded as a fifth vital sign. Before pulse oximetry, arterial puncture for blood gas analysis was the only method available to determine [Formula: see text] and to identify the presence of hypoxemia. Pulse oximetry is based on the principle that oxygenated hemoglobin (OHb) absorbs more near-infrared light than deoxyhemoglobin (HHb) and HHb absorbs more red light than OHb. It is important to understand the principles of pulse oximetry, how the equipment works, and its limitations to interpret the information it provides. Accordingly, we used colored balloons to introduce the physics of how a pulse oximeter detects and measures oxyhemoglobin and deoxyhemoglobin in pulsatile (arterial) and nonpulsatile (venous and capillary) blood. The foundations of oximetry started in the 1700s with Johann Lambert (1728-1777). We approached this complex physics in a straightforward way while still providing an understanding of the fundamental concepts developed by Johann Lambert in 1760. Educators must go beyond teaching the facts and encourage students to think, investigate, and appreciate the subject matter in a broader framework. To achieve these goals, we used a simple and inexpensive experimental approach to introduce the physics of how a pulse oximeter detects and measures oxyhemoglobin and deoxyhemoglobin in blood. We approached this complex physics in a straightforward way while still providing an understanding of the fundamental concepts developed by Johann Lambert in 1760.
Topics: Hemoglobins; Humans; Oximetry; Oxygen; Oxyhemoglobins; Veins
PubMed: 35759527
DOI: 10.1152/advan.00093.2022 -
Scientific Reports May 2022There has been growing recognition of the utility of combining the verbal fluency test and functional near-infrared spectroscopy (fNIRS) to assess brain functioning and...
There has been growing recognition of the utility of combining the verbal fluency test and functional near-infrared spectroscopy (fNIRS) to assess brain functioning and to screen for psychiatric disorders. Recently, an emotional analogue of the semantic fluency test (SFT) has been developed that taps partly different processes from conventional verbal fluency tests. Nevertheless, neural processing during the emotional SFT remains elusive. Here, fNIRS was used to compare frontal cortical activation during emotional and non-emotional SFTs. The goal was to determine whether the emotional SFT activated overlapping yet distinct frontal cortical regions compared with the conventional, non-emotional SFT. Forty-three healthy young adults performed the emotional and non-emotional SFTs while hemodynamic changes in the bilateral frontopolar, dorsomedial, dorsolateral, ventrolateral, and posterolateral frontal cortices were measured by fNIRS. There were significant increases in oxyhemoglobin concentration and significant decreases in deoxyhemoglobin concentration (i.e., activation) in frontopolar, dorsolateral, and ventrolateral frontal regions during both the non-emotional and emotional SFTs. Also, complementary analyses conducted on changes in the two chromophores using classical and Bayesian hypothesis testing suggested that comparable frontal cortical regions were activated while performing the two tests. This similarity in activation occurred in a context where non-emotional and emotional SFT performances exhibited differential relationships with the overall level of negative mood symptoms. In conclusion, frontal cortical activation during the emotional SFT is similar to that during the conventional, non-emotional SFT. Given that there is evidence for discriminant validity for the emotional SFT, the neural mechanisms underlying the uniqueness of this test warrant further investigation.
Topics: Bayes Theorem; Frontal Lobe; Humans; Neuropsychological Tests; Oxyhemoglobins; Severe Fever with Thrombocytopenia Syndrome; Spectroscopy, Near-Infrared; Young Adult
PubMed: 35589939
DOI: 10.1038/s41598-022-12559-w -
Neonatology 2022Concentration of fetal hemoglobin (HbFc) in human neonates determines oxygen-carrying capacity of blood and the position of oxyhemoglobin dissociation curve....
INTRODUCTION
Concentration of fetal hemoglobin (HbFc) in human neonates determines oxygen-carrying capacity of blood and the position of oxyhemoglobin dissociation curve. Near-infrared spectroscopy enables the measurement of regional cerebral tissue oxygen saturation (rScO2) and in combination with measurements of pulsatile arterial oxygen saturation (SpO2), the calculation of cerebral fractional tissue oxygen extraction (cFTOE).
METHODS
We aimed to investigate the impact of HbFc on rScO2, cFTOE, and SpO2 in preterm and term neonates during the first 15 min after birth. Blood analyses provided total blood hemoglobin (Hb) and HbFc measurements. Correlations between HbFc, Hb and rScO2, cFTOE, and SpO2 in each minute were analyzed.
RESULTS
Ninety term and 19 preterm neonates without medical support were included. HbFc was significantly higher in preterm neonates, whereas there were no significant differences in Hb between the groups. In preterm neonates, we found positive correlations of both HbFc and Hb with rScO2 and negative correlations of HbFc and Hb with cFTOE in the first minutes after birth. In contrast, there were no significant correlations between the same parameters in term neonates. Correlations between HbFc or Hb and SpO2 were either insignificant, negligible, or very low in both groups.
DISCUSSION/CONCLUSION
In preterm neonates, higher HbFc was associated with higher rScO2 and lower cFTOE in the first minutes after birth. This phenomenon could not be confirmed in term neonates and might reflect immature autoregulation of oxygen delivery to the brain or lower oxygen consumption in preterm neonates in the first minutes of immediate postnatal transition.
Topics: Brain; Cerebrovascular Circulation; Fetal Hemoglobin; Humans; Infant, Newborn; Infant, Premature; Oximetry; Oxygen; Oxyhemoglobins
PubMed: 35882188
DOI: 10.1159/000525847 -
International Journal of Environmental... Jul 2017This study examined the physiological effects of touching wood with various coating with the palm of the hand on brain activity and autonomic nervous activity....
This study examined the physiological effects of touching wood with various coating with the palm of the hand on brain activity and autonomic nervous activity. Participants were 18 female university students (mean age, 21.7 ± 1.6 years). As an indicator of brain activity, oxyhemoglobin concentrations were measured in the left and right prefrontal cortices using near-infrared time-resolved spectroscopy. Heart rate variability (HRV) and heart rate were used as indicators of autonomic nervous activity. The high-frequency (HF) component of HRV, which reflects parasympathetic nervous activity, and the low-frequency (LF)/HF ratio, which reflects sympathetic nervous activity, were measured. Plates of uncoated, oil-finished, vitreous-finished, urethane-finished, and mirror-finished white oak wood were used as tactile stimuli. After sitting at rest with their eyes closed for 60 s, participants touched the stimuli with their palm for 90 s each. The results indicated that tactile stimulation with uncoated wood calmed prefrontal cortex activity (vs. urethane finish and mirror finish), increased parasympathetic nervous activity (vs. vitreous finish, urethane finish, and mirror finish), and decreased heart rate (vs. mirror finish), demonstrating a physiological relaxation effect. Further, tactile stimulation with oil- and vitreous-finished wood calmed left prefrontal cortex activity and decreased heart rate relative to mirror-finished wood.
Topics: Adult; Brain; Female; Heart Rate; Humans; Oxyhemoglobins; Parasympathetic Nervous System; Quercus; Relaxation; Spectroscopy, Near-Infrared; Surface Properties; Sympathetic Nervous System; Wood; Young Adult
PubMed: 28703777
DOI: 10.3390/ijerph14070773 -
The Journal of Extra-corporeal... Sep 2014Acute intravascular hemolysis during extracorporeal membrane oxygenation (ECMO) leads to increased levels of cell-free hemoglobin (FHb). Our aim was to investigate... (Observational Study)
Observational Study
Acute intravascular hemolysis during extracorporeal membrane oxygenation (ECMO) leads to increased levels of cell-free hemoglobin (FHb). Our aim was to investigate whether FHb levels are associated with nitric oxide (NO) consumption and clinical outcomes. A prospective observational study was performed involving pediatric patients on ECMO. Blood samples were collected before, during, and after the ECMO run, and plasma was evaluated for FHb, oxyhemoglobin, and NO consumption. Clinical data were collected including baseline patient characteristics, indications for ECMO, circuit changes, and mortality. Correlations between laboratory measures and associations between laboratory measures and clinical observations were evaluated. Twenty-three patients (11 male, 17 neonates) were enrolled with a median weight of 3.1 kg (interquartile range, 2.8-14.0 kg) and median ECMO run of 12 days (interquartile range, 5-19 day). There was a significant increase in FHb over time on ECMO (p = .007), and significant correlations were present between NO consumption and both FHb (r = .41, p = .01) and oxyhemoglobin levels (r = .98, p < .0001). Patients on ECMO for sepsis (n = 6) had lower average levels of oxyhemoglobin (mean [standard deviation {SD}] 14.5 [4.4] versus 19.0 [5.0] μM, p = .07) and NO consumption (mean [SD] 15.8 [4.1] versus 19.8 [3.7] μM, p = .04) during ECMO than patients with other indications. In the 3 days leading up to a circuit change, there were increases in mean total cell-free hemoglobin levels (24%/day, p = .08), oxyhemoglobin (37%/day, p = .005), and NO consumption (40%/day, p = .006) (n = 5). There were no significant associations identified between peak or average plasma measures of hemolysis and type of ECMO (venovenous versus venoarterial) or mortality. For children on ECMO, we observed a strong correlation between increased levels of plasma FHb and elevations in oxyhemoglobin and NO consumption; however, these changes were not associated with increased mortality. Increased hemolysis before circuit changes may be both a marker and a contributor to circuit failure.
Topics: Biomarkers; Extracorporeal Membrane Oxygenation; Female; Hemolysis; Humans; Infant; Infant, Newborn; Male; Metabolic Diseases; Nitric Oxide; Oxyhemoglobins; Prospective Studies
PubMed: 26357787
DOI: No ID Found