scholarly journals A method for modelling the oxyhaemoglobin dissociation curve at the level of the cerebral capillary in humans

2020 ◽  
Vol 105 (7) ◽  
pp. 1063-1070
Author(s):  
Rasmus H. Dahl ◽  
Sarah Taudorf ◽  
Damian M. Bailey ◽  
Kirsten Møller ◽  
Ronan M. G. Berg
Keyword(s):  
Dissociation Curve ◽  
Oxyhaemoglobin Dissociation Curve ◽  
Cerebral Capillary

Effects of fetal haemoglobin on systemic oxygenation in preterm infants and the development of retinopathy of prematurity PacIFiHER Report No. 2

2021 ◽  
pp. bjophthalmol-2021-319546
Author(s):  
Kim Jiramongkolchai ◽  
Michael X Repka ◽  
Jing Tian ◽  
Sue W Aucott ◽  
Jennifer Shepard ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Preterm Infants ◽  
Retinopathy Of Prematurity ◽  
Neonatal Intensive Care ◽  
Blood Gas ◽  
Dissociation Curve ◽  
Fetal Haemoglobin ◽  
Oxyhaemoglobin Dissociation Curve ◽  
Increased Risk ◽  
Oxygenation Indices

Background/aimsFetal haemoglobin (HbF) has an oxyhaemoglobin dissociation curve that may affect systemic oxygenation and the development of retinopathy of prematurity (ROP). The study aim is to characterise the effects of HbF levels on systemic oxygenation and ROP development.MethodsProspective study conducted from 1 September 2017 through 31 December 2018 at the Johns Hopkins NICU. Preterm infants with HbF measured at birth, 31, 34 and 37 weeks post-menstrual age (PMA), complete blood gas and SpO2 recorded up to 42 weeks PMA, and at least one ROP exam were included.ResultsSixty-four preterm infants were enrolled. Higher HbF was associated with significantly higher SpO2, lower PCO2, lower FiO2 from birth to 31 weeks PMA and 31 to 34 weeks PMA (rs=0.51, rs=−0.62 and rs=−0.63; p<0.0001 and rs=0.71, rs=−0.58 and rs=−0.79; p<0.0001, respectively). To maintain oxygen saturation goals set by the neonatal intensive care unit, higher median FiO2 was required for HbF in the lowest tercile from birth compared with HbF in the highest tercile to 31 weeks and 31 to 34 weeks PMA; FiO2=35 (21–100) versus 21 (21–30) p<0.006 and FiO2=30 (28–100) versus 21 (21–30) p<0.001, respectively. Preterm infants with ROP had poorer indices of systemic oxygenation, as measured by median levels of SpO2 and PCO2, and lower levels of HbF (p<0.039 and p<0.0001, respectively) up to 34 weeks PMA.ConclusionLow HbF levels correlated with poor oxygenation indices and increased risk for ROP. O2 saturation goals to prevent ROP may need to incorporate relative amount of HbF.

Methaemoglobinaemia in the perioperative period with regional block

2021 ◽  
Vol 14 (9) ◽  
pp. e245135
Author(s):  
Arianna Cook ◽  
Stuart Grant ◽  
Sharon Kapeluk ◽  
Patrick Steele
Keyword(s):  
Nitric Oxide ◽  
Differential Diagnosis ◽  
Case Report ◽  
Oxygen Delivery ◽  
Perioperative Period ◽  
Interesting Case ◽  
Erector Spinae ◽  
Dissociation Curve ◽  
Oxyhaemoglobin Dissociation Curve ◽  
Anaesthetic Gases

Methaemoglobin is a form of haemoglobin with oxidised ferric (+3) iron rather than ferrous (+2) iron, which causes a leftward shift in the oxyhaemoglobin dissociation curve and prevents oxygen delivery. Anaesthesiologists need to be familiar with this differential diagnosis for hypoxia given the use of drugs in the perioperative setting known to induce methaemoglobinaemia, including benzocaine and lidocaine, antibiotics such as dapsone and anaesthetic gases, including nitric oxide. This case report details an interesting case of symptomatic methaemoglobinaemia in the perioperative period in the setting of dapsone use and an erector spinae block performed with ropivacaine.

scholarly journals A New Model for the Oxyhaemoglobin Dissociation Curve

2002 ◽  
Vol 30 (5) ◽  
pp. 376-387 ◽  
Author(s):  
C. Anstey
Keyword(s):  
Chloride Ion ◽  
Dissociation Curve ◽  
New Model ◽  
Alternative Structures ◽  
Standard Data ◽  
Oxyhaemoglobin Dissociation Curve ◽  
Andersen Model ◽  
Allosteric Effector ◽  
Curve Model ◽  
Haemoglobin Molecule

This paper describes a new model for the oxygen-haemoglobin dissociation curve in humans. The model is based on the known structural alterations that occur in the quaternary haemoglobin molecule during oxygenation and deoxygenation. The two alternative structures, tense and relaxed, are described using hyperbolic tangent curves and linked with a probability function to obtain the completed mathematical description of the oxygen-haemoglobin dissociation curve. Model accuracy is assessed by a bias/precision analysis of calculated logit (S) and P50 against gold standard data. A mechanism for the transition between the two structures involving the chloride ion as a major allosteric effector is proposed. Results were analysed against the Siggaard-Andersen model for bias, precision and calculated P50 in four saturation ranges—0.00<SO 2< 1.00, 0.20<SO 2< 0.80, 0.90<SO 2< 1.00 and 0.97<SO 2< 1.00. In each range except for 0.20<SO 2 <0.80, bias, precision and calculated P50 for the new model are significantly better (P<0.05). Analysis of calculated P50 across the entire saturation range revealed significant drift out of the acceptable range in the Siggaard-Andersen model for SO 2 >0.92. The new model remained within tolerance across the saturation range 0.00<SO 2 <1.00. The new model is significantly more accurate than the popular Siggaard-Andersen model, particularly in the range SO 2> 0.90.

scholarly journals THE EFFECT OF ALTHESIN (CT1341) ON THE OXYHAEMOGLOBIN DISSOCIATION CURVE IN VITRO

1976 ◽  
Vol 48 (11) ◽  
pp. 1083-1086
Author(s):  
T. ISHIKAWA ◽  
K. WAKUTA ◽  
K. KANDA ◽  
Y. OKUDA
Keyword(s):  
Dissociation Curve ◽  
Oxyhaemoglobin Dissociation Curve

Improved gasometric methods for estimating oxygen content and percentage saturation in haemoglobin dissociation curve determinations

1955 ◽  
Vol 144 (914) ◽  
pp. 55-67 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Oxygen Content ◽  
Equilibrium Constants ◽  
Gas Analysis ◽  
Dissociation Curve ◽  
Dissolved Nitrogen ◽  
Oxyhaemoglobin Dissociation Curve ◽  
Oxygen Percentage ◽  
Percentage Saturation ◽  
First Time

By using carbon monoxide as a reagent for releasing oxygen from blood solutions (instead of the customary potassium ferricyanide) and by combining the techniques of the Van Slyke constant-volume gasometric apparatus and the Scholander gas analysis apparatus, a precise method has been devised of estimating oxygen content and carbon monoxide capacity simultaneously on one and the same sample of blood solution. The procedure eliminates various errors inherent in the determination of oxygen percentage saturation, when oxygen content and capacity are successively measured on separate samples. The method has been extensively tested on sheep blood solutions containing 3 to 4 g haemoglobin/100 ml. and is considered to give an accuracy of ± 0.5 in the oxygen percentage saturation of such solutions. In its present form the method is only applicable to solutions containing a negligible amount of dissolved nitrogen, but it is probable that this restriction could be removed by the simple addition to the technique suggested in the text. Modifications are also described in the usual tonometer technique for equilibrating blood solutions with various pressures of oxygen, and for transferring the equilibrated blood solution to the Van Slyke apparatus for analysis. The techniques of the present paper have been specially used for obtaining oxyhaemoglobin dissociation curve data of higher accuracy than hitherto available. From these improved data it has for the first time been possible to calculate directly, and in many cases with fair precision, the values o f the equilibrium constants of the four successive reactions of haemoglobin with oxygen.

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