...OXYGEN is readily released at the tissue level because the partial pressure of oxygen is lower in the tissues and also the pH is acidic! Bohr effect facilitates loading and unloading of oxygen from haemoglobin (Hb), which states that oxygen binding affinity of Hb is inversely related to CO2 and H+ ion concentration (more in tissues; less in lungs).
P.S. Each human red blood cell (RBC) contains approximately 270 million of haemoglobin (Hb) molecules; each Hb molecule carries four haem moieties. Hb constitutes about a third of the total red blood cell volume.
AFFINITY is high by virtue of low 2,3 DPG in fetal blood, does not mean it won't release oxygen to the tissues. HbF (fetal haemoglobin, P50 19 mm Hg) carries 30% more oxygen than HbA (adult haemoglobin, P50 26.8 mm Hg) by allowing all 4 molecules of oxygen to bind to all 4 haem moieties in each Hb molecule, which is not so efficient in HbA due to higher level of 2,3 DPG and therefore, less than 4 molecules of oxygen bind.
Maintenance of Airway and SUPPLY of oxygen, if ensured, the minimum oxygen required in a premature neonate 4.35 ml/kg/min can be achieved (at birth 6-7 ml/kg/min and in adults 3-4 ml/kg/min). There is higher oxygen consumption in neonates, infants and children because of higher heart rate and respiratory rate. Thereafter, it is about margin of safety, which should always be there to have more oxygen reserve in haemoglobin and myoglobin.
TREAT the patient, not the numbers! - this dictum requires continuous engagement with the patient while getting the input from different sources together with thorough UNDERSTANDING, which builds up with repetition and rumination about the facts and figures!
A PREMATURE neonate would definitely receive blood transfusion when symptomatic. Blood transfusion to neonates is traditionally given for apnoea, bradycardia, poor feeding, poor weight gain and pallor. A premature neonate can be given blood transfusion of packed RBC or whole blood from mother, 10 -15 ml/kg, if matches.
Neonates can produce enough cardiac output, even 400 ml/kg/min compared to adult 100 ml/kg/min. Cardiac output is one of the principal contributors to systemic oxygen delivery and in neonates it is nearly 4 times compared to adults by virtue of higher heart rate.
Isovolaemic anaemia, including euvolaemic anaemia of prematurity, is better tolerated and allows a substantially lower critical threshold for blood transfusion. It is usually achieved by transfusing FFP (fresh frozen plasma), which provides the vitamin K dependent coagulation factors, II,VII,IX.X and decreases intraoperative blood loss.
A large randomised study of critically ill patients proved that 7-9 g% haemoglobin in euvolaemic adults had similar 30 day mortality and reduced in-hospital mortality compared to high 10–12 g% Hb.
Compared to adrenaline infusion (0.05 to 0.3 μg/kg/min) to increase contractility and afterload, increasing preload with packed red blood cell (PRBC) does not increase oxygen consumption, though systemic oxygen transport (SOT) is increased by both methods.
On an average in an adult, one MET is 3.5 ml/kg/min of oxygen consumption in resting state. MET (metabolic equivalent) is an unit to calculate and compare physical activity in terms of total energy expenditure. For the elderly it is less, depending on the activity.
A person breathes 7 or 8 liters of air per minute. Air is about 21% oxygen. Exhaled air has about 16% oxygen (so useful in mouth-to-mouth breathing while resuscitating), so consumption is about 5%. Therefore, a person uses about 550 liters of pure oxygen each day.
Each breath has about 200ml of CO2. With 12 breaths per minute, that yields about 3,456 liters per day.
Critical haemoglobin thresholds in premature infants:
https://fn.bmj.com/content/84/3/F146
Blood Transfusions In Premature Babies:
https://www.verywellfamily.com/blood-transfusions-in-the-nicu-2748424
Red blood cell:
https://en.m.wikipedia.org/wiki/Red_blood_cell
Oxygen–hemoglobin dissociation curve:
https://en.m.wikipedia.org/wiki/Oxygen%E2%80%93hemoglobin_dissociation_curve
Physiology of haemoglobin:
https://academic.oup.com/bjaed/article/12/5/251/289041
APACHE II ("Acute Physiology And Chronic Health Evaluation II") - a ICU scoring system:
https://en.m.wikipedia.org/wiki/APACHE_II
Minimal Rates of Oxygen Consumption in Sick and Premature Newborn Infants:
https://adc.bmj.com/content/archdischild/41/218/407.full.pdf
The standard oxygen consumption value equivalent to one metabolic equivalent (3.5 ml/min/kg) is not appropriate for elderly people:
https://www.ncbi.nlm.nih.gov/m/pubmed/15223593/
Adult and Foetal Haemoglobin:
https://www.fastbleep.com/wiki/article/846
P.S. Each human red blood cell (RBC) contains approximately 270 million of haemoglobin (Hb) molecules; each Hb molecule carries four haem moieties. Hb constitutes about a third of the total red blood cell volume.
AFFINITY is high by virtue of low 2,3 DPG in fetal blood, does not mean it won't release oxygen to the tissues. HbF (fetal haemoglobin, P50 19 mm Hg) carries 30% more oxygen than HbA (adult haemoglobin, P50 26.8 mm Hg) by allowing all 4 molecules of oxygen to bind to all 4 haem moieties in each Hb molecule, which is not so efficient in HbA due to higher level of 2,3 DPG and therefore, less than 4 molecules of oxygen bind.
Maintenance of Airway and SUPPLY of oxygen, if ensured, the minimum oxygen required in a premature neonate 4.35 ml/kg/min can be achieved (at birth 6-7 ml/kg/min and in adults 3-4 ml/kg/min). There is higher oxygen consumption in neonates, infants and children because of higher heart rate and respiratory rate. Thereafter, it is about margin of safety, which should always be there to have more oxygen reserve in haemoglobin and myoglobin.
TREAT the patient, not the numbers! - this dictum requires continuous engagement with the patient while getting the input from different sources together with thorough UNDERSTANDING, which builds up with repetition and rumination about the facts and figures!
A PREMATURE neonate would definitely receive blood transfusion when symptomatic. Blood transfusion to neonates is traditionally given for apnoea, bradycardia, poor feeding, poor weight gain and pallor. A premature neonate can be given blood transfusion of packed RBC or whole blood from mother, 10 -15 ml/kg, if matches.
Neonates can produce enough cardiac output, even 400 ml/kg/min compared to adult 100 ml/kg/min. Cardiac output is one of the principal contributors to systemic oxygen delivery and in neonates it is nearly 4 times compared to adults by virtue of higher heart rate.
Isovolaemic anaemia, including euvolaemic anaemia of prematurity, is better tolerated and allows a substantially lower critical threshold for blood transfusion. It is usually achieved by transfusing FFP (fresh frozen plasma), which provides the vitamin K dependent coagulation factors, II,VII,IX.X and decreases intraoperative blood loss.
A large randomised study of critically ill patients proved that 7-9 g% haemoglobin in euvolaemic adults had similar 30 day mortality and reduced in-hospital mortality compared to high 10–12 g% Hb.
Compared to adrenaline infusion (0.05 to 0.3 μg/kg/min) to increase contractility and afterload, increasing preload with packed red blood cell (PRBC) does not increase oxygen consumption, though systemic oxygen transport (SOT) is increased by both methods.
On an average in an adult, one MET is 3.5 ml/kg/min of oxygen consumption in resting state. MET (metabolic equivalent) is an unit to calculate and compare physical activity in terms of total energy expenditure. For the elderly it is less, depending on the activity.
A person breathes 7 or 8 liters of air per minute. Air is about 21% oxygen. Exhaled air has about 16% oxygen (so useful in mouth-to-mouth breathing while resuscitating), so consumption is about 5%. Therefore, a person uses about 550 liters of pure oxygen each day.
Each breath has about 200ml of CO2. With 12 breaths per minute, that yields about 3,456 liters per day.
Critical haemoglobin thresholds in premature infants:
https://fn.bmj.com/content/84/3/F146
Blood Transfusions In Premature Babies:
https://www.verywellfamily.com/blood-transfusions-in-the-nicu-2748424
Red blood cell:
https://en.m.wikipedia.org/wiki/Red_blood_cell
Oxygen–hemoglobin dissociation curve:
https://en.m.wikipedia.org/wiki/Oxygen%E2%80%93hemoglobin_dissociation_curve
Physiology of haemoglobin:
https://academic.oup.com/bjaed/article/12/5/251/289041
APACHE II ("Acute Physiology And Chronic Health Evaluation II") - a ICU scoring system:
https://en.m.wikipedia.org/wiki/APACHE_II
Minimal Rates of Oxygen Consumption in Sick and Premature Newborn Infants:
https://adc.bmj.com/content/archdischild/41/218/407.full.pdf
The standard oxygen consumption value equivalent to one metabolic equivalent (3.5 ml/min/kg) is not appropriate for elderly people:
https://www.ncbi.nlm.nih.gov/m/pubmed/15223593/
Adult and Foetal Haemoglobin:
https://www.fastbleep.com/wiki/article/846
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