Pages

Thursday, May 19, 2016

Practical Issues in blood transfusion in pediatrics

1. Amount of transfusion to be given: It has been seen that transfusion with PRBC at a dose of 20 mL/kg is well tolerated and results in an overall decrease in number of transfusions compared to transfusions done at 10 mL/kg. There is also a higher rise in hemoglobin with a higher dose of PRBCs.

 2. Properties of RBC products used in neonatal transfusion: a. RBCs should be freshly prepared and should not be more than 7 days old.  This translates into a high 2, 3-DPG concentration and higher tissue extraction of oxygen. 

3.Blood should be of newborn's ABO and Rh group. It should be compatible with any ABO or atypical red cell antibody present in the maternal serum.

4.   Volume and rate of transfusion: 
a. Volume of packed RBC = Blood volume (mL/kg) x (desired minus actual hematocrit)/ hematocrit of transfused RBC 
b. Rate of infusion should be less than 10 mL/kg/hour in the absence of cardiac failure. 
c. Rate should not be more than 2 mL/kg/hour in the presence of cardiac failure. 
d. If more volume is to be transfused, it should be done in smaller aliquots.

Tuesday, May 17, 2016

▶️ THE FETAL TRAP 🤖


🔹The placenta forms a barrier to the transfer of drugs between the mother and the fetus, but increasing lipid-solubility, decreasing maternal protein binding, decreasing molecular weight, increased materno-fetal concentration gradient and placental blood flow etc will increase the placental transfer of drugs

🔹The relative distribution of the drug across the placenta is represented by Feto-Maternal (F/ M) concentration ratio

🔹Pethidine and diamorphine are both metabolised in the fetus to less lipid-soluble products like norpethidine and morphine respectively, which remain on the fetal side of the placenta. The elimination half-lives of these drugs are also longer in the fetus because of immature hepatic metabolism. This again prolongs its existence in the fetal side.

🔹Lipid solubility of drugs like thiopentone sodium are high; so they cross the placenta easily, and can accumulate as the pH is lower in the fetus

🔹Diazepam is metabolised to less lipid-soluble products. So it can have an F/ M ratio of 2 even one hour after maternal administration.

🔹Local anaesthetic agents are weak bases which are largely UN-IONISED  at physiological pH, and cross the placenta readily. But fetal 'trapping' occurs in severe acidosis, when the molecules become IONIZED in the fetal side.

#pharmacology , #DrugMetabolism ,#PlacentalTransfer , #anesthesia

Tuesday, May 10, 2016

SI UNITS & NON SI UNITS OF PRESSURE


▪️Pressure is force applied over a unit area. Pressure  = Force/Area. It's SI unit is Pascal.

▪️️There are 7 base SI units , from which others are derived (which are known as derived SI units)

▪️Pascal is a derived SI unit. It is N.m-2. It is represented by the symbol Pa.

▪️One pascal is equal to a force of one newton applied over an area of one square metre. (N.m−2) 

▪️The pascal is a small amount (1 N is equal to just 102 g weight) 

▪️For this reason kilopascals (kPa) are used as standard.

▪️The standard atmospheric pressure is: 101.325 kPa = 1.013 bar = 14.696 psi =1 atm

Friday, May 6, 2016

VISCOUS FACTS❗️


⌛️Dynamic or absolute viscosity is a measure of the resistance of a fluid or gas to flow. It is measured using a viscometer or rheometer.

⌛️The SI unit of dynamic (or absolute) viscosity is the pascal-second (Pa·s), equivalent to N·s/ m2.

⌛️Viscosity is independent of flow rate

⌛️Viscosity is independent of pressure

⌛️️For a gas, viscosity decreases as its temperature increases 

⌛The relationship between viscosity and temperature and pressure only holds true for those fluids and gases that exhibit ‘Newtonian’ properties, i.e. substances that will always flow irrespective of forces acting upon them (e.g. crystalloid solutions and water). 

⌛️ Blood is a non-Newtonian fluid and its viscosity depends largely on haematocrit (and varies with flow rate).

⌛️Blood viscosity is increased by volatile anaesthetic agents, smoking and aging❗️

⌛️A thixotropic substance is one that becomes less viscous over time when agitated. If it becomes more viscous with agitation, this is known as a rheopectic material.

⌛️Kinematic velocity is defined as the dynamic velocity of a substance divided by its density.

Tuesday, May 3, 2016

ERRORS THAT CAN HAPPEN WITH THE SAMPLING FOR ARTERIAL BLOOD GAS ANALYSIS AND POSSIBLE CONSEQUENCES


❎AIR BUBBLES IN SYRINGE: may wrongly increase the Pao2 , Sao2 and pH

❎DILUTION OF THE SAMPLE WITH SALINE FLUSH OR HEPARIN: may wrongly increase Pao2 , while it decrease Paco2 , glucose, lactate , potassium and hemoglobin 

❎VENEPUNCURE DURING SAMLE COLLECTION: may wrongly decrease Po2 and So2 while it increases Pco2

❎ CLOTTING OF THE SAMPLE: may wrongly increase the potassium concentration 

#ABGerrors , #abg , #AbgSampling

ERRORS IN ABG SAMPLING: CAUSES & CONSEQUENCES



🔹Reduced pH (anaerobic metabolism)
🔹Reduced PaO2 (utilization of dissolved oxygen)
🔹Raised PaCO2 ( production of CO2 from continued metabolism)
🔹Reduced glucose ( utilization if glucose stores)
🔹Increased lactate( anaerobic metabolism)

#abg , #AbgErrors

CALCULATION OF THE VOLUME OF OXYGEN CYLINDER REQUIRED FOR A TRANSFER


▫️For this, we should know:
     1. Oxygen delivered = FiO2 x Minute Volume 
     2. Duration of the transfer

▫️For e.g. If we are expecting a duration of 2 hours (120 minutes) and we are having Size E cylinders and also need to deliver an FiO2 of 1 @ 6L / min

1. O2 delivered = 1 x 6 = 6L/ min
2. Size E has 660 L of O2, which will suffice for 660/6= 110 minutes ; so for 120 minutes, we need 2 cylinders 

#AnesthesiaGas , #OxygenCylinder


Monday, May 2, 2016

DIPPING IN DOPPLER


🎯The Doppler effect can be explained by considering a series of water-waves travelling out from the centre of a pond, in a circular form

🎯The frequency of the waves is related to the medium and the speed at which they are travelling. 

🎯The frequency of the waves reaching the periphery is less than the frequency nearer the centre. 

🎯If a detector was in the periphery it would detect the frequency of the waves whose frequency will be less

🎯But if the detector then started moving towards the source, the frequency would increase as the detector would be picking the waves nearer to the centre, whose frequency will be more.

🎯The Doppler effect describes the change in frequency of sound waves if the source of sound is moving in relation to the detector. The frequency is increased if the source is moving towards the detector and reduced if it is moving away.

🎯APPLICATIONS OF DOPPLER EFFECT

✔️It allows the confirmation of flow within peripheral arteries as well as in the brain, where the circle of Willis can be scanned.

✔️In echocardiography

✔️in obstetric practice when a fetal heart rate monitor is used

#doppler ,#anesthesia , #usg

Thursday, April 28, 2016

MOBILE PHONES & MEDICAL EQUIPMENTS


🔹Researchers at University of Amsterdam have recorded nearly 50 incidents of electromagnetic interference in hospitals and classified 75% of them as hazardous.

🔹Researchers are of the opinion that mobile phones should not come within 1 meter to hospital beds and equipment 

🔹They are likely to induce errors in the functioning of equipments such as Ventilators , Pacemakers , Syringe pumps etc

🔹They observed that the General Packet Radio Service ( GPRS ) signal generation technology that allows wireless internet access has been particularly associated with the problem 

🔹 More studies are needed to get more clear information about this issue.

#MobilePhoneHazards , #ICUequipments , #MobilephonesHospital