Metabolic Medicine Made Simple :Respiratory Alkalosis

Respiratory Alkalosis is characterized by increased pH and a reduction in PaCO2.

Typical causes include :

Hyperventilation due to pneumonia
High altitude
Salicylate intoxication.




Usual human blood pH is maintained between 7.35 - 7.45
HCO3- is normally 24 meq/l
PaCO2 is usually 40 mmHg.

Metabolic acid base disorders are due to a primary chnge in concentration of HCO3-
Respiratory acid base disorders are due to a primary change in PCO2.

In pneomina,hypoxia causes Tachypnea that leads to hyperventilation which causes CO2 loss leading to alkalosis / Respiratory Alkalosis

Causes of Respiratory Acidosis :

Respiratory suppression
Narcotic overdose
Neurological diseases causing airway muscle diseases.
COPD

Chemistry Made Simple : Composition of the Matter

 Overall , matter can be divided into two general categories :

Distinct Substance and Mixtures.

Distinct Substance :

In this substance,the smallest particle retains the property of the substance.

Element :

This is a disinct substance that is made of only one kind of atom.

Atom:

These are building blocks of matter that cannot be easily created nor destroyed.

Compound:

If two or more kinds of atoms join together in a definite grouping,this distinct substance is called a compound.

Metabolic Medicine Made Simple : Biochemical changes in Loop Diuretic Therapy

Loop diuretics act by inhibiting the Na - K- 2Cl carrier in the loop of henle.

This results in increased excretion of sodium.

Loop diuretics also result in increased excretion of potassium and this can lead to hypokalemia.

Loop diuretics  result in incresed distal solute delivery as well as increase in aldosterone level which combine to result in increased hydrogen ion excretion leading to metabolic alkalosis.

Loop diuretics are used to treat Chronic Liver Disease patients with ascites and volume overload  and their potential side effects include : Hypokalemia,Metabolic Alkalosis and Pre-renal failure.





Biochemical changes in other conditions :

Acute Renal Failure :

This will lead to metabolic acidosis and hyperkalemia.
It will also cause mild increase in BUN and creatinine.


Bowel Ischemia :

This will result in lactic acidosis.



Opiod medication:

This will lead to hypoventilation and subsequent respiratory acidosis.

Chemistry Made Simple : Matter

Matter :

Anything that occupies space and has mass is called Matter.

Mass:

The quantity of matter which a substance posseses is called Mass.

Inertia:

The property of mass to resist a change of its position or motion is called Inertia.

Density:

Is defined as relationship of mass to its unit volume.

Denoted by D , D = m/V

where D is density, m is mass and V is volume of the substance.

Unit of mass in chemistry is Gram / g and Volume is cm3 / cubic centimeter or milliliter.

States of Matter:

Matter has 3 states:

Solid : has a definite size and a definite shape.

Liquid has a definite volume but takes the shape of the container

Gas has neither a definite shape nor a definite volume.

These three states are interchangable .

Aerodynamics Made Simple : Aircraft and Airplanes

Aerodynamics
Aerodynamics is the study of the motion of air, particularly its interaction with a solid object, such as an airplane wing.
Aerodynamics is a sub-field of fluid dynamics and gas dynamics, and many aspects of aerodynamics theory are common to these fields.
 The term aerodynamics is often used synonymously with gas dynamics, the difference being that "gas dynamics" applies to the study of the motion of all gases, and is not limited to air.

  Aircraft

A machine that can fly, held aloft in the air, is called an aircraft.

Airplanes and helicopters are two types of aircraft.

Some kinds of aircraft, primarily helicopters, use rotors or spinning blades to fly, while the lift of other aircraft comes from jet engines or the shape of the aircraft's wing.

Still other aircraft, including hot air balloons, use buoyancy ,generally a gas that's lighter than airfor lift and flight.

Balloons were actually the first vehicles referred to as aircraft, along with airships. The word was adapted from nautical terminology.

Airplane


Airplane is an aircraft that has a fixed wing and is powered by propellers or jets.

An airplane is a flying vehicle that has fixed wings and engines or propellers that thrust it forward through the air.

 It's most common when you travel long distances to take an airplane.

Metabolic Medicine Made Simple : Metabolic Acidosis with raised Anion Gap

Causes of Metabolic Acidosis with raised Anion Gap include :

Aspirin Ingestion
Ethylene Glycol Poisoning
Methyl Alcohol Ingestion
Uremic Acidosis
Lactic Acidosis








Normal Anion Gap is 6 - 12
pH less than 7.35 is indicative of Metabolic Acidosis.

In patients with markedly elevated anion gap and if frank uremia is not present,the osmolar gap should be calculated to assess for ethanol,methanol or ethylene glycol intoxication.




The serum Osmolality is calculated by using the following formula :

Serum Osmolality = 2 (Na + Glu / 18 + BUN /2.8 )

The Osmolar gap is calculated by the following formula :

Osmolar Gap = Observed Osmolarity - Calclated Osmolarity.





Osmolar Gap metabolic acidosis is seen in :

Acute Methanol
Ethanol or
Ethylene glycol.

Ethylene Glycol Poisoning

This occurs following antifreeze ingestion.
It is characterized by presence of rectangular envelope shaped calcium oxalate crystals in the urine.
Serious sequelae of this poisoning include :

Acute Respiratory Distress Syndrome
Heart failure
Renal failure

Aspirin / salicylate toxicity causes :

Mixed Anion gap metabolic acidosis and respiratory alkalosis with no osmolar gap.


Methyl Alcohol poisoning :

This causes visual changes ( snowfield vision ) and acute pancreatitis.
It doesnot cause renal failure or urine crystals.

Uremia / Renal failure :

It can cause anion gap metabolic acidosis due to failure to excrete acids.


Lactic Acidosis 

can  result from numerous causes including poor delivery of oxygen to the tissues and poor oxygen utilization by the tissues.

The result is an anion gap metabolic acidosis.

Metabolic Medicine Made Simple : Mixed Metabolic and Respiratory Acidosis

pH would be below 7.35.

HCO3- would be reduced suggestive of Metabolic Acidosis.

PaCO2 would be reaised or inapprprately normal.

Winter formula is used to calculate what PaCO2 ought to be in order to compensate for the metabolic acidosis and that PaCO2 is inappropriately normal.

Winter formula is as follows :

PaCO2 = 1.5 (HCO3-) + 8

Metabolic Medicine Made Simple : Metabolic Alkalosis

}()); Metabolic Alkalosis :

Human blood pH is maintained between 7.35 - 7.45.

This is done by various mechanisms the most significant being regulation of CO2, carbonate and hydrogen atoms by the lungs and the kidneys.





A pH of more than 7.45 is considered alkalosis and a pH of less than 7.35 is considered acidosis.




The pCO2 and HCO3- values can then be used to differentiate between a respiratory or a metabolic cause of acid base disturbance.

The normal HCO3- is 24 meq/l and the normal PCO2 is 40 mmHg.



Any deviation from these normal values is indicative of an acid base disorder.

Metabolic acid base disorders are due to a primary change in concentration of HCO3 while respiratory acid base disorders are due to a primary change in PCO2.


Main causes of Metabolic Alkalosis includes :

Exogenous administration of an alkali.

Removal of acidic gastric secretions due to vomiting or NG tube aspiration.

Renal Hydrogen ion loss due to mineralocorticoid excess

Contraction Alkalosis.

Electrolytes & Metabolic Medicine Made Simple : Metabolic Acidosis

Metabolic Acidosis :

Metabolic acidosis is indicated by a low pH < 7.4 and low serum bicarbonate < 24 meq / l.

There are different causes of metabolic acidosis :


Acute Renal Failure :

It occurs due to failure of the kidneys to excrete acids generated during normal protein metabolism namely inorganic phosphates and sulfates.

It may have various causes such as acute hypovolemia due to vomiting and diarrhoea , GI bleed leading to hypotension and ischemia.

Type I Renal Tubular Acidosis :

It is characterized by low tubular Ammonium production.
The primary defect in this disease is failure to excrete sufficient hydrogen ions in urine.
Without sufficient hydrogen ions in tubular fluid,ammonium cannot be produced.


Type 2 Renal tubular Acidosis :

This is characterized by defective tubular bicarbonate reabsorption .
It is often inherited and may be a components of Fanconi Syndrome.
Type II RTA can also occur with use of drugs like Carbonic Anhydrase Inhibitors.

Causes of Decreased Anion Gap Metabolic Acidosis include :

Plasma cell Dyscrasias

Lithum intoxication.

Paraproteinemias.






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Metabolic Medicine Made Simple : Post ictal Metabolic Acidosis

Post seizure metabolic acidosis is usually the result of a grand mal / tonic clonic seizure.

Seizures result in an accelerated production of lactic acid in the muscle and reduced hepatic lactate uptake.

This post - ictal lactic acidosis is transient and usually resolves within 60 - 90 minutes.

In such patients,the most appropriate treatment is observation and repeating the chemistry panel after 2 hours to see if the acidosis has improved /resolved on its own.

If it has not resolved,it is better to look for other potential causes of metabolic acidosis.
.
The common causes of ketosis include :

Diabetes

Alcoholism

Starvation

The use of bicarbonate in the treatment of lactic acidosis or ketoacidosis is very contraversial.

It is only recommended in severe acute acidosis pH < 7.2

Full correction with bicarbonate should not be sought.

Only a sufficient amount of bicarbonate should be given to correct the ph to 7.2.

In lactic acidosis,bicarbonate treatment may paradoxically depress cardiac performance and worsen the acidosis by enhancing lactate production.

Serum lipase levels are generally used to assess for pancreatic disease but may also be elevated in DKA and other conditions making the test poorly specific for any one disease process.