Acid-Base Balance and Fluids and Electrolytes
Respiratory acidosis refers to a medical defect in which hypoventilation occurs leading to increased concentration of carbon dioxide in the blood and decreased level of pH. Decreased pH in the blood is generally known as acidosis. The body cells continuously respire and release carbon dioxide. The lungs may fail to efficiently expel the CO2. This condition is known as alveolar hypoventilation and results to hypercania (increased PaCO2). Increased PaCO2 leads to a decrease in the ratio of HCO3- to PaCO2 as well as the pH level (Kee, Paulanka & Polek, 2010). There are two types of respiratory acidosis; acute and chronic respiratory acidosis. The acute condition is experienced in the event that ventilation in the lungs abruptly fails. This failure may occur when drugs or cerebral diseases cause depression in the central respiratory center. Neuromuscular disease may also inhibit adequate ventilation causing this condition. In addition, asthma and the chronic obstructive pulmonary disease may obstruct the airway thus causing acute respiratory acidosis. Acute respiratory acidosis occurs as a secondary condition to obesity hypoventilation syndrome and disorders such as COPD (Kee, Paulanka & Polek, 2010). The compensation mechanism in this condition involves two steps. Firstly, cellular buffering occurs for period of minutes or even hours. It slightly raises HCO3 whereby for every 10-mm Hg PaCO2 increase, there is a correspondent 1 mEq/L increase in HCO3. Secondly, renal compensation takes place for a period of 3-5 days. This process occurs in the kidneys whereby more carbonic acid is excreted and more bicarbonate is reabsorbed. The condition is treated by administering bronchodilator drugs and using noninvasive positive-pressure ventilation which is also known as BIPAP or CPAP. Caution should be observed since if too rapid corrections are made it could lead to metabolic alkalemia (Kee, Paulanka & Polek, 2010). Respiratory alkalosis
This is a medical condition in which increased respiration increases pH level of the blood and reduces CO2 arterial levels. Respiratory alkalosis may occur iatrogenically due to excessive mechanical ventilation. It can also occur due to drug use, fever, high altitudes and pregnancy among other causatives. The symptoms of this particular condition include low carbon dioxide levels in the blood and peripheral paraethesiae. It may influence the ionic balance of calcium ions resulting to hypocalcaemia symptoms with no decrease in the serum calcium levels. However, when the chronic condition occurs, it results in to hypocalcaemia and hyperphosphatemia through inclusion of renal PTH- resistance (Slatter, 2003). During respiratory alkalosis, an individual hyperventilates thus increasing the level of carbon dioxide expelled from the lungs. The respiratory system responds to these alterations according to Le Chatelier's principle. Bicarbonate and hydrogen ions circulating in the blood are moved via carbonic acid which acts as a medium. The two are used to increase CO2 levels through a reaction which involves carbonic anhydrase enzyme (Slatter, 2003). The reaction occurs as shown:
As a result of the reaction, hydrogen ion concentration decreases while the pH increases. In addition, calcium ions concentration decreases. The treatment of this condition is only erffective when the stimulus is curbed. Treatment should be done cautiously since rapid correction of chronic respiratory alkalosis could trigger metabolic acidosis due to a decrease in serum bicarbonate. Treatment involves decrease of the lungs tidal volume, breathing in to a bag, reassurance and treatment for psychological stress (Slatter, 2003). Metabolic Acidosis
This is a medical condition which occurs acid quantities accumulate in the body or when the kidneys do not efficiently eliminate enough acid. Metabolic acidosis may result in to academia. This is may be because of kidney failure to form bicarbonate (HCO3) or increased hydrogen ions production in the body. There are various causes of this condition and it can result in to death and comma. Metabolic acidosis is due to too much acid accumulation in the body. There are various types of this condition. The primary causes of metabolic acidosis are classified according to their impact on the anion gap; increased and normal anion gap. The latter is caused by renal tubular acidosis, longstanding diarrhea, intoxication, toluene, and kidney failure among others. Increased anion gap is caused by ketoacdosis, uremia, lactic acidosis and methanol intoxication among others (Reddi, 2014). Metabolic acidosis involves four compensatory mechanisms. The blood regulates its acidity level through four buffering mechanisms; bicarbonate buffering system, respiratory compensation, intracellular buffering and renal compensation. The buffer occurs in two separate processes: that from water and CO2 and increased renal generation (Reddi, 2014). The buffering reactions are:
The relationship between bicarbonate buffering system components and blood pH can be described mathematically by the Henderson-Hasselbalch equation:
When the compensatory mechanisms are ineffective, it is urgent for one to undergo medical treatment to reduce the risk of cardiac arrhythmias. Treatment is done with intravenous bicarbonate. An individual is given 50-100 mmol of bicarbonate at a time. The process is keenly monitored by using the arterial blood gas readings. This form of treatment could seriously complicate the lactic acidosis hence, should be handled with great care. In addition, if the condition is severe, one is advised to seek the aid of a nephrology team since dialysis is also effective (Reddi, 2014). Metabolic Alkalosis
This is a metabolic condition whereby tissue pH increases above the normal range which arises from decreased concentration of hydrogen ions and in turn results to increased bicarbonate. The causes of this alkalosis are classified in to two categories based on the chloride levels of urine; chloride responsive and chloride resistant. The former is caused by retention of bicarbonate, hyperaldosteronism, liddle syndrome, and alkalotic agents among others. Chloride responsive metabolic alkalosis may be caused by congenital chloride diarrhea, cystic fibrosis, and posthypercapnia among others. Compensatory mechanisms occur in the lungs (Reddi, 2014). The lungs retain CO2 by reducing breathing rate the CO2 retained is used to form carbonic acid intermediate. This in turn decreases the pH. However, respiratory compensation is incomplete. Reduced hydrogen ions concentration represses the peripheral chemoreceptors. However, due to the hypoventilation, PCO2 levels increase. Therefore, renal compensation occurs to complete the process. However, this process is less effective than the former process. It involves increased HCO3- excretion since the bicarbonate filtered surpasses the renal tubule ability to reabsorb it. Treatment in this case relies on status of the patient's volume and underlying etiology. The doctor may administer antiemetics, potassium-sprang diuretics, gastric suction or acetazolamide (Reddi, 2014). The human lungs and kidneys change as the individual ages. For instances, alveoli get shallower, coiled collagen fibers become less resilient and the surface area reduces hence reducing expiration rate. The changes in the kidneys include hormonal changes which affect the amount of water saved by the kidneys, high blood pressure among others. These changes in both the lungs and kidneys are bound to affect the acid-base balance processes (Rogers, 2010).
Slatter, D. H. (2003). Textbook of small animal surgery. Philadelphia, PA: Saunders. Kee, J. L. F., Paulanka, B. J., & Polek, C. B. (2010). Handbook of fluid, electrolyte, and acid-base imbalances. Clifton Park, NY: Delmar Cengage Learning. Reddi, A. S. (2014). Fluid, electrolyte and acid-base disorders: Clinical evaluation and management. Rogers, K. (2010). The respiratory system. New York: Britannica Educational Pub. in association with Rosen Educational Services.