Jennifer Jackson Respiratory and Metabolic Acidosis and Alkalosis
Unit 7 Assignment
10/13/15
Anatomy and Physiology 2
Prof. Maryjoyce Rotella

The acid-base balance in the body largely depends on the hydrogen ion (H+) concentration. In general, high H+ makes the solution acidic with pH less than 7 while low H+ will make the solution basic or alkaline with pH higher than 7 (Lewis, 2013). Acidosis develops when the arterial pH drops below 7.35 while alkalosis develops when the arterial pH rises above 7.45 (Appel & Downs, 2008). The normal metabolic balance generally keeps the carbonic acid and bicarbonate ion to 1: 20 ratio. As the ratio changes, the body will respond to acid-base imbalance through compensation mechanisms to control acids through buffer system by either releasing or taking up H+ depending on the pH changes. Deviations from normal PCO2 cause respiratory problems while deviations from the normal HCO3− cause metabolic problems. Respiratory alkalosis is a condition that occurs when there is carbonic acid deficit as PaCO2 drops to less than 35 mm Hg. The blood pH increases while PaCO2 decreases but the bicarbonate (HCO3−) undergoes no changes (Apple & Downs, 2008). Respiratory alkalosis is primarily caused by hyperventilation due to conditions that stimulate the respiratory center such as oxygen deficiency at high altitudes, pulmonary diseases, congestive heart failure, and acute anxiety. Respiratory acidosis occurs when there is carbonic acid excess that raises the blood levels of CO2 above 45 mmHg. The blood pH decreases than 7.35 as PaCO2 increases while there is very mild or no change in the levels of HCO3− (Appel & Downs, 2008). Respiratory acidosis can develop due to some chronic conditions that include paralysis of respiratory or chest muscles, emphysema, and depression of respiratory center due to intake of drugs or head trauma. Acute causes include acute respiratory distress syndrome, pulmonary edema, and pneumothorax. Metabolic acidosis occurs when there is HCO3− deficit as blood concentrations drop below 22mEq/L. The blood pH decreases while the PaCO2 levels remain unchanged but the HCO3− decreases. The common causes of metabolic acidosis include bicarbonate loss due to diarrhea or renal dysfunction, excessive accumulation of chloride or organic acids such as lactic acid causing lactic acidosis or ketones causing ketoacidosis, and failure of the kidneys to excrete H+ (Appel & Downs, 2008). Metabolic alkalosis is a condition that develops when there is HCO3− excess when the blood concentration levels increase over 26 mEq/L. The pH increases and the PaCO2 remain unchanged while the HCO3− levels increase. The metabolic alkalosis usually develop due to loss of chloride ions or excess ingestion of sodium bicarbonate due to various conditions that include loss of stomach acid due to excessive vomiting, excess use of alkaline drugs, antacids, or certain diuretics, endocrine disorders, and severe dehydration (Appel & Downs, 2008). If the acid-base imbalances arise as respiratory issue due to changes in PaCO2, the renal mechanisms can bring about metabolic compensation with kidneys acting to assist (Appel & Downs, 2008). The kidneys eliminate H+ and retain HCO3− to compensate for respiratory acidosis. The kidneys on the other hand will conserve H+ and eliminate HCO3− to compensate for respiratory alkalosis If the underlying problem is metabolic due to changes in HCO3−, the respiratory compensation takes place with lungs acting to assist. The respiratory compensation for metabolic acidosis occurs through hyperventilation or hyperactive breathing in attempts to give off CO2 to change the PaCO2 and drive normalization of the arterial pH (Appel & Downs, 2008). The lungs will be assisting through exhalation of CO2 that can be powerful in changing levels of volatile acids but not the fixed acids such as the lactic acid. For the body correction, the kidneys will try to eliminate H+ and conserve bicarbonate ions if possible. The body compensatory mechanism may also help through potassium ion (K+) exchange with excess H+ in the extracellular fluids where H+ go into the cells while displacing K+ out of the cells. The respiratory compensation for metabolic alkalosis, meanwhile, occurs through compensatory hypoventilation such as through suppression of breathing to hold CO2 (Feldman, Alvarez, Trevino, & Weinstein, 2012). The respiratory compensation in metabolic alkalosis will be quite challenging since hypoventilation will be limited by hypoxia. The body correction of the imbalance requires kidneys to conserve H+ and eliminate HCO3− in urine but because metabolic alkalosis most commonly occurs with renal dysfunction, the compensation cannot count on kidneys. When the regular compensatory mechanisms fail to correct the imbalances, various treatments are provided for each condition to deter harm and potential damages the acid-base imbalances can cause to the body. The treatment of respiratory acidosis includes restoration of ventilation, administration of intravenous lactate solution that will be converted into HCO3− in the liver, and treatment of underlying dysfunction or disease. In the event of suspected opioid ingestion causing the respiratory acidosis, intravenous naloxone as antidote will be administered (Appel & Downs, 2008). The treatments aim to offset and normalize the PaCO2 and HCO3− levels. Restoration of ventilation regulates exhalation of CO2 to reverse the decreasing PaCO2 driving the carbonic acid increase. The treatments of respiratory alkalosis include breathing into a paper bag to help in slowing down the ventilation to restore up the lowering pCO2 and carbonic acid levels. Other treatments include administration of intravenous chloride-containing solution to replace HCO3−, and other replacement remedies for lost HCO3−. The metabolic acidosis treatment is through administration of lactate-containing solution to restore the metabolic balance as lactate solution will be converted into HCO3− in the liver. The treatment aims to raise the HCO3− levels to its normal levels so the blood pH will increase back to normal. The treatment of metabolic alkalosis includes administration of electrolytes to replace the lost ones, intravenous administration of chloride-containing solution, and treatment of the underlying disorder. Administration of chloride-containing solution will help to restore the metabolic balance as chloride ions replace HCO3−. The treatment aims to lower back to restore the blood concentration levels of HCO3− and the pH to normal. Aging naturally causes structural and physiological changes in the body that have impacts to the acid-base balance processes. The physiological functions and responses of the body to carry out the regulatory and compensatory processes slow down due to old age. The metabolic balance can easily drift to imbalances due to declining efficiency and responsiveness of the body physiological functions to maintain body homeostasis. The kidneys and the lungs with critical roles in keeping the acid-base processes undergo significant changes at old age. Old age cause structural and physiological changes in renal functions (Musso & Oreopoulos, 2011). As body cells and organs start to degenerate during the process of aging, fibrous tissues develop in kidneys and start to replace the normal glomerular tissues from the age of 30s. Old age can cause fatty degeneration of renal tubules. Some renal tissues start to atrophy and the glomerular filtration rate gradually decline. The structural degeneration and declining renal functions decrease the capabilities of the kidney to respond to compensatory action stimulations. Just like the kidneys, the lungs and the surrounding organs with influences in maintaining efficient respiratory functions undergo degenerative changes too. The aging lung muscles start to degenerate and gradually atrophy. The spine, ribs, and muscles undergo changes causing curvature that make the space in the chest cavity smaller. The changes within the respiratory organs cause reduction of volumes of the thoracic cavity and lungs and can alter the respiratory accessory muscles (Lowery, Brubaker, Kuhlmann, & Kovacs, 2013). The reduced respiratory muscle strengths influenced by the changes can alter the respiratory efficiency to sufficiently meet the increased metabolic demands for oxygen. The effects in the respiratory functions can also impact the capabilities of the respiratory system to regulate the acid-base balance particularly that the regulation of the breathing speed and depth during ventilation can become less efficient (Lewis, 2013).

References
Appel, S. & Downs, C. (2008). Understanding acid-base balance. Nursing, 38(1), pp. 9-11. doi: 10.1097/01.NURSE.0000336658.39936.0c
Feldman, M., Alvarez, N. M., Trevino, M., & Weinstein, G. L. (2012). Respiratory compensation to a primary metabolic alkalosis in humans. Clinical Nephrology, 78(5), 365-369. doi:10.5414/CN107631
Lewis, J. (2013). Overview of acid-base balance. Retrieved from http://www.merckmanuals.com/home/hormonal_and_metabolic_disorders/acid- base_balance/overview_of_acid-base_balance.html
Lowery, E., Brubaker, A., Kuhlmann, E. & Kovacs, E. (2013). The aging lung. Clinical Interventions in Aging, 8(1), pp. 1489-1496. doi: http://dx.doi.org/10.2147/CIA.S51152.
Musso, C., & Oreopoulos, D. (2011). Aging and physiological changes of the kidneys including changes in glomerular filtration rate. Nephron, 119, pp. 1-5. doi: http://dx.doi.org/10.1159/000328010