Untitled Document (23) PDF - Medical Physiology

Pathology​ Condition Metabolic Acidosis Overproduction of hydrogen ions​ Excessive oxidation of fatty acids: Diabetic ketoacidosis Starvation Hypermetabolism: Heavy exercise Seizure activity Fever Hypoxia, ischemia Excessive ingestion of acids: Ethanol or methanol intoxication Salicylate...

Pathology​ Condition Metabolic Acidosis Overproduction of hydrogen ions​ Excessive oxidation of fatty acids: Diabetic ketoacidosis Starvation Hypermetabolism: Heavy exercise Seizure activity Fever Hypoxia, ischemia Excessive ingestion of acids: Ethanol or methanol intoxication Salicylate intoxication Underelimination of hydrogen ions​ Kidney failure Underproduction of bicarbonate​ Kidney failure Pancreatitis Liver failure Dehydration Overelimination of bicarbonate​ Diarrhea Respiratory Acidosis Underelimination of hydrogen ions​ Respiratory depression: Anesthetics Drugs (especially opioids) Electrolyte imbalance Inadequate chest expansion: Muscle weakness Airway obstruction Alveolar-capillary block Box 9.4 Causes of Metabolic Alkalosis ▪ Diuretics: The loss of hydrogen ions and chloride from diuresis causes a compensatory increase in the amount of bicarbonate in the blood. ▪ Excessive vomiting or gastrointestinal suctioning: Leads to an excessive loss of hydrochloric acid. ▪ Hyperaldosteronism: Increased renal tubular reabsorption of sodium occurs, with the resultant loss of hydrogen ions. ▪ Ingestion of and/or infusion of excess sodium bicarbonate: Causes an increase in the amount of base in the blood. ▪ Massive transfusion of whole blood: The citrate anticoagulant used for the storage of blood is metabolized to bicarbonate. Box 9.3 Causes of Metabolic Acidosis ▪ Diabetes mellitus or diabetic ketoacidosis: An insufficient supply of insulin causes increased fat metabolism, leading to an excess accumulation of ketones or other acids; the bicarbonate then ends up being depleted. ▪ Excessive ingestion of acetylsalicylic acid: Causes an increase in the hydrogen ion concentration. ▪ High-fat diet: Causes a much too rapid accumulation of the waste products of fat metabolism, leading to a buildup of ketones and acids. ▪ Insufficient metabolism of carbohydrates: When the oxygen supply is not sufficient for the metabolism of carbohydrates, lactic acid is produced and lactic acidosis results. ▪ Malnutrition: Improper metabolism of nutrients causes fat catabolism, leading to an excess buildup of ketones and acids. ▪ Renal insufficiency, acute kidney injury, or chronic kidney disease: Increased waste products of protein metabolism are retained; acids increase, and bicarbonate is unable to maintain acid-base balance. ▪ Severe diarrhea: Intestinal and pancreatic secretions are normally alkaline; therefore, excessive loss of base leads to acidosis. Box 9.2 Causes of Respiratory Alkalosis ▪ Fever: Causes increased metabolism, resulting in overstimulation of the respiratory system. ▪ Hyperventilation: Rapid respirations cause the blowing off of carbon dioxide (CO2), leading to a decrease in carbonic acid. ▪ Hypoxia: Stimulates the respiratory center in the brainstem, which causes an increase in the respiratory rate in order to increase oxygen (O2); this causes hyperventilation, which results in a decrease in the CO2 level. ▪ Overventilation by mechanical ventilators: The administration of O2 and the depletion of CO2 can occur from mechanical ventilation, causing the client to be hyperventilated. ▪ Pain: Overstimulation of the respiratory center in the brainstem results in a carbonic acid deficit. ▪ Severe anxiety and hysteria: Often is neurogenic and related to a psychoneurosis; however, this condition leads to vigorous breathing and excessive exhaling of CO2. Box 9.1 Causes of Respiratory Acidosis ▪ Asthma: Spasms resulting from allergens, irritants, or emotions cause the smooth muscles of the bronchioles to constrict, resulting in ineffective gas exchange. ▪ Atelectasis: Excessive collection of mucus, with the collapse of alveolar sacs caused by mucous plugs, infectious drainage, or anesthetic medications, results in ineffective gas exchange. ▪ Brain trauma: Excessive pressure on the respiratory center or medulla oblongata depresses respirations. ▪ Bronchiectasis: Bronchi become dilated as a result of inflammation, and destructive changes and weakness in the walls of the bronchi occur. ▪ Bronchitis: Inflammation causes airway obstruction, resulting in inadequate gas exchange. ▪ Central nervous system depressants: Depressants such as sedatives, opioids, and anesthetics depress the respiratory center, leading to hypoventilation (excessive sedation from medications may require reversal by opioid antagonist medications); carbon dioxide (CO2) is retained, and the hydrogen ion concentration increases. ▪ Emphysema and chronic obstructive pulmonary disease: Loss of elasticity of alveolar sacs restricts air flow in and out, primarily out, leading to an increased CO2 level. ▪ Hypoventilation: CO2 is retained and the hydrogen ion concentration increases, leading to the acidotic state; carbonic acid is retained and the pH decreases. ▪ Pneumonia: Excess production of mucus and lung congestion cause airway obstruction, resulting in inadequate gas exchange. ▪ Pulmonary edema: Extracellular accumulation of fluid in pulmonary tissue causes disturbances in alveolar diffusion and perfusion. ▪ Pulmonary emboli: Emboli cause obstruction in a pulmonary artery, resulting in airway obstruction and inadequate gas exchange