Question

Clinical Perspectives

The Metabolic Café

You are sitting in a small cafe’ in Provincetown on Cape Cod while studying for your upcoming anatomy and physiology II test on fluid, electrolyte, and acid-base homeostasis. The following characters share your company in the café.

1. Determine if each character is in fluid balance, water intoxication, or dehydration. Determine the compensation mechanism that is taking place to return their body to homeostasis. Explain any hormone or electrolyte changes that are causing the condition and the hormone and electrolyte changes that occur during the compensatory stage. (ADH, angiotensin II, aldosterone, atrial natriuretic peptide, Na, Cl, K)

2. Determine if each character is in acid-base balance or is at risk for: metabolic acidosis, metabolic alkalosis, respiratory acidosis, or respiratory alkalosis. What are the compensatory mechanisms that are taking place in each one of the following characters? For example: Metabolic compensation involves renal excretion of H+ ion and reabsorption of bicarbonate ion to correct respiratory acidosis.

For example, compensatory formula for metabolic alkalosis: You need to increase the H+ ions in the body so the respiratory compensation is Hypoventilation

H2O + CO2 à H2CO3 à H + HCO3

What are the three Buffer Systems doing to quickly and temporarily try to return the acid-base balance to homeostasis in each of the characters that are out of homeostasis?

• Protein buffer system: -COOH, NH2, Hb
• Carbonic acid-bicarbonate buffer system: H2CO3, -HCO3
• Phosphate buffer system: HPO4, H2PO4

Mr. Bud. He is a construction worker that has been working on the Cape Cod Canal for the past ten years. He has been working outdoors in the direct sunlight where the temperature is 95 degrees Fahrenheit and humidity is 80%. He's sitting at the bar at 4 PM drinking 16 oz. Bud Lite beers with an equal number of bourbon shots. He's not eating the salty bar snacks because he is watching his weight although he's on his third Budweiser and weighs 255 pounds, 5’ 8” tall. His lunch also consisted of 3 Bud Lites.

Questions: Is Mr. Bud at risk for water intoxication, dehydration, or in fluid balance? What factors are affecting Mr. Bud's body fluid level and which hormones for fluid balance are affected by his lifestyle? Is his fluid volume dropping? If so, which hormones are released to compensate for this loss?

Mrs. Lovely and Mr. Money. Mrs. Lovely is closing in on 40 years old. She's the first one at the exercise club in the morning at 6 AM (the nanny takes the kids to school) and performs aerobic exercise for no less than two hours, five days a week. She does not believe in rehydration because she's afraid of water weight gain. She wants to return to a size O before her 40^th birthday. Her percentage body fat is around 5%. Following her workout, she spends 20 minutes in the dry heat sauna then has a 45-minute massage. Her total caloric intake for a typical day is 1300 calories with few carbohydrates. She's sipping Lady Grey black tea.

Questions: Is Mrs. Lovely at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting her body fluid level and which hormones for fluid balance are affected by her lifestyle? Is her fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Mrs. Lovely at risk for respiratory or metabolic alkalosis or acidosis? What is the compensatory mechanism working to rectify her self-induced condition?

Mr. Money works 60 hours per week and does not pay much attention to what he eats or drinks. Breakfast consists of two cups of black coffee. He suffers from a hiatal hernia and despite his doctor's advice he continues to work long stressful hours, drink coffee and alcohol, and eat fatty foods. Consequently, he experiences vomiting first thing in the morning and several times per day. His BP is 145/90 and higher during stress. He also has a mild heart condition for which he takes diuretics. He takes Prilosec and a handful of over-the-counter antacids daily. He drinks a glass full of sodium bicarbonate and water each night before bed to quell the heartburn. He and Mrs. Lovely usually eat out together for dinner (nanny cooks and puts the kids to bed too) at which time he tries to impress Mrs. Lovely with a show of concern for healthful eating by ordering a salad with grilled salmon for dinner accompanied by several glasses of white wine.

Questions: Is Mr. Money at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting his body fluid level and which hormones for fluid balance are affected by his lifestyle? Is his fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Mr. Money at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify his self-induced condition?

Mr. Macho. He is sitting at the bar with his friends. He is the sole surviving bachelor of his over 30 group of friends. He still lives in his parent’s house, is 31 years old, and exercises at the gym six days per week. He takes laxatives daily to keep his body weight down so he can maintain the same physique he had in high school. He's trying to impress his friends by eating 12 jalapeno peppers stuffed with cheese accompanied by an equal number of tequila shots.

Questions: Is Mr. Macho at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting his body fluid level and which hormones for fluid balance are affected by his lifestyle? Is his fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Mr. Macho at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify his self-induced condition?

The Lovers. They are sitting in the corner at a small table. Dante is finishing his masters’ degree in philosophy and plans to work at the nonprofit agency until he can form his own cult movement and ultimately run for a political office at the federal level to convert our government to Socialism. He's drinking his third cappuccino, which is the only thing he has had to drink all day. He has labored, slow, shallow breathing resulting from a gunshot wound to his chest when he was a teenager. He rolls his own cigarettes and smokes the equivalent of one pack per day.

Questions: Is Dante at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting his body fluid level and which hormones for fluid balance are affected by his lifestyle? Is his fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Dante at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify his self-induced condition?

Sally loves everything sweet and suffers from a moderate to severe anxiety problem. She also loves carbonated drinks and frequently drinks soda and water. She also drinks no less than two 12 oz. glasses of water with bicarbonate soda every day because her friend told her it was good for her skin. Sally takes 10-12 tablets of TUMS per day for the “calcium” and she likes the taste. She is eating a candy cane ice cream sundae with marshmallow sauce accompanied by an orange sherbet Sunkist soda float. She’s beginning to nervously hyperventilate while listening to Dante as he begins pontificating again about the need for Communism in the United States.

Questions: Is Sally at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting her body fluid level and which hormones for fluid balance are affected by her lifestyle? Is her fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Sally at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify her self-induced condition?

Mr. Salty. This is not his lucky day. He just turned 50 and it’s time for his first Colonoscopy. He is consuming 4 liters of the horrid hypertonic solution of sodium bicarbonate, sodium chloride, and potassium chloride. He’s had dibs on the men’s room all afternoon.

Questions: Is Mr. Salty at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting his body fluid level and which hormones for fluid balance? Is his fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Mr. Salty at risk for respiratory or metabolic / alkalosis or acidosis?

Mr. Puffy. This gentleman is 65 years old. He has smoked two packs of non-filter cigarettes per day since he was 15 years old. His face is ruddy with a nose like WC Fields. His lips and nose are blue and he is breathing through pursed lips, having trouble evacuating the air from his lungs. He has a barrel chest. The expiratory area of his respiratory center is fully activated. He sips a small glass of port wine and reminisces about the old days.

Questions: What is your understanding of Mr. Puffy’s respiratory diagnosis? Is Mr. Puffy at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify his self-induced condition?

Young couple with their first baby. This is their first excursion out of the house with baby. They’ve been unable to sleep because baby is awaking all-night and asleep all day. Baby has been vomiting for the past 2-3 days, unable to keep down clear liquid or formula. Her mother told them not to worry; “spitting up” is normal. They're both exhausted and trying to enjoy their first restaurant dinner together for months. Baby is in her car seat trying to sleep but appears fidgety.

Questions: Is baby at risk for an acid- base imbalance? If so, is it respiratory or metabolic alkalosis or acidosis? What is the compensatory mechanism working to rectify this condition?

Aquarius. She's sitting alone at a table drinking distilled water hoping to be discovered by a famous movie producer. She has the lead role in a small off-Broadway play. Directors in the past have often told her that she should drink a lot of water before a performance to help with her voice quality. Her aesthetician recommends 4-5 liters of pure water per day for her skin hydration. Taking this to heart, she has been drinking at least this much water a day and more. She will only eat protein, no carbohydrates, and takes laxatives to maintain a slender figure. She's also a novice jogger with great determination, putting in at least five miles per day. She rehydrates with pure water only. The only thing she has had to drink today is distilled water.

Questions: Is Aquarius at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting her body fluid level and which hormones are affected by her lifestyle? Is her fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Aquarius at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify her self-induced condition?

Answer 1

Mr. Puffy

Questions: What is your understanding of Mr. Puffy’s respiratory diagnosis? Is Mr. Puffy at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify his self-induced condition?

Ans. Mr. Puffy is suffering from emphysema. Ruddy face, breathing through pursed lips, cyanosis and a barrel chest are all typical symptoms of emphysema. Smoking is an etiological factor for emphysema. Emphysema is defined as abnormal permanent enlargement of air spaces distal to the terminal bronchioles, accompanied by the destruction of alveolar walls and without obvious fibrosis. Due to the destruction of the alveolar walls, exchange of gases is impaired. This puts him at an increased risk for accumulation of carbon dioxide in the blood leading to respiratory acidosis. To compensate for this the kidneys increase the urinary excretion of hydrogen ions and resorption of HCO3−.

Q2. Young couple with baby

Questions: Is baby at risk for an acid- base imbalance? If so, is it respiratory or metabolic alkalosis or acidosis? What is the compensatory mechanism working to rectify this condition?

Ans. The baby has been vomiting since the past 2-3 days. The baby can develop metabolic alkalosis. This leads to excess loss of water and electrolytes from the body. The secretions of the stomach are rich in HCl which are lost in the vomitus. Along with this Na and K are also lost. This causes the kidneys to retain Na in exchange of H+. As the H+ ions are excreted into the urine, there is metabolic alkalosis. To compensate for the respiratory rate will reduce, leading to accumulation of carbon dioxide. CO2 is then consumed toward the formation of the carbonic acid intermediate, thus decreasing pH.

Q3. Aquarius and overhydration

Questions: Is Aquarius at risk for water intoxication, dehydrated, or in fluid balance? What factors are affecting her body fluid level and which hormones are affected by her lifestyle? Is her fluid volume dropping? If so, which hormones are released to compensate for this loss? Is Aquarius at risk for respiratory or metabolic / alkalosis or acidosis? What is the compensatory mechanism working to rectify her self-induced condition?

Ans) Aquarius is at the risk for water intoxication and also electrolyte imbalance. She is consuming only proteins and no carbohydrates in her diet. She has also been abusing laxatives. Laxative abuse will put her at risk of developing hypokalemia and metabolic alkalosis. Overhydration also causes hyponatremia.

Her fluid volume is not dropping. Due to overhydration she has excess fluid volume. She is not at the risk of respiratory or metabolic alkalosis/acidosis. The main concern is electrolyte imbalance and fluid overload. She has to be treated with diuretics and her diet has to be modified to include carbohydrates.