Fluid and Electrolyte Management — MCQs

10 questions

After 30% loss of blood volume in road traffic accident. What immediate management is to be given?

A 4-year-old child is brought to the emergency department with severe dehydration due to diarrhea. What is the initial management for severe dehydration?

Rehydration therapy in a 2 year old severely dehydrated child is -

What is the recommended rate of correction for sodium deficit in patients with chronic hyponatremia?

Which fluid is ideally given for a patient experiencing dehydration?

Five days after an uneventful cholecystectomy, an asymptomatic middle-aged woman is found to have a serum sodium level of 125 mEq/L. Which of the following is the most appropriate management strategy for this patient?

What is the preferred fluid in a poly-traumatic patient with shock?

Which of the following statements about normal saline is false?

A male patient presents to the emergency department. The arterial blood gas report is as follows: pH, 7.2; pCO2, 81 mmHg; and HCO3, 40 meq/L. Which of the following is the most likely diagnosis?

Q10

A hyperventilating patient has the following ABG values: pH=7.53, pCO2=20 mmHg, HCO3= 26 mEq/L. What is the most likely diagnosis?

Fluid and Electrolyte Management Indian Medical PG Practice Questions and MCQs

Question 1: After 30% loss of blood volume in road traffic accident. What immediate management is to be given?

A. IV fluid only (Correct Answer)
B. Dopamine
C. Vasopressor drug
D. IV fluid with cardiac stimulant

Explanation: ***IV fluid only*** - A 30% blood volume loss constitutes **Class III hemorrhagic shock**, where immediate replacement of circulating volume with **intravenous fluids (crystalloids)** is the priority to restore perfusion. - Rapid infusion of warmed crystalloids (2-3 liters) is essential to stabilize hemodynamics immediately. While **blood products will likely be needed** after initial fluid resuscitation in Class III shock, the **immediate first step** is crystalloid infusion. - The principle is "fluid first" - restore circulating volume before considering other interventions. *Dopamine* - Dopamine is a **vasopressor** and **inotropic agent** that increases blood pressure and cardiac output. - It is **contraindicated** as first-line treatment for hypovolemic shock, as the primary issue is lack of volume, not cardiac dysfunction or inadequate vascular tone. - Using inotropes on an empty vascular system is like "flogging a dying horse" - ineffective and potentially harmful. *Vasopressor drug* - Vasopressors constrict blood vessels and increase blood pressure, but they are **contraindicated in acute hypovolemic shock** until adequate fluid resuscitation is achieved. - In hypovolemic shock, vasopressors without correcting the volume deficit worsen organ perfusion by increasing afterload on an already volume-depleted cardiovascular system and reducing tissue oxygenation. - Remember: "Fill the tank before you pressurize the pipes." *IV fluid with cardiac stimulant* - While IV fluids are critical, adding a **cardiac stimulant** (like dobutamine or epinephrine) is **not indicated** as an immediate step in **hypovolemic shock** caused by blood loss. - The heart is functioning normally but has insufficient preload due to volume loss. Stimulating an empty heart can be detrimental and does not address the primary problem. - Cardiac stimulants are reserved for cardiogenic shock or refractory hypotension after adequate volume resuscitation.

Question 2: A 4-year-old child is brought to the emergency department with severe dehydration due to diarrhea. What is the initial management for severe dehydration?

A. Oral rehydration therapy
B. Intravenous fluids (Correct Answer)
C. Antidiarrheal medication
D. Antibiotics

Explanation: ***Intravenous fluids*** - For **severe dehydration**, rapid correction of fluid and electrolyte imbalances is critical, and **intravenous fluids** (normal saline or Ringer's lactate) are the **first-line treatment**. - As per **WHO and IAP guidelines**, children with severe dehydration require **IV fluid resuscitation** at 100 mL/kg over 3-6 hours (or 30 mL/kg bolus initially). - Signs of severe dehydration include **lethargy, sunken eyes, absent tears, very dry mucous membranes, poor skin turgor**, and inability to drink. - IV route ensures **rapid intravascular volume expansion** when oral intake is compromised or inadequate. *Oral rehydration therapy* - **ORT** is the treatment of choice for **mild to moderate dehydration only** (Plan B as per WHO). - In severe dehydration, children often have **altered consciousness, persistent vomiting**, or **circulatory compromise**, making oral intake ineffective or impossible. - ORT can be initiated once the child is alert and able to drink after initial IV resuscitation. *Antidiarrheal medication* - **Not recommended** in children with acute diarrhea, especially under 5 years. - Medications like loperamide can cause **ileus, drowsiness**, and may worsen outcomes. - They do **not address fluid and electrolyte deficits**, which is the immediate life-threatening concern. *Antibiotics* - Only indicated for **specific bacterial causes** (e.g., cholera, shigellosis with blood in stool, or proven invasive bacterial infection). - **Not part of initial management** for severe dehydration. - Indiscriminate use contributes to **antibiotic resistance** and delays critical rehydration.

Question 3: Rehydration therapy in a 2 year old severely dehydrated child is -

A. 75 ml/kg in 4 hours
B. 30 ml/kg in 1 hour, 70 ml/kg in 5 hours
C. 20 ml/kg in 30 min, 80 ml/kg in 2.5 hours
D. 30 ml/kg in 30 min, 70 ml/kg in 2.5 hours (Correct Answer)

Explanation: ***30 ml/kg in 30 min, 70 ml/kg in 2.5 hours*** - This option reflects the recommended rehydration protocol for a severely dehydrated child aged **12 months to 5 years**, where the first 30 ml/kg are given rapidly over 30 minutes, followed by 70 ml/kg over the next 2.5 hours. - This rapid initial infusion helps to quickly restore **circulating volume** and improve perfusion during severe dehydration. *30 ml/kg in 1 hour, 70 ml/kg in 5 hours* - This protocol is typically used for children with **some dehydration**, not severe dehydration, and is usually administered orally when possible. - The slower rate of rehydration would be insufficient for a severely dehydrated child requiring more urgent fluid replacement. *20 ml/kg in 30 min, 80 ml/kg in 2.5 hours* - While reflecting a rapid initial phase, the total volume and distribution of fluids differ from the WHO guidelines for **severe dehydration** in this age group. - The **initial 20 ml/kg over 30 minutes** is generally a slightly lower first bolus than recommended for very severe cases, and the subsequent phase is also adjusted. *75 ml/kg in 4 hours* - This represents a **lower total volume** (75 ml/kg compared to 100 ml/kg) and a different time distribution for severely dehydrated children in the 12 month to 5 year age group. - This protocol is more aligned with the management of **some dehydration** rather than the urgent requirements of severe dehydration.

Question 4: What is the recommended rate of correction for sodium deficit in patients with chronic hyponatremia?

A. 0.5 mmol/hour (Correct Answer)
B. 1 mmol/hour
C. 1.5 mmol/hour
D. 2.0 mmol/hour

Explanation: ***0.5 mmol/hour*** [1] - This rate of correction is recommended to avoid **osmotic demyelination syndrome (ODS)**, also known as central pontine myelinolysis [1]. - The aim is to correct the sodium deficit gradually, with a maximum increase not exceeding **8-10 mmol/L in any 24-hour period** [1]. *1 mmol/hour* - This rate is generally considered too rapid for chronic hyponatremia and increases the risk of **osmotic demyelination syndrome**. - While acceptable in some acute severe cases, it is typically avoided in chronic settings where the brain has adapted to lower osmolality. *1.5 mmol/hour* - This rate would lead to an even faster correction of sodium, significantly elevating the risk of **osmotic demyelination syndrome**. - It would result in a correction of 36 mmol/L over 24 hours, far exceeding the recommended daily limit of 8-10 mmol/L. *2.0 mmol/hour* - Such a rapid correction rate is highly dangerous and almost guarantees the development of **osmotic demyelination syndrome**. - This aggressive correction would lead to severe brain injury due to rapid osmotic shifts.

Question 5: Which fluid is ideally given for a patient experiencing dehydration?

A. Plasma
B. Normal Saline (Correct Answer)
C. Blood
D. 5% dextrose

Explanation: ***Normal Saline*** - **Normal saline (0.9% sodium chloride)** is an **isotonic solution** that effectively increases **extracellular fluid volume**, making it ideal for treating **dehydration** and hypovolemia [1]. - It closely mimics the **osmolality of plasma** and stays predominantly in the intravascular space, helping to restore circulating volume [1]. *Plasma* - **Plasma** is primarily used for **coagulation factor deficiencies** or volume expansion in cases of severe **hypoproteinemia**, not routine dehydration. - It contains **proteins and clotting factors** that are not typically needed for simple dehydration and carries risks of **allergic reactions and transfusion-related acute lung injury (TRALI)**. *Blood* - **Blood transfusions** are indicated for patients with **significant anemia** or **acute blood loss**, not for generalized dehydration. - Using blood for dehydration would be inappropriate due to risks such as **transfusion reactions**, **infections**, and **iron overload**. *5% dextrose* - **5% dextrose in water (D5W)** is an **isotonic solution initially**, but once the dextrose is metabolized, it becomes **hypotonic**, causing free water to shift into the cells [1]. - While it provides some free water, it is not ideal for primary rehydration in cases of significant volume depletion due to its lack of electrolytes and potential for causing **hyponatremia** if given in large quantities [1].

Question 6: Five days after an uneventful cholecystectomy, an asymptomatic middle-aged woman is found to have a serum sodium level of 125 mEq/L. Which of the following is the most appropriate management strategy for this patient?

A. Administration of hypertonic saline solution
B. Hemodialysis
C. Restriction of free water (Correct Answer)
D. Plasma ultrafiltration

Explanation: ***Restriction of free water*** - The patient has **mild asymptomatic hyponatremia** (125 mEq/L) developed post-operatively, likely due to increased ADH secretion causing **dilutional hyponatremia**. [1, 3] - **Restricting free water intake** gently corrects the sodium concentration by limiting further dilution, allowing the kidneys to excrete excess water. [1] *Administration of hypertonic saline solution* - This is typically reserved for **severe (Na < 120-125 mEq/L) or symptomatic hyponatremia** (e.g., seizures, altered mental status). - In this asymptomatic patient, rapid correction with hypertonic saline can lead to **osmotic demyelination syndrome**, a severe neurological complication. [1] *Hemodialysis* - Hemodialysis is an invasive procedure generally indicated for **severe, refractory hyponatremia** or when there are signs of **water intoxication with cerebral edema**, neither of which is present here. - It is an **overly aggressive treatment** for mild asymptomatic hyponatremia. *Plasma ultrafiltration* - This procedure removes plasma water and solutes and is primarily used in cases of **fluid overload with hyponatremia** (e.g., in heart failure or renal failure) when other diuretics are ineffective. - In an asymptomatic patient with mild hyponatremia, ultrafiltration is **unnecessary and carries risks** associated with invasive procedures.

Question 7: What is the preferred fluid in a poly-traumatic patient with shock?

A. Ringer lactate (Correct Answer)
B. Dextran
C. Normal saline
D. Dextrose-normal saline

Explanation: ***Ringer lactate*** - **Ringer's lactate (RL)** is the **preferred initial resuscitation fluid** for poly-traumatic patients with shock according to **ATLS (Advanced Trauma Life Support) guidelines**. - It is a **balanced crystalloid** with electrolyte composition similar to plasma, providing effective volume expansion while minimizing the risk of **hyperchloremic metabolic acidosis** that occurs with large-volume normal saline administration. - The lactate in RL is rapidly metabolized to bicarbonate by the liver, helping to buffer any existing acidosis, and does not worsen lactic acidosis in trauma patients. - RL also contains **potassium and calcium**, which help maintain physiological electrolyte balance during resuscitation. *Normal saline* - While **normal saline (0.9% NaCl)** is an isotonic crystalloid, it has a **supraphysiological chloride concentration** (154 mEq/L) compared to plasma (100 mEq/L). - Large-volume administration in trauma can cause **hyperchloremic metabolic acidosis**, which can worsen outcomes and is particularly problematic in poly-trauma patients already at risk for metabolic derangements. - It remains acceptable as an alternative when RL is unavailable, but is no longer considered the first-line choice in modern trauma protocols. *Dextran* - **Dextran** is a colloid solution that carries significant risks including **anaphylactic reactions** and **coagulopathy** by interfering with platelet function and clotting factors. - These adverse effects are particularly dangerous in poly-traumatic patients who may already have traumatic coagulopathy. - It is **not recommended** for initial trauma resuscitation due to these risks and lack of proven superiority over crystalloids. *Dextrose-normal saline* - **Dextrose-containing solutions** are hypotonic after dextrose metabolism, leading to ineffective intravascular volume expansion as fluid shifts into the intracellular compartment. - They can worsen **cerebral edema** in head-injured trauma patients and cause dangerous electrolyte imbalances. - These solutions are **contraindicated** in acute trauma resuscitation.

Question 8: Which of the following statements about normal saline is false?

A. fluid of choice for hypovolemic shock
B. lead to hyperchloremic metabolic acidosis
C. fluid of choice for head injury patient
D. normal saline 0.9% is most suitable to treat acute severe hyponatremia (Correct Answer)

Explanation: normal saline 0.9% is most suitable to treat acute severe hyponatremia - While 0.9% normal saline can be used in some hyponatremia cases, **acute severe hyponatremia** (especially with neurological symptoms) typically requires **hypertonic saline (3%)** to rapidly increase serum sodium and prevent cerebral edema. [2] - Normal saline contains 154 mEq/L of sodium, which is often insufficient to correct severe hyponatremia quickly enough [1]. *fluid of choice for head injury patient* - **Normal saline (0.9%) is often *not* the fluid of choice for head injuries**; rather, **hypertonic saline** is often preferred as it can decrease intracranial pressure (ICP) by drawing water out of brain cells. - Isotonic fluids like normal saline can contribute to cerebral edema if given in large quantities, though it's still safer than hypotonic fluids. *fluid of choice for hypovolemic shock* - **Normal saline (0.9%) is generally considered the fluid of choice for initial resuscitation in hypovolemic shock** as it is an isotonic crystalloid that effectively expands intravascular volume [1]. - It readily distributes across the extracellular fluid compartment, restoring circulating blood volume. *lead to hyperchloremic metabolic acidosis* - **Normal saline (0.9%) contains a higher concentration of chloride (154 mEq/L) than plasma (98-106 mEq/L)**, and when infused in large volumes, it can lead to **hyperchloremia** [1]. - This excess chloride can shift the bicarbonate buffer system, resulting in a **non-anion gap (hyperchloremic) metabolic acidosis**.

Question 9: A male patient presents to the emergency department. The arterial blood gas report is as follows: pH, 7.2; pCO2, 81 mmHg; and HCO3, 40 meq/L. Which of the following is the most likely diagnosis?

A. Respiratory alkalosis
B. Metabolic acidosis
C. Respiratory acidosis (Correct Answer)
D. Metabolic alkalosis

Explanation: ***Respiratory acidosis*** - The **pH of 7.2** indicates **acidemia**, while the **elevated pCO2 (81 mmHg)** points to a primary respiratory problem [2]. - The elevated **HCO3 (40 meq/L)** suggests **renal compensation** attempting to buffer the increased carbonic acid [1]. *Respiratory alkalosis* - This condition presents with an **elevated pH (alkalemia)** and a **decreased pCO2**, which is opposite to the given ABG values [2]. - While there might be metabolic compensation with a decreased HCO3, the primary disturbance is an increase in respiratory rate leading to excessive CO2 exhalation. *Metabolic acidosis* - Metabolic acidosis is characterized by a **low pH** and a **low HCO3**, with a compensatory decrease in pCO2 [1]. - The given ABG shows a high HCO3, which rules out primary metabolic acidosis. *Metabolic alkalosis* - This condition would typically show an **elevated pH** and an **elevated HCO3**, with a compensatory increase in pCO2. - While both HCO3 and pCO2 are high in the given ABG, the low pH points to a primary acidosis, not alkalosis.

Question 10: A hyperventilating patient has the following ABG values: pH=7.53, pCO2=20 mmHg, HCO3= 26 mEq/L. What is the most likely diagnosis?

A. Metabolic alkalosis
B. Metabolic acidosis
C. Respiratory alkalosis (Correct Answer)
D. Respiratory acidosis

Explanation: ***Respiratory alkalosis*** - The pH of 7.53 indicates **alkalemia**, and the low pCO2 (20 mmHg) is the primary driver, signifying **respiratory alkalosis** - A hyperventilating patient exhales more CO2, leading to a decrease in its partial pressure in the blood and a subsequent rise in pH - The HCO3 is within normal range (26 mEq/L), indicating **uncompensated respiratory alkalosis** *Metabolic alkalosis* - This would be characterized by a high pH and an elevated **HCO3**, but the HCO3 is within the normal range (26 mEq/L) - While it causes alkalemia, the primary disturbance here is respiratory, not metabolic *Metabolic acidosis* - This would present with a **low pH** and a low **HCO3**, which is contrary to the given ABG values - The patient's pH is elevated, indicating an alkalotic state, not acidotic *Respiratory acidosis* - This would be defined by a **low pH** and an elevated **pCO2**, which is the exact opposite of the provided ABG results - The patient's high pH and low pCO2 rule out respiratory acidosis

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