DM Flashcards
Explain how Metabolic Acidosis and Potassium Shifts occur in DKA
Metabolic acidosis occurs when the blood becomes too acidic, often due to the accumulation of ketones (which are acidic).
The body tries to manage the high acidity (from the ketones) by moving hydrogen ions (H⁺) from the blood into the cells.
As hydrogen ions enter the cells, they displace potassium ions (K⁺), pushing potassium out of the cells and into the bloodstream.
Eventually, this potassium is excreted in urine, leading to a depletion of potassium from the body (potassium loss).
Putting it all together:
- Insulin deficiency causes the body to rely on fat breakdown, leading to ketosis (high levels of ketones).
- Ketones make the blood acidic, causing metabolic acidosis.
- To reduce acidity, the body moves hydrogen ions into cells, pushing potassium out of cells into the blood, but eventually, this potassium is lost in urine.
- Reduced kidney blood flow triggers secondary hyperaldosteronism, which worsens potassium loss.
- Potassium is an important mineral that your body needs to function properly, especially for your muscles and nerves.
- Secondary hyperaldosteronism occurs when there’s reduced blood flow to the kidneys. The kidneys respond by producing more aldosterone (a hormone).
- Aldosterone causes the kidneys to retain sodium (which helps keep blood pressure up) but also makes them excrete more potassium in the urine.
- Therefore, when there’s reduced blood flow to the kidneys (like in dehydration or shock), the body produces more aldosterone, which leads to more potassium being lost in the urine. This exacerbates or worsens the loss of potassium from the body.
- Ketosis happens when the body doesn’t have enough insulin to use glucose for energy, so it starts breaking down fat for energy instead.
- Insulin deficiency means there isn’t enough insulin to help the body use glucose (sugar) from the blood for energy.
- When the body breaks down fat, it releases free fatty acids (FFAs). These FFAs go to the liver, where they are converted into ketones.
- Ketones are acidic, and normally, the body can handle a small amount of them. But when ketone production is very high, as in uncontrolled diabetes, they accumulate in the blood, leading to ketosis.
- Metabolic acidosis occurs when the blood becomes too acidic, often due to the accumulation of ketones (which are acidic).
- The body tries to manage the high acidity (from the ketones) by moving hydrogen ions (H⁺) from the blood into the cells.
- As hydrogen ions enter the cells, they displace potassium ions (K⁺), pushing potassium out of the cells and into the bloodstream.
- Eventually, this potassium is excreted in urine, leading to a depletion of potassium from the body (potassium loss).
- Insulin deficiency causes the body to rely on fat breakdown, leading to ketosis (high levels of ketones).
- Ketones make the blood acidic, causing metabolic acidosis.
- To reduce acidity, the body moves hydrogen ions into cells, pushing potassium out of cells into the blood, but eventually, this potassium is lost in urine.
- Reduced kidney blood flow triggers secondary hyperaldosteronism, which worsens potassium loss.
This chain of events explains how uncontrolled diabetes or severe illness can lead to both ketosis (due to insulin deficiency) and significant potassium loss (due to metabolic acidosis and secondary hyperaldosteronism).
Let’s break down this text on Diabetic Ketoacidosis (DKA) to make it more understandable:
- In DKA, the body loses a significant amount of fluids and electrolytes, which are essential minerals in the body.
- The total body water loss in DKA comes from two main compartments in the body:
- Intracellular compartment: This is the fluid inside cells. About half of the water loss in DKA comes from here, and this happens early in the course of the acidosis (a condition where the blood becomes too acidic).
- Extracellular fluid compartment: This includes the fluid outside cells, such as blood plasma. The loss from this compartment happens later and leads to more noticeable symptoms.
- As DKA progresses, there is a significant reduction in the volume of extracellular fluid. This leads to:
- Haemoconcentration: The blood becomes more concentrated because there’s less fluid in it.
- Decreased blood volume: As a result, the overall volume of blood circulating in the body decreases.
- Blood pressure drops: The decrease in blood volume leads to lower blood pressure.
- Renal ischemia: The kidneys receive less blood flow, which can cause damage.
- Oliguria: This means reduced urine output, as the kidneys struggle to filter blood due to the lack of fluid and pressure.
- Potassium is a crucial electrolyte that’s often depleted in DKA, even though the initial plasma potassium levels (the amount of potassium in the blood) might appear normal or even high.
- The initial high potassium levels are misleading because:
- Water loss: There’s a greater loss of water relative to potassium, so the potassium concentration may seem elevated.
- Catabolism: The breakdown of proteins and glycogen (the stored form of glucose) releases potassium into the bloodstream.
- Acidosis: High levels of hydrogen ions (H⁺) in the blood push potassium out of the cells and into the blood.
- However, once treatment starts, the potassium levels in the blood can drop rapidly due to:
- Dilution: Intravenous fluids given to treat DKA dilute the potassium in the blood.
- Insulin therapy: Insulin helps move potassium back into the cells, lowering blood potassium levels.
- Ongoing renal loss: The kidneys continue to excrete potassium, further depleting the body’s potassium stores.
- The severity of hyperglycemia (high blood sugar) does not necessarily match the severity of metabolic acidosis (the acidity of the blood). This means that:
- Even if blood sugar levels aren’t extremely high, the patient might still have severe, life-threatening acidosis.
- For example, in pregnancy, women with Type 1 diabetes can develop DKA without extremely high blood sugar levels.
- Conversely, some patients may have very high blood sugar without severe acidosis. In such cases, they may develop a condition known as hyperosmolar state, where the blood becomes very concentrated due to the high glucose levels, but the acidosis is minimal.
- DKA involves significant fluid loss from both inside and outside the cells, leading to dehydration, low blood pressure, and kidney problems.
- Even though blood potassium levels might look normal or high at first, the body is actually low on potassium. When treatment starts, potassium levels can drop quickly.
- The severity of blood acidity (acidosis) doesn’t always correlate with how high the blood sugar is. Sometimes, life-threatening acidosis can occur even with moderate blood sugar levels, especially in certain situations like pregnancy.
What are the clinical features of DKA?
- Symptoms
• Polyuria, thirst
• Weight loss
• Weakness
• Nausea, vomiting
• Leg cramps
• Blurred vision
• Abdominal pain - Signs
• Dehydration
• Hypotension (postural or
supine)
• Cold extremities/peripheral
cyanosis
• Tachycardia
• Air hunger (Kussmaul
breathing)
• Smell of acetone
• Hypothermia
• Delirium, drowsiness, coma
(10%)
What are the investigations needed for a DKA patient?
This means that while it is crucial to conduct certain tests to gather more information about the patient’s condition, it is equally important to start providing the patient with fluids and insulin without waiting for the results of these investigations.
First- doctors can test the levels of certain substances like urea, electrolytes, glucose, and bicarbonate in your blood. This can be done using blood taken from a vein, which is less painful than blood taken from an artery. The results can help doctors understand your body’s acid-base balance.
2- Another test that can be done is to check for ketones in your urine or blood. Ketones are chemicals that your body makes when it doesn’t have enough insulin to use sugar for energy.
3- An electrocardiogram (ECG) is a test that checks the electrical activity of your heart(due to reduced k). This can help doctors see if DKA is affecting your heart.
Doctors may also do an infection screen, which includes tests like a full blood count, blood and urine culture, C-reactive protein test, and chest X-ray. This is to check for any signs of infection, even though it’s common to see an increase in white blood cells in DKA, which is actually just a response to stress and not always a sign of infection.
What are the Indicators of severe diabetic ketoacidosis?
•- Blood ketones > 6 mmol/L
• - Bicarbonate < 5 mmol/L
•- Venous/arterial pH < 7.0 (H+ > 100 nmol/L)
• - Hypokalaemia on admission (< 3.5 mmol/L)
• - Glasgow Coma Scale score < 12 (p. 194) or abnormal AVPU scale
score (p. 188)
• - O2 saturation < 92% on air
• - Systolic blood pressure < 90 mmHg
• - Heart rate > 100 or < 60 beats per minute
• - Anion gap > 16 mmol/L
How do you manage DKA?
This text outlines the emergency management of Diabetic Ketoacidosis (DKA), focusing on the critical interventions required during the first 24 hours after diagnosis. Let’s break it down step by step:
-
IV Access and Initial Assessment:
- The first step is to establish intravenous (IV) access and assess the patient’s condition. Initial investigations (like blood tests) are performed to understand the severity of DKA.
-
Fluid Replacement:
-
0.9% Sodium Chloride (normal saline) is the primary fluid used for rehydration:
- If systolic blood pressure (BP) is > 90 mmHg: Give 1 liter of fluid over 60 minutes.
- If systolic BP is < 90 mmHg: Administer 500 mL rapidly over 10–15 minutes, then reassess. If BP remains low, repeat the fluid bolus and seek senior medical advice.
-
0.9% Sodium Chloride (normal saline) is the primary fluid used for rehydration:
-
Insulin Therapy:
- Continuous IV Insulin Infusion: Administer 50 units of human soluble insulin mixed in 50 mL of 0.9% sodium chloride at a rate of 0.1 units per kilogram of body weight per hour.
- If the patient normally uses a subcutaneous (SC) basal insulin analogue, continue with this as well.
-
Further Investigations and Monitoring:
- Investigations: Conduct more detailed tests as needed to identify the cause of DKA and monitor patient progress.
-
Monitoring Schedule:
- Hourly: Measure blood glucose, blood ketones, oxygen saturation, pulse, blood pressure, respiratory rate, and urine output.
- Every 2 hours: Check venous bicarbonate and potassium levels during the first 6 hours.
- Every 4 hours: Monitor plasma electrolytes.
-
Address the Precipitating Cause:
- Identify and treat the underlying cause of DKA, such as an infection or missed insulin doses.
-
Fluid Replacement:
- Continue IV fluid therapy with 0.9% sodium chloride, adjusting the infusion rate as follows:
- 1 liter over 2 hours (twice)
- 1 liter over 4 hours (twice)
- 1 liter over 6 hours
- Potassium Chloride may be added to the IV fluids based on blood potassium levels.
- Continue IV fluid therapy with 0.9% sodium chloride, adjusting the infusion rate as follows:
-
Add Glucose:
- Start an infusion of 10% glucose at 125 mL/hour once blood glucose levels drop below 14 mmol/L (252 mg/dL) to prevent hypoglycemia.
-
Fluid Replacement Caution:
- Be cautious with fluid replacement in vulnerable patients (older adults, pregnant women, those with renal or heart failure). If plasma sodium is extremely high (> 155 mmol/L), consider using 0.45% sodium chloride instead.
-
Monitor Progress:
- By this time, the patient’s condition should show signs of improvement. If there’s no improvement, seek a senior medical review.
- Continue administering IV fluids and insulin.
-
Assess for Complications:
- Watch for potential treatment complications, such as fluid overload or cerebral edema (swelling of the brain).
- Avoid Hypoglycemia: Adjust treatment to ensure blood glucose levels don’t drop too low.
-
Resolution of Ketoacidosis:
- By 24 hours, ketoacidosis should resolve, which means:
- Blood ketones should be below 0.3 mmol/L.
- Venous bicarbonate levels should be greater than 18 mmol/L.
- By 24 hours, ketoacidosis should resolve, which means:
-
If the patient is not yet eating/drinking:
- Continue IV insulin at a reduced rate (2–3 units/hour).
- Keep administering IV fluids and monitoring biochemical parameters.
-
If the patient can eat/drink:
- Switch back to subcutaneous insulin under the guidance of a diabetes team.
- Do not stop IV insulin until 30 minutes after administering short-acting SC insulin.
- Urinary Catheterization: Consider if the patient isn’t producing urine after 3 hours or is incontinent.
- Nasogastric Tube: Insert if the patient has a reduced level of consciousness or persistent vomiting.
- Central Venous Line: Insert for accurate fluid management if the patient has cardiovascular compromise, is elderly, pregnant, or has severe DKA.
- Arterial Blood Gases and Chest X-ray: Measure blood gases and repeat chest X-rays if oxygen saturation is below 92%.
- ECG Monitoring: Recommended in severe DKA cases to monitor the heart.
- Thromboprophylaxis: Administer low-molecular-weight heparin to prevent blood clots.
- The emergency management of DKA is a structured approach aimed at restoring fluid balance, correcting metabolic abnormalities, and addressing the underlying cause. It involves careful monitoring and adjustment of treatment based on the patient’s response, with special attention to preventing complications like hypoglycemia and fluid overload.
Break down how insulin regiment should be administered? In DKA
-
Standard Approach:
- The recommended treatment for DKA is a fixed-rate intravenous insulin infusion at 0.1 units per kilogram of body weight per hour. This means that if a person weighs 70 kg, they would receive 7 units of insulin per hour.
-
Alternative Methods:
- If intravenous (IV) insulin is not possible (due to lack of IV access), there are alternative methods:
- Intramuscular Injection: An initial loading dose of 10–20 units of soluble insulin is given, followed by 5 units hourly.
- Subcutaneous Injection: Using a fast-acting insulin analogue, the initial dose is 0.3 units per kilogram, followed by 0.1 units per kilogram hourly. This method is less preferred but still effective in situations where IV insulin isn’t feasible.
- If intravenous (IV) insulin is not possible (due to lack of IV access), there are alternative methods:
-
Target Decrease in Blood Glucose and Ketones:
- The goal is for blood glucose to fall by 3–6 mmol/L (about 55–110 mg/dL) per hour.
- Alternatively, blood ketone levels should decrease by at least 0.5 mmol/L per hour.
- A slower reduction rate helps to avoid the risk of hypoglycemia (dangerously low blood sugar) and cerebral edema (brain swelling), which is a particularly severe risk in children.
- If the blood glucose does not decrease as expected within 1 hour of starting the insulin infusion, the insulin dose should be re-evaluated.
- Insulin Resistance: In severe cases of DKA, the combination of ketosis, dehydration, acidosis (high acid levels in the blood), infection, and stress can make the body less responsive to insulin. However, most patients will respond well to the low-dose insulin regimen provided.
- Once the blood glucose level has dropped sufficiently(<14), 10% dextrose (glucose) infusion is introduced alongside the insulin. This helps maintain blood glucose levels and prevents hypoglycemia while allowing insulin to continue working on reducing ketones and restoring normal cellular metabolism.
- In recent years, it has become more common to continue administering long-acting insulin analogues subcutaneously during the initial management of DKA. This ensures that there is a steady background level of insulin even as the intravenous insulin is tapered off, which reduces the risk of in-hospital DKA recurrence.
- The switch back to the usual insulin regimen (administered by subcutaneous injection) should only occur when the patient is:
- Biochemically stable: Blood ketones, glucose, and pH levels have returned to normal.
- Able to eat and drink normally: This ensures that the patient can manage their insulin and blood sugar levels with food intake as usual.
- Fixed-Rate IV Insulin is the standard for managing DKA.
- Monitoring is critical to avoid complications like hypoglycemia and cerebral edema.
- Gradual transition to subcutaneous insulin prevents DKA recurrence and stabilizes the patient for ongoing diabetes management.
Break down how k regiment should be administered? In DKA
In the management of Diabetic Ketoacidosis (DKA), careful attention to potassium levels is crucial because both low (hypokalemia) and high (hyperkalemia) potassium levels can be dangerous and even life-threatening.
-
Initial Risk Factors:
- At the beginning of DKA treatment, the patient is often severely dehydrated, which can cause pre-renal failure (kidney dysfunction due to reduced blood flow). For this reason, potassium replacement is generally not recommended with the initial liter of fluids because adding potassium too early could worsen any underlying kidney issues and potentially lead to hyperkalemia.
-
Potassium Levels and Replacement:
- Potassium chloride is added to the IV fluids (0.9% sodium chloride) if the serum potassium level is below 5.5 mmol/L and the patient is producing urine. The presence of urine indicates that the kidneys are functioning sufficiently to handle the potassium load.
- Potassium levels between 4.0 and 5.5 mmol/L are considered the safe range during treatment.
- If potassium levels drop below 3.5 mmol/L, this is concerning because it indicates hypokalemia, which could cause muscle weakness, paralysis, or life-threatening heart arrhythmias. In this case, the potassium replacement regimen should be adjusted to increase potassium levels more aggressively.
-
Monitoring and Adjustments:
- Cardiac Monitoring: Since abnormal potassium levels can disrupt the heart’s electrical activity, leading to arrhythmias (irregular heartbeats), cardiac rhythm monitoring is essential in severe cases of DKA. This is particularly important when potassium levels are outside the normal range.
- Delay Potassium Replacement: Initially hold off on potassium replacement until kidney function is assessed (i.e., ensure the patient is passing urine).
- Add Potassium when Appropriate: Begin potassium replacement if levels are below 5.5 mmol/L and the patient is urinating, aiming to keep potassium between 4.0 and 5.5 mmol/L.
- Monitor Cardiac Function: Constantly monitor the heart rhythm in severe DKA cases, as both high and low potassium levels can trigger dangerous heart arrhythmias.
This careful balance is crucial because DKA can cause significant shifts in potassium between the inside and outside of cells, and the treatment itself can lead to rapid changes in potassium levels.
- > 5.5mmol/l, observe, no kcl
- 4.5-5.4mmol/l, give13mmol
- 3.5-4.4mmol/l give 26mm0l/l
- <3.5mmol/l, give 39mmol/l
What are the features of HHS
Hypovolaemia,
severe hyperglycaemia
(> 30 mmol/L (600 mg/dL)) and
Hyperosmolality (serum osmolality > 320 mOsmol/kg),
without significant ketonaemia
As with DKA, there is glycosuria, leading to an osmotic diuresis with loss of water, sodium, potassium and other electrolytes. However, in HHS, hyperglycaemia usually develops over a longer period (a few days to weeks), causing more profound hyperglycaemia and dehydration (fluid loss may be 10–12 L in a person weighing 100 kg).
The reason that patients with HHS do not develop significant ketoacidosis is unclear, although it has been speculated that
insulin levels may be too low to stimulate glucose uptake in insulin-sensitive tissues, but are still sufficient to prevent lipolysis and subsequent ketogenesis.
Common precipitating factors of HHS includes
infection
myocardial infarction
Cerebrovascular events or drug therapy (e.g. glucocorticoids).
What are the Poor prognostic signs in HHS
include hypothermia,
hypotension (systolic blood pressure
< 90 mmHg),
tachy- or bradycardia,
Severe hypernatraemia
(sodium > 160 mmol/L),
Serum osmolality > 360 mOsmol/kg,
and the presence of other serious comorbidities.
Mortality rates of HHS are higher than in DKA
