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Antidiuretic Hormone ADH PowerPoint PPT Presentation


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H 2 O. ADH. Antidiuretic Hormone ADH. Collecting Duct. Hypertonic Interstitial Fluid. Urine. Calcitonin. Calcium. Estrogen. Calcium. Parathormone. Calcium. Blood pH = 7.4 (7.35-7.45). Blood pH regulated by 1. Kidneys 2. Lungs 3. Buffers in blood.

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Antidiuretic Hormone ADH

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H2O

ADH

Antidiuretic HormoneADH

Collecting Duct

Hypertonic Interstitial Fluid

Urine


Calcitonin

Calcium


Estrogen

Calcium


Parathormone

Calcium


Blood pH = 7.4(7.35-7.45)

Blood pH regulated by

1. Kidneys

2. Lungs

3. Buffers in blood


H+ Secreted HCO3- Resorbed

Blood

H+

Kidney Nephron

Urine

HCO3-


Kidneys Regulate pH

  • Excreting excess hydrogen ions, retain bicarbonate

    • if pH is too low

  • Retaining hydrogen ions, excrete bicarbonate

    • if pH is too high


Lungs Regulate pH

  • Breathe faster to get rid of excess carbon dioxide if pH is too low

    • Carbon dioxide forms carbonic acid in the blood

  • Breathe slower to retain carbon dioxide if pH is too high


Carbonic Acid

Carbon Dioxide and Acid

CO2 + H2O H2CO3H++ HCO3-


More Carbon Dioxide = More Acid = Lower pH

  • Breathing slower will retain CO2 , pH will

    • decrease (more acid)

  • Breathing faster will eliminate more CO2 pH will

    • increase (less acid)


Blood pH Drops to 7.3How does the body compensate?

  • Breathe faster to get rid of carbon dioxide

    • eliminates acid


Blood pH Increases to 7.45How does the body compensate?

  • Breathe slower to retain more carbon dioxide

    • retains more acid


PG

The role of ADH:

  • ADH = urinary concentration

  • ADH = secreted in response to ⇑ osmolality;

    = secreted in response to ⇓ vol;

  • ADH acts on DCT / CD to reabsorb water

  • Acts via V2 receptors & aquaporin 2

  • Acts only on WATER


PG

Calculation of osmolality

  • Difficult: measure & add all active osmoles

  • Easy = [ sodium x 2 ] + urea + glucose

  • Normal = 280 - 290 mosm / kg


PG

Fluid shifts in disease

  • Fluid loss:

    • GI: diarrhoea, vomiting, etc.

    • Renal: diuresis

    • Vascular: haemorrhage

    • Skin: burns,sweat

  • Fluid gain:

    • Iatrogenic:

    • Heart / liver / kidney failure:


PG

Prescribing fluids:

  • Crystalloids:

    • 0.9% saline - not “normal” !

    • 5% dextrose

    • 0.18% saline + 0.45% dextrose

    • Others

  • Colloids:

    • Blood

    • Plasma / albumin

    • Synthetics eg gelofusion


PG

The rules of fluid replacement:

  • Replace blood with blood

  • Replace plasma with colloid

  • Resuscitate with crystalloid or colloid

  • Replace ECF depletion with saline

  • Rehydrate with dextrose


PG

How much fluid to give ?

  • What is your starting point ?

    • Euvolaemia ?( normal )

    • Hypovolaemia ?( dry )

    • Hypervolaemia ? ( wet )

  • What are the expected losses ?

  • What are the expected gains ?


PG

Signs of hypo / hypervolaemia:

Signs of …

Volume depletionVolume overload

Postural hypotension Hypertension

Tachycardia Tachycardia

Absence of JVP @ 45o Raised JVP / gallop rhythm

Decreased skin turgor Oedema

Dry mucosae Pleural effusions

Supine hypotension Pulmonary oedema

Oliguria Ascites

Organ failure Organ failure


PG

What are the expected losses ?

  • Measurable:

    • urine ( measure hourly if necessary )

    • GI ( stool, stoma, drains, tubes )

  • Insensible:

    • sweat

    • exhaled


  • Electrolyte (Na+, K+, Ca++) Steady State

  • Amount Ingested = Amount Excreted.

  • Normal entry: Mainly ingestion in food.

  • Clinical entry: Can include parenteral administration.


PG

Case 1:

  • A 62 year old man is 2 days post-colectomy. He is euvolaemic, and is allowed to drink 500ml. His urine output is 63 ml/hour:

    1. How much IV fluid does he need today ?

    2. What type of IV fluid does he need ?


PG

Case 2:

  • 3 days after her admission, a 43 year old woman with diabetic ketoacidosis has a blood pressure of 88/46 mmHg & pulse of 110 bpm. Her charts show that her urine output over the last 3 days was 26.5 litres, whilst her total intake was 18 litres:

    1. How much fluid does she need to regain a normal BP ?

    2. What fluids would you use ?


PG

Case 3:

  • An 85 year old man receives IV fluids for 3 days following a stroke; he is not allowed to eat. He has ankle oedema and a JVP of +5 cms; his charts reveal a total input of 9 l and a urine output of 6 litres over these 3 days.

    1. How much excess fluid does he carry ?

    2. What would you do with his IV fluids ?


PG

Case 4:

  • 5 days after a liver transplant, a 48 year old man has a pyrexia of 40.8oC. His charts for the last 24 hours reveal:

  • urine output:2.7 litres

  • drain output:525 ml

  • nasogastric output:1.475 litres

  • blood transfusion:2 units (350 ml each)

  • IV crystalloid:2.5 litres

  • oral fluids:500 ml


PG

Case 4 cont:

  • On examination he is tachycardic; his supine BP is OK, but you can’t sit him up to check his erect BP. His serum [ Na+ ] is 140 mmol/l.

  • How much IV fluid does he need ?

  • What fluid would you use ?


Case 5

  • 30yo girl

  • SOB, moist cough, chest pain

  • ESKD

  • Very little urine output

  • Has missed dialysis last 3 sessions


Case 5

  • What next?

    • Current weight 78kg

    • IBW 68kg

    • JVP twitching her ear

    • No peripheral oedema

    • Coarse crackles to mid zones

    • BP 240/110

    • P 100

    • Gallop rhythm

    • 4cm of liver in RUQ


Case 5

  • Assessment

    • Acute significant overload

    • Probably about 10kg


Case 6

  • 55yo lady

  • Presents to dialysis for her routine session

  • BP 78/30

  • History of dizziness for the last 6 hours

  • Current weight 58kg

  • IBW 59kg


Case 6

  • P 120

  • Chest clear

  • HS dual

  • No oedema

  • Admits to 24hours of diarrhoea

  • Thirsty

  • No JVP visible


Case 6

  • Dehydrated

  • Volume constricted

  • Hypotensive due to decreased circulating fluid volume

  • Resuscitation?


The End


Acknowledgements

  • Paddy Gibson – 4th year teaching ppt 2009

  • Robert Harris – Fluid Balance ppt 2009

  • Heather Laird-Fick – Fluid and electrolyte disorders ppt 2009

  • JXZhang Lecture 14 – ppt 2009

  • Dennis Wormington – fundamentals of fluid assessment ppt 2009


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