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Anaesthesiology
Acid–Base, Fluids, and Electrolytes
Built from Barash Clinical Anesthesia, 9th Edition
What’s inside
14 sections · 198 slides
Overview
- Scope of this topic
- Map of the topic
- Key messages from this topic
Acid–Base Equilibrium
- Daily acid load and the language of acid–base
- Origin of an acid–base disturbance
- Prevalence of acid–base disorders in hospital
- The four primary acid–base disturbances
- Physiologic consequences of severe acidemia
- Physiologic consequences of severe acidemia (pH below 7.2)
- Physiologic consequences of severe alkalemia
- Physiologic consequences of severe alkalemia (pH above 7.6)
- Methods of quantifying acid–base disturbance
- Metabolic acidosis: definition and mechanisms
- The anion gap
- Anion gap versus non-anion gap acidosis
- Causes of metabolic acidosis
- Etiologies of metabolic acidosis
- Treatment of metabolic acidosis
- Metabolic alkalosis: definition and mechanisms
- Chloride-responsive versus chloride-resistant alkalosis
- Why urine chloride separates the two groups
- Etiologies of metabolic alkalosis
- Treatment of metabolic alkalosis
- Respiratory alkalosis: definition and causes
- Etiologies of respiratory alkalosis
- Consequences and management of respiratory alkalosis
- Carbon dioxide manipulation in practice
- Respiratory acidosis: definition and causes
- Etiologies of respiratory acidosis
- Respiratory acidosis: effects and management
Interpretation of the Arterial Blood Gas
- Approaching the arterial blood gas
- Six-step approach to a blood gas
- Expected compensation and its formulae
- Primary acid–base disturbances with expected compensation
- Steps 4 to 6: the gaps and delta-delta
- Stepwise approach to arterial blood gas interpretation
- Stepwise approach to arterial blood gas interpretation (continued)
- Worked case one: presentation and interpretation
- Worked case one: stat laboratory findings
- Worked case two: presentation and interpretation
- Worked case two: stat laboratory findings
Fluid Physiology
- Body fluid compartments
- Compartment volumes in a 70-kg man
- Starling forces and the glycocalyx
- Osmolarity, osmolality and tonicity
- Predicting and measuring volume expansion
- Catecholamines and intravascular fluid retention
- Water balance and thirst
- Renin–angiotensin–aldosterone response to low volume
- Defending circulating volume
- Antidiuretic hormone: release and action
- Range of urinary concentration
- Range of urinary concentration
- Nephron filtration, reabsorption and excretion of water
- Vasopressin, urinary osmolality and plasma osmolality
Fluid Replacement Therapy
- Maintenance fluid, dextrose and glucose targets
- Hourly and daily maintenance water requirements
- Surgical fluid losses and goal-directed therapy
- Acid–base consequences of gastrointestinal losses
- Fluid losses and liberal fluid in minor surgery
- Postoperative nausea and pain after large-volume fluid
- Fluid strategy in major surgery
- Conservative fluid in lung injury, and colloid physiology
Choosing the Fluid
- Claimed advantages and disadvantages of colloid versus crystalloid intravenous fluids
- Claimed advantages and disadvantages of colloid versus crystalloid intravenous fluids (continued)
- Cochrane evidence and albumin in sepsis
- Albumin verdict and hydroxyethyl starch
- Fluids, intracranial pressure and the SAFE trial
- Buffered crystalloid and hypertonic alternatives
- Hypertonic saline: evidence and risks
- Hypertonic resuscitation fluids: advantages and disadvantages
Assessing Fluid Status
- Assessing volume status at the bedside
- Static parameters and their limits
- Arterial waveform analysis and fluid challenge
- Doppler, echocardiography and non-invasive monitors
Sodium
- Physiologic role and control of sodium
- Regulation of the total body electrolyte mass and plasma concentrations
- Hyponatraemia: definition and surgical impact
- Clinical features and perioperative causes of hyponatraemia
- Hypotonic, isotonic and hypertonic hyponatraemia
- Non-hypotonic hyponatraemia and the algorithm
- European guideline diagnostic algorithm for hyponatremia
- Hypervolaemic versus hypovolaemic hyponatraemia
- Euvolaemic hyponatraemia
- Syndrome of inappropriate antidiuretic hormone
- Common associations with the syndrome of inappropriate antidiuretic hormone
- Diagnostic criteria for the syndrome of inappropriate antidiuretic hormone
- Cerebral salt wasting versus SIADH
- Cerebral salt wasting, vaptans and targets
- Treatment guidelines in the management of hyponatremia
- Osmotic demyelination syndrome
- Consequences of rapid changes in plasma sodium concentration
- Correction limits and hypernatraemia
- Three mechanisms of hypernatraemia
- Central and nephrogenic diabetes insipidus
- Common medications associated with hypernatremia
- Common medications associated with hypernatremia (continued)
- Extrarenal water losses
- Sodium intake, evaluation and treatment of hypernatraemia
- Hypernatremia: underlying etiologies, examination, and laboratory findings
- Hypernatremia: underlying etiologies, examination, and laboratory findings (continued)
Potassium
- Potassium: role and renal handling
- Renal cellular mechanism of potassium excretion
- Potassium shifts and hypokalaemia
- Four classes of cause of hypokalaemia
- Commonest causes of hypokalaemia
- Common etiologies of hypokalemia
- Common etiologies of hypokalemia (continued)
- Investigating and repleting hypokalaemia
- Diagnostic algorithm for the evaluation of hypokalemia
- Hyperkalaemia: definition and grading
- Clinical features of hyperkalaemia
- ECG progression with rising potassium
- Electrocardiographic manifestations of hyperkalemia
- Four mechanisms of hyperkalaemia
- Pseudo-hyperkalaemia
- Causes of hyperkalaemia
- Common causes of hyperkalemia
- Emergency management of hyperkalaemia
- Emergency management of hyperkalaemia
- The emergent management of hyperkalemia
Calcium
- Distribution and measurement of calcium
- The three calciotropic hormones
- Maintaining calcium homeostasis
- Calcium: hormones and cardiovascular role
- Calcium in haemostasis
- Hypocalcaemia: definition, signs and causes
- Clinical manifestations of hypocalcemia
- Massive transfusion and citrate
- Why citrate overwhelms the liver
- The diamond of death
- Calcium chloride versus calcium gluconate
- Calcium salts, and hypercalcaemia defined
- The management of hypocalcemia
- The clinical manifestations of hypercalcemia
- Other causes of hypercalcaemia
- Etiologies of hypercalcemia
- Treatment of hypercalcaemia
Magnesium
- Magnesium: distribution and handling
- Magnesium as an enzymatic cofactor
- Magnesium as a calcium antagonist
- Clinical uses of magnesium sulfate
- Common indication and dosages for the perioperative use of magnesium sulfate
- Hypomagnesaemia: severity and causes
- Serum magnesium levels and associated symptoms
- Investigating and repleting magnesium
- Hypermagnesaemia: presentation and treatment
Phosphorus
- Phosphate: roles, distribution and control
- Hypophosphataemia: mechanisms and treatment
- Three mechanisms of hypophosphataemia
- Clinical manifestations of hypophosphatemia
- Hypophosphatemia: acute treatment
- Hyperphosphataemia: definition and mechanisms
- Three objectives in treating hyperphosphataemia
- Conventional approach to managing hyperphosphatemia
- Phosphate binders, dialysis and the three D's
Summary
- Summary: acid–base
- Summary: fluids
- Summary: electrolytes
References
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- Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Edition