Hypokalaemic, hyperchloraemic metabolic acidosis requiring ventilation

An unrecognised case of metabolic acidosis following neobladder augmentation cystoplasty

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Hyperchloraemic metabolic acidosis is a well established complication following urinary diversion.

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Patients with orthotopic neobladder with high residual urine and large capacity are at particular risks.

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A delay in the diagnosis can lead to significant morbidity.

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The risks of metabolic acidosis should be clearly documented on discharge to ensure early recognition by non-specialists.

Introduction

Presentation of case

Discussion

Conclusion

Acute Hypercapnic Respiratory Failure due to Thyrotoxic Periodic Paralysis

Acute hypercapnic respiratory failure is a potentially life-threatening complication of profound hypokalemia usually seen in patients with large total-body potassium (K+) deficits. It has rarely been reported in thyrotoxic periodic paralysis (TPP), which is due to intra-cellular shifts of K+. The authors report on a 29-year-old man who presented with sudden onset of muscle paralysis in all extremities and acute progressive respiratory insufficiency requiring artificial respiratory support. He was treated with intravenous KCl. After six hours, muscular strength had returned to normal, with plasma K+ concentration of 3.0 mmol/L. At the eighth hour, rebound hyperkalemia (6.6 mmol/L) developed with high-tented T waves, even after the KCl was discontinued. Ventilatory support was uneventfully weaned at 14 hours. Elevated free thyroxine and undetectable thyroid-stimulating hormone confirmed the diagnosis of TPP. TPP should be kept in mind as a cause of acute respiratory failure in association with acute muscle weakness to avoid delayed diagnosis and improper management.

Anions and the anaesthetist

Anions are the negative components of most chemical structures and play many important physiological and pharmacological roles that are of interest to the anaesthetist. Their relevance is reviewed with a particular emphasis on the inorganic anions (halides, bicarbonate, phosphate and sulphate) and the significance and limitations of the anion gap. Organic anions (albumin, lactate) are also discussed, albeit briefly. The suitability of anions for their role in neurotransmission and acid-base balance is outlined.

Urinary diversion and reconstruction

Orthotopic bladder augmentation and substitution has been established as the standard procedure for urinary diversion in many institutions, with current studies reporting mainly on continence rates and procedure-associated complications, such as the risk of impairment of neobladder function by local tumor recurrences in the small pelvis. Similarly, in other types of continent diversion, such as continent cutaneous diversion and rectal reservoirs, current interest is primarily directed towards minimization of surgery-associated complications.