Hypomagnesaemia associated with diabetes

mellitus may cause laryngospasm

A.Papaioannou ,S.Papantonaki, V.Nyktari,H.Psmpoulos ,P.Karatsis,O,Fraidakis and H.Askitopoulou.Department of Anaesthesiology,University hospital of Heraklion and Department of Anesthesia and surgery,District General Hospital of Agios Nikolaos,Crerte,Greece

Acta Anesthesial scand 2006;50:512-513Prented in Singapore

Presented by :Dr.Reem AlsafarSupervised by:

Dr.Badea mohammed

Magnesium is the 4th most abundant cation in the human body and the second most prevalent intracellular cation after k+.

Although hypomagnesaemia is associated with serious complications,magnesium is not rotinely investigated in pre-operative period.

Case report

A 34 year old female patient was scheduled for excision of a nodule of RT breast under GA

Her medical history included: DM type 1 (diagnosed 5 years ago)

Hypothyroidism (thyriod hormone level were within normal range.

During admission the day of surgery ,her glucose level were high (327mg/dl) and the surgery was postponed for a few hours until her blood glucose was controlled with intravenous insulin ,glucose and potassium.

2 hours later, glucose level fell to 190mg/dl and it was decided to proceed with the procedure.

Induction:

The patient was induced with :

-Fentanyl 100mic and

-Propofol 160mg

A LMA was inserted and confirmed by auscultation and capnograghy.

Maintenance: Anesthesia was maintained with 1MAC desflurane

and 50%N2O and O2.

After about 10min , the patient stopped breathing and efforts to manually ventilate her either via the LMA or the face mask were unsuccessful because of increased airway resistance.

Laryngospasm was considered and additional doses of propofol (up to 100mg) and lidocaine (80mg) were administered to deepen the level of anesthesia but proven to be in effective .

Urgently the patient was intubated and anesthesia continued uneventfully and surgery was carried out as planned.

Emergence and recovery: At the end of surgery , the patient was easily aroused

and was calm and fully oriented . In recovery room, she stayed 1h with normal vital

signs . Just before discharge to the word she had a second

episode of laryngospasm with strider and crowing that resolved with positive pressure ventilation via face mask.

As larngospasm was uncommon for fully awake person ,the suspicion of electrolyte disturbances was raised (especially calcium and magnesium)

blood samples were sent for analysis with the following results:

-total calcaium 8.4mg/dl (normal range 8.5- 10.5mg/dl).

-magnisium ↓o.84meq/l (normal range 1.5-2.4meq/l). -albumin 4.2g/l. Venius blood gas analysis showed: -PνO2 50.6mml -PνCO2 47.3mmol -pH 7.355 -ionized calcium ↓3.2mg/dl (normal range 4.5-5mg/dl)

Management: An iv infusion of calcium glulconate and magnesium sulfate

was sarted. After 6h, Mg level improved :

Mg=1.42 meq/l , Ca=8.1mg/dl Finally normalized after 14h:

Mg=2meq/l , Ca=8.4mg/dl The patient was referred to a tertiary centre and after thorough

investigation , the endocrinologist concluded that DM was the cause of hypomagnesaemia whereas hypocalcaemia was considered to be secondary effect of hypomagnesaemia.

Discussion Laryngospasm is described as:I. A prolonged reflex glottic closure mediated by the superior

laryngeal nerve and it usually associated with insufficient depth of anesthesia during manipulation of the airway or surgical stimulation attempted extubation when the patient is not fully awake .

II. It is also well described as a manifestation of tetany that results from increased excitability of the periepheral nerves and it is caused by electrolyte disturbances .

Cont. discussion

Symptoms and signs: Hypomagnesaemia in clinical practice is usually

asymptomatic. Symptoms and signs may be evident when serum magnesium

decreases to <1.2meq/dl some investigator suggest that isolated hypomagnesaemia do

develop symptoms and signs of neuromuscular irritability including tremor ,muscle twitching trousseaus and chvosteks sign and frank tetany.

Other investigator suggest hypomagnesaemia rarely shows specific symptoms and signs ,and muscle irritability results from combination of hypomagnesaemia and hypocalcaemia.

Cont. discussion

Hypomagnesaemia and homeostasis: Magnesium plays an important role in homeostasis of calcium

Hypomagnesaemia results in impaired secretion PTH as well as resistance to the action of PTH on bones and kidney.

Secondary hypocalcaemia is present in approximately one third of the patient present hypomagnesaemia .

Cont. discussion

DM and hypomagnesaemia: Diabetic patients have a 25-38% prevalence of

hypomagnesaemia and many of these cases are undetected in asymptomatic state .

Hypomagnesaemia associated with DM are multifactorial and it is attributed to:

1. Osmotic renal losses from glycosuria.2. Decreased intestinal magnesium absorption3. Redistribution of magnesium from plasma to RBCs

caused by insulin .

In conclusion

it is suggested that in case of recurrent peri-operative laryngospasm ,electrolyte measurements of

magnesium and calcium might be helpful in the diagnosis and treatment of the patients.