Crook in Tallarook

SOAP: an acronym for subjective, objective, assessment and plan that can be used to set out a medical record

You are a locum doctor in a rural emergency department that is "..far, far away.." from your usual working environment. 

Subjective:

This 70 year old woman was told to go to the Emergency Department of a rural Hospital in South Australia after an abnormality was found on a routine blood test. 

Referral letter from the Hawkins Clinic 

"Thank you for seeing C.... T......, aged 70 years, who I contacted you about this evening. History of CRF [chronic renal failure] and today had a blood test as enclosed. [At first I could not contact her, but] I managed to contact her on her mobile, [she] was in the Medical Ward visiting her husband [who has widespread metastatic cancer]. She will go down to the ED for workup (says she is feeling "pretty crook") ........."

She had been feeling unwell for the past 24 hours: nauseated, light headed and having cramps in her hands. She has not vomited or had diarrhoea, but has been anorexic. She has an ileostomy bag, but there has been no change in the volume or colour of urine draining into the bag. There had been no recent change in her medications.

Past History: 

  • Ileal conduit urinary diversion 38 years ago, complicated by deep vein thrombosis (DVT)
  • Hypomagnesemia - 18 years ago
  • Jejunal surgery 17 years ago
  • Chronic renal failure noted 13 years ago
  • Pernicious anaemia and primary hypothyroidism - 13 years ago
  • Recurrent DVT 12 years ago - lifelong anticoagulation commenced
  • Non insulin dependent diabetes mellitus diagnosed 10 years ago 
  • Acute on chronic renal failure 9 years ago - arteriovenous (AV) fistula created and patient was on haemodialysisfor some months. The patient's renal function improved sufficiently for dialysis to be stopped. The right AV fistula remained patent after ceasing haemodialysis, and gradually increased in size.
  • Mitral incompetence, mild tricuspid incompetence and elevated right heart pressures noted 7 years ago
  • Rheumatoid arthritis - diagnosed 2 years ago
  • Obstructive sleep apnoea - diagnosed 21 months ago
  • Right AV fistula revision - 18 months ago

Medications: 

The relevant medications were: aluminium tablets, magnesium tablets, calcium carbonate tablets, warfarin, codeine, endone, prednisolone and thyroxine. The patient was not on any anti-hypertensive medications nor diuretics nor potassium tablets. 

 

Objective:

Vital signs: Heart rate was 45 beats per minute, and the rhythm was occasionally irregular.

Blood Pressure: 125/ 65 mm Hg; respiratory rate was 15 beats per minute, and the SaO2 was 95% on room air.

Cardiovascular system: The jugular venous pressure was 3 cm, there was a pansystolic murmur at the apex, and auscultation of the lungs was normal. 

A very large, patent, C-shaped fistula extended from the medial epicondyle of the elbow to the middle of the forearm (Figure 1).

Figure 1

There was no peripheral oedema in the legs.

Abdomen: There was no tenderness or palpable masses on examination of the abdomen. Bowel sounds were normal. 

The initial 12 lead ECG is shown in Figure 2. Occasional ventricular ectopic beats were seen on the cardiac monitor 

Figure 2

Figure 2

The main findings in Figure 2 are:

  • Sinus bradycardia with a heart rate of about 47 beats per minute. The P waves in the frontal leads have a low amplitude; in Lead II the P wave amplitude is less than 0.10 mv,  the duration of the P wave is 0.12 msec and the P wave is notched. The P waves are most prominent in the V leads.
  • Normal PR interval of (about) 0.12 seconds 
  • Left anterior hemiblock (frontal plane QRS axis of - 44 degrees)
  • T waves are upright in all the leads except Lead aVR and Lead V1. The T waves are tall and have a pointed tip ("steeple T waves") in Lead II and Leads V2 to V6. This appearance is strongly suggestive of hyperkalaemia
  • U waves are seen in Leads V3 to V6

Assessment: 

ECG changes of hyperkalaemia in a person with chronic renal failure

 

Plan:

1. Check blood tests taken earlier that day (Figure 3 below)

Figure 3

Figure 3

The repeat blood potassium concentration in the Emergency Department was 7.9 mmol/L

2. Intravenous access. The patient had thick arms and ankles, and the only vein suitable for cannulation was a small vein in the crook (2) of the left elbow. This vein had been used earlier that day to obtain blood. 

Man or mouse? The patient said that her veins were difficult to cannulate, and that the nursing staff at the hospital would insert a intravenous cannula into her right fistula if she needed intravenous fluids. She was surprised at the reluctance of the locum doctor to do the same, and at first refused to allow him to attempt to cannulate the vein in the left cubital fossa. After some discussion she agreed to allow cannulation of the left cubital fossa vein, and if that failed for cannulation of the (right) external jugular vein.

The left cubital fossa vein was cannulated without any problems.

3. The patient was then treated with intravenous (IV) calcium gluconate, IV insulin and IV glucose, nebulized salbutamol,  2 litres of IV saline and a oral ion exchange resin.

Outcome: 

Two hours after beginning treatment the patient's serum potassium concentration was 4.8 mmol/L.

A second ECG (Figure 4) was taken two and a half hours after the initial ECG.

Figure 4

The main findings in Figure 4 are:

  • Sinus rhythm with a heart rate of about 60 beats per minute.
  • P waves in the inferior leads are taller and more prominent.
  • The PR interval has increased to 0.20 msec
  • The QRS width has decreased from 112 msec to 99 msec
  • The frontal plane QRS axis has changed from - 44 degrees to - 32 degrees
  • The T wave changes of hyperkalaemia have resolved (Figure 5)
  • U waves are no longer seen in the precordial leads

Figure 5

 

Comments: 

1. "Things are crook in Tallarook"

This is a catchphrase for any bad situation, formed from a rhyme on the place name. Tallarook is a town on the Hume Highway in Victoria, Australia. It is close to the army base of Puckapunyal. The original phrase was "Things is crook in Tallarook",  which was the title of a song published in 1942 by Jack O'Hagan (although the origins of the song probably go back to the time of the Great Depression). O'Hagan was a popular Australian song writer in the first half of the last century, whose other songs included "I'm off To Woop Woop" and "Along The Road To Gundagai".

 

2. "Crook of the left elbow". The dictionary says that "crook is a .....a bend in something, esp. at the elbow in a person's arm"

 

3. Most persons with longstanding ileal conduit urinary diversion (implantation of ureters into a isolated loop of bowel that drains into an external bag) develop chronic renal failure due to a combination of obstruction, reflux of urine and infection. In this case renal impairment developed 25 years after creation of the ileal conduit, and the patient needed haemodialysis 9 years ago.

The renal failure in this setting is (usually) a combination of renal tubule damage and interstitial fibrosis. The kidneys cannot conserve sodium i.e. there is a persistent state of urinary sodium loss. The patient is thus at increased risk of developing acute on chronic kidney injury because of saline depletion. To counteract this the patient received regular infusions of saline (administered using her right arm fistula)

Serial blood tests results over a three week interval before presentation showed a progressive decrease in renal function (measured as the effective glomerular filtration rate: eGFR) with:

  • An increase in the blood urea and creatinine concentrations
  • A decrease in the blood bicarbonate concentration and an increase in the blood phosphate concentration
  • A stable blood potassium concentration for two weeks before a marked increase in concentration in the week before presentation
  • The blood magnesium concentration was below normal despite the worsening renal function

 

4. The main ECG changes in this case due to hyperkalaemia were :

  • Decrease in the size of the P waves
  • Decrease in the heart rate
  • (Slight) widening of the QRS complex
  • Appearance of tall and peaked T waves

These changes were reversed when the blood potassium concentration returned to a normal level.

 

5. Hypokalaemia can be associated with the development of U waves, and U waves usually disappear in the setting of hyperkalaemia. In this case U waves were present when the blood potassium concentration was 7.9 mmol/L and disappeared when the blood potassium concentration was 4.8 mmol/L.

A similar case was described in a patient with chronic renal failure (Chhabra L, Spodick DH. Discordant U waves in the setting of hyperkalaemia. BMJ Case Reports. 2013;2013:bcr2013010183. doi:10.1136/bcr-2013-010183). In the reported case the U waves decreased in size but were still present when the blood potassium concentration became normal.  

 

Important Points:

Well described (early) effects of hyperkalaemia are:

  • Decrease in the size of P waves,
  • Decrease in the heart rate
  • Increase in QRS width
  • Development of tall and peaked T waves

In chronic renal failure, hyperkalaemia may be associated with the presence of U waves