A case of bilateral total Knee replacement ( Case discussion )

shenxiu2

63 years old lady ,60 kg .

Diagnosis :
Bilateral knee osteoarthritis.
Ischaemic heart Disease , stable , ECG showed sinus rhythm , Q in inferior leads, Echo: Good Left Ventricular function , EF=56%. Presently no cardiac symptoms.
Hemoglobin =11g%
Renal function & electrolytes normal.
BP =150/70mmHg , heart rate 75/min.SpO2 98%

Planned for bilateral total knee replacement . ( She came from neighboring country , & wished to complete both knee surgery at one time.)

Anesthesia : Combined epidural spinal anesthesia .
                    Epidural at L 23 , catheter in space 3 cm .
                    Spinal at L34 , given 0.5% heavy bupivacaine 2.3ml + Fentanyl 20mcg.

Surgery :
1430  Tourniquet on right thigh. At 350 mmHg .
1435  Surgery started . BP =150/70 - 170/70mmHg , Heart rate = 75-85/min
1640  Right side knee surgery completed . Drain inserted. Knee bandaged .Tourniquet off.
1700  Tourniquet on left thigh . At 350mmHg . Patient redraped .
1705   Surgery started . BP = 100/50-110/50mmHg.
1730   Epidural Ropivacaine 0.75% 3ml, 4ml , 3ml given at 15minutes interval.
1900   Left knee  surgery completed , drain inserted , knee bandaged & torniquet on left thigh off.
           Total intravenous fluid given were 1700ml ringer's lactate solution.
1905   Patient was to be transfer out to recovery room . While putting patient on the transferring trolley , we noticed the patient
           became unresponsive , pale . We quickly connect back all the monitors : ECG =irregular heart rate , occasional atrial fibrillation,  SpO2 98% , Bp=58/30mmHg.
1910   500ml of colloid solution was rapidly infused , BP=98/40mmHg ,she was transferred to ICU for further management.

1. What could be the cause of the hypotension?
2. What lesson can we learn from this case incident?
3. How should we manage this patient?


  

1001

Insufficient fruid administration.
Alterations in blood volume induced by tourniquet application.
Products of anaerobic metabolism caused by tourniquet application.

shenxiu2

2# 1001
1. What could be the cause of the hypotension?

Hypovolemia --------when the tourniquet was released on the right thigh , the right knee started to bleed . But because the patient was draped for the left knee operation , so the drain on the right knee was covered under the draping cloth , so noone had noticed it until the whole surgery was completed. (We found that the drain on the right knee contained 500ml blood at the end of the surgery.)

Beside that, the tourniquet inflation on the left thigh had masked the hypovolemia to a certain extent , the hypotention was not so obvious when the tourniquet on the left thigh was on , but as soon as the tourniquet on the left thigh was released , the blood pressure crashed down .

The hypotension was not noticed because routinely we will take off the monitorings  before transferring the patient to recovery room , so the low blood pressure was not recorded right after the tourniquest was released , but after the patient became unconcious.

2. What lesson can we learn from this case incident ?

The lesson we can learn are :
1.Always check the drain after the release of tourniquet because the bleeding usually occur post-operatively .
2.Remember to check the drain even when it is coverred under the drapes.
3. Tourniquet use can mask the hypovolemia & make the hypotension less severe , but when it is released , the hypotension can be profound.
4. Do not take off the monitors before or right after the tourniquet was released . Incidents like this can happen .

3. How should we manage this patient?

Fluid resuscitation & blood transfusion .
The patient was having Atrial fibrillation , her electrolytes need to be checked .( This patient was having hypokalemia , when it was corrected, her cardiac rhythm returned  to sinus rhythm.)
Hypotension & anemia may precipitate myocardial ischemia , So she will need close monitoring of her cardiac status.( She developed chest dyscomfort soon after that , and was treated with Nitrates infusion.)