Prophylaxis of venous thromboembolism in patients with lower limb plaster cast immobilisation

Prophylaxis of venous thromboembolism in patients with lower limb plaster cast immobilisation

Report by E Brown, Foundation SHO Anaesthetics

Royal Shrewsbury Hospital, Shrewsbury, UK

Checked by A Bleetman, Consultant Emergency Medicine

Birmingham Heartlands Hospital, Birmingham, UK

A short cut review was carried out to establish whether patients with lower limb plaster cast immobilisation require venous thromboembolism (VTE) prophylaxis. Nineteen papers were found, of which four were relevant. The clinical bottom line is that for patients requiring lower limb plaster cast immobilisation for injury (fractures and soft tissue), there is evidence supporting the use of low molecular weight heparin (LMWH) as thromboprophylaxis for venous thromboembolism.

Three part question

In [patients with leg injuries requiring lower limb plaster cast immobilisation] is [low molecular weight heparin] necessary to [prevent venous thromboembolism]?

Clinical scenario

A 48‐year‐old man attends the emergency department with pain and swelling in his right calf after a game of squash. Clinical examination supported by ultrasound identifies a partial rupture of the Achilles tendon. You decide to treat him with an equinus plaster cast and arrange follow up. You wonder whether you should prescribe LMWH for venous thromboembolism prophylaxis for the duration of immobilisation in the cast.

Search strategy

Medline 1950 to week 4 August 2006 using the Dialog Datastar interface: ((casts) OR (casts‐surgical#.de.) OR (plaster ADJ cast)) AND ((leg) OR (leg#.w..de.) OR (lower ADJ limb) OR (lower‐extremity#.de.)) AND ((low ADJ molecular ADJ weight ADJ heparin) OR (heparin‐low‐molecular‐weight#.de.) OR (lmw ADJ heparin) OR (lmwh) OR (thromboprophylaxis)) AND ((deep ADJ vein ADJ thrombosis) OR (venous‐thrombosis#.de.) OR (venous ADJ thromboembolism) OR (thromboembolism#.w..de.) OR (pulmonary ADJ embolism) OR (pulmonary‐embolism#.de.)) LIMITED to human AND English.

EMBASE using the Dialog Datastar interface 1950 to week 4 August 2006: ((cast) OR (plaster ADJ cast) OR (plaster‐cast#.de.)) AND ((leg) OR (leg#.w..de.) OR (lower ADJ limb) OR (lower ADJ extremity)) AND ((low ADJ molecular ADJ weight ADJ heparin) OR (low‐molecular‐weight‐heparin#.de.) OR (lmw ADJ heparin) OR (lmwh) OR (thromboprophylaxis)) AND ((deep ADJ vein ADJ thrombosis) OR (deep‐vein‐thrombosis#.de.) OR (venous ADJ thromboembolism) OR (venous‐thromboembolism#.de.) OR (pulmonary ADJ embolism) OR (lung‐embolism#.de.)) LIMITED to human AND English

Cochrane Issue 3, 2006. (‘cast' and ‘venous thrombosis' OR ‘venous thromboembolism' OR ‘deep vein thrombosis' OR ‘pulmonary embolism')

Search outcome

A total of 17 papers were found, of which four were relevant (table 3).

Table 3.

Author, date, country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study weaknesses
Kock et al, 1995, Germany	239 patients with leg injuries requiring conservative treatment in plaster cast or cylinder cast as outpatients. 176 received 32 mg s.c. mono‐embolex until cast removal. 163 received no treatment	Prospective, randomised, single centre, open, control trial	DVT found at cast removal by clinical examination, leg measurement, ultrasound and duplex scanning, with phlebography to confirm positive findings	There were no DVTs in the prophylaxis group (0%), whereas 7/163 (4.3%) in the no treatment group had DVT. This reached significance (p<0.006)	No placebo. No assessor blinding. Method of randomisation not specified
Lassen et al, 2002, Denmark	371 patients with leg fracture or Achilles tendon rupture requiring at least 5 weeks of immobilisation in plaster cast or brace. 217 received reviparin s.c. 1750 units daily and 223 received placebo	Prospective, randomised, double‐blind, placebo‐controlled multicentre (6 hospitals) trial	DVT found by ascending venography within 1 week of cast removal. Ventilation–perfusion scanning performed in those showing clinical signs of pulmonary embolus	DVT diagnosed in 17 (9%) in the reviparin group; 35 (19%) in the placebo group: the difference was significant (p<0.05). 2 patients developed confirmed PE, both in the placebo group	Some patients received surgical intervention; results for these patients not distinguishable from those receiving conservative treatment. No detail of placebo content
Jorgensen et al, 2002, Denmark	205 patients with planned plaster cast on lower extremity for 3 weeks. 99 received 3500 IU tinzaparin s.c. daily; 106 received no treatment	Prospective, randomised, assessor‐blinded, multicentre (3 centres) controlled trial	DVT on ascending venography on day of cast removal	DVT found in 10/99 (10%) of the treatment group and 18/106 (17%) in the control group. These results were not significant (p = 0.15)	Not statistically significant result; possibly attributable to either high drop out rate (95 of original 300) or low dose of LMWH. No placebo control
Kujath et al, 1993, Germany	253 outpatients with lower limb injury treated conservatively in lower limb plaster cast. 126 allocated to receive 36 mg s.c. fraxiparin daily, 127 received no treatment	Prospective, randomised, open single centre, controlled trial	DVT at cast removal by USS. Positive or doubtful findings confirmed by venography	The group with no prophylaxis had 21 DVTs (16.5%) compared to 6 in the prophylaxis group (4.8%). The difference was significant (p<0.01).	No placebo. No assessor blinding. Adverse effects of treatment not reported

DVT, deep vein thrombosis; LMWH, low molecular weight heparin; PE, pulmonary embolism; s.c., subcutaneous; USS, ultrasound scan.

Comments

Patients receiving subcutaneous injections on a daily basis need either to be trained to self‐inject, to return to a health professional each day, or else remain an inpatient. The vast majority of patients in these studies were outpatients and coped well with self‐injecting. Further research is needed to assess the cost‐effectiveness of the increased resources needed to offer this treatment. No two studies used the same LMWH; the appropriate dose of any particular LMWH treatment has yet to be determined. There appears to be no significant increased risk of bleeding complications or other adverse reactions from LMWH for venous thromboembolism prophylaxis.

Clinical bottom line

In patients requiring lower limb plaster cast immobilisation for injury (fractures and soft tissue), there is evidence supporting the use of LMWH as thromboprophylaxis for venous thromboembolism.