The Use of Specialised Amino Acid Mixture in Pressure Ulcer Wound Healing Rates- A Placebo Controlled Trial

Pressure ulcers are defined as areas of localised damage to the skin, muscle or underlying tissue, caused by shear, friction or unrelieved pressure, usually over bony prominences. They are associated with many health conditions that cause prolonged bed rest, immobility, inactivity or poor sensation and can significantly contribute to morbidity and mortality, particularly in the aged population. International prevalence rates range widely from 4.6%- 83.6% due to methodological differences and classification systems. In Singapore, a study on the prevalence of pressure ulcers in 3 hospitals revealed a prevalence of 9% to 14%.

Pressure ulcers often fail to heal in a timely and orderly manner, resulting in a chronic non-healing wound. Many intrinsic and extrinsic factors have been identified that can disrupt the wound healing processes of haemostasis, inflammation, proliferation, angiogenesis and remodelling. One of the factors gaining more interest for its impact on wound healing processes is nutritional status.

Arginine is a semi-essential amino acid because even though the body normally makes enough of it, supplementation is sometimes needed during critical illness and severe trauma. There have been numerous research studies focusing on using arginine to enhance wound healing and pressure ulcer prevention. It is required for promotion of nitrogen balance, cell proliferation, T lymphocyte function and collagen accumulation. It also changes into nitric oxide, which is known for its vasodilatory and angiogenic properties.

Glutamine is conditionally essential amino acid because it can be manufactured in the body, but under extreme physical stress the demand for glutamine exceeds the body's ability to make it. Adequate amounts of glutamine are generally obtained through diet alone because the body is also able to make glutamine on its own. Certain medical conditions, including injuries, surgery, infections, and prolonged stress, can deplete glutamine levels. Since glutamine plays a key role in the immune system, a deficiency in this nutrient can significantly slow the healing process.

Beta-hydroxy-Beta methylbutyrate (HMB) is a metabolite of leucine, an essential amino acid. HMB supplementation was associated with increased muscle mass accretion. HMB appears to assert its effect via inhibiting muscle proteolysis and modulating protein turnover.

Recently, arginine has been found to accelerate wound healing in combination with HMB and glutamine. It was shown that healthy subjects who are supplemented orally with arginine had a significant rise in plasma arginine and ornithine levels that led to enhanced rate of collagen synthesis. In another recent study, a HMB/Arginine/Lysine mixture increased protein turnover in elderly patients over a year long period. However, there is no known randomised controlled trial done on patients with chronic hard to heal wounds in acute healthcare settings.

AIM To compare pressure ulcer healing rates in patients supplemented with a commercial HMB/Arginine/Lysine mixture (Abound) and standard high protein, high energy iso-nitrogenous medical nutritional supplements versus patients supplemented with only standard high protein, high energy iso-nitrogenous medical nutritional supplements.

OUTCOME INDICATORS

• Percentage change in wound size (length, depth, area)
• Percentage change in proportion of viable wound tissue (Refer to wound data collection for details)

The study will take on a comparative, randomised controlled trial design.

Inclusion criteria

• Patients with pressure ulcers stage II, III or IV, non-healing admitted to Changi General Hospital for > 2 weeks
• Patients who are able to attend outpatient follow-up appointments for dietary and wound review

Exclusion criteria

• Age < 21 years old
• Poorly controlled Diabetic Patients (HbA1c >7.0%)
• Patients on Total Parenteral Nutrition
• Patients in MICU/ SICU/ Medically Unstable/ Palliative Care
• Patients with severe Sepsis
• Length of stay < 2 weeks
• Patients who require fluid restriction < 1L/d
• Patients on any other wound healing supplements (e.g. Zinc, Vitamin A and Vitamin C)
• Patients with lower extremity ulcers with untreated peripheral vascular disease
• Patients with deep tissue infection and/or requiring debridement of necrotic or sloughy tissue
• Patients unable to attend outpatient follow-up appointments
• Patients who cannot tolerate oral intake > 70% EER and/or Fluid intake 30ml/kg BW
• Patients who require protein restriction
• Patients who are unable to give consent (absence of next-of-kin)