Abnormalities of muscle metabolism and histology in malnourished patients awaiting surgery: effects of a course of intravenous nutrition

Hand grip strength: outcome predictor and marker of nutritional status

BACKGROUND & AIMS

Among all muscle function tests, measurement of hand grip strength has gained attention as a simple, non-invasive marker of muscle strength of upper extremities, well suitable for clinical use. This review outlines the prognostic relevance of grip strength in various clinical and epidemiologic settings and investigates its suitability as marker of nutritional status in cross-sectional as well as intervention studies.

METHODS

Studies investigating grip strength as prognostic marker or nutritional parameter in cross-sectional or intervention studies were summarized.

RESULTS AND CONCLUSIONS

Numerous clinical and epidemiological studies have shown the predictive potential of hand grip strength regarding short and long-term mortality and morbidity. In patients, impaired grip strength is an indicator of increased postoperative complications, increased length of hospitalization, higher rehospitalisation rate and decreased physical status. In elderly in particular, loss of grip strength implies loss of independence. Epidemiological studies have moreover demonstrated that low grip strength in healthy adults predicts increased risk of functional limitations and disability in higher age as well as all-cause mortality. As muscle function reacts early to nutritional deprivation, hand grip strength has also become a popular marker of nutritional status and is increasingly being employed as outcome variable in nutritional intervention studies.

Protein-energy undernutrition in hospital in-patients

Impaired nutritional status has been frequently reported in surveys estimating its prevalence amongst patients in hospital. While there is no doubt that protein-energy undernutrition has serious implications for health, recovery from illness or surgery and hospital costs, lack of nationally or internationally accepted cut-off points and guidelines for most nutrition-related variables make nutritional assessment difficult and proper comparisons between studies impossible. In reviewing published work in which the prevalence of undernutrition has been assessed, it can be seen that each study defined undernutrition, or nutritional risk, using different methodology. This present review aims to highlight the problems which arise when deciphering these studies, and the resulting difficulty in determining the true prevalence of undernutrition and nutritional risk, amongst both general and specific groups of hospital in-patients. It is widely agreed that routine hospital practices can further adversely affect the nutritional status of sick patients in hospital. How this occurs, and the potential effects of impaired nutritional status on clinical outcome are examined. The methods currently available to assess nutritional status are evaluated in the knowledge that such assessments are difficult in clinical practice. The review concludes by proposing that if we want the medical and nursing professions to consider the nutritional status of hospital patients seriously, definitions of undernutrition and nutritional risk, and cut-off values for the nutritional variables measured must be agreed to allow evidence-based practice. Outcome measures which allow clear comparisons between groups and treatments must be used in studies assessing the effects of nutritional interventions.

Effect of anthropometric characteristics and socio-economic status on physical performances of pre-pubertal children living in Bolivia at low altitude

We have previously observed that 11-year-old children of low socio-economic status (LSES) showed a delayed physical growth of approximately 2 years and developed lower normalized short-term power output than children of high socio-economic status (HSES) of the same age. In contrast, maximal oxygen uptake (VO2max) per unit of fat free mass was no different in either group. The aim of this study was to evaluate the effect of anthropometric characteristics between HSES and LSES prepubertal children in aerobic and anaerobic performance. To compare children of the same body dimensions, 11-year-old boys (n = 30) and girls (n = 31) of LSES and 9-year-old boys (n = 21) and girls (n = 27) of HSES were studied. Anthropometric measurements, VO2max (direct test), maximal anaerobic power (Pmax, force-velocity test) and mean anaerobic power (P, Wingate test) were determined. In these children having the same body dimensions: mean VO2max were the same in LSES and HSES children [1.2 (SD 0.2) l.min-1]; Pmax and P were lower in LSES subjects [154.0 (SD 33.2) vs 174.6 (SD 38.4) W and 116.3 (SD 23.3) vs 128.2 (SD 28.0) W, respectively]; the linear relationships between VO2max and fat free mass were the same in LSES and HSES boys but, in the girls, the LSES group had lower values. For anaerobic performance, the relationships were significantly different: the slopes were the same but LSES values for the both sexes were lower. These results would suggest that factors other than differences in body dimensions alone were responsible for the lower performance of LSES girls and boys. Cultural factors and motor learning, structural and functional alterations of muscle induced by marginal malnutrition have been discussed.

Nutritional management of the head and neck cancer patient

Approximately one third of patients with advanced cancer of the head and neck are severely malnourished. Another one third of patients suffer from mild malnutrition. Adequate nutritional support given before cancer therapy will reduce therapy-related complications in severely malnourished patients. Patients who are less severely malnourished should receive definitive cancer therapy promptly with concurrent concern for nutritional support. Advantages of nutritional support are that patients feel better, have a higher tolerance to therapy with fewer complications, and achieve a higher response rate to therapy. The disadvantages to such a program are modest but real. This therapy is expensive and it is hard to prove its long-term benefit. Attempting treatment may be frustrating in poorly motivated patients. Appropriate delivery of nutritional support in selected patients has been determined as highly rewarding to the physician.

Nutrition as a prognostic indicator in amputations. A prospective study of 47 cases

The nutritional status was evaluated prospectively in 47 consecutive patients who were amputated for lower extremity ischemia. It was good in 13 patients, reduced in 18, and poor in 16. Malnourished patients had a higher frequency of impaired wound healing, and an increased risk of postoperative cardiopulmonary and septic complications; all 6 deaths occurred in these groups.

Effect of malnutrition on aerobic and anaerobic performance of fast- and slow-twitch muscles of rats

The effect of malnutrition on the functional properties of fast- and slow-twitch muscles from rats was studied using aerobic and anaerobic preparations. A 2-day fast and hypocaloric feeding to a weight loss of 25% were used as models of malnutrition. Soleus (slow-twitch) and extensor digitorum longus (EDL) (fast-twitch) muscles were studied using an in situ preparation with the blood supply intact and an in vitro preparation to which cyanide had been added to render the muscles anaerobic. We found that a 2-day fast had little effect on the function of muscles stimulated in situ, whereas anaerobic stimulation produced a decrease in force per gram of muscle weight in the soleus, but not in the EDL, compared with control values. Hypocaloric feeding resulted in a slowed relaxation rate, an increased Fs/Fmax ratio, and an upward shift of the force-frequency curve relative to controls when studied in situ. Under anaerobic conditions, soleus muscles from hypocaloric rats continued to show a slow relaxation rate and demonstrated a loss of force per gram of muscle weight compared with controls, particularly at low stimulation frequencies. EDL muscles from hypocaloric rats had an increased relaxation rate and were able to maintain force with anaerobic stimulation. Soleus and EDL muscles from the fasted and hypocaloric groups had lower activities of phosphofructokinase. We conclude that slow-twitch muscles from malnourished rats are at a disadvantage when required to function under anaerobic conditions. These findings suggest that muscle performance may be impaired in malnourished patients subjected to hypoxia.

Investigations on the biochemical characteristics of chronically underperfused muscle

During operation, biopsies from the gastrocnemius muscle and, in some cases, from the sartorius muscle were taken from 32 patients with peripheral arterial occlusive disease and from 5 subjects with normal peripheral circulation. In patients with inadequate circulation only during exercise, when compared with the control group, increased activities of enzymes involved in oxidative metabolism (malate dehydrogenase, nicotinamide adenine dinucleotide phosphate-dependent isocitrate dehydrogenase, cytochrome C oxidase, creatine kinase), in amino acid metabolism (asparate aminotransferase, alanine aminotransferase), and in anaerobic glycoysis (lactate dehydrogenase) were found. In patients with circulatory disturbances that manifested themselves already at rest, enzyme activities were, with the exception of LDH, lower than those of patients with exclusively exercise-related insufficiency. By means of intraindividual comparisons with the corresponding enzyme activities in the sartorius muscle, the author was able to show that the changes found were not simply the result of differences in training conditions. The diminished concentrations of energy-rich phosphate are an expression of the anaerobic metabolic state in patients with inadequate circulation at rest. It is concluded that chronic ischemia of muscle leads to changes in the energy metabolism of the cell. In the presence of more nearly adequate circulation at rest, the portion of oxidative potential of the total energy metabolism increases. In contrast, if there is an inadequate circulation at rest, the mainly anaerobic glycolysis becomes quantitatively predominant.

Effect of intravenous nutrition on nutrition and function in acute attacks of inflammatory bowel disease

The effect of IV nutrition on protein nutriture and physiological function in 19 patients who were clinically malnourished and had acute exacerbations of inflammatory bowel disease was studied. Total body protein, plasma proteins, respiratory muscle function, and skeletal muscle function were measured at the commencement of a 14-day course of IV nutrition and 7 and 14 days later. Final measurements were made after recovery approximately 200 days later. Compared with a group of matched controls, the patients had lost approximately 35% of their body protein stores with accompanying physiological impairments of 20%-40%. After 4 days of IV nutrition, there were improvements in all the physiological measurements (approximately 12%) but no significant change in total body protein. During convalescence, there were further improvements in physiological function, which were accompanied by an increase in body stores of protein. We conclude that there is an early and rapid improvement in physiological function with IV nutrition in patients hospitalised for exacerbations of inflammatory bowel disease even though this is not accompanied by significant protein gain. Later during anabolic recovery, physiological improvements occur in association with repletion of total body protein. Short courses of IV nutrition in these patients prevent protein loss and result in significant improvements in skeletal muscle function and respiratory muscle function.

Skeletal muscle enzyme activities and metabolic substrates during exercise in patients with postoperative fatigue

Subjective fatigue was quantified before and 20 days after uncomplicated elective abdominal surgery in 12 patients and compared with changes in heart rate, enzyme activities and skeletal muscle substrates before and after bicycle exercise for 10 min at 65 per cent of patients' preoperative maximum work capacity. Fatigue increased from a mean(s.e.m.) preoperative level of 2.5(0.5) arbitrary units to 4.6(0.5) on postoperative day 20 (P less than 0.01). Body-weight, triceps skinfold thickness and arm circumference decreased postoperatively (P less than 0.02). Postoperative values of muscle enzyme activities indicative of oxidative phosphorylation capacity (citrate synthase and 3-OH-acyl coenzyme A dehydrogenase) were lower than preoperative values (P less than 0.05). Lactate dehydrogenase was unaltered and resting values of muscle glycogen and adenosine triphosphate were higher after operation (P less than 0.05). In response to exercise, heart rate, muscle glucose, glucose-6-phosphate and lactate increased (P less than 0.05), while muscle glycogen and creatine phosphate decreased (P less than 0.05). Increase in postoperative fatigue correlated with the increase in heart rate (P less than 0.05), while no significant correlations were found between fatigue and muscle parameters. Our results suggest that lack of exercise and malnutrition may be of importance in the decrease in work capacity and in fatigue after operation.

What rate of infusion of intravenous nutrition solution is required to stimulate uptake of amino acids by peripheral tissues in depleted patients?

We examined the effect of varying the quantities (0, 0.1, 0.2, 0.3, and 0.4 gN.kg-1.[day]-1) of nitrogen input on N balance, 3-methylhistidine (3MH) excretion, plasma amino acid concentration and the net flux of amino acids across the leg in depleted patients requiring parenteral nutrition. The calorie-to-nitrogen ratio was 140 to 1 (kcal:1 gN) and consequently the patients received varying amounts of calories (8, 14, 28, 42, and 56 kcal.kg-1.[day]-10. There was negative nitrogen balance and net loss of amino acids from the limb during fasting. An infusion of 0.2 gN.kg-1.[day]-1 of IVN reversed the net catabolic process and resulted in equilibrium of peripheral total amino acid flux and of tyrosine flux without a decrease in 3MH excretion. Net uptake of total amino acids and tyrosine in peripheral tissues was achieved with 0.4 gN.kg-1.[day]-1 and 56 kcal.kg-1.[day]-1. This was associated with a fivefold increase in 3MH excretion (p less than 0.01), indicating that net anabolism occurred with increased protein turnover. Fifty per cent of the amino acids taken up by peripheral tissues during infusions of 0.4 gN.kg-1.[day]-1 was due to the uptake of glutamate (Glu) and 20% was due to the uptake of branched chain amino acids (BCAA). Plasma Glu concentration, [Glu], did not increase with increasing IVN infusion, but BCAA concentrations did. Although the mean plasma [Glu] did not change with IVN infusion, there was an independent effect of plasma [Glu] (p less than 0.0001) and of N input (p less than 0.0001) on Glu flux, indicating that even at high infusion rates the maximal capacity of peripheral tissues to take up Glu had not been reached.

Pre-operative parenteral nutrition in patients with oesophageal cancer: a prospective, randomised clinical trial

A prospective randomised clinical trial was conducted to examine the efficacy of 2 weeks pre-operative parenteral nutrition (PPN) for the prevention of complications following surgery for oesophageal cancer. Forty patients were studied, the diet of twenty being supplemented by pre-operative parenteral nutrition. There were no significant differences in age, nutritional status, tumour staging and histology between the two groups of patients. The use of PPN resulted in a significant gain in body weight and nitrogen but failed to produce an overall reduction in post-operative morbidity and mortality rates. However patients receiving PPN exhibited two types of changes in serum albumin levels. Those with a fall in serum albumin levels associated with an increase in body weight (indicating an expansion of extracellular volume) had a significantly higher incidence of post-operative pulmonary complications than the group exhibiting a rise in serum albumin levels concomitant with increase in body weight. These data suggested that two weeks PPN might not be adequate in certain patients and a longer period of PPN is required. They also show no clinical benefit from the routine use of pre-operative parenteral nutrition in all patients, but do not exclude benefit in selected groups.

Identification and assessment of the malnourished patient

The assessment of protein-energy malnutrition has become important for identifying patients whose nutritional status increases their risk of an adverse outcome during hospitalization. Anthropometric, biochemical and immunological measurements, used either alone or in combination are not sensitive or specific enough for monitoring short-term nutritional changes, although some of these variables are associated with an increased incidence of postoperative complications after surgical procedures. The sensitivity of clinical assessment is dependent on the training of the clinician and the outcome variable being sought. For most clinicians, objective measurements are needed to raise their awareness to potential nutritional problems. The relationship of nutritional status to clinical events, particularly stress events during hospitalization, is critical to the interpretation of nutritional measurements and relating them to outcome variables. A classification based on the concepts of nutritional depletion and stress is presented. The prevalence of PEM has been shown to be between 20 and 30% in western hospitals, depending on the population studied and the criteria used to define PEM. In studies which have claimed an association between nutritional status and outcome, the contribution of nutritional variables to the development of postoperative complications has been overestimated and the relevance of technical factors underestimated.

Impaired glucose metabolism in surgical patients improved by intravenous nutrition: assessment by the euglycemic-hyperinsulinemic clamp

Malnutrition is associated with glucose intolerance. This could be related to decreased pancreatic insulin secretion and/or peripheral insulin resistance. We have used the euglycemic-hyperinsulinemic clamp and continuous indirect calorimetry to assess the disposal of an intravenous glucose load in 13 malnourished patients with benign disease (median age, 55 years; mean weight loss 21 kg +/- 8 SD). Seven normally nourished controls were also studied (median age, 62 years) and eight patients were restudied after 14 days on continuous glucose-based intravenous nutrition (IVN). With hyperinsulinemia of 90 microU/mL, malnourished patients disposed of 6.1 mg glucose/kg fat-free body (FFB).min +/- 1.7 SD and oxidized 1.9 mg/kg FFB.min +/- 1.4 SD. Controls disposed of a similar amount of glucose (6.6 mg/kg FFB.min +/- 3.5 SD) but oxidized significantly more (3.0 mg/kg FFB.min +/- 2.3 SD). After two weeks of glucose-based IVN, both glucose disposal rate (9.5 mg/kg FFB.min + 2.3 SD) and oxidation rate (3.9 mg/kg FFB min +/- 1.0 SD) increased significantly. Respiratory quotient was low in malnourished patients (.88 +/- .12), but above 1.0 in controls (1.07 +/- 0.18) and patients after IVN (1.10 +/- 0.11), showing net lipogenesis in these groups. Malnourished patients can metabolize normal amounts of glucose under conditions of hyperinsulinemia and, although carbohydrate oxidation rate is initially impaired, it becomes normal after 2 weeks of IVN.

Weight loss with physiologic impairment. A basic indicator of surgical risk

It is a long held belief that weight loss is a basic indicator of surgical risk. Many experienced surgeons, however, think otherwise. We have investigated the proposition that weight loss is a risk factor for postoperative complications but only when associated with clinically obvious physiologic impairment. Before major surgery, 102 patients had a careful history taken to ascertain if there had been recent weight loss and a reduction in the capacity for activity. Physical examination included assessment of mood, skeletal muscle function, respiratory muscle function, and wound healing. Plasma albumin was also measured. Using this information the patients were placed into one of three groups. Group I (N = 43) were normal, group II (N = 17) had weight loss greater than 10% but no clinical evidence of physiologic impairment, and group III (N = 42) had weight loss greater than 10% with clear evidence of dysfunction of two or more organ systems. The patients in group III had significantly more postoperative complications (p less than 0.05). They also had more septic complications (p less than 0.02) including a higher incidence of pneumonia (p less than 0.05) and a longer hospital stay (p less than 0.05) than patients in each of the other two groups. Objective measurements of body stores of protein and liver, and psychologic, respiratory, and skeletal muscle function, confirmed the validity of the clinical classification into the risk groups. The results demonstrate that weight loss is a basic indicator of surgical risk in modern practice providing it is associated with clinically obvious impairment of organ function. They suggest that adequate body protein stores are necessary for normal body function and for minimizing the risks of surgery.

Wound healing response in surgical patients: recent food intake is more important than nutritional status

We have recently found that an impairment of the wound healing response (WHR) occurs in surgical patients with protein-energy malnutrition before there are any measurable changes in body fat and protein stores. The hypothesis of this study was that the patients' recent food intake is more important in determining the WHR than the patients' overall nutritional status. We have measured the recent food intake (by dietary recall), the WHR (by hydroxyproline accumulation in subcutaneous GORE-TEX implants), the pre-operative weight loss (per cent), and body fat and protein stores (by in vivo neutron activation analysis) in 83 patients awaiting a major elective gastrointestinal resection, and divided them into two groups: adequate recent food intake (n = 59) and inadequate recent food intake (n = 24). There was no significant difference between these two groups for age, sex, diagnosis, surgical procedure, weight loss (per cent), or the amount of body fat and protein stores but there was a significant difference in the WHR (1.81 +/- 0.16 s.e.m. versus 1.04 +/- 0.22 s.e.m. nmol hydroxyproline/mg GORE-TEX, P less than 0.005). These results show that pre-operative food intake has a greater influence over the wound healing response than absolute losses of protein and fat from body stores and they suggest that the maintenance of a normal food intake up until the time of surgery is of importance in preventing an impairment of the wound healing response.

The efficacy of subcutaneous goretex implants in monitoring wound healing response in experimental protein deficiency

This combined biochemical and histological study demonstrated that subcutaneously implanted Goretex tubing can be used to monitor and detect variations in wound healing potential in rats subjected to experimental hypoproteinaemic and normal refeeding conditions. Induced hypoproteinaemia was observed to be associated with a marked diminution in cellular infiltration, collagen synthesis and fibrous deposition within the implant. All these effects were completely reversed by subsequent refeeding of normal diet. Although regional variations in fibroblastic response attributable to biologic variability, were observed within individual control implants, or between paired controls, they were relatively minor as compared to the marked differences observed at the macroscopic, microscopic and biochemical level between implants removed from normally fed and protein deficient animals.

Abnormal muscle fructose bisphosphatase activity in malnourished cancer patients

Malnourished patients without cancer have abnormal glucose metabolism, low activities of the key enzymes of glycolysis in muscle, and abnormal muscle fiber-type distribution. Malnutrition in cancer is also associated with altered glucose metabolism, and therefore muscle enzyme activities and fiber types were measured in 17 malnourished patients with gastrointestinal cancer (weight loss, 18.1% +/- 7.9 SD). These patients were matched with 17 depleted noncancer patients (weight loss, 22.8% +/- 10.25 SD) and 17 normal controls. Results of in vitro measurement of the maximal activity of phosphofructokinase (PFK), hexokinase (HK), and oxogluterate dehydrogenase (OGD) were similar in both undernourished groups and lower than that of normal controls. Both groups also had reduced Type II fiber size and number. The activity of fructose bisphosphatase (FBP) was significantly higher in cancer patients (0.62 mu ml min-1 g +/- 0.26 SD) than in noncancer patients (0.39 +/- 0.15), but similar to that in controls (0.65 +/- 0.29). As FBP is involved in substrate cycling, inappropriately high activity reflects an inability to adapt to malnutrition that could lead to high rates of cycling and wasteful energy expenditure at times of maximal activation of the cycle.

Impaired wound healing in surgical patients with varying degrees of malnutrition

The relationship between nutritional state and wound healing was examined in 66 adult surgical patients. Wound-healing response was assessed by measuring the collagen content (hydroxyproline) of fine tubes of Gore-tex inserted subcutaneously along standardized needle track arm wounds. After a period of 7 days, the tubes were removed and it was found that there was a higher hydroxyproline content in the tubing of 36 normally nourished patients than there was in the tubing of 21 patients with mild protein energy malnutrition (p less than 0.01) and 9 patients with moderate to severe protein energy malnutrition (p less than 0.01). There was no difference in the wound-healing response between the two latter groups of patients who had significantly different degrees of malnutrition. The results suggest that a definite abnormality in the wound-healing response exists in malnourished surgical patients, but it occurs earlier in the course of the illness than previously supposed.

The effect of pre-operative total parenteral nutrition on energy-rich phosphates, electrolytes and free amino acids in skeletal muscle of malnourished patients with gastric carcinoma

The effect of two weeks of total parenteral nutrition (TPN) on energy-rich phosphates, muscle water, electrolytes and free amino acids in skeletal muscle were determined in ten malnourished patients with gastric carcinoma. The total adenine nucleotide pool, phosphocreatine, creatine and glycogen were decreased before TPN, and only glycogen returned to normal after TPN compared with controls. Total muscle water and the intramuscular concentrations of sodium and chloride were initially increased and were not influenced by TPN. The total non-essential amino acids in muscle were decreased by 9 per cent, mainly due to a 15 per cent decrease in glutamine. The concentrations of free amino acids in muscle were not affected by two weeks of TPN. This study demonstrates disturbances in energy, water and amino acid metabolism in skeletal muscle of malnourished patients with gastric carcinoma, and that two weeks of TPN could not normalize these changes, except in the case of glycogen. The reason for this might be enzyme abnormalities due to adaptation to energy or protein deficit. A longer period of refeeding might therefore be necessary to improve peripheral metabolism in these patients.