Relationship of admission thyroid function tests to outcome in critical illness

One hundred and eighty patients had serum thyrotropin, total triiodothyronine and free thyroxine concentrations measured within 3 h of admission to the Intensive Therapy Unit to assess whether thyroid function tests could predict outcome in critical illness. Overall mortality was 30.6%. Nonsurvivors were older (p = 0.001), and had higher APACHE II scores (p < 0.001) and predicted mortalities (p < 0.001). There was no difference in the median values of thyrotropin, total triiodothyronine and free thyroxine concentrations between survivors and nonsurvivors. Thyrotropin concentration was subnormal in 15 patients, normal in 152 and elevated in 13 patients. In contrast, 80 patients had subnormal triiodothyronine concentration. Free thyroxine was subnormal in five patients. Thyrotropin, total triiodothyronine and free thyroxine concentrations were not related to outcome (p = 0.360, p = 0.622, p = 0.726, respectively). No variable independently predicted death. Total triiodothyronine concentrations were lower in patients who received dopamine before admission to the intensive therapy unit than those who did not (p = 0.008); thyrotropin and free thyroxine concentrations were not influenced by dopamine administration. Serum concentrations of thyrotropin, total triiodothyronine and free thyroxine measured within 3 h of admission to the intensive therapy unit are not predictive of outcome.     

Adrenocortical function in myasthenia pseudoparalytica]

Chenodeoxycholate (3alpha-, 7alpha-dihydroxy-5beta-cholanoate) was linked to Sepharose 4B by an ethylenediamine bridge. When 3alpha-hydroxysteroid dehydrogenase and 7alpha-hydroxysteroid dehydrogenase preparations were applied to a column of covalently linked chenodeoxycholate, both enzymes were retarded at pH 6.7; the 7alpha-OH oriented enzyme more than the 3alpha-OH enzyme. Approximately forty-fold purification of 7alpha-hydroxysteroid dehydrogenase was achieved in one step. Although no significant purification of 3alpha-hydroxysteroid dehydrogenase occurred, the background value in the fluorometric enzymatic estimation of bile acids by eluted 3alpha-hydroxysteroid dehydrogenase was markedly reduced. Molecular weight estimation by Sephadex G-200 gave the values of 47,000 for 3alpha-hydroxysteroid dehydrogenase and 105,000 for 7alpha-hydroxysteroid dehydrogenase.     

Protein metabolism in critical illness

In summary, protein metabolism of critically ill patients is a field open to new investigations that will help us to understand better the mechanism behind 'autocannibalism', which is still today associated with mortality. Although the underlying disease is the major determinant of mortality, nutritional depletion will add morbidity, an addition that grows over time in the ICU. With conventional treatment the velocity of the catabolic process can at best be slowed down and the patient be bought time for other types of treatment to work. New forms of specific nutrition and adjuvant therapies may give us tools to prevent muscle depletion, without endangering the supply of essential substrates to the tissues in the splanchnic area. Muscle is at present a limiting organ for the ICU patient in two respects. A depleted muscle can no longer provide enough substrates for the splanchnic organs to maintain intestinal integrity and to maintain a high immunocompetence. In addition, a depleted muscle will be restored back to normal only very slowly; in elderly patients restoration may not even occur at all. The effects of an attenuation of muscle depletion on rehabilitation time have yet to be evaluated. An understanding of protein metabolism may be the key to better patient care in the ICU in the future.     

Oxygen delivery in critical illness

Oxygen consumption is physiologically dependent on DO2 below the critical DO2. Thus, patients in overt shock have physiologic dependence of VO2 on DO2. The first priority of prevention and reversal of tissue hypoxia is to balance oxygen demand and oxygen supply. Pathologic dependence of VO2 on DO2 has not yet been demonstrated convincingly in critically ill patients. Furthermore, in our opinion, contradicting results of RCTs of supernormal DO2 versus normal DO2 do not support routine maintenance of supernormal levels of DO2. Finally, we suggest that intensivists continue to assess DO2 and VO2 carefully. Global assessment of VO2 and DO2 appears inadequate to detect occult tissue hypoxia in most critically ill patients. However, research focused on regional assessment such as gastric tonometer measurement of gastric mucosal PCO2 and pH provides opportunity for safe, convenient detection of occult tissue hypoxia in critically ill patients.     

Energy balance in critical illness

Energy balance is the difference between energy consumed and total energy expended. Over a given period of time it expresses how much the body stores of fat, carbohydrate and protein will change. For the critically-ill patient, who characteristically exhibits raised energy expenditure and proteolysis of skeletal muscle, energy balance information is valuable because underfeeding or overfeeding may compromise recovery. However, there are formidable difficulties in measuring energy balance in these patients. While energy intake can be accurately recorded in the intensive care setting, the measurement of total energy expenditure is problematic. Widely used approaches, such as direct calorimetry or doubly-labelled water, are not applicable to the critically ill patient. Energy balance was determined over periods of 5-10 d in patients in intensive care by measuring changes in the fat, protein and carbohydrate stores of the body. Changes in total body fat were positively correlated with energy balance over the 5 d study periods in patients with severe sepsis (n 24, r 0.56, P = 0.004) or major trauma (n 24, r 0.70, P < 0.0001). Fat oxidation occurred in patients whose energy intake was insufficient to achieve energy balance. Changes in body protein were independent of energy balance. These results are consistent with those of other researchers who have estimated total energy requirements from measurements of O2 consumption and CO2 production. In critically-ill patients achievement of positive non-protein energy balance or total energy balance does not prevent negative N balance. Nutritional therapy for these patients may in the future focus on glycaemic control with insulin and specialised supplements rather than on energy balance per se.     

Nutrition support in critical illness

Sepsis, shock, multiple trauma, and burns are often associated with altered metabolism characterized by severe catabolism, wasting of the lean body mass, immune dysfunction, and compromised wound healing. Nutrition support is one of the mainstays in the management of these critically ill patients and is aimed at minimizing these complications. The purpose of this article is to compare stress hypermetabolism and starvation metabolism, to review current recommendations for the provision of energy and substrate to the critically ill patient, and to review pertinent literature regarding enteral vs parenteral nutrition. Finally, this article will provide a brief overview of new and future therapies with emphasis on specific substrates and growth factors and the potential for their use in the critically ill patient.     

Adrenocortical function in patients with active pulmonary tuberculosis

STUDY OBJECTIVE: To assess adrenal function in patients with acute pleuropulmonary tuberculosis (APT) and compare it with that function in patients with community-acquired pneumonia (CAP). PATIENTS: Over a period of 6 months all consecutive patients 18 years of age or older with newly diagnosed APT and CAP were entered into the study. MEASUREMENTS: The whole patients had the following investigations: 1) Serum Na+, K+ and glucose concentrations 2) Systolic and diastolic blood pressures. 3) An ultrasonographic study of the adrenal glands. 4) A standard ACTH stimulation test. RESULTS: There was no significative difference in the serum cortisol level between the two groups at any time of the ACTH stimulation test (basal, 30 and 60 minutes), neither when taking into account the increments between basal and 60 minutes after stimulation serum cortisol levels. All patients in both groups had normal ACTH stimulation test with a peak stimulated cortisol level at 60 minutes > 504 nmol/L. CONCLUSIONS: We did not find evidence of adrenal cortical dysfunction in patients with acute pleuropulmonary tuberculosis or with community-acquired pneumonia in our hospital.     

Family coping during critical illness

The suprachiasmatic nuclei (SCN) of the anterior hypothalamus contain the master circadian pacemaker in mammals. On the occasion of the 25th anniversary of the discovery of the SCN as the circadian clock, Charles A. Czeisler and Steven M. Reppert organized a meeting to review milestones and recent developments in the study of the SCN. The discovery that the SCN contain tissue necessary for generation of circadian rhythmicity was established by lesion studies published in 1972. The second phase of study demonstrated unequivocally that the SCN contain an autonomous circadian pacemaker. The principal studies in this period showed the presence of metabolic and electrical activity rhythms in the SCN in vivo and progressed to studies showing that the SCN maintain rhythmicity in vitro, demonstrating that the transplanted SCN can restore circadian function following destruction of the host SCN and ultimately showing that single SCN "clock cells" exhibit independent rhythms in firing rate. The third phase of study, aimed at identifying the biochemical and molecular mechanisms responsible for rhythmicity within the SCN, has begun with the identification of circadian mutants (tau mutant hamsters and Clock mutant mice) and the isolation of the Clock gene. This report traces the important steps forward in our understanding of the suprachiasmatic circadian clock by recounting the information presented at the SCN Silver Anniversary Celebration.     

The stress response of critical illness

The integrated stress response to tissue trauma is crucial for the maintenance of homeostasis. An exaggerated or prolonged response may be detrimental in compromised patients. Knowledge of the involved afferent pathways will suggest therapeutic interventions that may modulate the intensity of the stress response. Described are these concepts as they relate to perioperative medicine.     

Enhancing function in life transitions and serious illness

Function, which encompasses functional ability and functional status, is discussed within the context of three conceptual models of nursing. Functional ability is the person's capacity to perform biological, psychological, and social activities, whereas functional status is the actual performance of those activities. Comprehensive assessment of function encompasses instrumental and expressive elements of functional ability and functional status, with attention given to the internal, external, and cultural factors that influence function. The goal of nursing interventions is to help the individual attain the highest possible and most desirable level of function.     

Predominant involvement of motor fibres in patients with critical illness polyneuropathy

Critical illness polyneuropathy (CIP) is a recognized cause of muscle weakness and failure of weaning from a ventilator. In order to characterize the features of CIP, we have examined 28 consecutive surgical patients with severe sepsis using bedside electrophysiology. Of the 28 patients (median APACHE II score 31), 20 developed moderate to severe CIP, as shown by the presence of moderate to severe denervation activity on resting EMG. The median nerve compound muscle action potential (CMAP) amplitudes were reduced to 3.24 (SEM 0.48) mV, while sensory nerve action potential (SNAP) amplitudes obtained from the same nerve were normal (13.1 (1.9) microV). In approximately 50% of these patients, the reduction in CMAP exceeded 50% of the lower limit of normal. Similar results were obtained from stimulation of the ulnar nerve. We conclude that CIP is a major complication in patients with severe sepsis and prolonged artificial ventilation. It predominantly involves motor fibres and thus markedly interferes with weaning from the ventilator.     

n-3 versus n-6 polyunsaturated fatty acids in critical illness

The aim of this study was to evaluate bone mineral density changes in patients with juvenile chronic arthritis (JCA) and to determine the most likely causes of osteoporosis in these patients. Eighteen (11 male, 7 female) patients suffering from JCA and 14 healthy controls (10 male, four female) were included in this study. The mean age of the patients and control groups were 11.0 +/- 3.2 and 10.9 +/- 2.9 years respectively. Disease activity was determined by clinical and laboratory evaluation and 'Articular Disease Severity Score' (ADSS). Bone mineral density (BMD) of the femoral neck and lumbar spine was measured by dual photon absorptiometry. BMD of the patients at the lumbar spine was significantly lower than the control group (p < 0.05). This difference was more marked in patients treated with steroids. Femoral neck BMD was also lower in the patient group but this difference was not statistically significant. There was a negative correlation between ADSS and BMD at the spine. In conclusion, trabecular bone loss is characteristic for osteoporosis in JCA. Our results indicate that steroid treatment and disease severity are important factors in the development of osteoporosis in JCA.