Patrick A. Lasala

Effect of immediate postoperative nutritional support on length of hospitalization.

This study is a retrospective review of the effect of nutritional support on duration of hospitalization in patients undergoing radical cystectomy. Thirty-five patients were randomly assigned to receive either 5% dextrose (D5W) solution plus electrolytes or total parenteral nutrition (TPN) following operation. The assigned nutritional regimen was continued for 1 week after operation until oral intake resumed. If the patients receiving D5W remained incapable of oral intake after 1 week, TPN was instituted. The group receiving immediate postoperative TPN had a median duration of hospitalization of 17 days, while the median duration for the group receiving 5% dextrose solution was 24 days. All other patient characteristics, such as age, sex, stage/grade of tumor, and extent of preoperative radiotherapy, were similar in the two groups. These results demonstrate that immediate postoperative institution of nutritional support reduced hospitalization time following radical cystectomy. This indicates that the routine use of 5% dextrose as postoperative nutrition should be reevaluated.

The response to TPN. A form of nutritional assessment.

Malnutrition in surgical patients is associated with an increased incidence of postoperative mortality and morbidity. Preoperative nutritional support has been shown to be efficacious in reducing the incidence of these complications, although the postoperative complication rate in these patients continues to be greater than in their wellnourished counterparts. This study attempts to determine whether the postoperative course can be either influenced by or predicted from the preoperative response to nutritional support. Thirty-two patients with nutritional depletion who received an average of 1 week of total parenteral nutrition prior to a major abdominal operation were studied. These patients were followed for postoperative complications. Of the 16 patients who exhibited the characteristic response to early nutritional support, diuresis of the expanded extracellular fluid compartment with a resultant loss of weight (127.9 ± 5.7 to 124.6 ± 5.8 (SEM) lbs, p < .001) and rise in serum albumin (3.21 ± 0.14 to 3.46 ± 0.15 gms%, p < 0.001), only one developed a complication in the postoperative period. The other 16 patients did not exhibit this response. They retained additional fluid, gained weight (119.3 ± 8.1 to 121.3 ± 8.2 lbs, p < .025), and showed a decrease in serum albumin levels (3.14 ± 0.14 to 3.00 ± 0.14%), p < 0.01). Eight of these patients developed a total of 15 postoperative complications (p < 0.01). This study demonstrates that the response to preoperative TPN is an important factor in assessing operative risk and morbidity. The need to individualize preoperative nutritional support and the timing of surgical intervention is clearly demonstrated.

Changes in respiratory control induced by amino acid infusions.

We compared the metabolic and respiratory responses to a 4-h infusion of an amino acid solution consisting primarily of branched-chain amino acids (BCAA) to those after a standard amino acid solution in healthy subjects. Both the BCAA solution and the standard amino acid solution increased minute ventilation (mean increase 22%, p less than .001, and 18%, p less than .01, respectively), mean inspiratory flow (19%, p less than .01, and 19%, p less than .05) and oxygen consumption (9%, p less than .02, and 5%, NS). PaCO2 decreased (mean decrease 6%, p less than .01); there was a major increase in the ventilatory response to CO2 inhalation during administration of the BCAA solution but not the standard amino acid solution. Increased plasma norepinephrine concentration (mean increase 75%, p less than .001) during the infusion of the standard amino acid solution but not the BCAA solution suggested increased sympathetic activity. The results demonstrate augmented respiratory effects of amino acid infusions by BCAA enrichment, and a dissociation between the respiratory stimulation, metabolic rate, and sympathetic activity.

Response to Total Parenteral Nutrition in the Extremely Malnourished Patient

Changes in serum albumin levels and body weight are often used as indicators of the efficiency of a nutritional support regimen. Patients with moderate nutritional depletion demonstrate two distinct patterns of response during refeeding. The first is characterized by a decrease in the previously expanded extracellular fluid space with a rise in serum albumin and a loss of weight and the second by continued fluid retention with weight gain and no rise in serum albumin concentration. The second pattern has been observed in patients with ongoing stress such as infection. This study examines severely malnourished patients with no apparent inflammatory complications and demonstrates that this group responds to nutritional support in a pattern similar to that seen in the stressed patient. Eight patients with profound malnutrition were studied during the 1st week of nutritional support. Nitrogen balance was measured and the findings confirmed that all patients were anabolic. Sodium balances were used as an indicator of changes in the extracellular fluid compartment. Body weight and serum albumin were assessed daily. Body weight increased from 59 +/- 4 to 62 +/- 4% of normal (p less than 0.01) while serum albumin changed insignificantly (3.00 +/- 0.27 to 2.85 +/- 0.23 g/100 ml, NS) during the initial week of an adequate nutritional support regimen (nitrogen balance was +21.0 +/- 4.3 g, p less than 0.05). These changes were associated with a positive sodium balance (+215 +/- 20 mEq, p less than 0.05). These data confirm that some extremely malnourished patients do not experience a diuresis during the initial phase of nutritional support but rather may retain water and increase body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of parenteral nutritional repletion on muscle water and electrolytes. Implications for body composition

Nutritional depletion and repletion are associated with changes in the size of the extracellular and intracellular fluid compartments. Although the effect of nutrition on whole body composition is well established, the distribution of changes among the various body tissues is not. This study correlates changes in skeletal muscle composition with whole body electrolyte and nitrogen balance in an attempt to establish the contribution made by skeletal muscle to the changes in whole body fluid and electrolyte composition. Total parenteral nutrition was administered to ten patients for 16 to 25 days. Oxygen consumption, CO2 production, and balances of N, Na, and K were measured daily. Muscle biopsies were taken prior to administration of TPN, in the middle, and at the end of the nutritional regimen. Prior to administration of parenteral nutrition, muscle concentrations of water, sodium, and chloride were significantly higher than normal. With institution of the nutritional support regimen, all three concentrations decreased. The calculated loss in muscle water could account, at most, for only one-sixth of the loss in total body water. Muscle Na loss could account for approximately one-half of the whole body change. Potassium concentrations in the depleted patients were not significantly decreased from normal values and showed a negligible increase with TPN. Since the ratio of K to dry fat-free solids in muscle was constant, most of the whole body changes could be accounted for by assuming that nearly all N is deposited in muscle. Nutritional support results in restoration of cell mass with a contraction of the extracellular fluid (ECF) compartment. The changes in the ECF must occur in tissues other than muscle, while the restoration of cell mass occurs primarily in muscle.

Effect of parasympathetic blockade on ventilatory and cardiac depression induced by opioids

We have previously shown that delta-opioid agonists decrease ventilation and heart rate. Because of these results and the known interactions between opioid and acetylcholine metabolism, we hypothesized that opioids induce cardiorespiratory changes via the parasympathetic nervous system. To test this hypothesis, we administered atropine sulfate (systemically) at maximal effect of D-Ala-D-Leu-enkephalin (DADLE; a preferential delta-opioid agonist), injected intracisternally, and examined its effect on cardiorespiratory function. All experiments were performed on chronically instrumented and conscious adult dogs. Mean instantaneous minute ventilation or VT/TTOT decreased and PaCO2 increased after DADLE; atropine had little effect on these changes. Naloxone, even in small doses, reversed opioid effects on VT/TTOT and PaCO2. Atropine, however, reversed the DADLE-induced depression in cardiac rate. In doses that reversed this cardiac depression, atropine had no effect on cardiorespiratory function at rest, i.e., with no prior administration of DADLE. We conclude that DADLE decreases heart rate by increasing parasympathetic activity to the heart and induces hypoventilation by a different mechanism. We speculate that the opioid-induced ventilatory depression is due to either direct opioid action on central respiratory regulation or parasympathetic non-muscarinic or non-cholinergic mediating mechanisms.

The saphenous system for long-term parenteral nutrition

Three case reports describing the use of inferior vena caval catheterizations for total parenteral nutrition (TPN) are presented. Five anterior femoral vein cutdowns were advanced through the saphenous bulb, femoral, and iliac veins into the inferior vena cava. Four catheters were used for the purpose of TPN administration, the 5th for blood product administration and intraoperative monitoring. Five catheters were left in place without thrombotic or septic complications for a total of 10 months. The technique of elastomer catheter insertion in the tributary of the greater saphenous vein under local anesthesia is described.

Blood Rheology and Oxygen Transport

Donald Mathews, Patrick LaSala, and Shu Chien series of progressively smaller vessels-arteries, arterioles, Depts. of Physiology, Neurological Surgery, and Anesthesiology and capillaries. From a solitary aorta, the flow is partitioned Columbia University College of Physicians and Surgeons into more than a billion capillaries. It is in the capillaries that one of the most important functions of blood occurs, i.e., THE CIRCULATORY system is uniquely designed for sevoxygen transfer to the tissue cells. The blood flows from Teral functions, one of the most important being oxygen capillaries into a series of venules, veins, and the superior and transport. This is accomplished through the interaction of the inferior vena cavae, and the number of vessels decreases heart, lungs, blood vessels, and the blood. Blood is a complex with successive generations of converging flow. fluid consisting of plasma and cells, primarily red blood cells, suspended in it. The ability to deliver oxygen depends partly BASIC RHEOLOGICAL PRINCIPLES on the relative concentrations of these elements and the As blood flows from the aorta to the capillaries, most of the interactions between them. It also depends on the properties pressure head generated by the heart is dissipated, particuof the vessels through which the blood flows. Blood rheology larly in the arterioles, which are the primary resistance is the study of blood flow and the response of blood to vessels. The flow of blood across the circulatory system (0) deforming forces in the circulatory system. is directly proportional to the pressure drop from the arterial to the venous side of the circulatory system (PA Pv) and THE CIRCULATORY SYSTEM inversely proportional to the resistance to blood flow (R): The circulatory system can be thought of as a circuit through which the heart pumps blood, generating the presPA-PV sure head needed for flow to occur. The left ventricle pumps Q= R (1) with a higher pressure than the right. Normal mean systemic blood pressure in the aorta and large arteries is 90 to 100 The resistance to blood flow has two components: vascummHg. Blood flows into the aorta and then into a branching lar hindrance (Z) and blood viscosity (Na):