The protective action of allopurinol in an experimental model of haemorrhagic shock and reperfusion.

Haemorrhagic shock was induced in anaesthetized, open-chest dogs by controlled arterial bleeding, sufficient to reduce and maintain mean arterial blood pressure at 40 mmHg for 30 min. The blood volume was then restored to the pre-shock level by rapid, intravenous reinfusion of the blood shed during the shock period. Haemorrhagic shock produced significant haemodynamic changes, characterized by a marked depression of myocardial function. Cardiac output (1226 +/- 57 ml min-1), peak aortic blood flow (6030 +/- 383 ml min-1) and maximum rate of rise of left ventricular pressure (2708 +/- 264 mmHg s-1) were all reduced by more than 50%. The haemodynamic profile was markedly improved by reinfusion of shed blood but this improvement was not sustained. There was a gradual decline such that 50% of the untreated animals suffered complete circulatory collapse and death between 60 and 120 min following reinfusion. Neither haemorrhagic shock, nor reinfusion of shed blood produced any consistent or significant changes in the myocardial adenine nucleotide pool. The ATP, ADP and AMP levels were, respectively, 25.9 +/- 4.2; 15.6 +/- 1.0; 4.3 +/- 1.9 nmol g-1 protein, before haemorrhagic shock; 21.6 +/- 3.4; 21.5 +/- 2.5; 10.2 +/- 2.7 nmol g-1 protein, after 30 min haemorrhagic shock; and 29.9 +/- 3.9; 16.5 +/- 1.2; 4.2 +/- 1.1 nmol g-1 protein, 60 min following reinfusion of shed blood. Pretreatment with allopurinol (50.0 mg kg-1 i.v.), 60 min before inducing haemorrhagic shock, had no significant effect upon the haemodynamic response to shock, but did prevent the gradual decline seen following reinfusion in the untreated animals. All of the allopurinol-treated animals displayed significantly better haemodynamic profiles than the untreated animals, furthermore, there was a 100% survival rate in this group. 5 Allopurinol had no significant effect upon the myocardial adenine nucleotide pool either during haemorrhagic shock or following reinfusion of shed blood.

Nitrogen balance in postoperative patients receiving parenteral nutrition.

Fifteen patients were given parenteral nutrition with hyperosmolar glucose during the postoperative period (days 1 to 5): nine received an average of 10.5 gm of nitrogen and 2,340 kilocalories/day, six were given an average of 5.9 gm of nitrogen and 1,600 kilocalories/day. Eight patients (controls) received no nitrogen and 520 kilocalories/day. The results of this study confirm our early findings that total parenteral nutrition is capable of reversing the negative nitrogen balance of the immediate postoperative period; this reversal depends on administration of adequate nitrogen and calories. In patients with moderate surgical procedures, at least 8 gm of nitrogen and 1,800 kilocalories/day are required to correct the negative nitrogen balance. When total parenteral nutrition is instituted, adequate nitrogen and calories should be given even if insulin is required to control hyperglycemia.

A prospective study of incisional time, blood loss, pain, and healing with carbon dioxide laser, scalpel, and electrosurgery.

Carbon dioxide laser incisions are reported to be less painful, less bloody, and less prone to seroma formation and to heal better than scalpel or electrosurgical incisions. We compared all three modalities in a prospective randomized study of cholecystectomy incisions. Time required for the incision and incisional blood loss was less with electrosurgery than with the carbon dioxide laser or scalpel. Postoperative pain and wound healing, however, were the same for all three techniques. The carbon dioxide laser appears to offer no advantage over conventional means of making a standard incision.

Vascular trauma in the groin: contrast between iliac and femoral injuries.

Vascular injuries to the groin are common and often life-threatening. Injuries above the inguinal ligament, to the iliac system, are associated with a 37 percent mortality. Associated intraabdominal injuries are common. These patients must be identified promptly, given broad-spectrum antibiotics and taken immediately to the operating room for exploration through a midline incision. Injuries below the inguinal ligament are usually to the femoral vessels and are rarely fatal. These patients may be evaluated more extensively before leg exploration. Associated intraabdominal injuries are unusual, but disability from femoral fractures and nerve injuries are common.

Complications of tube thoracostomy for acute trauma.

Closed tube thoracostomy is a common and very useful procedure in therapy of acute thoracic injury. However, it is not without risk. With aggressive use of this procedure in the emergency department, the incidence of technical complications was 1 percent. Our review suggests that complications can be further diminished by the routine use of large thoracostomy tubes that are placed well up on the chest after confirmation of an open pleural space, by avoiding the use of a trocar for tube placement, and by the use of a high volume, low pressure suction system. Empyema was the most common complication associated with tube thoracostomy after trauma. It occurred in 2.4 percent of the patients. Its exact causes is not known, and the role of prophylactic antibiotics needs to be established.

Intrathoracic and intravascular migratory foreign bodies.

Intrathoracic and intravascular migratory foreign bodies are a small but distinctive subgroup of missile injuries. The intravascular bullet embolus can be treated like arterial or venous emboli of any other sort and removed as indicated. Wandering bullets in body cavities should be removed when they need to be, just like bullets imbedded in the body in a fixed position. And, contrary to the popular belief, very few bullets wander.

Advanced techniques in thoracic trauma.

Technologic aid is available for the three central problems of hemorrhage, lung damage, and cardiac damage. Autotransfusion, new modes of ventilator support, extracorporeal oxygenation, balloon pumping, and left ventricular assist are available for the trauma patient. The author explains these new devices and their role in thoracic trauma cases.

Nutritional support in the injured patient.

After injury, the stress reaction causes hypermetabolism and consequent depletion of the body's tissues. Nutritional support should be begun early and should be given by the enteral route if possible. New developments may allow the modulation of the stress and immune responses by nutrient therapy.

Variability of the Harris-Benedict equation in recently published textbooks.

The Harris-Benedict equation, as cited in a selection of textbooks of medicine, surgery, and nutrition, was compared with the original monograph published by the Carnegie Foundation. A significant amount of variation was found in published versions of this equation. Of 24 published versions, eight were sufficiently variant to produce errors of 7% to 55% in calculations of nutrition requirements. The error is usually in the constant term for one of the two Harris-Benedict equations. Either the constant term for men is increased to a value approximately the same as for women, or the constant term for women is reduced to be approximately equal to that for men. The primary reason appears to be the lack of availability in medical libraries of the original Carnegie Foundation publication by Harris and Benedict.

Factors influencing nutritional assessment in abdominal trauma patients.

Previous work has shown that an abdominal trauma index (ATI) based on anatomic severity of injury reliably predicts complications following abdominal trauma, whereas the Prognostic Nutritional Index (PNI) does not. This study was undertaken to reconcile the disparity between the PNI and ATI as predictors of postoperative morbidity and mortality. Twenty-four patients undergoing immediate laparotomy following acute abdominal trauma were evaluated. Their mean age was 32.8 years (range 18-59 years); 18 were men. All patients underwent nutritional assessment within 12 hours of surgery. A statistical comparison of blood replacement, operating time, ATI, and PNI was performed. The mean PNI was 51 and mean blood replacement was 12.5 units. Using linear regression the PNI and amount of blood replacement correlated significantly (r = 0..44, p less than 0.05). Operating time and ATI did not correlate with PNI. In conclusion, the PNI was more strongly influenced by blood loss than severity of intraperitoneal injury. For this reason it is relatively ineffective in predicting complications following trauma.

Nitrogen balance and electrolyte requirements in intralipid-based hyperalimentation.

The present study was directed at determining whether or not a relatively low-calorie regimen in which 40 to 50% of the calories are provided as fat will produce positive nitrogen balance in most patients, and at establishing the electrolyte requirements for such a regimen. Clearly, the recommended regimen is successful in promoting nitrogen balance and provides adequate electrolytes. Further experience will be necessary to determine the place of intravenous fat emulsions in the clinical practice of total parenteral nutrition.

Elevated pulmonary vascular resistance in patients dying from multiple organ failure.

Twenty-one patients with multiple organ failure were studied with hemodynamic monitoring. The five survivors were compared with the 16 nonsurvivors. Significant differences were found in the cardiac index (CI), the left ventricular stroke work index (LVSWI), and the pulmonary vascular resistance index (PVRI). The CI was higher in survivors (4.38 +/- 1.71) than in nonsurvivors (3.43 +/- 1.49). The LVSWI was also higher (43.0 +/- 16.8, 28.7 +/- 12.8) than in nonsurvivors (47.4 +/- 2.91). The PVRI was lower in survivors (168 +/- 122) than in nonsurvivors (474 +/- 291). It is postulated that the elevated PVRI in MOF is related to the adult respiratory distress syndrome.

The effect of intravenous safflower oil emulsion on the clotting mechanism.

A new fat emulsion for intravenous use, derived from safflower oil (Abbott Laboratories), was studied. The clotting mechanism was compared with a battery of tests performed during the infusion of total parenteral nutrition (TPN) using glucose alone and during infusion of TPN using both glucose and fat. Five adult surgical patients underwent TPN with 7.0 per cent amino acid solution for ten days, receiving glucose as their only nonprotein calorie source on days one, two, nine, and ten (40 kcal/kg/day). On days three through eight, 10 per cent fat emulsion (600-900 ml/day) was given each day to provide one-third of the nonprotein calories. Simplate bleeding time, prothrombin time, activated partial thromboplastin time, fibrinogen (Biuret method), platelet count, platelet aggregation, serum functional antithrombin, and viscoelastic curves were measured on days one, three, six, and ten. Some of these studies were abnormal at baseline and during the study. No significant changes were seen with fat emulsion infusion. The patients did not exhibit any evidence of clinical bleeding. This new intravenous fat emulsion did not appear to be associated with alterations in the clotting mechanism. However, two of five patients showed increases in serum triglycerides and one patient died during the study.

Comparison of total parenteral nutrition with 25 per cent and 45 per cent branched chain amino acids in stressed patients.

Administration of total parenteral nutrition (TPN) solutions high in branched chain amino acids (BCAA) is thought to improve metabolic support during stress. This prospective, randomized, double blind study compared 45 per cent BCAA with 25 per cent BCAA in 12 patients. Seven patients had multiple trauma; two, gastrointestinal surgery; one, pancreatitis; and two, cirrhosis. The TPN regimen was 1.0-1.5 gm/kg/day amino acids and 30-45 glucose kcal/kg/day. The BCAA formula used was high in isoleucine and valine, but not leucine. Amino acid plasma levels, blood chemistries, 3-methylhistidine excretion, and nitrogen balance were studied. Control studies showed negative nitrogen balance (-7.1 +/- 2.9 gm) (mean +/- SEM), elevated insulin (61 +/- 21 microunit/ml), and elevated 3-methylhistidine (3MH) excretion (688 +/- 309 micromol); plasma leucine (93 +/- 11 nmol/ml) and isoleucine (37 +/- 23) were low, and valine (155 +/- 20) was elevated. Plasma methionine (40 +/- 9) and tyrosine (70 +/- 12) were high normal. Phenylalanine (85 +/- 5) was elevated. Both groups showed increased nitrogen excretion and positive nitrogen balance during the study (25 per cent, 2.0 +/- 1.4 gm/day; 45 per cent, 1.2 +/- 2.6 gm/day). Three-methylhistidine excretion changed little in either group (557 +/- 149, 414 +/- 91), insulin rose (135 +/- 27, 65 +/- 19), and plasma leucine (82 +/- 4, 71 +/- 9) changed little. Plasma isoleucine (51 +/- 3, 155 +/- 16) and valine (173 +/- 11, 691 +/- 23) both rose, more in the 45 per cent group. Methionine (67 +/- 12, 37 +/- 4) and tyrosine (51 +/- 6, 50 +/- 10) changed little.(ABSTRACT TRUNCATED AT 250 WORDS)

Venous gas embolism associated with argon-enhanced coagulation of the liver.

Argon-enhanced coagulation (AEC) is a method for operative coagulation of tissues that utilizes a jet of argon gas encompassing an electrofulguration arc. Concern has been raised that the argon jet may produce harmful venous gas embolization. Two questions were addressed by this study. First, does AEC result in generation of venous gas emboli, and if so, what is the influence of gas flow rate and coagulation power on the amount of gas emboli generated? Second, does the amount of venous gas emboli generated by AEC produce harmful hemodynamic effects? Two AEC units were evaluated during coagulation of cut sections of the liver in pigs. The number of gas emboli generated was measured by an ultrasonic Doppler flow cuff placed around the caudal vena cava. Hemodynamic variables measured following AEC included systemic and pulmonary arterial pressure, pulmonary wedge pressure, and cardiac output by thermodilution. Venous gas emboli were produced during AEC of the liver. The number of gas emboli generated increased with increasing gas flow rates, but was not affected by coagulation power. No change in any of the measured hemodynamic variables was observed following AEC of the liver. The following recommendations were made: (1) Surgeons using AEC should select an argon flow rate as low as feasible to clear a bleeding tissue surface of blood and debris. (2) Although AEC seems to be associated with tolerable amounts of venous gas embolism, surgeons and anesthesiologists should be aware that the potential for harmful venous gas embolism exists. (3) In patients where extensive use of AEC is planned, appropriate monitoring and precautions for gas embolism should be undertaken.

Thermokinetics of cold cardioplegic arrest.

This study was designed to test the hypothesis that the rapidity with which the heart rewarms following cold cardioplegic arrest depends upon the technique of cannulation. In dogs, temperatures were monitored at multiple myocardial sites during rewarming, using four different cannulation techniques: caval cannulation with total bypass, caval cannulation with partial bypass, atrioventricular cannulation, and atrial cannulation. A mathematical model was constructed to facilitate analysis of the data, assuming that the rewarming process can be described by first order kinetics. Using this model, the half time of rewarming was defined as the time required for the myocardium to rewarm halfway from initial temperature to core temperature. Analyzing the several cannulation techniques in terms of the half time of rewarming, several conclusions were drawn: myocardial temperature distribution is non-homogeneous, rewarming is relatively rapid, partial bypass produces more rapid rewarming than total bypass, atrioventricular cannulation produces more rapid rewarming than either caval or atrial cannulation, and the principle routes of rewarming were from the posterior parieties and from blood entering the right side of the heart during partial bypass.

Caloric and nitrogen balances as predictors of nutritional outcome in patients with burns.

Measurement of energy expenditure with indirect calorimetry allows determination of caloric balance. The present study was done to determine the predictive value of caloric and nitrogen balances for nutritional outcome. Energy expenditure was obtained weekly and interpolated between measurements for daily caloric balance. Nitrogen balance was obtained weekly. Because nitrogen output fluctuated, interpolation of daily values was not possible. Nutritional outcome was defined by whether body weight was lost or maintained and by levels of visceral proteins (albumin, prealbumin, and transferrin). The study group included 12 patients with 7% to 82.5% total body surface area burns. Eleven patients survived their burn injuries, and one died of congestive heart failure at 38 days, after her burn wounds had healed. Nine patients had good nutritional outcomes (group 1) and three had poor nutritional outcomes (group 2) (including the one who died). Nitrogen balance was 1.3 +/- 1.0 gm/day in group 1 and 4.5 +/- 1.7 gm/day in group 2 (mean +/- SEM; p > 0.10). Caloric balance was 515 +/- 130 kcal/day in group 1 and -667 +/- 140 in group 2 (p < 0.001). Caloric balance was significantly different between the two groups, whereas nitrogen balance was not. Caloric intake correlated positively with nitrogen intake (r = 0.92). Nitrogen intake was 16% of total caloric intake. Nitrogen intake from blood products was appreciable and averaged 15% of total nitrogen intake (range, 0% to 47%); 11.3 +/- 1.6 gm/day in group 1 and 14.8 +/- 3 gm/day in group 2 (p > 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac dysrhythmias in the acute setting: pathophysiology or anyone can understand cardiac dysrhythmias.

Cardiac dysrhythmias are easy. Unlike the lung (which has formidable neuroendocrine, metabolic, and respiratory responsibilities), the heart is simple. It is an innervated muscular pump. A resting Purkinje or ventricular muscle cell membrane maintains a charge of about 90 millivolts. The five phases of a cardiac action potential are similar to the action potential in skeletal muscle, however, the cardiac action potential lasts a hundred times longer. When sodium specific "fast" channels and calcium specific "slow" channels open, positive ions rush into the myocardial cell, thus causing rapid membrane depolarization. In order to produce an action potential, some stimulus must decrease the membrane potential from -90 millivolts to "threshold" or -60 millivolts. Purkinje fibers do not have a stable phase for diastolic potential. These fibers continuously depolarize during diastole. Hypoxemia or hypokalemia may exacerbate this diastolic depolarization, thus promoting "hyperexcitability" or "automatic" ectopy. When myocardium is damaged, characteristically with myocardial ischemia, rapid conduction of cardiac impulses may be slowed dramatically. Very slow impulses may course through muscle such that by the time the activation wave front returns to the initiating site, this origin has had a chance to repolarize. This is the basis for re-entrant dysrhythmias. All cardiac dysrhythmias are automatic, re-entrant or both.

Cardiac dysrhythmias in the acute setting: recognition and treatment or anyone can treat cardiac dysrhythmias.

The two primary goals in dysrhythmia therapy are: to control the ventricular rate (between 70 and 100 beats per minute) and to maintain sinus rhythm. Maintenance of sinus rhythm is definitely secondary. If a patient is hemodynamically unstable, but has a ventricular rate between 60 and 100 beats per minute, the trouble is almost certainly not due to the cardiac rhythm. Normal conduction velocity is fast. An impulse is transmitted by healthy Purkinje fibers at 2 to 3 meters per second. This means that the entire ventricle, when activated by the Purkinje system, is activated in 80 milliseconds. When a superventricular impulse is transmitted to the ventricles via the A-V node, the ventricle should be activated (depolarized) in less than 80 milliseconds. Conversely, if an impulse is generated at an ectopic ventricular site, it does not access the high velocity Purkinje system as rapidly. A ventricular origin beat (PVC) thus, takes longer to activate the entire ventricle. The QRS is, therefore, longer (or wider). A wide QRS signifies aberrant ventricular conduction. When a dysrhythmia originates above the A-V node, the therapy is pharmacologic A-V nodal blockade (verapamil). When a dysrhythmia originates below the A-V node, therapy is pharmacologic (Lidocaine) or electrical (cardioversion). If uncertain or a patient is unstable, cardioversion is always acceptable. Thus; with an unstable patient, proceed immediately to cardioversion; with a narrow complex tachycardia (superventricular) proceed to verapamil; and with a wide complex (ventricular) tachycardia give Lidocaine and proceed to cardioversion.