Colon blood flow in the dog: effects of changes in arterial carbon dioxide tension.

A new method for measuring blood flow in the colon using a 133Xenon clearance technique has been developed in the greyhound. Values for 133Xe tissue blood partition coefficient for colon have been established. The mean basal colon blood flow in 35 animals was 39.8 cm3.min-1.100g-1 with a coefficient of variation for repeat measurements of 8.7%. Hypercapnia produced a significant rise in colon blood flow to a mean maximum level of 62.2 cm3.min-1.100g-1 and hypocapnia a significant fall to a mean level of 27.9 cm3.min-1.100g-1. For arterial carbon dioxide tension (PCO2) values between 2 and 12 kPa (15 and 90 mmHg) there was a straight line relationship between colon blood flow and arterial PCO2. When hypercapnia was prolonged for 75 min, the initial rise in colon blood flow was only partially sustained, while prolonged hypocapnia for a similar period resulted in sustained reduction in flow. Mean resting colon oxygen consumption in 35 animals was 1.17 cm3.min-1.100g-1 and this was not significantly affected by hypocapnia. Hypercapnia to arterial PCO2 levels between 8 and 14 kPa (60 and 105 mmHg), however, produced a significant rise in colon oxygen consumption. Since changes in colon blood flow during and after surgery may affect healing of colonic anastomoses, these results may be relevant when considering anaesthetic techniques for patients undergoing colon resection.

The effect of etomidate on adrenocortical function in dogs before and during hemorrhagic shock.

The effects of the hypnotic agent ethyl phenylethyl imidazole carboxylate (etomidate), on corticosteroidogenesis were studied in greyhound dogs during a 2-h period of anesthetic followed by a further 2 h of anesthetic combined with hemorrhage. Three groups of dogs were studied. The first, a control, received thiopentone and pentobartitone for induction and maintenance of anesthesia. A second control group received the chemically unrelated hypnotic preparation, althesin, after induction with thiopentone and pentobarbitone. In the first control group and the althesin-treated control group, changes in plasma ACTH and in plasma renin and angiotensin II concentrations were followed closely by changes in the levels of their respective dependent corticosteroids. A third experimental group received etomidate after induction of anesthesia with thiopentone and pentobarbitone. In these, in contrast, plasma levels of progesterone, 17 alpha-hydroxyprogesterone, corticosterone, cortisol, and aldosterone decreased during the experiment even failing to respond to massive rises in plasma ACTH concentration, renin, and angiotensin II levels after hemorrhage. However, the ability of 11-deoxycortisol and 11-deoxycorticosterone to respond was retained. These results suggest that etomidate inhibits corticosteroidogenesis directly, probably acting at more than one point in the biosynthetic pathway. It is suggested that it inhibits mitochondrial steroid hydroxylation (e.g. side chain cleavage, 11 beta-hydroxylation), but not 21-hydroxylation which occurs outside the mitochondrion.

Aspirin inhibits the early myocardial release of thromboxane B2 and ventricular ectopic activity following acute coronary artery occlusion in dogs.

Acute coronary artery occlusion in anaesthetized open-chest greyhounds led to early release of thromboxane B2 (TxB2) into venous blood draining the ischaemic region. No release occurred from the remainder of the left ventricular wall (coronary sinus sampling). TxB2 release and ventricular ectopic activity were positively correlated (r = 0.863) 2 min post-occlusion. Aspirin (3 mg/kg i.v.) suppressed both local TxB2 release and ectopic activity and prevented ventricular fibrillation. It is suggested that TxB2 release is a factor contributing to early post-infarction arrhythmias.

Liver function in septic shock.

Serum liver function tests were estimated in 57 patients admitted to an Intensive Therapy Unit (ITU) with a diagnosis of septic shock. Following an initial biochemical disturbance, persisting hyperbilirubinaemia was associated with a poor prognosis. Post-mortem liver histology in 22 patients showed varying degrees of non-specific reactive change, venous congestion, ischaemic necrosis, fatty change and intrahepatic cholestasis in 16 cases. In the remaining six cases there was moderately severe cholestasis with inspissated bile in the cholangioles. The possible aetiology of the observed cholestasis is discussed.

Assessment of host resistance in critically ill surgical patients by the response to recall skin antigens.

The cell-mediated immunity (CMI) of 47 critically ill surgical patients admitted to an Intensive Therapy Unit was assessed by their response to recall skin antigens and found to be markedly reduced. Thirty-seven patients showed no reaction to initial skin testing (NR), and there were 21 deaths in this group. Ten patients reacted (R) to initial skin testing and only one of these patients died (p less than 0.025). Repeat skin testing was performed on 22 NR patients. Eight became R on repeat testing and there was one death in this group, whilst 14 remained NR and there were 11 deaths in this group (p less than 0.025). The major clinical difference between R and NR patients was a greater incidence of severe sepsis in the NR patients. These findings suggest that the use of recall skin antigens to assess CMI may be a valuable investigation in critically ill surgical patients and that initial and persisting failure to react to skin tests is associated with a poor outcome.

The use of inotropic drugs in myocardial contusion: 2 case reports.

Myocardial contusion is a common complication of blunt chest injury. Severe heart failure and shock may result. The haemodynamic consequences of myocardial contusion in two patients are described; both received inotropic agents. In the first patient dobutamine was successful in improving myocardial function; dopamine had similar effects on the heart. In the second patient dopamine, preferred for its renal effects, produced a short-term improvement in myocardial function. The rational use of pharmacological agents in this condition demands precise understanding of the underlying haemodynamic disturbances.

Sickness scoring and response to treatment as predictors of outcome from critical illness.

A physiological sickness scoring system (SS), based on the APACHE II score, has been used to assess outcome from critical illness in 128 patients admitted to a general intensive care unit. Physiological data were collected on each patient from admission until death or discharge from the unit, and survival was recorded as survival to home. The admission SS correctly classified 80.6% of survivors, and 70.4% of non-survivors. Predictive power did not improve with time using the daily SS. However, when the proportional change in SS over time was included in the analysis, predictive power improved; and at day 4, 87.1% of survivors and 75% of non-survivors were correctly classified. At intermediate levels of sickness severity (admission score of 13-18), a reduction in SS of 30% by day 4 reduced the risk of death by 32%; at higher levels (greater than 18) a similar reduction in SS was associated with a 47% reduction in death-risk. Failure to obtain a reduction in score by day 4 was associated with increased risk of death. Survivors consistently showed a greater fall in SS by day 4 than non-survivors. The APACHE score and its modifications provide an accurate, unitary measure of physiological disturbance. Correction of abnormal physiology, and the measurement of responsiveness to therapy are important components in the prediction of outcome from critical illness.

Myocardial contusion in blunt chest trauma: a ten-year review.

A retrospective review was undertaken of 169 patients admitted to an Intensive Therapy Unit with a major chest injury to determine the incidence, clinical features and outcome of patients with myocardial contusion. This injury occurred in 29 (17%) patients, of whom 24 (83%) had significant cardiovascular complications and five died as a direct result of the injury. The interval between injury and diagnosis was 3.2 +/- 2.3 days (mean +/- SD) from injury and in six patients the diagnosis was made only at necropsy. Increased awareness of myocardial contusion is required for earlier diagnosis and prevention of complications.

Sedation in intensive care: morphine and renal function.

Intravenous morphine infusions have been administered to 12 critically-ill patients during controlled ventilation. Acute oliguric renal failure was present in 4 patients, who were treated with a combination of haemofiltration and haemodialysis. Severity of physiological disturbance was assessed using a modified APACHE Score, level of sedation by a linear-analogue scale, and blood morphine levels by high-pressure liquid chromatography. Morphine clearance was impaired in renal failure, and was dependent on haemofiltration volumes; accumulation of morphine did not occur during this form of treatment. Conscious level was clearly more closely related to the degree of physiological disturbance than blood morphine levels; and for a given blood morphine level, depression of consciousness was more pronounced the greater the degree of physiological disturbance. Use of a physiological sickness score may help to clarify some of the factors influencing cerebral function during critical illness. Careful clinical monitoring of level of sedation is important in patients with oliguric renal failure receiving morphine, and haemofiltration appears to reduce the risk of morphine accumulation in these patients.

Endotoxaemia in septic shock: clinical and post mortem correlations.

The Limulus amoebocyte lysate assay was used as one of a series of laboratory and clinical investigations on a group of 31 patients suffering from septic shock in order to assess the clinical significance of this assay for the detection of circulating endotoxin in clinical gram-negative sepsis. Four patients with cardiogenic shock served as controls. Endotoxin was detected in the bloodstream of all patients with septic shock during the 24 h following referral and was not detected in the control patients. Eventual clinical recovery was associated with the disappearance of endotoxin from the peripheral blood. Blood cultures were unhelpful as a prognostic indicator in these critically ill patients. A quantitative assay of endotoxin in blood may allow a more precise relationship with the clinical manifestations of major sepsis.

Movement of the critically ill within hospital.

Critically ill patients can be safely moved within hospital using a mobile intensive care unit (MICU). The MICU allows the critically ill to benefit from specialised investigation and treatment they might otherwise be denied. The MICU in use at the Western Infirmary, Glasgow is described and its merits outline in the light of clinical experience gained over a twelve month period.

Cell therapy in shock: a reasonable prospect or a lost cause?

Almost any insult to the body can set in motion the sequence of physiologic and biochemical changes leading to shock. In the absence of effective treatment widespread disruption of the body's biological mechanisms inevitably follows. This review will describe some of cellular and subcellular disturbances associated with the shock syndrome, the persistence of which lead to (multiple) organ failure. Current views as to the mechanisms of these disturbances will be outlined with particular reference to hypovolemic and septic shock. Finally, an indication will be given of the relevant therapeutic implications, now and in the future.

A three year retrospective analysis of septic shock in a general hospital.

PIP: Records of all patients with a clinical diagnosis of septic shock were reviewed retrospectively; cases occurred from August 1968-July 1971 in a general teaching hospital with 667 beds. In the 3-year period, 80 patients (38 males and 42 females) presented with 82 episodes of septic shock; this represented 14% of total hospital admissions to Intensive Care. The age range was from 15-78 years, with a mean of 52+ or -16 years. The incidence of the syndrome increased with age, reaching a maximum in the 7th decade. 66 (0f 71) of the surgical/gynecological referrals followed operative procedures, of which 1/2 were undertaken electively. By the time of referal to the Intensive Care Unit, pyrexia, hyperventilation, cyanosis, vasoconstriction, pallor, and sweating were commonly present, although 16 patients presented with warm hypotension; moderate hypotension was present in 48 patients, and severe hypotension was present in 18. Dehydration, oliguria, and azotemia were frequently present on admission. Abnormalties in serum electrolytes were common. Blood gas analysis on admission revealed that marked hypoxemia was commonly present in association with hypocapnia and metabolic acidosis. Blood cultures were performed in 62 patients and positive results were obtained in 38 on at least 1 occasion. Of a total of 47 positive blood cultures, 33 were gram-negative organisms and 5 were gram-negative anaerobic bacilli. The former were sensitive to gentamisin and the latter were resistant to both the cephalosporins and ampicillin. Gram-positive organisms were sensitive to cloxacillin and cephalosporins. Initial mortality was 64%, which increased to 70% including late deaths after return to wards. Nonsurvivors were significantly older than survivors (P .005); they were more frequently dehydrated (P .005); and they were more subject to the development of tachycardia and cardiac arrhythmias. Nonsurvivors were also considerably more hypoxemic than survivors. There was a marked difference between nonsurvivors and survivors in mode of presentation and infection source; nonsurvivors were characterized by either mediastinitis as a consequence of leakage of an esophageal anasotmosis or fecal peritonitis.^ieng