Regional spinal cord and brain blood flows in the rat.

Regional spinal cord blood flow and blood flow in different brain areas were measured in 18 rats by the microsphere technique. By the use of spheres labeled with two different isotopes injected 5 min apart, double determinations were made. The consistency of the results from the two injections was very good. Blood flow was highest in the lumbar part of the spinal cord, somewhat lower in the lower thoracic part, lowest in the upper thoracic part, and again higher in the cervical cord; the mean values of the two determinations were 0.98, 0.74, 0.42, and 0.48 ml X min-1 X g-1 tissue for these regions, respectively. The brain areas investigated were the brain stem, cerebellum, and right and left hemispheres; the respective mean values of the two blood flow determinations in these areas were 0.54, 0.58, 0.33, and 0.38 ml X min-1 X g-1 tissue.

Spread of epidural blockade in the anaesthetised pig using technetium99 and sensory-evoked potentials.

Our objective was to determine the extension and duration of a stable segmental thoracic or lumbar epidural blockade by lidocaine in the 20 to 25-kg pig. Fourteen anaesthetised pigs were investigated. The radioactive isotope technetium99 (Tc99) was added to lidocaine to evaluate the spread in the epidural space. One ml of this solution was administered via an epidural catheter either at the Th(6-7) or L6-S1 level. Sensory-evoked potentials (SEPs) were measured following peripheral nerve stimulation, to determine duration and sensory extension of the epidural blockade. The thoracic anatomical mean spread was 14.2 vertebrae. The end points of the spread were C3-C7 and Th8-Th13 and the lumbar anatomical mean spread was 10.2 vertebrae. The end points were Th10-Th12 and L6-S1. It was possible to abolish the SEPs with 2 and 4% lidocaine. A smaller volume of lidocaine was needed if a second dose was administered within 20 min. With 4% lidocaine it was possible to abolish the SEPs for more than 180 min. The use of 1 ml of 4% lidocaine repeated after 20 and 60 min at the Th(6-7) or L6-S1 level achieved a stable thoracic or lumbar epidural blockade.

Microsphere measurement of regional intestinal blood supply and cardiac output in the rat.

The regional blood supply to consecutive segments of the small intestine in the anaesthetized rat was investigated with a radioactive microsphere technique. A blood flow gradient with the lowest flow in the distal segments (0.85--0.89 ml/min.g) and the highest in the proximal segments (1.13--1.15 ml/min.g) was observed. Very few microspheres were found in the portal vein blood, indicating negligible arteriovenous shunting in the splanchnic area. The mean cardiac outputs in two consecutive measurements were 27.9 and 28.7 ml/min . 100 g, respectively. The cardiac output and regional blood flow values were in accordance with those obtained with other techniques.

Factors influencing early postoperative recovery after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

BACKGROUND: Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) can prolong survival in selected patients with peritoneal carcinomatosis (PC). However, there is little data on patients' recovery process after this complex treatment. This study aimed to describe the in-hospital postoperative recovery and factors related to the recovery of patients who undergo CRS and HIPEC. METHOD: A retrospective audit of the electronic health record (EHR) was undertaken for 76 PC patients (42 women, 34 men) treated primarily with CRS and HIPEC between 2005 and 2006 in Sweden. RESULTS: Oral intake, regaining bowel functions and mobilisation usually occurred between 7 and 11 days postoperatively. Patients experienced nausea for up to 13 days postoperatively. Forty-two patients were satisfied with their pain management, which usually took the form of epidural anaesthesia and which continued for about one week post-surgery. Sleep disturbance was observed in 51 patients and psychological problems in 49 patients during the first three postoperative weeks. Tumour burden, stoma formation, use of CPAP, primary diagnosis, and the length of stay in the ICU were factors related to an early recovery process. CONCLUSION: Drinking, eating, regaining bowel functions and mobilisation were re-established within 11 days of CRS and HIPEC. Tumour burden, stoma formation, use of CPAP, primary diagnosis and the length of stay in the ICU all had an impact on postoperative recovery, and should be discussed with the patients preoperatively and taken into consideration in designing an individualised patient care plan, in order to attain a more efficient recovery.

Central and regional haemodynamics during controlled hypotension produced by adenosine, sodium nitroprusside and nitroglycerin. Studies in the pig.

Controlled hypotension was induced in pigs by the infusion of adenosine, sodium nitroprusside (SNP) or nitroglycerin (TNG). Central and regional haemodynamics were studied using the microsphere technique during control and hypotensive periods. All three drugs produced decreases in mean arterial pressure (MAP), but it was very difficult to maintain stable values of hypotension with TNG, and it was necessary to increase continuously the dose of SNP to produce stable hypotension. Adenosine produced an increase in cardiac output (CO), maintained blood flow to the cerebrum, cerebellum, heart, kidneys and adrenal glands and increased blood flow to the spinal cord and splanchnic organs, except the spleen. SNP and TNG decreased CO, but blood flow to the aforementioned organs (except the spleen) was maintained. Urine flow was greatly impaired during the infusion of adenosine.

Experimental ischaemia of the small intestine. Effect of antibiotic and antithrombotic drugs on the mucosal exchange circulation.

Factors of decisive importance for the fate of the intestine following circulatory occlusion incluse the bacterial flora of the intestine, intravascular thrombosis peripheral to the level of occlusion, and the capacity of the collateral circulation. Standardized ischaemia of the small intestine was produced in the rat by ligation of a given number of mesentric end arcades. The passive absorption of radioiodide from a defined, central loop within the ischaemic intestinal segment-as an expression of the exchange circulation of the intestinal mucosa-was determined 14 days after induction of the ischaemia. Different forms of treatment were studied. In Sprague-Dawley rats the effect of heparin, oxitetracycline (OCD) and a combination of these two drugs was examined both concerning the survival of the animals and with regard to the available exchange circulation in the mucosa of the ischaemic intestinal segment. The survival frequency was increased in all treatment groups. The exchange circulation in the ischaemic segment was improved significantly by ODC-treatment and by treatment with heparin and ODC combined. Treatment with heparin alone gave no improvement of the mucosal circulation.

Effect of epidural clonidine on spinal cord blood flow and regional and central hemodynamics in pigs.

Epidural clonidine is reported to produce analgesia in humans. To investigate the effect of epidural injection of this alpha 2-adrenoceptor agonist on spinal cord blood flow as well as on regional and central blood flow and hemodynamics, 11 anesthetized pigs were studied. Each pig received clonidine in increments of 3, 10 and 30 micrograms/kg, each dose given in a volume of 5 ml via a lumbar epidural catheter. The tip of the catheter was located in the lumbar epidural space. The microsphere method was used to measure regional circulation. The measurements were made 45 min after each dose. Each pig served as its own control. The lowest dose of epidural clonidine (3 micrograms/kg) did not affect regional blood flow to the spinal cord or to any other organ. The intermediate and high doses were associated with local vasoconstriction in the lumbar and thoracic parts of the spinal cord that produced a statistically significant reduction in flow of 25-35% (P less than 0.05). Blood flow to the brain, cerebellum and the cervical parts of the spinal cord was not significantly changed, nor was renal blood flow. In the adrenal and in skeletal muscles a marked reduction of the blood flow occurred after the high dose, 61% and 78%, respectively. These findings indicate that epidural clonidine 3 micrograms/kg, a dose of clinical interest, is not likely to produce dangerous vasoconstriction in the spinal cord.

The antianabolic effect of tetracyclines in a consecutive clinical series.

In a series of 58 tetracycline-treated patients from an intensive care unit 33 patients were given oxytetracycline and 25 patients were given doxycycline. In 50 of the patients the serum creatinine level never exceeded 2 mg/100 ml. The serum urea/creatinine ratio was repeatedly determined in all patients. The oxytetracycline group displayed significantly higher mean values for this ratio during treatment than the doxycycline group. This was interpreted as a probable antianabolic effect due to the oxytetracycline therapy.

Hemodynamic effects of phenoxybenzamine and volume replacement in segmental ischemia of the rat small intestine.

Segmental ischemia of the small intestine in the rat was established by ligating the mesenteric arterial end arcades of 1/4 of the length of the small intestine. Regional and central blood flow was measured with the microsphere technique before and 2 h after induction of the ischemia. In one series of rats an i.v. infusion of 16 ml plasma per kg body weight (b.w.) was given during the experimental period, which maintained the central circulation. However, the impairment of blood supply to the whole small intestine caused by the segmental ischemia was not normalized. Two other series of rats were treated with either phenoxybenzamine alone, 3 mg.kg-1 b.w., or the same dosage of phenoxybenzamine plus plasma infusion (16 ml.kg-1 b.w.). The central circulation was deteriorated and the blood flow to the small intestine reduced in the rats receiving phenoxybenzamine alone. Both the central circulation and the blood supply to the non-ischemic parts of the intestine were maintained in rats treated with both phenoxybenzamine and plasma. Combined treatment with phenoxybenzamine and volume replacement thus seems to be valuable for limiting the secondary hemodynamic changes caused by segmental intestinal ischemia.

Hemodynamic effects of methylprednisolone in rats subjected to segmental intestinal ischemia.

Massive doses of methylprednisolone were given to rats subjected to segmental intestinal ischemis. The central and regional blood flows were studied with the microsphere technique. Ischemia was induced by ligating the arteries to 1/4 of the length of the small intestine. In rats subjected to 2 h of segmental intestinal ischemia methylprednisolone seemed to prevent the decrease in blood flow, previously noted in untreated rats, in the regions where the arteries were not occluded. When adequate volume replacement was given in combination with methylprednisolone, the blood flow in the ischemic region showed a slight improvement. The edema in the ischemic segments tended to be less marked in rats treated with methylprednisolone.

Regional and central hemodyanamics during segmental ischemia of the small intestine in the rat.

The influence of segmental small intestinal ischemia on the central circulation and on the regional blood flow to consecutive segments of the small intestine in the rat was investigated with the microscphere method. Ischemia was established by ligating 11 arterial mesenteric end arcades, corresponding to one quarter of the total length of the small intestine. The blood supply to different organs and central circulatory variables were determined before, and 10 min, 30 min, 2 h and 14 days after the establishment of the ischemia. After 10 min of ischemia, there was an increase of the blood flow to the segments distal to the ischemic region but after 30 min, this blood flow was the same as the control flow. The central circulatory variables weere not affected. After 2 h of ischemia, the blood supply to both the ischemic and the non-ischemic part of the small intestine had deteriorated considerably. Thus, the vascular resistance in the ischemic segments and the segments surrounding it was increased. Cardiac output was reduced by about 50%. In the experimental group investigated 14 days after establishment of the ischemia, the mortality rate was about 50%. In the survivors, the intestinal blood supply had returned to normal.

Continuous positive pressure ventilation during epidural blockade--effects on cardiac output distribution.

BACKGROUND: It has been shown that when cardiac output (CO) decreases during continuous positive pressure ventilation (CPPV), its regional distribution adapts with a favouring of vital organs. Does epidural blockade modify this adaptation? METHODS: Regional blood flows were assessed by the microsphere technique (15 microm) in 17 anaesthetised pigs during spontaneous breathing and CPPV with 8 cm H2O end-expiratory pressure (CPPV8) before and after epidural blockade. The block was induced at either the Th6-7 (Thep) or the L6-S1 (Lep) level with 1 ml of lidocaine 40 mg x ml(-1). RESULTS: When Lep was combined with CPPV8, mean arterial pressure and CO decreased significantly, and they decreased even more when combined with Thep. In contrast, the relative perfusion of the central nervous system, heart and kidneys remained stable during the four conditions studied. The adrenal perfusion during CPPV8 was obviated by epidural blockade. The absolute and relative perfusion of the skeletal muscle decreased during epidural blockade. The administered doses of epidural lidocaine did not affect blood flow in the spinal cord. CONCLUSIONS: The locally mediated nutritive vasoregulation of vital organs outweighed the sympathetic blockade induced by epidural blockade. During Thep blockade the animals were less capable of responding to the haemodynamic changes induced by CPPV8, probably due to the blockade of the cardiac part of the sympathetic nervous system.

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil.

BACKGROUND: Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO). METHODS: General hemodynamics and regional blood flows assessed by microsphere technique (15 microns) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H2O end-expiratory pressure (CPPV8) before and after intravenous administration of propanolol (0.3 mg.kg-1 followed by 0.15 mg.kg-1.h-1, n = 8) or verapamil (0.1 mg.kg-1 followed by 0.3 mg.kg-1.h-1, n = 8). RESULTS: CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase. CONCLUSIONS: The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.

Central haemodynamics and regional blood flows during thoracic epidural analgesia combined with positive pressure ventilation. An experimental study in the pig.

Cardiac output, central haemodynamics and regional blood flows were studied in pigs. The microsphere technique was used for blood flow determinations. Measurements were made during spontaneous breathing (SB) and during intermittent positive pressure ventilation with 0.8 kPa (8 cmH2O) positive end-expiratory pressure (8 PEEP) before and during thoracic epidural analgesia (TEA). TEA in the pig caused reduced cardiac output due to reduced heart rate with maintained stroke volume. During TEA there was also a reduction of mean arterial blood pressure which ran almost parallel to the decrease in cardiac output with maintained systemic vascular resistance during SB and at 8 PEEP. The distribution of cardiac output was basically the same during SB and at 8 PEEP as it was before TEA. However, myocardial blood flow and relative perfusion decreased during TEA, both during SB and at 8 PEEP. TEA also reduced spinal cord blood flow within the thoracic region during SB and at 8 PEEP.

The effects of alpha adrenergic blockade on central haemodynamics and regional blood flows during positive pressure ventilation. An experimental study in the pig.

The effects of alpha receptor blockade on cardiac output distribution in pigs were studied. Recordings were made during spontaneous breathing (SB), during ventilator treatment with 8 Pa positive end-expiratory pressure (8 PEEP), after alpha blockade during SB (SB-alpha) and at 8 PEEP (8 PEEP-alpha). The microsphere method was used for blood flow determinations. The animals received either 5 ml.kg-1.h-1 (Group A) or 10 ml.kg-1.h-1 (Group B) of fluids. In Group A on SB-alpha, CO was maintained due to tachycardia but mean arterial pressure (MAP) decreased, renal blood flow and urine production decreased. At 8 PEEP-alpha, CO decreased despite increased heart rate (HR), MAP decreased alarmingly, renal blood flow decreased, urine production ceased and cerebral blood flow decreased, reflecting failing autoregulation. In Group B, CO increased during SB-alpha, SVR decreased, myocardial blood flow increased and organ blood flows were otherwise unchanged. At 8 PEEP-alpha, MAP, SVR, renal, pancreatic and splenic blood flows decreased in Group B. Gastric, intestinal and muscular blood flows were unchanged at 8 PEEP-alpha in Group B which is interpreted as an effect of the alpha blockade. In both groups peripheral arterio-venous shunting increased after alpha blockade.

Delayed dopamine treatment of segmental small intestinal ischaemia in the rat.

Two groups of rats were subjected to segmental ischaemia of the small intestine for 2 h. According to our previous findings such ischaemia causes impairment of the central circulation as well as of the splanchnic blood flow. Dopamine treatment was initiated 30 or 90 min after the establishment of ischaemia. In the 30-min group cardiac output increased and the blood flow was normalized in those parts of the small intestine where the arteries were not ligated (the non-occluded parts). This result corresponds well to our previous observations when dopamine treatment was started immediately after the establishment of ischaemia. In the 90-min group cardiac output was not affected. Again the intestinal blood flow was normalized in the non-occluded parts. In both groups the pancreatic circulation was impaired.

Haemodynamic effects of phenoxybenzamine and dopamine in segmental ischaemia of the rat small intestine.

Two groups of rats were subjected to a segmental intestinal ischaemia of a degree which, according to earlier investigations with this experimental model, causes secondary impairment of the splanchnic blood flow. Both groups were given plasma and an alpha-adrenergic blocking agent (phenoxybenzamine). They were also given dopamine but in different doses, 12 and 50 micrograms X min-1 X kg-1 b.w., respectively. It was found previously that a normal blood flow in the non-occluded parts of the small intestine could be maintained by phenoxybenzamine or the lower dose of dopamine alone in combination with plasma, but the higher dopamine dose caused vasoconstriction, probably because of an alpha-stimulating effect. The combined treatment with penoxybenzamine and dopamine in the present experiments normalized the intestinal blood flow in the non-occluded parts in both groups, i.e. also in the group treated with the higher dose of dopamine. Moreover, the pancreatic circulation was normalized in both groups. Hence alpha-adrenergic blockade combined with dopamine and plasma administration seems to have a positive effect on the splanchnic circulation during segmental intestinal ischaemia in the rat.

Effects of positive end-expiratory pressure on cardiac output distribution in the pig.

Cardiac output (CO) and the blood flow to the heart, cerebellum, kidney, pancreas, spleen and skeletal muscle were studied in 20 pigs during spontaneous breathing (SB) and intermittent positive pressure ventilation (IPPV) with a positive end-expiratory pressure (PEEP) of 0, 8, 16 or 24 cmH2O. Microspheres (15 micrometers) labelled with either 85-sr or 141-Ce were used. Injection of microspheres labelled with one of the isotopes was given during SB (all pigs) and with the other isotope during IPPV with PEEP of 0, 8, 16 or 24 cmH2O (five pigs at each level). CO decreased by 11% during IPPV with PEEP of 0 and 31%, 53% and 66% during PEEP of 8, 16 or 24 cmH2O, respectively. Mean arterial blood pressure was fairly well maintained in all groups except the group with PEEP of 24 cmH2O. The perfusion of the six organs deteriorated, but when taken as fractions of CO measured at the same time, the blood flow to the heart, cerebellum and kidney increased with increasing airway pressure, while that to the pancreas, spleen and skeletal muscle decreased. The vascular resistance of the three former organs did not change, while in the latter it increased markedly. It is concluded that when CO decreases as a result of positive pressure ventilation, a redistribution takes place, mainly due to vascular constriction in skeletal muscle, which acts to preserve the blood flow to vital organs.