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PubMedDate not supplied

[Spinal cord ischemia following subrenal aortic clamping].

The paraplegia caused by an aortic clamping just below the Renal artery is a rare but very complication in aortic surgery. Such a complication is even rarer if we consider the few cases reported in literature following a reconstructive surgery for occlusive chronic diseases of aortiliac axes. The authors have studied the case of a patient bearing the syndrome of Leriche; this one had an aortic clamping below the kidney and soon after developed an acute ischaemic syndrome below the spinal medulla with flaccid paraparesis, anal and vesical sphincteric diseases and persistence of deep tactile sensibility. After a reconstruction of vascular anatomy of the medulla they emphasize the importance, in such a disease, of the "arteria radicularis magna" of Adamkievicz and its place of origin. After they discuss the severe physioopathologic moments that are connected: with the direct ischaemia following aortic clamping in the cases where the arteria radicularis magna rises at a level lower than the clamping itself; with the embolism or thrombosis caused by surgical manipulation peroperatively (it might be the cause of paraplegia more frequent in aneurysmectomia surgery); with the severe hypotension per- and post operatively for the existence of arteriosclerotic disease of the lumbar arteries. Finally they analyses preoperatively diagnostic possibilities and per operatively methods used in preventing this sort of complication.

Aorta, Abdominal↗
PubMedDate not supplied

Dissection of the thoracic aorta following partial clamping.

A case is reported in which an extensive dissection of the thoracic aorta was observed after partial clamping during surgery on that blood vessel. The unfavourable outcome of the operation and the accurate investigation of the post-mortem material suggest a lesion of the artery wall secondary to tangential clamping by Satinsky's clamp. The possible pathogenetic mechanisms of lesions induced by vascular clamping are also discussed.

Aged↗
PubMed1988

Deleterious effects of splanchnic congestion on hepatic energy metabolism following repeated portal triad cross-clamping in dogs.

Thirty minutes of warm hepatic ischemia produced by portal triad cross-clamping was repeated five times at 30-minute intervals in three groups of five dogs each: Group A was subjected only to portal triad cross-clamping; Group B received simultaneous clamping of the celiac axis and the superior mesenteric artery; and Group C had a simultaneous splenojugular shunt. The arterial blood ketone body ratio (acetoacetate/beta-hydroxybutyrate: KBR), reflecting the NAD+/NADH ratio in liver mitochondria, decreased significantly after each cross-clamping in all groups. After the first declamping, there was no significant difference in the recovery rate of the KBR among the three groups. After the second declamping, the recovery rate in Group A decreased significantly compared with the rates of Groups B and C (P less than 0.05). After the fourth declamping, the recovery rate in Group B was significantly lower than that of Group C (P less than 0.05). The hepatic energy charge [(ATP + 1/2ADP)/(ATP + ADP + AMP)] 30 minutes after the fifth declamping decreased significantly to 0.75 +/- 0.01 in Group A, compared with 0.84 +/- 0.01 in Group C (P less than 0.01). The lactate and total free plasma amino acid levels in the arterial blood increased significantly in the order of Groups A, B, and C. It is suggested that the inflow of stagnant portal venous blood to ischemic liver impairs hepatic energy metabolism.

Amino Acids↗
PubMed1988

Periventricular/intraventricular haemorrhage and umbilical cord clamping. Findings and hypothesis.

The timing of umbilical cord clamping in 38 women with preterm labour was randomly assigned. Ultrasonographic evidence of periventricular/intraventricular haemorrhage (PVH/IVH), assessed blindly, was found in 77% of the group clamped early compared with 35% of those in whom clamping of the cord was delayed for 1 minute. A hypothesis to explain the possible contribution of the haemodynamic events which accompany cord clamping to the development of PVH/IVH is presented.

Adult↗
PubMed1988

Anaesthetic problems in cross clamping of the thoracic aorta.

Cross clamping of the descending thoracic aorta is performed in this hospital for graft replacement of suprarenal aneurysms or during endarterectomy for extensive aortic occlusive disease. The anaesthetic management of nine patients is described and the surgical results are presented. Proximal aortic clamping and declamping lead to profound haemodynamic changes. Myocardial infarction, ventricular failure and even death may result. Renal preservation during clamping and massive blood transfusion are also problems of this surgical approach. The measures taken to ameliorate the consequences of proximal aortic clamping are discussed in detail.

Aged↗
PubMed1988

Use of silicone elastomer for improvement of intestinal clamp.

An intestinal clamp was improved by application of a silicone elastomer measuring 3, 4 and 5 millimeters in thickness to the nip surfaces to reduce nip force or to make pressure distribution more uniform. For the 1 kilogram weight, the output from the pressure sensor, which was placed on the blade, was decreased as the thickness of the silicone elastomer was increased. Pressures loaded on central and marginal regions of the large intestine were more than seven times greater than that on the mesenteric region with use of a conventional clamp. In contrast, pressures on all of the mesenteric, central and marginal regions were relatively low and uniform with use of clamps equipped with silicone elastomer. These results indicate that the clamp equipped with the silicone elastomer damages tissues only to a small extent because of the dispersion effect of the pressure and the uniformity of the pressure distribution.

Anastomosis, Surgical↗
PubMedDate not supplied

Prevention of spinal cord injury after cross-clamping of the thoracic aorta.

Paraplegia has been a devastating and unpredictable complication following cross-clamping of the thoracic aorta. In this study, the effect of the pressure gradient between the aortic pressure distal to occlusion and cerebrospinal fluid pressure (CSFP), defined as relative spinal cord perfusion pressure (RSPP), on the development of spinal cord injury was investigated. In 32 mongrel dogs, the thoracic aorta just distal to the left subclavian artery was cross-clamped. After a complete loss of somatosensory evoked potentials (SEP) had been confirmed, the dogs were divided into six groups by an additional cross-clamp interval and RSPP as follows: Group I (n = 6): 0 mmHg for 10 minutes; Group II (n = 8): 0 mmHg for 20 minutes; Group III (n = 3): 7.5 mmHg for 20 minutes; Group IV (n = 3): 7.5 mmHg for 40 minutes; Group V (n = 6): 15 mmHg for 40 minutes and Group VI (n = 6): 15 mmHg for 60 minutes. RSPP was adjusted by either withdrawal of cerebrospinal fluid or injection of normal saline solution into the subarachnoid space. SEP were generated by the stimulation of bilateral peroneal nerves. The incidence of postoperative paraplegia was 0% in Groups I and V, 33% in Group III, 50% in Group VI and 100% in Groups II and IV. This study showed that RSPP plays an important role in the development of spinal cord injury during cross-clamping of the thoracic aorta. Therefore, RSPP should be maintained at as high a level as possible in order to prevent spinal cord injury even if SEP disappear during aortic occlusion.

Animals↗
PubMedDate not supplied

[Clamps for cardiovascular surgery of children].

Brief information on auricular clamps, rack-type clamps for temporary hemostasis of blood vessels, clamps for compressing and joining aortal ends together, clamps for catching blood vessels is given. The instruments are available in 12 types, all are atraumatic and easy to use.

Cardiovascular Surgical Procedures↗
PubMed1985

Is paraplegia after repair of coarctation of the aorta due principally to distal hypotension during aortic cross-clamping?

The hypothesis is presented that paraplegia after coarctation of the aorta is principally due to hypotension of sufficient severity and duration. In a group of 103 patients who underwent surgery during a 10-year period, the distal aortic pressure was maintained above 60 mm Hg while the aorta was cross-clamped or the period of cross-clamping was limited to less than 20 minutes. No neurologic problems occurred. In 17 of the 103 cases aortic pressure decreased below 60 mm Hg, occurring in 8% of patients with the aorta occluded below the left subclavian artery but in 30% of those occluded above. Therapeutic measures used in the 17 patients included infusion of metaraminol in five and limiting cross-clamp time to less than 20 minutes in 11. The theory is proposed that ligation of intercostal arteries in a patient with coarctation cannot injure the spinal cord because the normal direction of blood flow is reversed. Certainly, in patients without a coarctation, such as thoracic aneurysms, ligation of a critical intercostal artery may injure the spinal cord. However, in patients with coarctation the direction of blood flow is reversed, blood flowing from the intercostals into the distal aorta. The vague relationship long noted between development of collateral circulation, including rib notching, and the frequency of paraplegia probably depends not on the presence of enlarged intercostal arteries but on whether their temporary occlusion at the time of aortic cross-clamping results in distal hypotension. Data with somatosensory-evoked potentials measured during operations on the thoracic aorta in 25 patients found no changes in sensory potentials as long as the distal aortic pressure remained above 60 mm Hg, but a gradual disappearance was found at lower pressures. In five of six patients with large thoracicoabdominal aneurysms in whom sensory potentials were absent for longer than 30 minutes, paraplegia resulted. Use of somatosensory potentials provides a significant method for evaluating methods to protect from paraplegia. This method should be far more productive than are simple clinical experiences because the fortunate rare occurrence of paraplegia, one in 200, greatly limits available data.

Aorta, Thoracic↗
PubMed1985

Electrophysiologic and voltage clamp analysis of the effects of sotalol on isolated cardiac muscle and Purkinje fibers.

The effect of dl-, d- and I-sotalol on electrophysiologic characteristics of guinea-pig papillary muscles, sheep and rabbit Purkinje fibers was studied. Standard electrophysiologic and voltage clamp techniques were used. At concentrations between 10(-6) and 10(-4) M, the main effect of sotalol consisted of prolongation of the action potential duration. In voltage clamp experiments this effect correlated with a substantial reduction of the time-dependent K current activated during the plateau of the action potential and a small reduction of the background K current. At concentrations above 10(-4) M, a secondary shortening of the action potential concomitant with a fall in maximal rate of depolarization was seen. In voltage clamp experiments this effect correlated with a decrease of a slowly inactivating Na current. In the absence of catecholamines d- and I-sotalol exerted identical effects on action potentials and voltage clamp currents.

Action Potentials↗
PubMed1985

Differential endothelial injury caused by vascular clamps and vessel loops. II. Atherosclerotic vessels.

Performance of a vascular anastomosis or repair requires meticulous, gentle technique and a bloodless operative field. Many vascular surgeons rely on commercial "atraumatic" vascular clamps for the latter; however, most experimental evidence incriminates clamps as agents of moderate to severe endothelial and medial injury. Our previous studies in normal canine aortoiliac vessels have demonstrated that silastic rubber vessel loops did not cause injury in that setting; this study examines in vivo atherosclerotic human femoropopliteal artery segments. Ten centimeter segments of perfused femoropopliteal arteries were exposed during performance of above-knee lower extremity amputation for endstage vascular insufficiency. DeBakey, Cooley, Fogarty, and bulldog vascular clamps, and double-looped silastic rubber vessel loops were applied at 3-centimeter intervals for 15 minutes. Each segment was then examined under scanning electron microscopy. All vascular clamps caused endothelial and presumed medial injury; no injury was seen with the vessel loops. Selective and preferential use of silastic rubber vessel loops is thus advocated to minimize iatrogenic complications.

Adult↗
PubMed1974

Discrete waves and phototransduction in voltage-clamped ventral photoreceptors.

Discrete waves in the voltage-clamped photoreceptor of Limulus are remarkably similar in all essential properties to those found in an unclamped cell. The latency distribution of discrete waves is not affected by considerable changes in the holding potential in a voltage-clamped cell. Both large and small waves occur in voltage-clamped and unclamped cells and in approximately the same proportion. Large and small waves also share the same latency distributions and spectral sensitivity. We suggest that small waves may result from the activation of damaged membrane areas. Large waves have an average amplitude of approximately 5 nA in voltage-clamped photoreceptors. It probably requires several square microns of cell membrane to support this much photo-current. Thus the amplification inherent in the discrete wave process may involve spatial spread of activation from unimolecular dimensions to several square microns of cell membrane surface. Neither local current flow, nor pre-packaging of any transmitter substance appears to be involved in the amplification process. The possible mechanisms of the amplification are evaluated with relationship to the properties of discrete waves.

Animals↗
PubMed1984

[The euglycemic insulin and hyperglycemic clamp technic. Methods for the determination of insulin sensitivity of tissues and glucose sensitivity of the B cell. A review].

The estimation of insulin-dependent glucose metabolism and endogenous insulin secretion in man by means of the euglycaemic insulin clamp- and hyperglycaemic clamp-technique is described. In the euglycaemic insulin clamp study plasma insulin concentration is acutely raised by approximately 100 microU/ml by a primed-continuous insulin infusion, while plasma glucose is maintained at the fasting level by means of a variable glucose infusion. Under these conditions of euglycaemic hyperinsulinaemia the amount of glucose infused plus the residual endogenous glucose release equals the amount of glucose taken up by all cells of the body. This rate of glucose metabolism ("M") thus represents an index of tissue sensitivity to exogenous insulin. In the hyperglycaemic clamp study plasma glucose is acutely raised by 125 mg/dl above basal. The amount of glucose infused to maintain hyperglycaemia too serves as a measure of tissue sensitivity to endogenous insulin. In addition, glucose-induced insulin secretion can be estimated on the basis of the plasma insulin response provided that insulin extraction by the liver remains constant.

Blood Glucose↗
PubMed1984

[Experimental model producing global brain ischemia by clamping the aorta in dogs].

Canine cerebral blood flow is supplied not only through carotid and vertebral arteries, but also through rich network of collaterals. Therefore, it is said that total body arrest is requested to assure the global brain ischemia. The global ischemic models, reported previously, were by the simultaneous occlusion of aorta and vena cava. In our model, however, the global cerebral ischemia was produced by clamping only the ascending aorta. Cardiovascular changes such as increases in left ventricular and pulmonary arterial pressure, and decrease in left ventricular dp/dt followed after ceasing of ascending aortic blood stream. The heart continued to beat during 60 minutes of the clamping. Despite of increased central venous pressure, sagittal sinus pressure and intracranial pressure remained unchanged during the aorta clamping. Ten-minutes of total cerebral ischemia was produced in 46 dogs and successful studies on cerebral and systemic variables were carried out in 68% of them. The method of clamping the aorta without occlusion of vena cava seems to be unsuitable for long term survival study because of severe loading of lung circulation. However, we conclude that this simple model is of great use for short term experiment on global brain ischemia.

Animals↗
PubMed1978

[Description of a new modified clamp for the parametrium in abdominal hysterectomies (author's transl)].

A new modified clamp for the parametrium is presented which facilitates abdominal hysterectomy in large myomatous uteri. The curbed clamp has a blunt angle of 160 degrees to its handle and permits clamping of the parametrium parallel to the longitudinal axis of the cervix. The clamp appears to be an enrichment of the available instruments for abdominal hysterectomies.

Broad Ligament↗
PubMedDate not supplied

[Significance of partial pressure and pH value of umbilical venous blood and umbilical arterial blood in the diagnosis of the condition of the newborn infant following early or late cord clamping].

The condition of the newborn at birth is documented by the Apgar score and by the blood gas analysis of the umbilical arterial blood. The question arises whether the estimations are still valid if the cord is clamped late. The investigations have been performed on 20 newborn at term: 10 babies were clamped late and 10 immediately after birth. The blood was analysed from both vessels near the placenta and the child. The pH, base excess, PCO2 and PO2 showed in both groups the expected gradients along the umbilical circulation. There was also no difference of these parameters between the two groups of early (EC) and late (LC) cord clamping: pH LC 7,26 (SD 0.05), EC 7.32 (SD 0,04)), base excess (LC - 7.7 meq/1 (SD 2.3); EC -5.2 meq/1 (SD 5.0)), PCO2 (LC 52 mmHg (SD 7); EC 44 mmHg (SD 6)) and P02 (LC 18 mmHg (SD 3); EC 17 mmHg (SD 3)). From these observations it may be concluded that the start of ventilation does not influence the blood gases in the umbilical vessels of the late clamped newborn. It may be caused by the sudden ceasing of the umbilical circulation at birth.

Acid-Base Imbalance↗
PubMed1983

Perioperative antimicrobials for cesarean delivery: before or after cord clamping?

To determine neonatal risk of exposure to intrapartum antimicrobials given to reduce maternal infection following cesarean delivery, 642 mother-infant pairs were evaluated. In 464, the mother was given an initial dose of antimicrobial(s) before cord clamping, whereas in the remaining 178 administration of these drugs was not begun until after delivery. Despite the facts that all infants were at equivalent risk for infection and that none were proved to have bacteremia, 28% of those exposed to intrapartum maternal antimicrobials were evaluated for sepsis whereas only 15% of those not exposed were evaluated (P less than .001). Excess hospital charges for infants in whom sepsis workup was initiated was $127 greater than that for infants not suspected of having sepsis (P less than .025). Of 305 women given three-dose perioperative antimicrobial therapy, 255 were given the initial dose before cord clamping and 24% experienced a subsequent uterine infection. This was not significant when compared with a uterine infection rate of 22% in 50 women in whom three-dose therapy was not initiated until after cord clamping. As maternal benefits that accrue from such intrapartum therapy are equivalent regardless of the timing of three-dose treatment, and as fetal exposure to these drugs has significant clinical and economic impacts, it is concluded that antimicrobials given to these women at high risk should be withheld until after cord clamping.

Anti-Bacterial Agents↗
PubMed1981

A new bone-holding clamp for use during internal fixation of fractures.

A new bone-holding clamp for general use during internal fixation of tubular bone fractures is described. The clamp overcomes the common problem of slippage of the reduced position of fracture ends during internal fixation. Further advantages include minimal damage to the periosseous soft tissue and periosteum, which means that the blood vessels are preserved, and the unrestricted working area provided during the operation. Owing to its design the clamp also acts as a self-retaining retractor. The clamp could be described as that 'extra hand' for which the surgeon so often feels the need during the critical stages of osteosynthesis.

Fracture Fixation, Internal↗