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PubMed1995

[History of surgical instruments: 2. The first atraumatic vascular clamp by E. Höpfner (1903)].

The author describes one of the first atraumatic vascular clamps specifically developed for vascular surgery in 1903, and used for temporary arterial occlusion. This forceps was about 15 cm long, and its spring steel jaws were separated in the middle, but approximated toward the ends. This clamp was developed by Edmund Höpfner (b. 1873) in 1903, at the Berlin University Hospital, department of Surgery, when he performed end-to-end anastomoses of divided arteries in dogs as part of his doctoral thesis. The Höpfner clamp was in common use in Germany until the 1960s.

Anastomosis, Surgical↗
PubMed1994

[The history of surgical instruments: 1. The Mikulicz peritoneal clamp].

The peritoneal clamp, which has been developed by the Breslau surgeon Johann von Mikulicz-Radecki (1850-1905), is presented on the basis of original publications from 1900. At this time, Mikulicz had been a full professor of surgery at the Medical Faculty of the University of Breslau. After laparotomy, Mikulicz recommended to seize the peritoneum with 4 to 8 clamps, developed by him to protect the wound of the abdominal wall from manipulations and to prevent a retraction of the peritoneum: "The fastened clamps are changed in their position in a way, that the grips lie out of the area of the wound on the abdominal wall." Moreover, a brief description of the Breslau surgeon's life and work is given. Further, we refer on his importance on the development of modern surgery in Germany.

History, 19th Century↗
PubMed1994

[Surgical treatment of descending thoracic aortic aneurysm with simple aortic cross-clamping versus left heart bypass using centrifugal pump].

Surgical treatment has been employed in 52 patients (pts) with descending thoracic aortic aneurysm (DS-TAA). Based on the adjuncts during aneurysmal repair, the series is divided into 2 groups; simple aortic cross-clamping was utilized to manage the lesion in group SC (n = 42), while left heart bypass using a centrifugal pump was employed during the period of aortic occlusion in LHB group (n = 10). Of these 52 pts, 4 died in hospital (group SC:2, group LHB:2). The most common complication was the respiratory failure following the renal failure. No paraplegia occurred in both groups. Biochemistric measurements of alanine aminotransferase, creatinine (CRN) and amylase (AMY) showed no difference between group SC and group LHB. In pts of SC group with normal renal function, post-operative maximum (post Max) CRN during the first month had a logarithmic correlation with total aortic cross-clamp time (TAXT). The post Max CRN of LHB group with normal renal function remained less than 3.0 mg/dl even in the case with TAXT over 60 minutes. There is also a linear correlation of post Max AMY in pts of SC group. Late survival at 4 years, including hospital death, were 83% in SC group and 63% in LHB group. We conclude that DS-TAA cases with TAXT of less than 30 min with good distal organ function can be managed with simple aortic cross-clamping; otherwise usage of LHB was recommended to support distal circulation.

Adult↗
PubMed1993

[Myocardial protection during aortic cross-clamping for more than 240 minutes].

The efficacy of cold crystalloid cardioplegia (St. Thomas II solution) during aortic cross-clamping more than 240 minutes was evaluated in 5 patients with non-coronary diseases undergoing heart surgery. The ischemic time ranged from 257 to 302 minutes with the mean of 274 minutes. As the technique of myocardial protection, multidose antegrade crystalloid cardioplegia was used at an interval of 20 minutes. These patient were compared with another patient group with clamping time 120-180 minutes. There was no difference between the two groups in terms of mortality, cardiac index, CK, CK-MB, GOT, LDH. These findings suggest that cold crystalloid cardioplegia provided clinically satisfactory myocardial protection during the aortic cross-clamping for more than 240 minutes.

Adult↗
PubMed1993

[Efficacy of myocardial preservation using HTK solution in continuous 120 min cross-clamping method--a comparative study with GIK method].

The aim of this study is to investigate the efficacy of HTK solution in the 120 minutes cross-clamping method in comparison with conventional intermittent cardioplegia using GIK solution. Fifty-four open heart surgery were performed with cardioplegic solution using either HTK solution (HTK) or GIK solution (GIK). In the HTK, HTK (3L) was infused for the initial dose and 1L was added every 60 min after 120 min of cross-clamping. In GIK, 1L of GIK solution was intermittently infused initially and then every 30 min together with continuous cold blood perfusion. The effect of two cardioplegic solution was evaluated by postoperative cardiac function (CI, %SF), released enzymes (CPK), histology and dosage of catecholamine. Postoperative CI was 3.67 +/- 0.76 in HTK, and 4.34 +/- 1.04 in GIK (NS). % SF was 26.0 +/- 5.26 in HTK and 25.6 +/- 0.76 in HTK, and 4.34 +/- 1.04 in GIK (NS). %SF was 26.0 +/- 5.26 in HTK and 25.6 +/- 9.2 in GIK (NS). The CK-MB (IU/dl) level after reperfusion was significantly decreased in HTK at 60 and 180 min after reperfusion. Histology at 60 min of ischemia revealed a significant increase of edema of mitochondria in GIK. Postoperative catecholamine dose was 2.65 +/- 1.3 in HTK and 10.3 +/- 3.4 in GIK (p < -0.01). PH of myocardium was well maintained around 7.4 during cross-clamping in HTK, however, it was decreased in GIK. In conclusion, The HTK method offers a reliable cardiac protection due to effective buffering using Histidine in comparison with GIK.

Cardioplegic Solutions↗
PubMed1993

Metabolic effects of lacidipine: a placebo-controlled study using the euglycaemic hyperinsulinaemic clamp.

1. Twelve healthy male volunteers received lacidipine 4 mg and matching placebo, each for 2 weeks, in a randomised, double-blind crossover study, and attended on 4 study days to evaluate the effects of single and multiple dosing using the euglycaemic hyperinsulinaemic 'clamp'. 2. On each study day, a primed constant-rate infusion of soluble insulin (1.5 mu kg-1 min-1) was administered for 180 min with a variable-rate infusion of 20% dextrose to maintain euglycaemia (5.2 mmol l-1). Whole-body insulin sensitivity was calculated during the past 40 min of the 'clamp'. At frequent intervals, measurements of BP and HR were recorded and venous blood samples collected for serum insulin, C-peptide, potassium, triglyceride (TG) and plasma noradrenaline concentrations. 3. Lacidipine was generally well tolerated and there were no adverse biochemical events. Mean values for insulin sensitivity +/- s.d. were 8.9 +/- 1.6 and 9.1 +/- 2.0 mg kg-1 min-1 after single doses of lacidipine and placebo respectively (95% CI, -1.0, 1.3), and correspondingly 9.6 +/- 2.1 and 9.7 +/- 1.5 mg kg-1 min-1 after 2 weeks (95% CI, -1.0, 1.3). 4. There was a significant reduction in fasting serum TG concentrations after 2 weeks of lacidipine: 0.7 +/- 0.3 mmol l-1 vs 0.9 +/- 0.6 (P < 0.001). However, changes in serum TG and potassium concentrations during the 'clamp' were not significantly different between the 4 study days. 5. Thus, in 'insulin sensitive' volunteers, lacidipine reduces fasting serum TG concentrations but has no effect on insulin-stimulated uptake of glucose, potassium and TG under euglycaemic hyperinsulinaemic conditions.

Adolescent↗
PubMed1995

Ketanserin effects on insulin sensitivity in nonobese, nondiabetic hypertensive patients: an evaluation by the euglycemic-hyperinsulinemic clamp technique.

The aim of this study was to assess the effects of ketanserin on insulin resistance in nondiabetic hypertensive patients. Eleven nonobese, nondiabetic mild to moderate hypertensives (6 males, 5 females, aged 39-59 years), after a 4 week run-in period on placebo, were treated with ketanserin 40 mg twice daily for 12 weeks. Blood pressure (BP) (by standard mercury sphygmomanometer) and insulin sensitivity (by the euglycemic hyperinsulinemic clamp technique) were evaluated at the end of the placebo period and at the end of the treatment period. Ketanserin produced a significant decrease in BP (from 160 +/- 13/100 +/- 4 mmHg to 146 +/- 10/89 +/- 5 mmHg p < 0.01). The amounts of exogenous glucose required to hold glucose levels constant during clamp were not changed by ketanserin as compared to placebo 34.5 +/- 3.5 g vs 33.8 +/- 3.1 g). The rate of glucose infusion required during the last 60 minutes of the clamp, used as an indicator of insulin sensitivity, was not different before and after treatment (5.52 +/- 0.41 mg/min/ kg vs 5.21 +/- 0.39mg/min/kg). These results suggest that in nonobese, nondiabetic hypertensive patients ketanserin monotherapy is effective in reducing BP values without affecting insulin sensitivity.

Adult↗
PubMed1996

How I do it: emergency nasal packing using an umbilical cord clamp to secure a Foley catheter for posterior epistaxis.

Posterior nasal balloon tamponade using a Foley catheter is a well-known, easy, and quick way to bring an end to a posterior epistaxis in emergency situations. To prevent loosening and displacement of the balloon away from the choana, some metallic devices that may crush or tear the catheter are often used. Being light and easy to install, a plastic umbilical cord clamp is a good alternative. While providing a stable double grip on the catheter, the Hollister umbilical clamp does not crush it. When the clamp is removed, saline can be aspirated from the balloon and the catheter left in place with the nasal packing. Afterward, if needed, the saline can be reinjected to restore the tamponade.

Balloon Occlusion↗
PubMed1996

Echocardiographic monitoring of minimally invasive mitral valve surgery using an endoaortic clamp.

BACKGROUND AND AIMS OF THE STUDY: Twenty-four patients underwent minimally invasive mitral valve repair (n = 16) or mitral valve replacement (n = 8) using the Port-Access system. Intraoperative transesophageal echocardiography (TEE) was used in these patients to: (i) reassess valve pathology preoperatively; (ii) guide and continuously assess placement and position of the aortic endoclamp; (iii) measure aortic root diameters, aortic distensibility and aortic wall appearance prior to and after aortic endoclamping; (iv) evaluate the de-airing procedure; (v) evaluate the results of mitral valve repair; and (vi) guide weaning from cardiopulmonary bypass (CPB). METHODS AND RESULTS: Placement and positioning of the endoclamp was guided effectively in all but one patient who had acute retrograde aortic dissection with the onset of femoro-femoral bypass. The mean position of the tip of the endoclamp was 2.8 +/- 0.5 cm from the aortic valve annulus. The position was stable in all but five patients in whom repositioning and additional clamp volume were required. There was only a poor relationship between balloon volume and sinotubular junction diameter. The dynamic movement of the aorta was well preserved after clamping and the elasticity module did not change significantly (1.6 +/- 0.71 vs. 1.5 +/- 0.75 dynes x 10(6)/cm2). No intimal tears or wall edema was observed after clamp release. De-airing was incomplete in five patients, two of whom had transient ST-elevations with regional wall motion abnormalities. Weaning of CPB was therefore postponed until the ECG had normalized. All mitral valve repairs but one were successful (equal to or less than grade I residual mitral insufficiency). One patient with persistent grade II mitral insufficiency underwent valve replacement using the same approach. CONCLUSIONS: TEE can effectively guide minimally invasive mitral valve surgery using the Port-Access system. Placement and positioning of the endoclamp and its effects on the aortic wall can be evaluated. De-airing, weaning from CPB and the results of the procedure were effectively monitored using TEE.

Aorta↗
PubMed1996

Non clamping anastomosis of the ascending and arch aneurysm using retrograde cerebral perfusion.

Twelve consecutive patients requiring surgery for replacement of ascending aortic aneurysms (n = 3), ascending arch aortic aneurysms (n = 2), or type A aortic dissections (n = 7) were treated without aortic cross clamping. Retrograde cerebral perfusion (RCP) with circulatory arrest (mean RCP time: 46.0 +/- 15.9 minutes, range 20 to 65 minutes) and continuous retrograde cardioplegia (mean cardiac ischemic time: 134.4 +/- 39.7 minutes, range: 40 to 180 minutes) were employed. In the patients with aortic dissection, the intimal tear at the origin of the brachiocephalic artery (BCA) was resected completely, the aortic wall was trimmed and closed with Teflon felt. The distal anastomosis was created using an open technique. Air and debris were completely evacuated by returning blood from the cerebral vessels and femoral artery. Then the artificial graft was clamped, and cardiopulmonary bypass resumed. The proximal anastomosis was performed during rewarming. The operations were elective in seven cases, and emergent in five cases. Graft replacement of the ascending aorta was performed in ten patients (including two BCA reconstructions). The remaining two patients were treated by patch repair (n = 1), primary anastomosis (n = 1). There were no perioperative deaths. One patient had a transient neurological deficit. The distal false lumen was occluded completely in five of seven patients with aortic dissections. The other two patients had a secondary tears in the descending aorta. Thus retrograde cerebral perfusion and continuous retrograde cardioplegia without aortic cross clamping is an effective technique in the replacement of the ascending and arch aorta.

Adult↗
PubMed1977

[Membrane potential clamping in the horizontal cells of the fish retina].

The membrane potential of horizontal cells was clamped using uniform polarization of a layer of these cells by means of current passed via extracellular electrodes. It is shown that the voltage-current relationship of the nonsynaptic membrane of horizontal cells has in some cases sections with a negative slope. With fast shifts in the clamped potential level the changes in the membrane resistance are completed less than for 20 ms. Comparison of responses to light stimulation recorded with potential clamp and without it showed that participation of the nonsynaptic membrane in generation of responses to light stimulation can change significantly the form of the latter.

Animals↗
PubMed1997

Effect of timing of cord clamping on the iron status of infants at 3 months.

OBJECTIVE: To determine the effect of timing of cord clamping on iron stores of term infants at 3 months of age. DESIGN: Prospective randomized clinical trial. SETTING: Tertiary hospital. SUBJECTS: 107 term neonates born to mothers with uncomplicated pregnancies and with hemoglobin more than 10 g/dl. METHODS: The 107 infants were randomized to either early (n = 48) or late (n = 59) clamping groups at the time of delivery. Outcome measures evaluated were serum ferritin and hemoglobin in the infant at 3 months age. RESULTS: The groups were comparable for maternal age, parity, weight, supplemental iron intake in pregnancy, infant's birth weight, gestation and sex. Maternal and cord ferritin and hemoglobin values at birth were comparable. The infant ferritin at 3 months were also similar. CONCLUSIONS: Iron stores at 3 months in term infants are not influenced by timing of cord clamping at birth.

Analysis of Variance↗
PubMed1997

The clamp fixation method in cemented total knee arthroplasty. Dynamic experimental and radiographic studies of the tibial baseplate clamper.

The clamp fixation method using the Tibial Baseplate Clamper in total knee arthroplasty (TKA) is a superior procedure compared to conventional cement fixation methods. A dynamic experimental study and a radiographic study were performed to make sure the efficiency of the clamp fixation method was satisfactory. As a result, this procedure showed the large initial pressure force and a lack of variance in the force applied over time, and also it had a large depth of cement penetration compare to the pusher method. The clamp fixation method will help the surgeon achieve excellent cement fixation in TKAs because it has the many advantages of a gentle, yet strong, constant, and, most importantly, simple approach surgeons can use to reduce operating time while cementing all three prostheses simultaneously.

Arthritis, Rheumatoid↗
PubMed1997

Evaluation of the calcium-PTH axis and renal handling of phosphate by calcium and citrate clamp techniques in normal subjects and in patients with heavy proteinuria.

We studied the effect of induced hyper- and hypocalcemia on parathyroid function and renal handling of phosphate in healthy subjects (n = 10) and in patients with heavy proteinuria, mean 5.6 +/- 1.9 g/24 hours (n = 5). We used calcium and citrate clamp techniques. Hypercalcemia was rapidly induced by calcium infusion and maintained for 120 min, and correspondingly, hypocalcemia by citrate infusion. The suppression of intact PTH secretion during calcium clamp was similar (to the level of < or = 0.8 pmol/l) in both groups. The response of the parathyroid glands to hypocalcemia was similar in normal subjects and proteinuric patients. Both groups showed a peak of PTH secretion at 10 min, 18.9 +/- 6.7 pmol/l in healthy subjects and 20.4 +/- 7.4 pmol/l in patients. The peak levels were 4.8-7.2 times and 4.0-6.7 times the baseline level, respectively. Thereafter the plasma PTH concentration declined to a fairly constant steady-state level (twice the baseline level) in spite of maintained hypocalcemia. The area under the curve of the plasma concentrations of intact PTH at various times (AUC0-120) was 890 +/- 324 pmol/l/min in normal subjects and 989 +/- 331 pmol/l/min in proteinuric patients, the difference between the groups being again not significant. The renal threshold phosphate concentration (TmPO4/GFR) increased during calcium infusion and decreased during citrate infusion in both groups. During recovery from hypocalcemia PTH levels were lower than during hypocalcemic induction at corresponding serum calcium levels. Using calcium and citrate clamp techniques, we found that the response of the parathyroid glands in acute and maintained hypercalcemia and hypocalcemia, and renal phosphate handling in patients with heavy proteinuria was not different from that of healthy subjects.

Adult↗
PubMed1998

Clamping breath alcohol concentration reduces experimental variance: application to the study of acute tolerance to alcohol and alcohol elimination rate.

An oral loading dose was combined with intravenous infusion of 6% alcohol at rates adjusted on-line to close the gap between measurements of breath alcohol concentration (BrAC) and a target of 50 mg%. The goal was to minimize the deviation from a prescribed course of BrAC over time. In a pilot study of 10 young men, subjects underwent three experimental sessions: twice at 50 mg% and once in a 0 mg% control condition. The pilot study assessed the performance of the BrAC clamp, its potential utility in studies of acute tolerance to alcohol, and the retest reliability of directly measuring the alcohol elimination rate (AER) calculated from the steady-state infusion rate. Reduced variance was demonstrated in 4 of 5 experimental parameters, compared with results of an earlier approach using a split-dose oral administration procedure. Subjects' perceptions about alcohol effects were measured in one BrAC clamping session, using Schuckit's Subjective High Assessment Scale: 3 of 15 Schuckit's items demonstrated statistically significant indices of acute tolerance to alcohol. Within-subject AERs calculated in the steady-state had a coefficient of variation of 6.5%. Details of the BrAC clamping procedure are provided. The pilot study demonstrated the ability to prescribe experimental parameters of the brain's exposure to alcohol while preserving experimental flexibility in studies of acute tolerance to alcohol and AER.

Adult↗
PubMed1998

Umbilical cord clamping. An analysis of a usual neonatological conduct.

Here we described a critical analysis of the neonatological procedure of early cord clamping, meaning this, within 40 seconds after birth. Fifty three cases are here analysed, in which this practice was not performed, but instead a late umbilical cord clamping was done after birth or after the cord had stopped beating. Variations in hematocrito values within 24 to 36 hours after birth were studied. A transitory polycithemia, with a maximum peak 12 hours post-delivery was observed. These values returned to normal levels between 24 and 36 hours after birth. K vitamin was not administered to any of the newborns. No pathology appeared related to this transitory polycithemia. In can be concluded that the late umbilical cord clamping represents no risk to the new-born and that the pathological phenomena described under these circumstances may be attributed to the increase in K vitamin dependent coagulation factors that are induced by the routinary administration of phitonadione to all normal newborns.

Adult↗
PubMedDate not supplied

Can clamping of splenic vessels prevent abrupt increase of portal vein pressure and migration of transplanted hepatocytes to the liver after intrasplenic hepatocyte transplantation?

BACKGROUND/AIMS: It is well known that hepatocyte transplantation can retain some proper functions, significantly improve the survival rate of rats with different models of acute fulminant hepatic failure, correct some congenital genetic disorders, and improve liver function in cirrhosis. Portal hypertension and hepatic embolization have been described following intrasplenic hepatocyte transplantation. We evaluated the effect of temporary occlusion of splenic vessels on changes in portal vein pressure and on distribution of transplanted hepatocytes after hepatocyte transplantation into the spleen in normal rats. METHODOLOGY: Liver cirrhosis has been induced in rats by 1% dimethylnitrosamine (Sigma, St. Louis, Mo) dissolved in normal saline at the dose of 10 ml of DMN/Kg, i.p., 3 consecutive days a week for 4 weeks. Donor hepatocytes were harvested by in situ ethylenediaminetetraacetic acid (EDTA) perfusion. Changes in portal vein pressures were monitored by a pressure monitor and distribution of transplanted hepatocytes was assayed by measurement of radioactivity of 51Cr-labeled transplanted hepatocytes according to clamping or non-clamping during intrasplenic hepatocyte transplantation. RESULTS: The changes in portal pressure remained significantly high 10 min after hepatocyte transplantation in the nonocclusion groups compared to the occlusion groups. However, the changes in portal vein pressures in cirrhotic rats returned to normal faster than in normal rats after cell transplantation in the nonocclusion groups. The distribution of 51Cr-labeled transplanted hepatocytes into the spleen significantly diminished radioactivity of the liver at 10 min, 2 hours, and 24 hours in the occlusion groups compared to the nonocclusion groups. Also, duration of clamping time of splenic vessels did not influence the initial distribution of transplanted hepatocytes at the time of intrasplenic hepatocyte injection. CONCLUSIONS: These results suggested that temporary occlusion of splenic vessels should be routinely used during intrasplenic hepatocyte transplantation.

Animals↗
PubMedDate not supplied

Enhancement of blood glucose lowering effect of a sulfonylurea when coadministered with an ACE inhibitor: results of a glucose-clamp study.

BACKGROUND: To investigate if coadministration of enalapril alters the metabolic effect of glibenclamide by employing an euglycemic glucose-clamp technique in healthy volunteers. METHODS: A double-blind crossover study with nine healthy normotensive volunteers (age 27 +/- 3 y, BMI 23.3 +/- 2.0 kg m(-2); mean +/- SD)-randomly assigned to a 3-day treatment of either 5 mg enalapril or placebo. In the morning of the fourth day, volunteers orally received 3.5 mg glibenclamide together with either 10 mg enalapril or placebo. Blood glucose levels of volunteers were allowed to fall by 10% from fasting levels and were kept constant thereafter by employing a Biostator-based euglycemic glucose clamp. RESULTS: Coadministration of enalapril-compared with placebo-resulted in a temporarily higher metabolic effect of glibenclamide (AUC GIR(0-120)229 +/- 173 vs 137 +/- 44 mg kg(-1), p < 0.01; mean +/- SD), which lasted from 120 min to 240 min after enalapril administration. In parallel, the maximal metabolic effect of glibenclamide tended to be higher with enalapril (GIR(max)5.2 +/- 1.9 vs 4.1 +/- 1.3 mg kg(-1) min(-1); p = 0.19). However, the total metabolic effect of glibenclamide was almost identical between volunteers taking enalapril or placebo (AUC GIR(0-600)1267 +/- 334 vs 1286 +/- 249 mg kg(-1), ns). In contrast, serum insulin levels, C-peptide levels, and serum glibenclamide profiles were not significantly different between enalapril and placebo. CONCLUSIONS: The results of this study may explain the higher incidence of hypoglycemic episodes observed in patients with type 2 diabetes when taking ACE inhibitors together with sulfonylureas or insulin. ACE inhibitors may cause a temporary increase of the insulin sensitivity, which leads to an increased risk of hypoglycemia under these conditions.

Adult↗