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Biomedical subjects

A Kulier

Publications and source records attributed to A Kulier.

8 recordsLinked to original sources
PubMed2001

[Perioperative anemia].

Anemia is a frequent finding, particularly in the elderly population, and usually indicative of a serious disease. The main causes of preoperative anemia are acute or chronic hemorrhage, iron deficiency, renal insufficiency, inflammatory and neoplastic diseases. A preexisting mild anemia may be enhanced or unmasked by surgically induced bleeding or repeated diagnostic phlebotomies, and by a postoperative erythropoietic dysfunction caused by the surgical trauma, irrespective of any hemorrhage. Low hemoglobin values are associated with a distinct increase of mortality and morbidity, both in the normal population and perioperatively and in the critically ill patients. The anemia-associated risk is exacerbated by preexisting cardiovascular disease, important intraoperative blood loss and advanced age. In contradiction to established therapeutical concepts, the administration of allogeneic blood beyond hemoglobin levels of 8-10 g/dl has not been found to decrease perioperative or intensive care morbidity or mortality. Rather, in addition to the inherent long-term risks of transfusions, a liberal transfusion strategy seems to increase the incidence of postoperative complications. Thus, current transfusion guidelines tend to be interpreted in an increasingly restrictive manner. Depending on the urgency of the clinical situation, the primary goal should be to diagnose and treat the underlying disease, rather than to focus on the symptom anemia. Time permitting, the patient's cardiovascular and pulmonary status should be optimized preoperatively. Furthermore, iron should be substituted to treat and prevent deficiency. Recombinant human erythropoietin has successfully been used to treat anemia of chronic renal failure and chronic disease, as well as in the perioperative and intensive care setting, and to support the efficiency of autologous programs.

Aged↗
PubMed2000

The influence of positioning on spectroscopic measurements of brain oxygenation.

This study was designed to evaluate the influence of body position during neurosurgical and cerebrovascular operations on regional cerebral oxygen saturation (rSO2). Awake volunteers (group I; n = 14), anesthetized patients (group II; n = 48) undergoing lumbar discectomy, and 12 patients undergoing carotid endarterectomy (group III) with internal carotid artery (ICA) stenosis were studied. Anesthesia in the patient groups was performed with sevoflurane (1.1 Vol% insp.) in N2O2/O2 mixture (FiO2 0.4) rSO2 was monitored with a INVOS 4100 cerebral oxymeter (Somanetics Corporation, Troy, MI). Measurements were done in all groups in supine position with head turned to the right and left side. Furthermore, in groups I and II, rSO2 was measured in right lateral, left lateral, prone, or sitting position. In each position the parameters were registered at three times (1, 3, and 5 min after taking up the position). In the healthy volunteers, the mean rSO2 values of both hemispheres were 71.3 +/- 5.0%. No significant changes of rSO2 were found interhemispherical and upon turning the head to both sides or positioning to the prone and both lateral positions. After assuming the sitting position, the decrease of rSO2 was not significant. In group II, rSO2 decreased significantly in the sitting position. In group III, baseline readings for rSO2 obtained from the side of ICA stenosis were significantly lower, compared to the contralateral side. After turning the head to the ipsilateral side, this difference diminished. In contrast, turning the head toward the contralateral side, the rSO2 difference remained nearly constant, both values decreasing constantly throughout the observation period. In conclusion, after different positioning maneuvers awake and under anesthesia, alterations of rSO2 can be registrated by near-infrared spectroscopy (NIRS).

Adult↗
PubMed1996

Magnetic resonance imaging of cerebrospinal fluid volume and the influence of body habitus and abdominal pressure.

BACKGROUND: Although the cerebrospinal fluid (CSF) is the pathway of anesthetic delivery and the diluent for neuraxially administered drugs, little is known about its volume, including variability among individuals, longitudinal distribution, or influence of body habitus. Models made to investigate subarachnoid anesthetic distribution lack valid dimensions. CSF volume was measured in volunteers, and the effect of obesity and abdominal compression on CSF volume was evaluated using magnetic resonance imaging. METHODS: Low thoracic and lumbosacral axial magnetic resonance images of 25 healthy volunteers were obtained at 8-mm intervals by fast spin-echo sequence, which highlights CSF. A repeat image series was performed in 15 subjects during external abdominal compression. In two subjects, images were obtained without compression for the entire vertebral column. Dural sac and spinal cord areas were determined in a blinded fashion for each image using video/digital analysis. Area of the sac minus area of the cord constituted area of CSF and roots ("CSF/root"); this area multiplied by 8 mm resulted in CSF/root volume per section. RESULTS: There is great interindividual variability in CSF/root volume. From the T11-T12 disc to the sacral terminus of the dural sac, the mean volume for all subjects is 49.9 +/- 12.1 ml (mean +/- SD; range 28.0-81.1 ml). This volume was significantly less in relatively obese subjects (42.9 +/- 9.5 ml) than in nonobese subjects (53.5 +/- 12.9 ml). Abdominal compression decreased CSF/root volume by 3.6 +/- 3.2 ml. Sections through intervertebral foramina showed the biggest decrease with abdominal compression, with a lesser change in sections with veins and no change in the absence of these anatomic features. Total vertebral CSF/root volume in two subjects was 94.84 and 120.01 ml, respectively. CONCLUSIONS: CSF volume is widely variable between individuals. The decreased CSF volume that results from increased abdominal pressure, such as with obesity or pregnancy, may produce more extensive neuraxial blockade through diminished dilution of anesthetic. The mechanism by which increased abdominal pressure decreases CSF volume is probably inward movement of soft tissue in the intervertebral foramen, which displaces CSF.

Abdomen↗
PubMed1996

Sympathetic and mesenteric venous responses to baroreceptor or chemoreceptor stimulation during epidural anesthesia in rabbits.

BACKGROUND: Baroreceptor and chemoreceptor reflexes maintain homeostasis through mechanisms that involve sympathetic activation. Because sympathetic control of the mesenteric veins plays a central role in hemodynamic responses to stress, the effects of epidural blockade on reflex responses to hypoxia and bilateral carotid occlusion (BCO) were examined by monitoring direct measures of splanchnic sympathetic neural traffic and mesenteric venous capacitance. METHODS: Rabbits were studied during alpha-chloralose anesthesia and mechanical ventilation. Sympathetic efferent nerve activity to the mesenteric vessels was measured by surgically placed electrodes, and mesenteric venous diameter was measured by videomicroscopy. Heart rate and mean arterial pressure were monitored by intraarterial cannulation. Intraluminal venous pressure was monitored by a servo-null micropressure technique. Responses were recorded during repeated administration of three different stresses, F1O2 = 0% for 40 s, F1O2 = 11% for 2.5 min, and BCO for 60 s. Animals received either thoracolumbar epidural blockade (0.4 ml/kg lidocaine 1.5%; n = 7) or 15 mg/kg intramuscular lidocaine (n = 7). RESULTS: Hypoxia and BCO produced sympathetic stimulation and active constriction of mesenteric veins. Epidural anesthesia accentuated the mean arterial pressure decrease from F1O2 of 0%, caused the 11% response to F1O2 to become depressor instead of pressor, and decreased the pressor effect BCO. Sympathetic efferent nerve activity and venous diameter responses to hypoxia and BCO were attenuated or eliminated. CONCLUSIONS: The hemodynamic effects of hypoxia result from a combination of direct depression and reflex activation. Thoracolumbar epidural anesthesia in rabbits impairs compensatory reflexes invoked by chemoreceptor stimulation and eliminates response to baroreceptor stimulation. Loss of splanchnic control of mesenteric capacitance contributes to the inhibition of the hemodynamic response to hypoxia or BCO during epidural anesthesia in rabbits.

Anesthesia, Epidural↗
PubMed1995

[Reduction in the use of donated blood in surgical medicine].

After rapid changes in transfusion practice over the past few years, blood conservation techniques have become standard in modern perioperative management. As a result, the amount of homologous blood products transfused has been markedly reduced in some types of surgical procedures. Provided that skillful surgical technique is applied and the use of blood products is restricted, autologous transfusion techniques (predonation of autologous blood, preoperative plasmapheresis, acute normovolaemic haemodilution, and intra- and postoperative blood salvage) can be performed with an acceptable risk for patients. In addition, stimulation of erythropoiesis with recombinant human erythropoietin, supplemental iron therapy, and improving haemostasis by aprotinin may further reduce homologous blood requirements. All patients undergoing elective surgery have to be informed about the side effects of transfusion of homologous blood products and the possibility of blood-saving methods. An individual blood conservation plan, based on the patient's status and surgery, the equipment available, and personal experience should be worked out by the responsible anaesthesiologist, whereby a combination of different methods may be most effective. If storage is necessary, autologous blood products should be preparated like homologous products. The feasibility of predonation and retransfusion of autologous blood in patients with infectious diseases like hepatitis or acquired immune deficiency syndrome and the amount of labaratomy testing are still under discussion. Although blood conservation programs are time-consuming and more expensive, they reduce the various risks of using homologous blood products.

Adolescent↗
PubMed1994

Erythropoietin in patients undergoing coronary artery bypass graft surgery.

Recombinant human erythropoietin (rHuEPO) has proved to be a useful drug that can aid in protecting patients from possible hazards of homologous blood. Use of rHuEPO for patients scheduled for coronary artery bypass graft (CABG) surgery can enhance the benefit of a preoperative autologous blood donation program while simultaneously minimizing its risks. The main objective are to decrease homologous transfusion requirements by increasing the amount of collected autologous blood and to maximize safety by ameliorating a pre- or postoperative anemia. The goal of this review is to assess the possible benefits of perioperative use of rHuEPO during CABG surgery. Furthermore, we evaluate its ability to augment the quality of collected blood and to lower the risk of autologous blood donation. Side effects, dosages, manner of administration, concomitant iron therapy and suggestions for special patient groups will be discussed.

Blood Transfusion, Autologous↗
PubMed1990

[Hemofiltration in acute kidney failure. Experiences of a surgical intensive care station].

Until recently acute renal failure (ARF) in critically ill patients has been known to have a very poor prognosis, particularly when associated with multiple organ failure (MOF). Mortality rates for ARF in combination with at least two other failing organ systems have ranged over 90%. Despite the use of intermittent hemodialysis no better outcome was possible until continuous arteriovenous hemofiltration (CAVH) was introduced by Kramer in 1977. From several extracorporeal clearance methods we chose to evaluate the pump-driven intermittent venovenous hemofiltration (HF) system in the ICU and its effect on mortality in MOF. PATIENTS and METHODS. Over a period of 39 months we evaluated 63 patients, 58 of them with MOF undergoing altogether 532 sessions of HF. The reason for the development of ARF was prerenal in 47% (circulatory shock, hypovolemia), renal in 43% (septic) and other problems in 10% (ARDS, cardiac failure). After special optimizing therapy for patients with ARF (10), HF was required for treatment as defined by a serum creatinine greater than 3 mg/dl (BUN greater than 150 mg/dl), oliguria of less than 30 ml/h or a creatinine clearance of less than 20 ml/min. Vascular access was obtained by a double lumen venous cannula inserted into the subclavian vein. HF was performed by a machine equipped with 3 roller pumps and an electronic fluid equilibration system using a hollow fiber filter running for 6-8 h. The average flow of ultrafiltrate was 74 ml/min. RESULTS. The average decrease per hemofiltration of creatinine levels was 1.97 +/- 0.77 mg/dl, of BUN 73.5 +/- 28.3 mg/dl. Moreover, we noticed decreasing platelet counts, fibrinogen and osmolarity levels, as well as a slight increase in pH values. Mortality was 37%. DISCUSSION. When comparing HF with other clearance methods such as hemodialysis there are some remarkable advantages: easier handling of the fluid and electrolyte balance; the possibility of total i.v. alimentation in septic, hypercatabolic patients, safe and precise administration of antibiotics, glycosides and sedatives because of their highly predictable and steady elimination rates throughout HF; last but not least, the removal of renal and vasoactive toxins. There was practically no impairment of the cardiovascular system during HF. Our experiences in the ICU show that HF has been successfully used with decreasing mortality. This kind of treatment improved the fate of the critically ill patient with ARF alone or combined with MOF to the extent that the patient's prognosis was excellent if the main surgical problems could be solved.

Acute Kidney Injury↗