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Biomedical subjects

K Gefke

Publications and source records attributed to K Gefke.

11 recordsLinked to original sources
PubMed1994

Abdominal aortic aneurysm surgery: survival and quality of life in patients requiring prolonged postoperative intensive therapy.

The goal of this study was to identify patients who need longer care in the ICU (more than 48 hours) following abdominal aortic aneurysm (AAA) surgery and to evaluate the influence of perioperative complications on short- and long-term survival and quality of life. AAA surgery was performed in 553 patients, 51 (9%) of whom died within the first 48 hours. Of the 502 patients who survived for more than 48 hours, 109 required ICU therapy for more than 48 hours, whereas 393 patients were in the ICU for less than 48 hours. The incidence of preoperative risk factors was similar for the two groups. The cumulated survival rates for the two groups were 68% and 92% at 1 months, 52% and 88% at 1 year, and 60% and 33% at 6 years, respectively. This significant difference was primarily related to renal, pulmonary, and cardiac complications. However, assessment of the most severe complications and risk factors combined failed to permit identification of patients in whom the perioperative survival rate was 0%. Even 20% of patients with multiorgan failure survived for 6 months. Of those patients who needed ICU therapy for more than 48 hours, 41 (38%) were alive at the end of 1988. In response to a questionnaire, 78% stated that their quality of life had improved or was unchanged after surgery and had resumed working. These data justify a therapeutically aggressive approach, including ICU therapy following AAA surgery, despite failure of one or more organ systems.

Aortic Aneurysm, Abdominal↗
PubMed1994

Brain damage following low flow cardiopulmonary bypass in pigs.

Reduction of pump flow during cardiopulmonary bypass (CPB) reduces the formation of microemboli and trauma to the blood components, reduces both rewarming of the heart and the noncoronary collateral flow, and improves surgical exposure. Recent studies indicate that a reduction in pump flow, even at normothermia, does not increase the incidence of postoperative cerebral dysfunction. We examined the cerebral consequences of 2 h of normothermic CPB in pigs carried out at pump flows of either 70 ml/kg per min or 50 ml/kg per min, and compared the results with those of a nonperfused control group. We measured the regional cerebral glucose metabolism and the regional capillary diffusion capacity simultaneously in ten different brain regions. Brain morphology, the blood-brain barrier permeability to serum proteins and the regional cerebral water content were also determined in the same animals. Glucose metabolism decreased significantly in both CPB groups (P < 0.001), and significant differences were found between the capillary diffusion capacities of the three groups (P < 0.05), with decreases in eight out of ten brain regions examined in the 50 ml/kg per min group. The results indicate that a reduction of pump flows from 70 ml/kg per min to 50 ml/kg per min is deleterious to the brain, and that a pump flow of 70 ml/kg per min itself has an injurious effect, when normothermic CPB is carried out for 2 h without the use of vasoactive drugs to maintain the blood pressure. Mean arterial blood pressure (MAP) rather than pump flow seemed to determine the adequacy of the cerebral perfusion.

Animals↗
PubMed1994

Arterial line filtration protects brain microcirculation during cardiopulmonary bypass in the pig.

Microemboli in the brain may inhibit brain function during cardiopulmonary bypass, and in a previous study in pigs of normothermic nonpulsatile bypass we reported a significant decrease in cerebral glucose consumption secondary to interruption of the capillary flow, possibly caused by microemboli. In the present study we measured the regional cerebral glucose consumption and the regional capillary diffusion capacity (that is, the number of perfused capillaries) in 10 different brain regions in two separate groups of animals with and without an arterial filter during normothermic cardiopulmonary bypass. Inclusion of a 40 micron arterial filter in the bypass circuit increased the regional brain glucose consumption 27% (median; range -12% to 145%) and regional capillary diffusion capacity increased 123% (median; range 36% to 829%). No change in brain histologic features, the cerebrovascular permeability to serum proteins, or cerebral water content was observed. The arterial filter probably protects the cerebral microcirculation and prevents the decrease in cerebral glucose consumption otherwise seen during bypass.

Animals↗
PubMed1991

Effect of labetalol on cerebral blood flow and middle cerebral arterial flow velocity in healthy volunteers.

The effect of labetalol, a combined alpha- and beta-adrenoceptor antagonist, on the cerebral circulation was investigated in 7 normotensive subjects. Cerebral blood flow (CBF) was measured with the intravenous 133Xe method and mean flow velocity (Vmean) in the middle cerebral artery was determined using transcranial Doppler (TCD) ultrasound. Examination was performed before and then 15, 60 and 120 min after 0.75 mg/kg i.v. labetalol. Reactivity to inhalation of 5% CO2 in air was studied before, and again 90 min after labetalol administration. Neither CBF nor Vmean changed following labetalol administration, whereas a marked increase occurred during inhalation of CO2. The median CO2 reactivity was 3.2%/mmHg (range: 1.8-4.0) for CBF and 4.4%/mmHg (1.5-5.6) for Vmean. These results indicate that labetalol, given in moderate but clinically relevant doses, does not affect the cerebral circulation in normotensive subjects. Neither does it affect CO2 reactivity. The uniform results obtained with the two methods suggest TCD as a usable alternative to conventional CBF technique in the assessment of cerebral vasoactivity of various drugs in subjects with a normal cerebral circulation.

Adult↗
PubMed1989

[Intravenous lidocaine in the treatment of chronic pain caused by bone metastases].

A controlled double-blind investigation was undertaken in which ten patients with painful bone metastases were treated with intravenous lignocaine in a dosage of 5 mg/kg body-weight infused over a period of 30 minutes or the same volume of isotonic saline. None of the patients experienced prolonged pain relief but five patients experienced considerable pain relief immediately and/or one hour after the infusion of lignocaine.

Adult↗
PubMed1989

Brain histology, blood-brain barrier and brain water after normothermic and hypothermic cardiopulmonary bypass in pigs.

The effect of hypothermia during cardiopulmonary bypass (CPB) on cerebral histopathology, blood-brain barrier permeability to serum proteins and water content was evaluated. Pigs were subjected to non-pulsatile CPB for 2 h at either normothermia or hypothermia, and a group of anaesthetised pigs served as normothermic controls. The histopathology was assessed on paraffin embedded sections. The permeability of the cerebral vessels was studied by immunocytochemical demonstration of extravasated serum proteins. The cerebral water content was assessed by specific gravity measurements. The histological studies demonstrated hydropic degeneration of the brain parenchyma and perivascular swelling of the astrocytic endfeet throughout both white and gray matter in the normothermic CPB group. Similar changes were not encountered during hypothermic CPB, which suggests a beneficial effect of decreased temperatures on brain tissue during CPB. Neither normothermic nor hypothermic CPB induced significant changes in the cerebrovascular permeability or in the specific gravities.

Animals↗
PubMed1987

Brain microvascular function during cardiopulmonary bypass.

Emboli in the brain microvasculature may inhibit brain activity during cardiopulmonary bypass. Such hypothetical blockade, if confirmed, may be responsible for the reduction of cerebral metabolic rate for glucose observed in animals subjected to cardiopulmonary bypass. In previous studies of cerebral blood flow during bypass, brain microcirculation was not evaluated. In the present study in animals (pigs), reduction of the number of perfused capillaries was estimated by measurements of the capillary diffusion capacity for hydrophilic tracers of low permeability. Capillary diffusion capacity, cerebral blood flow, and cerebral metabolic rate for glucose were measured simultaneously by the integral method, different tracers being used with different circulation times. In eight animals subjected to normothermic cardiopulmonary bypass, and seven subjected to hypothermic bypass, cerebral blood flow, cerebral metabolic rate for glucose, and capillary diffusion capacity decreased significantly: cerebral blood flow from 63 to 43 ml/100 gm/min in normothermia and to 34 ml/100 gm/min in hypothermia and cerebral metabolic rate for glucose from 43.0 to 23.0 mumol/100 gm/min in normothermia and to 14.1 mumol/100 gm/min in hypothermia. The capillary diffusion capacity declined markedly from 0.15 to 0.03 ml/100 gm/min in normothermia but only to 0.08 ml/100 gm/min in hypothermia. We conclude that the decrease of cerebral metabolic rate for glucose during normothermic cardiopulmonary bypass is caused by interruption of blood flow through a part of the capillary bed, possibly by microemboli, and that cerebral blood flow is an inadequate indicator of capillary blood flow. Further studies must clarify why normal microvascular function appears to be preserved during hypothermic cardiopulmonary bypass.

Animals↗
PubMed1985

Effect of a mixture of pyridostigmine and atropine on forced expiratory volume (FEV1), and serum cholinesterase activity in normal subjects.

Pyridostigmine 0.143 mg kg-1 (maximum 10 mg) and atropine 0.0143 mg kg-1 (maximum 1 mg) were administered i.v. to six healthy male volunteers. Peripheral venous blood samples were drawn for measurement of serum cholinesterase activity. Maximum inhibition of the enzyme was found 5 min after injection with a decrease to 27 +/- 5% (mean +/- SEM) of the original activity. Forced expiratory volume in the first 1s (FEV1) was measured at fixed time intervals for 90 min. No decrease in FEV1 was observed; on the contrary, there was a small increase. We conclude that atropine effectively antagonizes the muscarinic side-effects of pyridostigmine on bronchial smooth muscle tone and bronchial secretions, when administered in clinical doses to normal human subjects.

Adult↗
PubMed1983

Lidocaine given intravenously as a suppressant of cough and laryngospasm in connection with extubation after tonsillectomy.

The preventive effect of lidocaine against coughing in the recovery period after general anaesthesia was observed. The study was carried out as a double-blind sequential trial. At the same time the incidence of laryngospasm was registered. Lidocaine or placebo was given intravenously just before extubation. Nineteen patients for tonsillectomy, all of them over the age of 15, randomly received a 2% solution of lidocaine 2 mg/kg body weight or placebo (saline) 2 min prior to expected extubation. We found that lidocaine in this dose given prophylactically just before extubation was able to inhibit and prevent coughing in the recovery period after general anaesthesia. None of the patients included in this study got laryngospasm, and none of the patients developed serious side-effects.

Adolescent↗