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Biomedical subjects

C Krettek

Publications and source records attributed to C Krettek.

At least 235 records · Page 13Linked to original sources
PubMed1991

[Acute posttraumatic lung failure. Its treatment through pressure-limited respiration and continuous postural change].

Nine patients (4 women and 5 men; mean age 31 [20-48] years) with severe posttraumatic adult respiratory distress syndrome (ARDS) were treated with continuous postural change (kinetic bed) and pressure-limited ventilation. Seven patients survived; only one patient died as a result of pulmonary insufficiency. As compliance was markedly reduced (less than 20 ml/cm H2O), low stroke volumes (up to 380 ml) and high respiratory rate (up to 45/min) were employed to keep airway peak pressure below 40 mmHg. Kinetic treatment lasted for a mean of 14 (2-28) days; artificial ventilation was maintained for 31 (9-49) days. Practical problems of the method are the intensive nursing care required for the kinetic bed and the risk of decubitus ulcers, as well as disconnection of infusion tubing. The results indicate that kinetic treatment with pressure-limited ventilation constitutes a low-risk and, in many cases, effective treatment of severe ARDS.

Adult↗
PubMed1991

Treatment of femoral shaft fractures in children by external fixation.

Non-operative management is still the treatment of choice for closed fractures of the femoral shaft in children. Indications for operative intervention would include: children with multiple injuries; severe soft tissue damage; cases where reduction is difficult to maintain; and children not suitable for management by traction. Since 1984, 16 children (mean age 10.3 years) have had stabilization of their femoral shaft fractures by external fixation (Monofixateur) in the Trauma Department of the Hannover Medical School. The external fixation remained in place for a mean of 63 days. Of the 16 children, 15 have been reviewed, with a mean follow-up of 28.2 months. No children who were completely managed with this fixation had any clinically relevant malalignment, but six cases had up to 2 cm difference in leg length. Our observations and experience show that external fixation is a useful alternative for the operative management of femoral shaft fractures in children. It produces good stability, is less invasive, and allows early mobilization. In order to avoid differences in leg length, we recommend a good anatomical reduction with the external fixation being carried out as early as possible.

Adolescent↗
PubMed1991

[Unreamed tibial nail in tibial shaft fractures with severe soft tissue damage. Initial clinical experiences].

In a prospective study, since March 1989, 55 tibial shaft fractures have been treated with a new, unreamed solid tibial nail (UTN). This nail was initially designed as a temporary implant. The first 33 cases with second or third degree soft tissue damage were reviewed 6 months or more after the operation. Fractures were classified according to Müller: 6 type A (18.2%), 15 type B (45.5%), and 12 type C (36.7%). In 9 cases (27.3%), there was GII (n = 4) or GIII (n = 5) closed soft tissue damage according to Tscherne's classification. The 24 open fractures (72.7%) comprised 11 OII, 3 OIIIA and 10 OIIIB fractures (Gustilo classification). 24 patients (72.7%) were polytraumatized, the mean PTS (Hannover Polytrauma Score) was 18 points (range: 8-65 points). All fractures were stabilized without reaming. The implant diameter was 8mm (n = 14) or 9 mm (n = 19). Static locking was performed in 31 cases. Dermatofasciotomy was necessary because of compartment syndrome in 14 cases. In 1 grade IIIB open fracture soft tissue coverage was performed with a latissimus dorsi myocutaneous free flap 4 days after nailing. In 32 of the 33 cases the use of an additional cast or brace was not necessary during the follow-up treatment; 1 patient had a cast for 8 weeks for the treatment of accompanying injuries. Full weight-bearing was achieved in 5 cases within 3 weeks, in 16 cases within 12 weeks, and in 30 cases within 26 weeks. In 16 cases (48.5%) the interlocking screws were removed after 5-26 weeks (mean: 10 weeks).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[New trends in the management of shaft fractures].

There is no major change in the indication of upper extremity fractures, although there is further refinement of plate design (LC-DCP), plate material (titanium), and operative technique ("biological osteosyntheses"). For lower extremity fractures, the external fixator has shown excellent results in the early phase of treatment, with some disadvantages the late phase. If a change to an intramedullary nail is planned, this should be performed in the early phase of treatment. The concept of the "pinless fixator" has shown great advantages for temporary stabilization, although further technical development is necessary. The claw interlocking nail allows easy distal locking without using X-rays. Unreamed nailing, with the advantage of less damage to the cortical blood supply and reduced pulmonary risk, will be of increasing importance, if the trend seen in current studies is confirmed.

External Fixators↗
PubMed1991

[Initial clinical experience with osteosynthesis of femoral shaft fractures with a newly developed intramedullary implant (claw interlocking nail)].

The implantation of distal interlocking screws in interlocking nailing can be difficult and time-consuming. With the AO Universal Femoral Nail as the basis, an implant was designed with which distal interlocking is accomplished from the inside of the nail by means of a simple claw mechanism. Instrumentation and interlocking are possible from the proximal standard approach, so that an additional operation adjacent to the knee (which is necessary when interlocking bolts are used) is superfluous; neither for the insertion nor for the removal of the interlocking mechanism is an image intensifier necessary. We stabilized 24 femoral shaft fractures with this new interlocking nailing device [20 fresh fractures, 3 refractures and 1 pathologic fracture caused by tumor metastasis from chronic myeloid leukemia (CML)]. The mean age of the patients concerned was 34.8 years (18-57 years). Fractures were classified according to the Müller classification with 11 type-A fractures (45.8%), 9 type-B fractures (37.5%) and 4 type-C fractures (16.7%). There were only 2 cases (8.3%) with open fractures. In 11 cases (45.8%) the fracture was located in the midshaft region, in 6 cases (25.0%) in the proximal shaft, and in 7 cases (29.2%) in the distal femoral shaft. Multiple trauma was present in 11 patients (45.8%), while in 8 patients (33.2%) the femoral shaft fracture was the only major injury. Full weight-bearing was allowed after a mean of 4.4 weeks (0.7-8.2 weeks). In 1 case we saw a deep venous thrombosis with pulmonary embolism obvious on clinical examination and scintigraphy. Two patients died of their multiple trauma, and of cachexia the patient with the CML metastasis died 6 weeks after stabilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

The role of supplemental lag-screw fixation for open fractures of the tibial shaft treated with external fixation.

Ninety-nine open fractures of the tibial shaft were treated with unilateral external fixation with or without supplemental lag-screw fixation. We compared the results in forty-four fractures in which only external fixation was used (control group) with those in fifty-five fractures that were stabilized with lag-screws and external fixation, and we found no statistically significant differences between the two groups with respect to the time to full weight-bearing, the time to union, or the rates of delayed union, osteomyelitis, malunion, superficial or deep pin-track infection, or loosening of the pins. The limbs in which the fracture was treated with external fixation and supplemental lag-screws had more than twice the rate of refracture of the control limbs (11 compared with 5 per cent), and the percentage of fractures having supplemental lag-screw fixation that needed bone-grafting to achieve union was more than twice that in the group treated with external fixation alone. We concluded that the routine use of supplemental lag-screw fixation is not indicated in patients who have an open fracture of the tibial shaft that has been stabilized with external fixation.

Adolescent↗
PubMed1989

[Distal radius fracture. Fracture stabilization with biodegradable osteosynthesis pins (Biofix). Experimental studies and initial clinical experiences].

K-wire stabilization and casting of unstable or intraarticular fractures of the distal radius has proven to be an effective method of treatment since many years. However the need of implant removal after fracture healing is a disadvantage of this method. For this reason we investigated on the use of biodegradable implants in a fracture model of the distal radius. The biomechanical testing with Polydioxanon-(PDS)-pins (Ethipin) showed too small primary stability for the use in vivo. Osteosyntheses with three Polyglycolacid-(PGA)-rods Biofix compared with three K-wires 1.6 mm on the other hand showed 82% initial stability. From May to September 1988 typical distal radius fractures in 11 patients have been stabilized with Biofix-rods. The result of primary reduction could be obtained in all cases. These first experiences suggested, that stabilization of distal radius fractures with Biofix-rods might alternatively be performed instead of K-wire pinning.

Adult↗
PubMed1989

[Management of femur shaft fracture in the growth age with the fixateur externe].

Non-operative management is still the treatment of choice today for femoral shaft fractures in children. Indications for operative intervention would include: - the child with multiple injuries, particularly with severe head injuries, in those patients with severe soft tissue damage associated with the fracture; in cases where the reduction is difficult to maintain, as in subtrochanteric fractures; and in children who are not suitable for management with traction. Since 1984, 16 children have had their femoral shaft fractures stabilized by external fixation (Monofixateur) here in the Trauma Department of the Hannover Medical School. The mean age of the patients was 10.3 years (seven to sixteen years). All cases were closed fractures with mild or moderate soft tissue damage. Eleven of the patients had a multiple injury, and four had subtrochanteric fractures. The external fixation remained in place for a mean of 63 days in those patients exclusively treated by this method. In four of the earlier cases there was a Schanz's screw infection and three of these required removal of the external fixation and treatment in a hip spica. After modifying the technique of Schanz's screw insertion, no further infections were seen. Fourteen of the sixteen children were reviewed, with a mean follow up of 21.7 months. None of the children who had been completely managed by this fixation had any clinically relevant malalignment. Six cases had leg lengthening of up to two centimetres. Leg length differences were seen more frequently and more severely in those cases where external fixation was delayed.

Adolescent↗
PubMed1989

[Biochemical and mathematical studies of the pre-bending and pre-stressing of the small fragment DC plate].

The effects of prebending and prestressing in compressional osteo-synthesis with application of the AO small-fragment DC plate on the bones of the forearm were examined. The necessary prestress force, the angle of prebending and the resulting center of compression in the fracture site were experimentally examined. These experiments were performed on fresh cadaver bones using the ulna and the radius. Additionally, after applying small-fragment DC plates with varying angles of prebending and varying forces of prestressing on perpendicular shaft osteotomies, stability tests were carried out. A theoretical analysis of the experiments performed was computed using the finite element method.

Biomechanical Phenomena↗
PubMed1989

[Results of treatment of 202 fresh tibial shaft fractures, managed with unilateral external fixation (monofixateur)].

From 1982 to 1986, a total of 202 lower leg fractures (70 closed, 132 open fractures) were treated with a monoexternal fixation device, and 148 cases were included in the follow-up study. The mean healing time was 15.4 weeks for closed fractures and 18.4 weeks for open fractures. Infection was occurred in 3.4% of the patients followed up (5.1% open fractures, as 0% closed fractures), aseptic delayed in 8.8%, and pin tract infection in 2.5%. The group of patients with open fractures treated with additional lag screws (n = 74) showed a higher rate of refractures (10.9% vs 4.5%) and bone grafting (65.5% vs 29.5%) than the control group without lag screws (n = 58). The healing times (15.8% vs 15.5 weeks) and rates of non-union (10.9% vs 11.4%) were similar in both groups. Among 14 cases of secondary intramedullary nailing, osteitis occurred in 2. In the dynamized group (n = 53) healing time was reduced to 16.0 weeks, as against 18.0 weeks in the n-dynamized group (n = 95).

Adolescent↗
PubMed1988

Ferrihaemoglobin formation by amyl nitrite and sodium nitrite in different species in vivo and in vitro.

The ferrihaemoglobin (HbFe3+) formation by amyl nitrite (AN) or sodium nitrite (NaNO2) was studied in different species including man, in vivo and in vitro. In in vivo studies AN was administered intravenously (i.v.), intramuscularly (i.m.), by inhalation, or orally. NaNO2 was injected i.v.. AN i.v. produced HbFe3+ much more rapidly than NaNO2 in dogs, cats, rabbits, and rats. In dogs, i.m. injection of AN was followed by a very slow linear increase in the HbFe3+ content. Inhalation of AN did not lead to HbFe3+ formation in dogs unless it was rebreathed in a closed (bag) or not completely open (gas mask) system. HbFe3+ was produced by oral AN in dogs, the effect being enhanced by addition of DMSO. Inhalation of AN by human volunteers in a gas mask and from ampoules crushed close to the nose did not induce haemoglobin oxidation to a practically significant extent, but it was associated with headache, tiredness, dizziness, and a fall in blood pressure. In in vitro studies, in contrast to NaNO2, AN produced HbFe3+ instantaneously in erythrocytes of various species and in purified human haemoglobin. AN 1 mol yielded 2 mol Fe3+. Only 20% of the oxygen released during the oxidation of haemoglobin by AN or NaNO2 was recovered. In 0.2 M phosphate buffer, pH 7.4, 0.01 mol O2/mol AN was consumed. CO2 was released in the presence of AN, but not of NaNO2, from blood, plasma, and 0.02 M NaHCO3 solution. The ratio (lactate)/(pyruvate) decreased when HbFe3+ was formed by AN or NaNO2.

Administration, Inhalation↗
PubMed1988

Effects of amyl nitrite on circulation, respiration and blood homoeostasis in cyanide poisoning.

The effects of intravenously (i.v.) administered or inhaled amyl nitrite (AN) were followed under chloralose anaesthesia in intact and cyanide-poisoned, spontaneously breathing beagles. The i.v. doses of AN were 0.03 and 0.15 mmol/kg and the i.v. dose of KCN was 0.06 mmol/kg. AN was inhaled in a closed system at 0.15 mmol/kg without previous poisoning and, in addition, at 0.074 mmol/kg (two ampoules at 0.3 ml AN) during artificial ventilation after poisoning with 0.045 mmol KCN/kg i.v.. Mean arterial pressure decreased by 15 and 40 mmHg, respectively, after i.v. injection of AN, associated with bradycardia and lowered peripheral blood flow. Respiratory minute volume rose by 65% with the higher dose. Arterial pO2 decreased by 20 mmHg while pCO2 rose by 6 mmHg. Within 30 min of injection, these changes were only partially reversible. Similar results were obtained following inhalation of AN in a closed system. Lactic acidosis and lowering of pH were produced by the i.v. route, but not by inhalation. Total haemoglobin increased. The lethality of KCN was abolished with AN doses that produced 10-30% ferrihaemoglobin. Artificial ventilation and simultaneous inhalation of AN after poisoning with lethal doses of KCN turned out to be ineffective therapeutic measures. The findings are compared with those of other papers dealing with cyanide poisoning and AN. It is pointed out that, for the present, there is no experimental proof for another antidotal mechanism of action of AN than ferrihaemoglobin formation.

Amyl Nitrite↗
PubMed1986

Intramedullary nailing combined with cerclage wiring in the treatment of fractures of the femoral shaft.

One hundred sixty-seven femoral shaft fractures were treated with open intramedullary nailing and cerclage wires. Complications requiring surgical reintervention developed in 11 patients (6.6%). Delayed union or nonunion in five patients (3%), deep infection in four patients (2.4%), or unstable fixation in two patients (1.2%) required one or more additional procedures to achieve union. The time to weight-bearing averaged 32 days in patients with isolated injuries and 62 days in patients with associated injuries. One hundred forty-five patients were followed until fracture union occurred. Rotational malalignment in one patient, angulation of 10 degrees or more in two patients, and limb shortening of more than 2 cm in two patients were noted. Loss of hip or knee motion in excess of 20 degrees developed in 15 patients and was always associated with injuries of the pelvis or ipsilateral lower leg. Intramedullary nailing and cerclage wiring significantly expands the indication for intramedullary fixation of fractures of the femoral shaft.

Bone Nails↗
PubMed1986

[Diagnosis and therapy of acute and chronic ligament instability of the lower ankle joint].

At the Casualty Clinic of the University Hospital in Hannover, from 1981 to 1985, a total of 35 patients were treated operatively for chronic instability of the transverse tarsal joint: combined instability of the ankle and transverse tarsal joints (n = 15), isolated instability of the subtalar joint (n = 17), and isolated instability of the pretalar joint (n = 3). A simple technique of radiological positioning permits easy and certain diagnosis of isolated anterolateral rotary instability of the subtalar joint. Modified Elmslie tendosis (n = 32), used as an indirect replacement for the interosseus talocalcaneal ligament, had good and very good results in 25 of 27 cases followed up after 3 years.

Ankle Injuries↗
PubMed1983

Effects and biotransformation of 4-dimethylaminophenol in man and dog.

The cyanide antidote 4-dimethylaminophenol . HCl (DMAP) was administered orally, i.v., or i.m. to man and dog. Ferrihemoglobin formation and changes of several parameters in human blood were investigated to obtain information on damage to liver, kidney, muscle, and red blood cells; in addition, the metabolism of DMAP was studied. In dogs, the initial rate of ferrihemoglobin production (DMAP, 3.25 mg/kg i.v. or i.m., 15 mg/kg orally) amounted to 28%, 3.5%, and 2% of the total hemoglobin per min; the corresponding values for man were 9%, 2%, and 2% per min. The dogs behaved normally while CPK increased after i.m. injection. In man, only i.m. injection of DMAP (3.25 mg/kg) was followed by increases in LDH, GOT, and CPK of 110, 260, and 490%, resp.; while total bilirubin, conjugated bilirubin, and iron concentration rose by 270, 120, and 50%, respectively. Bilirubin and iron concentration increased also after DMAP i.v. (3.25 mg/kg) or when it was taken orally (600 or 900 mg). The lactate concentration was not influenced while the pyruvate concentration increased by 50%. DMAP produced hemolysis in vitro. Generally, the values determined in vivo approached the starting level within 1 week. Intramuscular injection of DMAP induced reversible subjective and objective symptoms, e.g., local pain, swollen buttock, fever reaction. The urine showed no pathological changes. About 54% of DMAP taken orally was excreted as metabolites in the urine, 41% as glucuronide, 7% as sulfate, and 6% as thioethers. After i.v. administration the total of metabolites was somewhat higher, and the thioether proportion was 15%. The results indicate that DMAP is readily absorbed after oral administration but undergoes significant first pass effect in the liver. Therefore, the 4-fold i.v. dose must be administered orally to achieve the same ferrihemoglobin formation.

Administration, Oral↗
PubMed1983

Effects of 4-dimethylaminophenol, Co2EDTA, or NaNO2 on cerebral blood flow and sinus blood homeostasis of dogs in connection with acute cyanide poisoning.

The effects of the cyanide antidotes DMAP, Co2EDTA, and NaNO2 on cerebral blood flow (CBF) and cerebral blood gases were investigated in connection with acute poisoning of dogs by cyanide. The substances were injected intravenously. Local CBF as measured with thermocouples in the cingulum increased by 100-200% after a non-lethal dose of KCN (1 mg/kg) and by 50% after injection of NaNO2 (15 mg/kg), that oxidized some 20% of the total hemoglobin to ferrihemoglobin. Co2EDTA (10 mg/kg) induced a decrease in local CBF of 30% and in brain temperature of 0.5 degree C. The temperature diminished also after poisoning by KCN, but it rose by 0.15 degree C after the administration of NaNO2. Local CBF and sinus sagittalis blood flow increased by 60-160% for about 15 min, and the brain temperature decreased by 0.4-0.5 degree C when DMAP (3.25 mg/kg) or Co2EDTA (15 mg/kg) was injected 1 min after poisoning by cyanide (4 mg/kg), a dose that always caused respiratory arrest. Immediately after injection of DMAP the brain temperature rose transiently by 0.1-0.2 degree C. Co2EDTA did not exert such an effect. In the sinus sagittalis blood of artificially ventilated animals pCO2 decreased rapidly by 10-20 mmHg after poisoning and approached the initial level after treatment with DMAP or Co2EDTA. The highest value of pO2 was about 80 mmHg and 50 mmHg after injection of DMAP and Co2EDTA, respectively; thereafter pO2 declined to 20 mmHg or 40 mmHg at 20 min. The lactate concentration increased by 60-70% without tendency to return to normal.

Aminophenols↗
PubMedDate not supplied

Feasibility of preclinical cardiac output and systemic vascular resistance in HEMS in thoracic pain--the ultrasonic cardiac output monitor.

BACKGROUND: Cardiac output (CO) and systemic vascular resistance (SVR) are important hemodynamic parameters in emergency patients and for clinical early goal-directed therapy. This study evaluated the feasibility of CO and SVR determination using preclinical continuous wave Doppler ultrasound in a helicopter emergency medical service (HEMS) on emergency patients presenting with or without thoracic pain as a pilot observational study. METHODS: Forty-four consecutive medical emergency patients (62.8 +/- 22 years of age, 23 males) were classified at the scene as with (15 patients, 69 +/- 14 years of age, 40% male) or without (29 patients, 60 +/- 25 years of age, 59% male) thoracic pain by an emergency physician. Hemodynamic parameters were determined based on continuous wave Doppler noninvasively (USCOM, Sydney, Australia): stroke volume (SV), CO, cardiac index (CI), minute distance (MD), and SVR. RESULTS: Noninvasive SV, MD, CO, CI, and SVR determination is feasible using preclinical ultrasound in HEMS. Thoracic pain patients had higher SVR (2,709 +/- 891 vs 1,499 +/- 661 dyne*sec*cm-5) and lower CO/CI (3.37 +/- 1.1 vs 5.06 +/- 2.9 L/min, CI: 1.67 +/- 0.58 vs 3.18 +/- 1.34 L/min/m2) as well as a reduced aortic minute distance (11.2 +/- 3.3 m/min vs 19.1 +/- 8 m/min, P = .001) than patients without thoracic pain. Highest cardiac outputs were measured during and within 30 minutes after seizures (n = 5, 7.5 +/- 3.05 L/min). The range of CO measured in six cardiopulmonary resuscitation patients was 2.7 to 12 L/min; the level of CO was not associated with the establishing of sustained circulation. CONCLUSIONS: Determining SV, CO/CI, and SVR in different emergency situations in HEMS using rapid CW Doppler ultrasound is feasible. Thoracic pain patients have increased SVR and lower CO/CI and reduced aortic minute distance than do non-thoracic pain patients in the preclinical setting.

Aged↗