Biomedical subjects

M Blobner

Publications and source records attributed to M Blobner.

45 records · Page 3Linked to original sources

PubMed1996

[Neuromuscular and cardiovascular effect of mivacurium in anesthesia induction in patients with renal failure].

OBJECTIVE: Mivacurium produces a prolonged neuromuscular block (NMB) in anuric patients (13), in spite of its rapid hydrolysis by pseudocholinesterase (PChE) which is independent of renal function (17). In the present study the pharmacodynamics and the cardiovascular effects of a bolus dose of mivacurium (0.15 mg/kg) in relation to impairment of renal function were evaluated. METHODS: 60 patients (ASA class 2-4) were assigned to one of three groups according to the degree of renal dysfunction. Creatinine clearance (Krea-Cl) as a measure of renal function was calculated using weight, age, sex and serum creatinine concentrations. Group C (control): Krea-Cl > 50 ml/min; group P (preterminal): 20 ml/min < Krea-Cl < 50 ml/min; group T (terminal): Krea-Cl < 20 ml/min. PChE activity and dibucaine numbers were assessed preoperatively. Neuromuscular transmission (Train-of-Four) was monitored using electromyography (Relaxograph, Datex Inc.) with stimulation of the ulnar nerve. The response was recorded from the hypothenar muscle. Five minutes after induction of anaesthesia with propofol and fentanyl, 0.15 mg/kg mivacurium was given i.v. over 30 s. 150 s later patients were intubated. Anaesthesia was maintained by propofol (2-10 mg/kg/h) and fentanyl (0-5 micrograms/kg/h) infusion. Patients were ventilated with oxygen/nitrous oxide (FiO2 = 0.35). As soon as T1 recovered to 5% or more, mivacurium was administered continuously and this part of the study was finished. Times of onset (onset 10; onsetmax), maximal neuromuscular block (NMBmax), neuromuscular block when intubation was started (NMBTubus), and duration 5% (dur 5) were calculated. Arterial blood pressure and heart rate were recorded before anaesthesia, after induction of anaesthesia, 2-times after mivacurium application, and after intubation. All data were compared using Kruskal-Wallis test corrected for multiple comparisons, Friedman test, or chi 2-test (*: p < 0.05). Logarithms of dur 5 and PChEd were correlated using linear regression. RESULTS: Demographic data were comparable between all groups. PChEd was 3.7 (3.0/4.1) kU/l in group C, 3.2 (2.2/4.8) kU/l in group P, and 3.5 (2.5/4.0) kU/l in group T, respectively. There were no differences between groups, neither in the NMBmax, in NMBTubus, or in onset times. But dur 5 was significantly longer in patients with renal impairment, both preterminal and also end-stage (medians: 11 min in group K, 16 min in group P, 17 min in group T). Emphasis, however, is put on the broad range between 5 and 47 min of dur 5 in group P, and between 6 and 53 min in patients of group T which is clinically more important than the differences in the median values. Dur 5 correlates with PChEd (p = 0.0001). Intubation conditions were excellent (relaxed vocal cords, easy passage of the tube, without coughing) in approximately 70% of all 59 patients without significant differences between groups. In 8 patients conditions were poor (successful intubation, inspite of moderately adducted vocal cords, but moderate coughing after passage of the endotracheal tube). There were no clinically relevant hemodynamic changes in each group in the time between injection of 0.15 mg/kg mivacurium slowly and intubation 2.5 min later. DISCUSSION: Our findings suggest that 0.15 mg/kg mivacurium is an effective and safe intubation dose in healthy patients as well as in patients with renal impairment, inspite of a prolonged duration in patients with renal impairment. Low PChE in some, but not in all patients with a renal dysfunction indicates involvement of impaired hepatic function. There was a close correlation between the PChEd and dur 5. Therefore mivacurium dosage should be reduced in patients with compromised renal function, mainly if there are additional systemic, especially hepatic diseases. Thus, in patients with impaired renal function, relaxometry may be of high valu

Adolescent↗

PubMed1995

Effect of renal function on neuromuscular block induced by continuous infusion of mivacurium.

We have studied the effect of renal function on the pharmacodynamics of mivacurium. Sixty patients were allocated to three groups according to creatinine clearance: group C (control), creatinine clearance > 50 ml min-1; group P (preterminal renal failure), creatinine clearance < 50 ml min-1 > 20 ml min-1; group T(terminal renal failure), creatinine clearance < 20 ml min-1. Neuromuscular transmission (train-of-four) was monitored using electromyography from the hypothenar muscle with stimulation of the ulnar nerve. After an initial bolus, mivacurium was administered continuously to maintain a T1 of 5 (4)% of baseline. The dose of mivacurium necessary to maintain 95% neuromuscular block was similar in patients with normal renal function and patients with different levels of renal impairment. Recovery from neuromuscular block after ceasing mivacurium infusion was significantly prolonged in patients with preterminal renal impairment. There was a close correlation between mivacurium pharmacodynamics and pseudocholinesterase activity, but not creatinine clearance.

Adolescent↗

PubMed1994

[Comparative study of the recovery phase. Laparoscopic cholecystectomy following isoflurane, methohexital and propofol anesthesia].

Total intravenous anaesthesia (TIVA) is increasingly used in short-stay surgery such as laparoscopic cholecystectomy. TIVA may provide fast recovery of psychomotor function, thus being of benefit to both the patient's behaviour and postoperative management. The purpose of this prospective study was to compare postoperative recovery from TIVA using propofol or methohexitone as the hypnotic component and balanced anaesthesia with isoflurane. PATIENTS AND METHODS. After giving informed consent and approval by the ethical committee of our hospital, 51 patients (ASA I, II) were investigated in a prospective study. Patients were randomised to receive either isoflurane, methohexitone, or propofol. Perioperative management with regard to premedication, intraoperative analgesia, relaxation, ventilation, and postoperative analgesia was carried out identically for all groups. Postoperative vigilance, pain, and nausea scores were assessed 15, 30, 60, 120, and 360 min after extubation with a visual analogue scale (VAS). At the same points, psychomotor recovery was investigated with the following assays: sedation as shown in Table 1; orientation with ten questions as to person, time, and location; memory as expressed by the patient's ability to repeat five words; a calculation test with five subtractions of the number 7 beginning from 100; and word generation by the number of words with an initial "m" given within 1 min and with animal names. Data were analysed with Kruskal Wallis' test for multiple comparisons between the groups and with Friedman's test for repeated measurements. All values are given as medians (interquartile range) or ranges. RESULTS. There was no difference between the groups' physical condition (Table 2). All intraoperative parameters compared well between groups; the management of anaesthesia was smoother with isoflurane than with the other anaesthetics. Psychomotor recovery was somewhat faster in the propofol group than the methohexitone group, as indicated by sedation score, orientation, memory and calculation tests (Table 4), word generation tests (Fig. 4), and subjective vigilance score (Fig. 3). The difference in recovery time between the propofol and isoflurane groups was minimal and without any significance or relevance. The incidence of postoperative nausea was significantly lower after balanced anaesthesia with isoflurane (24%, P < 0.05) as compared to TIVA with either propofol (53%) or methohexitone (41%). However, there were only minor differences between the groups; the ability to cooperate and be mobilised was not limited. DISCUSSION. Each of the three techniques used in this study is suitable for anaesthesia in patients undergoing laparoscopic cholecystectomy. Since fast recovery of vigilance and psychomotor function is very important in outpatient surgery, opioid-supplemented propofol anaesthesia is well established. Inhalation anaesthesia with isoflurane in air/oxygen without adding nitrous oxide compares well to propofol TIVA for laparoscopic surgery.

Adult↗

PubMed1994

[Effect of capnoperitoneum on postoperative carbon dioxide homeostasis].

After laparoscopic cholecystectomy, carbon dioxide (CO2) must be exhaled after resorption from the abdominal cavity. There is controversy about the amount and relevance of postoperative CO2 resorption. Without continuous postoperative monitoring, after laparoscopic cholecystectomy a certain risk may consist in unnoticed hypercapnia due to CO2 resorption. Studies exist on the course of end-expiratory CO2 (Pe-CO2) alone over a longer postoperative period of time in extubated patients during spontaneous breathing. The goal of this prospective study was to investigate the amount of CO2 resorbed from the abdominal cavity in the postoperative period by means of CO2 metabolism. METHODS. After giving informed consent to the study, which was approved by the local ethics committee, 20 patients underwent laparoscopic cholecystectomy. All patients received general endotracheal anaesthesia. After induction, total IV anaesthesia was maintained using fentanyl, propofol, and atracurium. Patients were ventilated with oxygen in air (FiO2 0.4). The intra-abdominal pressure during the surgical procedure ranged from 12 to 14 mm Hg. Thirty minutes after releasing the capnoperitoneum (KP), CO2 elimination (VCO2), oxygen uptake (VO2), and respiratory quotient (RQ) were measured every minute for 1 h by indirect calorimetry using the metabolic monitor Deltatrac according to the principle of Canopy. Assuming an unchanged metabolism, the CO2 resorption (delta VCO2) at any given time (t) can be calculated from delta VCO2 (t) = VCO2 (t)-RQ(preop) VO2 (t). It was thus necessary to define the patient's metabolism on the day of operation. The first data were collected before surgery and after introduction of the arterial and venous cannulae for a 15-min period. Measuring point 0 was determined after exsufflation of the KP and emptying of the remaining CO2 via manual compression by the surgeon at the end of surgery. Patient's tracheas were extubated and metabolic monitoring started 30 min after release of the KP for 60 min. Simultaneously, a nasal side-stream capnometry probe was placed and the PeCO2 and respiratory frequency (RF) were obtained by the Capnomac Ultima (Datex) and registered every minute as well. Values were averaged over four periods of 15 min each. An arterial blood gas sample was drawn at the end of every 15-min period. Postoperative pain was scored by a visual analog scale and completed by a subjective index questionnaire on general well-being. All data were analysed by the Friedman or Wilcoxon test; P < 0.05 was considered significant. RESULTS. The findings do not indicate CO2 resorption in the postoperative period after laparoscopic cholecystectomy (Tables 2 and 3, Fig. 1). Arterial CO2 as well as PeCO2 were elevated postoperatively (45 mm Hg vs. 36 mm Hg intraoperatively), while VCO2 and VO2 were unchanged when compared to the preoperative measuring period. The postoperative RF was comparable to preoperative values. Calculated delta CO2 was lower than 10 ml/min and within accuracy of measurements. The post-operative pain index ranged between 3 and 4, and 3.75-15 mg piritramid was administered. All patients felt tired immediately after the operation, but scores improved slightly at the end of the 60-min period of metabolic monitoring. CONCLUSIONS. There is no significant resorption of CO2 from the abdominal cavity later than 30 min after releasing the KP. Up to this time, any CO2 remaining in the abdominal cavity after careful emptying by the surgeon has been resorbed and exhaled. An increased PeCO2 as late as 30 to 90 min postoperatively should rather be considered a consequence of residual anaesthetics and narcotics than of CO2 resorption.

Adult↗

PubMed1994

[Dose-response relationship of atracurium in underweight, normal and overweight patients].

OBJECTIVE: In patients with extreme stature or build, estimation of individual dosage requirements of muscle relaxants by body weight is unreliable. To define a more precise guideline for dosage of atracurium in clinical practice we compared in this prospective study in patients with a wide range of body weights the cumulative effective dose for a 95% twitch depression (ED95), the dosage necessary to maintain a 95% twitch depression (DD95) and the recovery from a 95% neuromuscular block with simple demographic data such as body weight, body size, body surface area and lean body mass (LBM). METHODS: 30 patients were divided into three groups according to the individual body weight: underweight, normal, overweight. The electromyographic response was monitored using train-of-four stimuli applied to the ulnar nerve. Neuromuscular block was induced by constant infusion of atracurium; the dose required for a 95% twitch depression was registered as ED95. The infusion rate was then adjusted to maintain a constant electromyographic response of the first twitch of 5 +/- 1% for at least 30 minutes and the required dose of atracurium was recorded as DD95. The neuromuscular recovery was studied regarding T1 and T4-ratio. Data are given as medians (25%-/75%-quartiles). RESULTS AND DISCUSSION: The cumulative ED95 in underweight patients (0.34 (0.31/0.48) mg/kg) exceeded (P < 0.05) those in normal (0.29 (0.26/0.30) mg/kg) and in overweight patients (0.22 (0.18/0.26) mg/kg). In contrast to calculations according to the normal weight (Mn) no difference in ED95 was seen between groups (normal: 0.29 (0.26/0.30) mg/kg Mn; underweight: 0.28 (0.26/0.32) mg/kg Mn; overweight: 0.31 (0.25/0.32) mg/kg Mn). The individual DD95 was best correlated with LBM (r = 0.465, p < 0.01). In view of the difficulty of estimating LBM in routine clinical practice it is emphasized that DD95 correlates only slightly less with normal weight (r = 0.404, p < 0.05). In spite of the variability of DD95 with regard to body weight, the recovery of neuromuscular transmission in the patients of the three groups is comparable. As a constant neuromuscular block cannot be maintained without monitoring muscular evoked responses, even if body build is taken into account, neuromuscular monitoring is advocated for longer infusion of atracurium.

Adolescent↗

PubMed1993

[Anesthesia for renal transplantation: continuous neuromuscular blockade with atracurium and the management of intraoperative hypertension with nifedipine].

Patients undergoing kidney transplantation often suffer from essential hypertension and coronary artery disease, for which perioperative treatment with nifedipine proved to be effective. If calcium-channel blockers and nondepolarizing muscle relaxants are used simultaneously, their synergistic effect at the neuromuscular cleft must be considered. On the other hand because of its extrarenal elimination no significantly altered effects are expected for patients with terminal renal failure. This prospective study comprised 30 patients undergoing kidney transplantation who were 2 kg over normal weight after a preoperative dialysis and infusion of lactated Ringer solution. Fifteen minutes after introduction of balanced anaesthesia with isoflurane, nitrous oxide and fentanyl, patients were assigned to the treatment group (N) with hypertension (mean arterial pressure (MAP > 110 mmHg) and subsequent management with nifedipine or to the control group (0). Treatment was aimed at keeping MAP between 90 and 110 mmHg. The neuromuscular status was electromyographically assessed by the train-of-four-principle. There were evaluated the duration of action of the initial dose of atracurium (0.5 mg/kg) from injection time to T1 = 2% (WZ 2), the dose of atracurium for a continuous neuromuscular blockade (DD 98 in mg/kg/h), the recovery time and the recovery index. Fourteen patients with hypertension received a bolus of 10 micrograms/kg nifedipine. A significant reduction in blood pressure (p < 0.05) to the desired range was achieved by a subsequent infusion of nifedipine of 5 to 40 micrograms/kg/h. In 16 patients MAP was kept between 90 and 100 mmHg without any additional therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

[The resorption of carbon dioxide from the pneumoperitoneum in laparoscopic cholecystectomy].

Laparoscopic cholecystectomy is claimed to be a minimally invasive procedure, but uptake of carbon dioxide (CO2) from the pneumoperitoneum (CO2-PP) can cause clinically relevant hypercapnia. In this prospective study, CO2 resorption during laparoscopic cholecystectomy was investigated. METHODS. In 30 patients (ASA I and II) total intravenous anesthesia was performed with propofol and fentanyl. Controlled ventilation was started with a tidal volume of 10 ml/kg min, a respiratory rate of 10/min, and FiO2 = 0.4 using an Engström Erica ventilator. When end-tidal CO2 (PeCO2) rose to 42 mmHg the respiratory rate was increased. In addition to standard monitoring, intra-abdominal pressure (IAP) was measured. Minute volume (VI), CO2 elimination (VCO2), oxygen uptake (VO2), and the respiratory quotient (RQ) were registered by indirect calorimetry from the Erica Metabolic Monitor. The CO2 resorption (delta VCO2) was calculated from the equation: delta VCO2(Mi) = VCO2(Mi) RQ(M1)VO2(Mi). (i = 1; 2; ...;5) All values are medians (interquartile range) or ranges. All parameters were compared at five measuring points that are characteristic for laparoscopic cholecystectomy: M1 baseline, 30 min after induction of anaesthesia, M2 10 min after starting CO2 insufflation, M3 while mobilising the gallbladder from the liver bed, M4 while extracting the gallbladder from the abdominal cavity, and M5 10 min after desufflating the CO2-PP (spontaneous breathing). RESULTS. A typical pattern of VCO2 was observed (Fig. 1). Baseline VCO2 was 165 (145-180) ml/min, PeCO2 was 33 (31-35) mmHg, and VI was 6.0 (6.0-7.0) l/min. After insufflation of CO2 to an IAP of between 14 and 20 mmHg, an increase in VCO2 to 201 (179-222) ml/min was registered (P < 0.05). During mobilisation of the gallbladder, the IAP was between 12 and 18 mmHg and no further increase in VCO2 (200 (179-229) ml/min) was observed. During extraction of the gallbladder from the abdominal cavity, the CO2-PP deflated and IAP dropped to 1-5 mmHg. In this phase, maximal VCO2 and delta VCO2 were measured at 232 (206-245) ml/min and 43 (30-57) ml/min (P < 0.05), respectively. PeCO2 rose to 40 (37-42) mmHg (P < 0.05) although VI was increased to 7.0 (6.0-8.4) l/min (P < 0.05). The complete pattern of VO2 is shown in Fig. 2, the RQ in Fig. 3, and delta VCO2 in Fig. 4. The values of PeCO2, IAP, and VI are listed in Table 2. DISCUSSION. The combination of increased VCO2 and stable VO2 during CO2-PP must be interpreted as indicating resorption of CO2 from the abdominal cavity. Essential CO2 resorption must be assumed during insufflation of the CO2-PP and immediately after a decrease in IAP. During dissection of the gallbladder no increase in CO2 resorption was observed, so the experimental finding [19] can be confirmed clinically that an IAP higher than the venous capillary pressure protects from further CO2 resorption by compressing the venous capillaries of the peritoneum. CO2 resorption is clinically relevant because VI must be increased to maintain normocapnia. Therefore, capnography is absolutely necessary during laparoscopic cholecystectomy.

Adult↗

PubMed1992

[Nifedipine prolongs a neuromuscular blockade caused by atracurium].

Calcium entry blockers are now widely employed in the treatment of cardiovascular diseases and perioperative hypertension. In patients with coronary heart disease nifedipine therapy should be continued perioperatively to avoid coronary artery spasm. Animal experiments have demonstrated that calcium entry blockers potentiate the neuromuscular blockade induced by nondepolarizing blocking agents. In patients, an atracurium-induced neuromuscular depression is prolonged by intravenous nifedipine. In this prospective clinical study we evaluated the effect of chronic oral nifedipine therapy on the duration of neuromuscular block by atracurium. Sixty patients anaesthetized with isoflurane in nitrous oxide/oxygen were recruited for this study. Thirty of these were on chronic oral nifedipine therapy and received their normal morning dose before premedication. The control consisted of 30 patients of similar age and status but not taking any calcium entry blockers. Monitoring included noninvasive blood pressure, heart rate, pharyngeal temperature, physical breathing parameters and neuromuscular transmission with a Datex Relaxograph TM ("train of four"-principle). After inducing hypnosis 0.5 mg/kg atracurium were administered for muscular relaxation. The duration of block from administration of the relaxant to recovery of first twitch height (T1) to 25% of control twitch height was registered as duration of initial block. When T1 reached 25% a repetition dose of 0.2 mg/kg atracurium was injected. The time till recovery of T1 to 25% was recorded as the duration of the repetition dose. Results were compared using Student's t-test for unpaired data. There was a significant prolongation of the duration of initial block from 38 min +/- 10 min in the control group to 46 min +/- 8 min in the therapy group (P < 0.01). The duration of the repetition dose rose from 30 min +/- 8 min in the control group to 38 min +/- 7 min in the therapy group (P < 0.001). Daily nifedipine doses varied from 10 mg in the morning to 40 mg divided into single doses with no influence on the prolongation of neuromuscular block. Our results confirm previous assumptions of synergistic effects of nifedipine and neuromuscular blocking drugs in patients. Chronic oral nifedipine therapy potentiates neuromuscular blockade by atracurium as does nifedipine intravenously. This effect should be considered in the treatment of cardiovascular diseases with nifedipine in the perioperative period.

Aged↗

PubMed1990

[Potentiation of nondepolarizing muscle relaxants by nifedipine iv in inhalation anesthesia].

Calcium entry blockers are now widely used in the treatment of cardiovascular diseases. Nifedipine is established for the treatment of perioperative hypertension during anesthesia. Previous animal experiments have demonstrated that calcium entry blockers potentiate the neuromuscular response induced by nondepolarizing blocking drugs. Occasional observations in patients have led to the suggestion that this phenomenon may be of clinical significance. The interaction of nifedipine with nondepolarizing muscle relaxants in patients was assessed in a prospective clinical study. PATIENTS AND METHODS. Atracurium or vecuronium was administered for muscular relaxation in 44 patients anesthesized with isoflurane in nitrous oxide/oxygen. Monitoring included checks on noninvasive blood pressure, heart rate, pharyngeal temperature, tidal volume, end-tidal CO2 and neuromuscular transmission with a Datex ABM 100 Relaxograph ("train of four"). In the first study protocol atracurium was given to the patients after the intubation dose of 0.5 mg/kg in equal repetition doses of 0.2 mg/kg whenever T1 reached 25%. In 12 patients with the second repetition dose 1 mg nifedipine was injected i.v. The duration of neuromuscular depression with nifedipine until T1 reached 25% again was compared with the duration without nifedipine in the same patient. In the second protocol, constant neuromuscular blockade was accomplished in 11 patients by administration of atracurium or vecuronium at a constant perfusion rate at a level of 75% twitch depression. After 15 min of stable neuromuscular blockade 1 mg nifedipine was injected. In the third study protocol, 1 mg nifedipine i.v. was given at the end of anesthesia when the patients began to breathe spontaneously (T1 was at least 25%). RESULTS. In each patient there was a significant prolongation of neuromuscular blockade from 29 min +/- 6 min up to 40 min +/- 8 min when nifedipdine was given with the second repetition dose (P less than 0.001). During continuous relaxation with constant neuromuscular depression nifedipine increased the neuromuscular blockade from 75% up to 90% +/- 4% (P less than 0.05). In patients with spontaneous breathing and fading but still existing neuromuscular blockade nifedipine injection resulted in hypoventilation. The cardiovascular effects of 1 mg nifedipine, although significant, attained no clinically relevant values. CONCLUSIONS. Our results confirm previous assumptions of synergistic effects of neuromuscular blocking drugs and nifedipine in patients. This synergistic effect includes both duration and intensity of neuromuscular blockade. In the postoperative period patients may be endangered by nifedipine therapy if recovery from the neuromuscular depression is not complete.

Adult↗