Effects of enflurane on inducibility of ventricular tachycardia.

The effects of enflurane on cardiac electrophysiologic parameters and on inducibility of ventricular tachycardia (VT) by programmed stimulation were studied in 12 patients (11 men, 1 woman, mean age +/- standard deviation 55 +/- 8 years) with drug refractory sustained monomorphic VT who underwent transcatheter ablation with high-energy direct-current shocks. One catheter ablation procedure was performed in 10 patients, whereas 2 ablation sessions were necessary in 2 patients. Programmed ventricular stimulation was performed on 2 separate days (mean interval 19). There were 2 baseline studies, 1 several days before ("baseline study I") and the second at the beginning of the ablation procedure ("baseline study II") while the patient was awake and nonsedated. The third programmed stimulation study was done 15 to 30 minutes after administration of anesthesia with enflurane, oxygen and nitrous oxide ("enflurane study"). Rate of sinus rhythm, QRS duration, PQ interval and ventricular effective refractory period were unaltered, whereas QTc interval increased significantly after initiation of anesthesia. Before and after induction of general anesthesia, clinical VT was inducible in all patients. However, in 1 patient, induction of VT was only possible by pacing in the left ventricle after enflurane administration. Based on these data, it is concluded that general anesthesia with enflurane, oxygen and nitrous oxide has no marked influence on inducibility of clinical VTs. Therefore, this type of anesthesia may be useful for nonpharmacologic, ablative procedures requiring general anesthesia.

Differential ventilation with low-flow CPAP and CPPV in the treatment of unilateral chest trauma.

A case of severe unilateral chest trauma with bronchopleural fistula is presented. Ventilatory therapy consisted of asynchronous independent lung ventilation (AILV). The injured lung was ventilated with intermittent positive pressure ventilation (IPPV) [tidal volume (TV) = 200 ml, f = 25/min, I:E = 0.5, minute volume (MV) = 5.0 l/min, FiO2 = 0.4], and the unaffected lung was ventilated with continuous positive pressure ventilation (CPPV) (TV = 600 ml, f = 12/min, I:E = 0.5, MV = 7.2 l/min, PEEP = 0.5 kPa, FiO2 = 0.4). Adequate gas exchange was obtained (PaO2 = 14.5 +/- 2.3 kPa, PaCO2 = 5.5 +/- 0.7 kPa), but high air leakage volumes persisted. Thus, differential low-flow CPAP (V = 5.0-7.5 l/min, PEEP = 0.5 kPa, FiO2 = 0.4) of the injured lung and CPPV (TV = 600 ml, f = 12/min, MV = 7.2 l/min, I:E = 0.5, PEEP = 0.5 kPa, FiO2 = 0.4) of the unaffected lung was applied for 36 hours. Further deterioration of pulmonary function was prevented, and the bronchopleural fistula closed after several hours. After another period of AILV the patient was treated with conventional mechanical ventilation, and finally weaned with high-flow CPAP.

The influence of urapidil, a new antihypertensive agent, on cerebral perfusion pressure in dogs with and without intracranial hypertension.

The influence of urapidil, an arylpiperazinederivate, on intracranial pressure (ICP), mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) was investigated in dogs with (group II) and without (group I) intracranial hypertension. After i.v. administration of urapidil, intracranial pressure remained unchanged and cerebral perfusion pressure decreased to the same extent as mean arterial pressure (20%). As in neurosurgical patients, autoregulation of cerebral blood flow is often lost; a sudden increase in blood pressure may lead to an increase in cerebral blood flow and to a damage of the blood bain barrier with consequent cerebral edema. Urapidil seems to be suitable for treating hypertensive episodes perioperatively in neurosurgical patients.

Single breath N2 washout in papain-induced pulmonary emphysema.

Single breath nitrogen washout tests were analyzed in dogs (n = 8) with healthy lungs and after development of emphysema. The animals were in the supine position and studied during anaesthesia and mechanical ventilation (FiO2 = 0.4, FiN2 = 0.6). During controlled expiration with constant flow (VE = 0.15 l/s) onset of phase IV of the alveolar plateau was related to airway closure of dependent lung regions (closing volume CV). In the control state, CV accounted for 6.2 +/- 1.5% VC, and closing capacity (CC) was lower than functional residual capacity (FRC). Likewise, gas exchange was normal in all animals (PaO2 = 24.7 +/- 3.32 kPa, PaCO2 = 5.18 +/- 0.53 kPa, PA-aO2 = 2.6 +/- 0.3 kPa). Panlobular emphysema (PLE) was induced by inhalation of papain (100 mg/kg). After three weeks development of PLE was documented by measurements of lung volumes (functional residual capacity (FRC), expired vital capacity (EVC), total lung capacity (TLC), residual volume (RV], pulmonary mechanics (dynamic and static compliance (Cdyn, Cstat), mean airway resistance (Raw], gas exchange (PaO2, PaCO2, PA-aO2), and by radiomorphological analysis. In the PLE-group, FRC and RV (p less than or equal to 0.05), and Cstat (p less than or equal to 0.01) were significantly elevated. CV increased to 16.2 +/- 2.7% VC (p less than or equal to 0.01) and CC exceeded FRC by 80 ml, indicating that tidal volume breathing took place within the range of closing volume. Oxygenation was significantly impaired (PaO2 = 18.6 +/- 3.72 kPa, PA-aO2 = 6.5 +/- 1.1 kPa, p less than or equal to 0.05), but not CO2-elimination. Pathological analysis by radiomorphological means showed dissiminate parenchymal lesions compatible with emphysema of grade II severity located predominantly in subpleural areas. In dogs with papain-induced PLE, premature closure of dependent airways is enhanced, which is due to structural changes and a loss of elastic recoil in the lungs.

High-frequency jet ventilation during oleic-acid induced pulmonary oedema.

In oleic acid-induced pulmonary oedema (OAPO) sequential intrapulmonary fluid accumulation occurs leading to different expiratory flow pattern in dependent lung regions. The potential effects on efficacy of high-frequency jet ventilation (HFJV, f = 3 Hz, I: E = 0.43, FiO2 = 0.4) were studied and compared with continuous positive pressure ventilation (CPPV, f = 12-18/min, I:E = 0.5, TV = 12 ml/kg, PEEP = 0.5 kPa, FiO2 = 0.4) in a dog model of OAPO. In the control state (lung-healthy dogs), 15 min after oleic acid lung injury (interstitial oedema, period I) and 60 min after onset of OAPO (alveolar oedema, period II), gas exchange, lung volumes, compliance, resistance and haemodynamics were measured. The course of lung oedema was determined indirectly by means of washout curves of helium (foreign gas bolus-test, FGB) and nitrogen (single breath-test for oxygen, SBO2). During control, there were no significant differences between the HFJV-group (n = 7) and the CPPV-group (n = 6) by virtue of gas exchange, lung volumes and haemodynamics. During period I, PaO2 decreased significantly both with HFJV (p less than 0.01) and CPPV (p less than 0.05), being lower in the HFJV-group (p less than 0.05). PaCO2, pulmonary and haemodynamic parameters were unchanged. Onset of phase IV of the alveolar plateau (closing volume CV) occurred significantly earlier (p less than 0.05) in all animals. Impaired ventilation of dependent lung regions, increased maldistribution of intrapulmonary gas and VA/Q-mismatching may be the underlying mechanisms for lower efficacy of HFJV during interstitial lung oedema. In period II, pulmonary and cardiocirculatory parameters had changed significantly in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of intensive care medicine in Germany.

As of 1991, intensive care medicine in Germany is not an independent medical specialty but a part of other main medical specialities such as anesthesiology, internal medicine, surgery, and pediatrics. Accordingly, there is neither formal training nor a separate board examination in intensive care medicine. As in other countries, intensive care units (ICUs) were established during the 1950s and 1960s, triggered by the positive experience with consolidation of polio victims in special respiratory care units. Surgical (or operative) ICUs predominantly are operated by anesthesiology departments, as anesthesiologists' expertise in respiratory and hemodynamic support qualifies them for the management of the critically ill patient in the perioperative phase. This article gives a brief review of the development of intensive care medicine in Germany, thereby providing the historical background for its present national and regional organization, facilities, and education and training programs.

Effect of intraoperative fluid administration and colloid osmotic pressure on the formation of intestinal edema during gastrointestinal surgery.

The effects of intraoperative changes in plasma colloid osmotic pressure (COP) on the formation of intestinal edema were studied in patients during modified Whipple's operation (hemipancreato-duodenectomy). Eighteen patients (ASA physical status I or II) were randomly assigned to one of three groups. They received either lactated Ringer's (RL group, n = 6), 10% hydroxyethyl starch (HES group, n = 6), or 20% human albumin (HA group, n = 6) as a volume replacement solution, which was given to maintain central venous pressure (CVP) at the preoperative level. Jejunal specimens were obtained after the first transsection of the jejunum and prior to the jejuno-jejunostomy. Their water fraction (g H2O/g tissue dry weight) was measured gravimetrically. COP was determined prior to induction of anesthesia and upon removal of the second jejunal sample. In the RL group, 3,850 +/- 584 ml (data are means +/- SEM) of volume replacement solution were infused from induction of anesthesia to removal of the second jejunal sample. In the HES group, 1,358 +/- 45 ml were infused, and in the HA group, 463 +/- 49 ml were infused. During this time, COP decreased from 20.3 +/- 0.5 mmHg to 14.1 +/- 0.6 mmHg in the RL group, remained at 22.0 +/- 0.9 mmHg in the HES group, and increased from 20.7 +/- 0.9 mmHg to 28.1 +/- 0.9 mmHg in the HA group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hemodynamic and respiratory changes in operations of the esophagus by unilateral ventilation]. / Hämodynamische und respiratorische Veränderungen bei Operationen am Oesophagus unter unilateraler Ventilation.

One-lung ventilation offers optimal operating conditions during intrathoracic surgery. Hemodynamic and respiratory changes were measured in 9 patients. Cardiac output was unchanged, arterial pO2 decreased and venous admixture increased markedly. The increase in mean pulmonary artery pressure and pulmonary vascular resistance are signs for hypoxic pulmonary vasoconstriction in the unventilated lung. In spite of an inspiratory oxygen concentration of 66% oxygen availability was decreased by about 20%. Anaesthesia and related procedures should not interfere with pulmonary autoregulation. Complete monitoring is necessary to safely assess oxygenation of the patient.

The influence of ketanserin, droperidol and hydergine on postoperative hypertension during early recovery following major abdominal surgery.

Forty adult patients, who developed postoperative hypertension (greater than 160/90 mm Hg) following major abdominal surgery were given double-blind, randomized either ketanserin 10 mg i.v. (n = 10), droperidol 5 mg i.v. (n = 10), hydergine 0.9 mg i.v. (n = 10) or placebo solution (n = 10). Following the injection of ketanserin or droperidol systolic and diastolic blood pressure decreased significantly (p less than 0.001 and p less than 0.01), but were no longer significantly lowered 30 minutes following the injection in 5 out of 10 ketanserin treated and in 8 out of ten droperidol treated patients. Neither hydergine nor placebo had a significant effect on blood pressure. It is concluded, that both ketanserin and droperidol have a moderate and short acting antihypertensive effect.

Cardio-respiratory changes and prostaglandins during one-lung-anesthesia.

In a clinical study the intraoperative changes in prostaglandin levels and their possible influence on venous admixture during one-lung anesthesia are investigated in 9 patients undergoing abdomino-thoracic resection of a carcinoma of the oesophagus. During one-lung anesthesia PaO2 decreased and Qsp/Qt increased significantly. In 7 of the 9 patients prostaglandin E2 in the arterial blood was significantly above normal level during two-lung- and one-lung ventilation, prostaglandin F2 alpha was below normal values in all patients during two-lung- and one-lung ventilation. The clear prevalence of vasodilating prostaglandin E2 may have reduced the effectiveness of hypoxic pulmonary vasoconstriction during one-lung ventilation.

Pretreatment technique for fast intubation with vecuronium: intubation conditions and unwanted effects.

In eighty patients 15 micrograms kg-1 of vecuronium was given 3 minutes before induction of anesthesia and 50 micrograms kg-1 was given at the time of induction. The trachea was intubated 60 seconds after the second dose. A wide spread of twitch depression was found. The 80 patients were divided into 4 groups retrospectively with respect to the degree of neuromuscular blockade during intubation. Tracheal intubation was performed when the mean twitch depression was 48.8 +/- 11.8 (SD)% and the conditions were satisfactory in 89% of the cases. Intubating conditions were different significantly between the four sub-groups (p less than 0.01). Ptosis occurred in 77 patients, diplopia in 13 patients and dyspnea in 2 patients between the first injection of vecuronium and induction of anesthesia. The administration of vecuronium in divided doses gives satisfactory intubating conditions in the majority of the patients, but close observation between the priming dose and the induction of anesthesia is mandatory. The method is not considered suitable for obese and is probably not indicated in severely ill patients.

Percutaneous venous cannulation and central venous line placement by means of ultrasonography and ultrasonic Doppler.

Ultrasonography is being increasingly used in the field of anesthesiology. One major indication is visualization of central venous vessels, in particular the internal jugular vein before and during cannulation by means of ultrasonography or ultrasonic Doppler. This should facilitate puncture with a higher rate of successful cannulations and decreased rate of complications related to needle probing during catheterization attempts. Furthermore, by using ultrasonography central venous catheters can be located in the vessels. The picture quality of various central venous catheters currently used in anesthesia and intensive care does not show any noticeable difference.

[High frequency ventilation. Study of the mechanisms of action]. / Ventilation à haute fréquence. Etude des mécanismes d'action.

Dried lungs and isolated bronchial trees dissected from large animals were submitted to high-frequency oscillation and jet-ventilation. The pattern of intrapulmonary pressure distribution and CO2 diffusion were measured through transalveolar chambers fixed to the perforated pleural surfaces and through airbags pasted on the isolated bronchial trees. Under oscillating conditions, the pressure profiles in different lung and bronchial compartments were inhomogeneous and frequency dependent; the pressure-wave amplitude was proportional to the oscillation frequency. On the other hand, the inhomogeneities found with jet-ventilation were mostly dependent on the airflow direction and position of the intratracheal cannula. Since these inhomogeneities were similar on dissected lungs as well as on isolated bronchial trees, it was concluded that they were essentially dependent on endobronchial aerodynamic effects. But the absence of the in vivo pulmonary and bronchial elastic recoil certainly modified the effects of these ventilation modes with respect to accepted clinical findings. Also results were shown to vary between individuals and within individuals, probably explaining the divergent results obtained by different authors.

Permeation of the blood-brain barrier by urapidil and its influence on intracranial pressure in man in the presence of compromised intracranial dynamics.

We studied eight patients undergoing craniotomy for intracerebral tumour surgery requiring monitoring of intracranial pressure. All these patients showed significantly increased systolic arterial pressure, during anaesthesia. Following an average dose of 0.8 +/- 0.22 mg/kg urapidil, systolic arterial pressure returned to baseline values without a significant change in intracranial pressure. In nine patients, urapidil concentrations in plasma and cerebrospinal fluid were assayed following an intravenous injection of urapidil. Urapidil was found in the cerebrospinal fluid in concentrations between 5 and 99 ng/ml after total cumulative bolus injections of 10-75 mg. There is evidence that in clinically applied doses urapidil permeates the blood-brain barrier and reaches cerebrospinal fluid concentrations that allow an interaction with central 5-hydroxytryptamine-1A receptors.