[Catheter malposition following puncture of the left internal jugular vein]

A central venous catheter was inserted into the left internal jugular vein but was abnormally directed into a peripheral pulmonary vein. This could be explained by an anomalous pulmonary venous return to the superior vena cava.

"Closing volume" during high-frequency ventilation in anesthetized dogs

Airway closure, mean airway pressure, gas exchange and different modes of artificial ventilation were investigated in anesthetized and paralyzed dogs with clinically healthy lungs. The animals were ventilated with either intermittent positive pressure ventilation (IPPV), continuous positive pressure ventilation (GPPV, positive end-expiratory pressure (PEEP) = 0.49 kPa) or high-frequency jet ventilation (HFJV, open system) of 2 and 30 Hz with an inspiratory to expiratory (I/E) - ratio of 30/70 and 60/40. Closing volume (CV) was determined by a modified technique, submitting the lung to constant subatmospheric pressure after an inspiratory vital capacity of oxygen. Two different tests for CV were used: the foreign gas bolus (FGB) with helium as nonresident gas and the single breath nitrogen dilution technique (SBO2). During conventional mechanical ventilation, CV decreased significantly (P less than 0.05) after establishing a PEEP of 0.49 kPa. During HFJV, CV increased significantly (P less than 0.01). This effect was predominantly dependent on I/E duration time ratio and to a lesser extent on ventilatory frequency. There were significant differences between CV obtained by the FGB-method (CV(helium] and CV derived from the SBO2-test (CV(SBO2], although both tests revealed the same proportional changes of CV during the different modes of ventilation. The elevated CV was associated with a decreasing Pao2 and increasing Aa-Do2 and Paco2, indicating substantial hypoventilation and mismatching of ventilation and perfusion. Mean airway pressure increased with both CPPV and HFJV, revealing a dissociation between airway pressure and regional FRC distribution during HFJV. It is concluded that certain modes of high-frequency ventilation lead to impaired distribution of inspired gas to dependent lung regions.(ABSTRACT TRUNCATED AT 250 WORDS)

[High frequency ventilation. Study of the mechanisms of 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.

[High-frequency ventilation. I. Distribution of alveolar pressure amplitudes during high frequency oscillation in the lung model]

The pattern of intrapulmonary pressure distribution was studied during high-frequency ventilation in order to explain the inconsistent results reported in the literature. Methods. Pressure and flow velocity (hot-wire anemometry) were measured in different lung compartments: 1. In transalveolar chambers sealed to the perforated pleural surfaces of dried pig lungs; 2. In emphysema-simulating airbags sealed to the isolated bronchial trees of dried pig lungs; and 3. In transalveolar chambers sealed to the perforated pleural surfaces of freshly excised pig lungs. Results. 1. The pressure amplitudes change from one area to another and depending on the exciting frequency. 2. High-frequency oscillation is associated with an increase in pressure amplitude when the exciting frequency rises, whereas with conventional high-frequency jet ventilation the pressure amplitude is more likely to decrease with frequency. 3. During high-frequency jet ventilation the local pressure amplitude changes with the position of the tube in the trachea rather than with the exciting frequency. 4. When the volume of the measuring chamber is doubled the resulting pressure amplitude falls to half the control value. 5. The pressure amplitude and mean pressure measured in the transalveolar chamber vary more or less independently from the peak flow velocity. High-frequency ventilation is thus seen to be a frequency-dependant, inhomogeneous mode of ventilation that can essentially be homogenized by systematically changing the exciting frequency. The frequency-dependant response to different lung areas to excitation is likely to result from an intrabronchially-localized aerodynamic effect rather than the mechanical properties of the lung parenchyma.

[ABS 800: expanding the possibilities of respiratory therapy]

A new module of the Dräger modular device system provides a means for demand CPAP (to increase FRC) and assisted spontaneous breathing. Both features together may largely increase the potency of ventilatory therapy for spontaneously breathing patients. The machine may reduce the need for full ventilatory support in acute respiratory failure, but also provides a valid and rational tool for respiratory therapy.

Viscoelasticity of tracheobronchial secretions in high-frequency ventilation

The effects of high-frequency ventilation (HFV) on the rheological properties of tracheobronchial secretions were investigated in vitro. The mucus was obtained by suction from 16 patients after major surgery of the larynx or hypopharynx. After short centrifugation, the mucus was treated with high-frequency vibrations of 3 or 30 Hz for 10 min in a chamber saturated with water vapor. The mucus was separated by a nonpermeable membrane from the ventilator's gas stream. Maximal, minimal, and mean viscosity were determined by a modified capillary viscosimeter. Under high-frequency vibrations, maximal, minimal, and mean viscosity slightly increased (p less than or equal to .001). Conversely, the mean viscosity of control samples did not change significantly. These findings indicate that high-frequency vibrations do not improve mucous rheology. Observed beneficial effects of HFV on mucociliary clearance may be caused by changes in the mucous subphase during HFV.

[Flow resistance in pediatric oro- and nasotracheal tubes]

Flow resistances of different endotracheal tubes used in paediatric anaesthesia were determined with varying gas flows of 3 to 10 lit. per minute. We found no significant differences between preformed orotracheal and nasotracheal tubes and ordinary endotracheal tubes consisting of PVC plastic and spiral tubes made of silicone material, respectively. Woodbridge tubes showed significantly higher resistance to all gas flows used. Because of their less favourable material and flow resistance properties, Woodbridge tubes cannot be recommended for paediatric anaesthesia.

[Recording of anesthesia and recovery phase with a new integrated anesthesia record]

A new combined anaesthesia and recovery room record is presented, consisting of a treble sheet of self-copying paper two times prefolded to the standard chart size. It meets the increasing requirements of pre-, intra-, and postoperative anaesthesiological documentation.

[Complications of Woodbridge tubes (spiral wire tubes)]

Flexometallic (armoured) tubes should have advantages in orofacial surgery and difficult positioning. They still have also the possibilities of tube obstruction, as shown in four case reports.

Pulmonary blood flow reduction by prostaglandin F2 alpha and pulmonary artery balloon manipulation during one-lung ventilation in dogs

The purpose of this experimental study was to compare two methods of pulmonary blood flow manipulation during one-lung ventilation (OLV), either reducing pulmonary blood flow to the non-ventilated lung by inflation of a pulmonary artery catheter balloon (PAB) or by infusion of prostaglandin F2 alpha (PGF2 alpha). Seven anaesthetized dogs were intubated with a Kottmeier endobronchial tube and ventilated with 66% O2. Systemic and pulmonary pressures and blood gases, cardiac output and airway pressure were measured, and the venous admixture (QSP/QT) was calculated. During two-lung ventilation (TLV) Pao2 was 43.6 +/- 1.9 kPa (mean +/- s.d.) and (QSP/QT) was 11 +/- 3%. OLV reduced Pao2 to 12.1 +/- 1.6 kPa (P less than or equal to 0.001) and increased QSP/QT to 40 +/- 4% (P less than or equal to 0.001). Mean pulmonary artery pressure and airway pressure increased. PAB inflation caused an increase in Pao2 to 19.9 +/- 2.9 kPa (P less than or equal to 0.02) and a decrease in QSP/QT to 27 +/- 6% (P less than or equal to 0.001). PGF2 alpha infusion (1.2 micrograms kg-1 min-1) into the pulmonary artery of the non-ventilated lung increased Pao2 to 22.4 +/- 3.3 kPa (P less than or equal to 0.001) and decreased QSP/QT to 25 +/- 4 (P less than or equal to 0.001). PGF2 alpha infusion resulted in a small increase in mean systemic and pulmonary artery pressures. During the infusion of 1.2 micrograms kg-1 min-1 of PGF2 alpha no signs of bronchoconstriction were observed. PAB inflation and PGF2 alpha infusion were equally effective in improving oxygenation and reducing venous admixture during OLV.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin F2 alpha improves oxygen tension and reduces venous admixture during one-lung ventilation in anesthetized paralyzed dogs

The authors investigated the effect of prostaglandin F2 alpha infused into the pulmonary artery of an acutely atelectatic lung in dogs. Seven dogs were anesthetized with piritramid and pentobarbital and intubated with a Kottmeier canine endobronchial tube. Cardiac output, pulmonary arterial, capillary wedge, and systemic arterial pressure were measured via indwelling catheters. Ventilating both lungs with 66% O2, PaO2 was 327 +/- 15 mmHg (mean +/- SD) and venous admixture (Qsp/Qt) was 11 +/- 3%. One-lung atelectasis reduced PaO2 to 91 +/- 12 mmHg and increased Qsp/Qt to 40 +/- 4%. Prostaglandin F2 alpha in doses of 0.4, 0.6, 1.2, and 1.8 micrograms X kg-1 X min-1 was infused into the pulmonary artery of the atelectatic lung through a second pulmonary artery catheter. Up to a dose of 1.2 micrograms X kg-1 X min-1 there was a dose-dependent reduction in Qsp/Qt to a minimum of 25 +/- 4% and an increase in PaO2 to 168 +/- 25 mmHg, which could be explained by enhanced pulmonary vasoconstriction in the atelectatic lung with increased blood flow diversion toward the ventilated lung. Infusion of 1.8 micrograms X kg-1 X min-1 decreased PaO2 to 156 +/- 32 mmHg and increased Qsp/Qt to 32 +/- 9%. Increased systemic effects of prostaglandin F2 alpha were observed and presumably were related to saturation of prostaglandin-dehydrogenase leading to vasoconstriction in both lungs and thus reduced blood flow diversion toward the ventilated lung.

Anesthetic management in patients with pheochromocytoma

In expert hands, perioperative mortality of elective removal of pheochromocytoma can almost be completely eliminated. Isoflurane and enflurane plus nitrous oxide have proved to be suitable anesthetic agents and there are potent drugs for the treatment of intraoperative cardiovascular disturbances. The major factor responsible for mortality reduction is a well-balanced pre-, peri- and postoperative fluid replacement.

[Tramadol infusion anesthesia with the substitution of enflurane and various nitrous oxide concentrations]

The synthetic opioid tramadol was given to 40 patients during surgery according to a fixed, calculated infusion scheme. Anesthesia was started with thiopental and the patients were given different nitrous oxide concentrations via a semi-open system (group 1: 60%, group 2: 75%). The aim of this study was to clarify whether this anaesthetic procedure is practicable or whether it has grave disadvantages in comparison with the anesthesia models used so far. Furthermore we wanted to clarify whether under this infusion scheme the proportion of N2O in the inspiratory mixture is sufficient or whether higher concentrations are required. In 24 of 40 patients analgesia or the depth of anaesthesia was insufficient so that additional enflurane application was necessary. Postoperative respiratory depression in three patients had to be treated with naloxone. The advantages of this procedure are the safe and easy practicability, absence of significant changes in the haemodynamic parameters, good postoperative response of the patients and postoperative pain relief as well as the low incidence of postoperative side effects such as nausea, vomiting and CO2-retention.

[Brain function and artificial respiration]

Haemodynamic changes (cerebral perfusion pressure, cerebral blood flow) and variations of blood gases (especially paCO2) induced by mechanical ventilation, can influence cerebral function. The cerebral response to these changes is modified by the individual pathophysiology of the cranial contents. The cerebral mechanisms of adaptation allow a safe ventilation of a patient without cerebral disorders, provided ventilation is within normal clinical limits. In patients, however, whose mechanisms of adaption are impaired locally or globally, the pathophysiological situation may become grossly changed by variations in the ventilatory pattern. A therapeutical application of this interaction is controlled hyperventilation to lower intracranial pressure. On the other hand, changes in the ventilatory pattern (variation of PEEP-level, variation of minute volume, bronchial toilet) can impair cerebral function critically. As the individual reactions cannot be predicted in this group of patients, monitoring of haemodynamic parameters (MAP, CVP, CO), blood gases, intracranial pressure, and EEG is of utmost importance.

[Hemodynamic and respiratory changes in operations of the esophagus by unilateral 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.

[A new weaning procedure (inspiratory flow assistance)]

Inspiratory Flow Assistance (IFA) refers to new breathing mode, able to diminish the work of breathing of a patient during spontaneous breathing with a respirator. By combination of IFA with CPAP or IMV it is especially useful during weaning from the respirator. The part of work of breathing done by the respirator. The part of work of breathing done by the respirator is only indirectly determinable. The measurements done on 10 long term ventilated patients during the weaning period show that only an IFA up to an airway pressure of 10 cm H2O above CPAP guarantees mainly spontaneous breathing, while an IFA up to higher airway pressures is more and more similar to an assisted ventilation.

[Pathophysiology and clinical aspects of single lung ventilation]

There are absolute and strong relative indications for provision of one-lung ventilation. The knowledge of the special physiology of one-lung ventilation as well as of the factors influencing hypoxic pulmonary vasoconstriction is necessary for adequate management of one-lung anaesthesia. Arterial hypoxaemia is a common complication of one-lung ventilation. Established techniques of treatment of hypoxaemia during one-lung ventilation are presented and several additional recent techniques are discussed.