Niels-Peter Preussler

Percutaneous transtracheal ventilation: effects of a new oxygen flow modulator on oxygenation and ventilation in pigs compared with a hand triggered emergency jet injector

The application of percutaneous transtracheal jet ventilation for emergency ventilation depends on special equipment which is often not available outside the operating room. The oxygen flow modulator is a new specially designed device for emergency ventilation using a low pressure oxygen supply. We studied the effects of the new device in comparison with a hand triggered emergency jet injector on oxygenation and ventilation in six pigs (21+/-1 kg). The animals were anaesthetized, tracheally intubated, and mechanically ventilated. Following central venous and pulmonary artery catheterization, a Paratrend 7 sensor was placed in the left femoral artery for continuous measurements of PaO(2) and PaCO(2). Then an emergency transtracheal airway catheter was inserted into the trachea after surgical exposure. In randomized order each animal was ventilated via the transtracheal airway catheter with the hand triggered emergency jet injector (inspiratory/expiratory (I/E) ratio of 1:1; respiratory rate of 60 min(-1); driving pressure 1.5 bar; FjetO(2) 1.0) and the oxygen flow modulator (FiO(2) 1.0 at an oxygen flow of 15 l min(-1); respiratory rate of 60 min(-1); I/E ratio of approximately 1:1) for 15 min each. After each phase of the experiment respiratory and hemodynamic variables were measured. Whereas PaO(2) was not significantly different between the two devices, PaCO(2) was higher during the hand-triggered jet ventilation. Thus, the efficacy of the oxygen flow modulator during the experiment was comparable with the efficacy of the hand triggered emergency jet injector.

The effects of increasing concentrations of isoflurane and desflurane on pulmonary perfusion and systemic oxygenation during one-lung ventilation in pigs.

During one-lung ventilation (OLV), hypoxic pulmonary vasoconstriction (HPV) reduces venous admixture and attenuates the decrease in arterial oxygen tension by diverting blood from the nonventilated lung to the ventilated lung. In vitro, desflurane and isoflurane depress HPV in a dose-dependent manner. Accordingly, we studied the effects of increasing concentrations of desflurane and isoflurane on pulmonary perfusion, shunt fraction, and Pao2 during OLV in vivo. Fourteen pigs (30–42 kg) were anesthetized, tracheally intubated, and mechanically ventilated. After placement of femoral arterial and thermodilution pulmonary artery catheters, a left-sided double-lumen tube (DLT) was placed via tracheotomy. After DLT placement, Fio2 was adjusted at 0.8 and anesthesia was continued in random order with 3 concentrations (0.5, 1.0, and 1.5 minimal alveolar concentrations) of either desflurane or isoflurane. Differential lung perfusion was measured with colored microspheres. All measurements were made after stabilization at each concentration. Whereas mixed venous Po2, mean arterial pressure, cardiac output, nonventilated lung perfusion, and shunt fraction decreased in a dose-dependent manner, Pao2 remained unchanged with increasing concentrations of desflurane and isoflurane during OLV. In conclusion, increasing concentration of desflurane and isoflurane did not impair oxygenation during OLV in pigs.

Percutaneous transtracheal emergency ventilation with a self‐made device in an animal model

Background:  Special equipment for emergency percutaneous transtracheal ventilation is often not immediately available. We used a self‐made device consisting of a three‐way stopcock connected between a G‐15 transtracheal airway catheter and an oxygen supply in a simulated ’cannot intubate, cannot ventilate’ scenario and tested the hypothesis that the effectiveness of the device depends on the body weight of the experimental animals.

The effects of xenon or nitrous oxide supplementation on systemic oxygenation and pulmonary perfusion during one-lung ventilation in pigs

During experimental one-lung ventilation (OLV), the type of anesthesia may alter systemic hemodynamics, lung perfusion, and oxygenation. We studied whether xenon (Xe) or nitrous oxide (N2O) added to propofol anesthesia would affect oxygenation, lung perfusion, and systemic and pulmonary hemodynamics during OLV in a pig model. Nine pigs were anesthetized, tracheally intubated, and mechanically ventilated. After placement of arterial and pulmonary artery catheters, a left-sided double-lumen tube was placed via tracheotomy. IV anesthesia with propofol was supplemented in random order with N2O/O2 60:40 or Xe/O2 60:40 or N2/O2 60:40. All measurements were made after stabilization at each concentration. Differential lung perfusion was measured with colored microspheres. Oxygenation (Pao2: 90 ± 17, 95 ± 20, and 94 ± 20 mm Hg for N2/O2, N2O/O2, and Xe/O2) and left lung perfusion (16% ± 5%, 14% ± 6%, and 18.8% for N2/O2, N2O/O2, and Xe/O2) during OLV did not differ among the 3 groups. However, mean arterial blood pressure (78 ± 25, 62 ± 23, and 66 ± 23 mm Hg for N2/O2, N2O/O2, and Xe/O2) and mixed venous saturation (55% ± 12%, 48% ± 12%, and 50% ± 12% for N2/O2, N2O/O2, and Xe/O2) were reduced during N2O/O2 as compared with the control group (N2/O2). Supplementation of IV anesthesia with Xe or N2O does not impair oxygenation nor alter lung perfusion during experimental OLV.

Effects of inhaled nitric oxide on oxygenation and haemodynamic performance during one-lung ventilation in pigs

Abstract Objective: To study the effects of 20 ppm inhaled nitric oxide (iNO) on haemodynamics and systemic oxygenation during one-lung ventilation (OLV) in vivo. Design: Prospective animal study with a cross-over design. Setting: Animal laboratory of a university hospital. Subjects: Eight female pigs. Outcome measures: The pigs were anaesthetized, tracheally intubated, and mechanically ventilated. Following placement of femoral arterial and pulmonary artery catheters, a left-sided double-lumen tube (DLT) was placed via tracheotomy After DLT placement, in each animal OLV was performed during intravenous anaesthesia in a cross-over design with and without iNO (20ppm) in 100% oxygen. After haemodynamic stabilization, haemodynamic measurements and blood gas analyses were made, in addition we measured differential lung perfusion with colored microspheres in three animals. Results and Conclusions: iNO did not improve oxygenation nor did iNO reduce pulmonary arterial pressure in our animal model. Mixed venous PvO2 and cardiac output were comparable during the study periods.

Transtracheale Oxygenierung bei Atemwegsverlegung durch einen Hypopharynxtumor

ZusammenfassungEin 42-jähriger alkoholabhängiger Patient wurde unter dem Bild einer generalisierten Zyanose bei respiratorischer Insuffizienz wegen eines fortgeschrittenen Hypopharynxtumors in der HNO-Klinik vorgestellt. Eine konventionelle Intubation erschien nicht möglich. Zur sofortigen Verbesserung der Oxygenierung erfolgte bei einer pulsoxymetrisch gemessenen SpO2 von 56% die Platzierung eines transkrikothyroidalen Katheters zur trachealen O2-Insufflation. Nach Anstieg der SpO2 auf 82% wurde der Patient transnasal fiberoptisch wach intubiert. Anschließend erfolgte in Allgemeinanästhesie die chirurgische Tracheotomie. Nach intensivmedizinischer Betreuung wurde der Patient am Folgetag zur weiteren Diagnostik auf eine internistische Normalstation verlegt. Anhand des Fallbeispiels wird auf die Notwendigkeit von Alternativverfahren zur notfallmäßigen Oxygenierung/Atemwegssicherung bei einer “cannot intubate, cannot ventilate”– Situation eingegangen.AbstractA 42-year-old male with a history of chronic alcoholism was admitted to the department of otolaryngology with acute respiratory insufficiency and generalised cyanosis due to a respiratory obstruction by a large tumour of the hypopharynx. Because of the size and location of the tumour and the risk of bleeding, orotracheal intubation by direct laryngoscopy was considered almost impossible. To improve oxygenation cricothyroidal punction and oxygen insufflation was done immediately and SpO2 increased from 56% to 82%. Awake fiberoptic nasotracheal intubation was performed under topical anaesthesia, then general anaesthesia was induced and controlled ventilation was started. After surgical tracheotomy the patient was transferred to an intensive care unit and 12 h later the patient was discharged from the ICU.