Wolfgang Oczenski

Recruitment maneuvers after a positive end-expiratory pressure trial do not induce sustained effects in early adult respiratory distress syndrome.

Background: Recruitment maneuvers performed in early adult respiratory distress syndrome remain a matter of dispute in patients ventilated with low tidal volumes and high levels of positive end-expiratory pressure (PEEP). In this prospective, randomized controlled study the authors evaluated the impact of recruitment maneuvers after a PEEP trial on oxygenation and venous admixture (Qs/Qt) in patients with early extrapulmonary adult respiratory distress syndrome. Methods: After a PEEP trial 30 consecutive patients ventilated with low tidal volumes and high levels of PEEP were randomly assigned to either undergo a recruitment maneuver or not. Data were recorded at baseline, 3 min after the recruitment maneuver, and 30 min after baseline. Recruitment maneuvers were performed with a sustained inflation of 50 cm H2O maintained for 30 s. Results: Compared with baseline the ratio of the arterial oxygen partial pressure to the fraction of inspired oxygen (Pao2/Fio2) and Qs/Qt improved significantly at 3 min after the recruitment maneuver (Pao2/Fio2, 139 ± 46 mm Hg versus 246 ± 111 mm Hg, P < 0.001; Qs/Qt, 30.8 ± 5.8% versus 21.5 ± 9.7%, P < 0.005), but baseline values were reached again within 30 min. No significant differences in Pao2/Fio2 and Qs/Qt were detected between the recruitment maneuver group and the control group at baseline and after 30 min (recruitment maneuver group [n = 15]: Pao2/Fio2, 139 ± 46 mm Hg versus 138 ± 39 mm Hg; Qs/Qt, 30.8 ± 5.8% versus 29.2 ± 7.4%; control group: [n = 15]: Pao2/Fio2, 145 ± 33 mm Hg versus 155 ± 52 mm Hg; Qs/Qt, 30.2 ± 8.5% versus 28.1 ± 5.4%). Conclusion: In patients with early extrapulmonary adult respiratory distress syndrome who underwent a PEEP trial, recruitment maneuvers failed to induce a sustained improvement of oxygenation and venous admixture.

Hemodynamic and catecholamine stress responses to insertion of the combitube®, laryngeal mask airway or tracheal intubation

UNLABELLED In a prospective, randomized, and controlled trial, we compared the stress responses after insertion of the Combitube (CT; Kendall-Sheridan Catheter Corp., Argyle, NY), the laryngeal mask airway (LMA), or endotracheal intubation (ET). Seventy-five patients scheduled for routine urological or gynecological surgery were randomly allocated to one of three groups and were ventilated via either an ET, a LMA, or a CT. All three devices could be inserted easily and rapidly, providing adequate ventilation and oxygenation. Insertion of the CT was associated with a significant increase in mean maximal systolic arterial pressure (160+/-32 mm Hg) and diastolic arterial pressure (91+/-17 mm Hg) compared with ET (140+/-24, 78+/-11 mm Hg; P < 0.05, P < 0.01, respectively) or insertion of the LMA (115+/-33,63+/-22 mm Hg, both P < 0.001). The mean maximal epinephrine and norepinephrine plasma concentrations after insertion of the CT (37.3+/-31.1 and 279+/-139 pg/mL, respectively) were significantly higher than those after ET (35.8+/-89.8 and 195+/-58 pg/mL, respectively) or insertion of a LMA (17.3+/-13.3 and 158+/-67 pg/mL, respectively). This might be attributed to the pressure of the pharyngeal cuff of the CT on the anterior pharyngeal wall. We conclude that insertion of the CT causes a pronounced stress response and that precautions should be taken when used in patients at risk of hypertensive bleeding. IMPLICATIONS In this study, we showed that the hemodynamic and catecholamine stress responses after insertion of the Combitube (Kendall-Sheridan Catheter Corp., Argyle, NY) were significantly higher compared with laryngeal mask airway or endotracheal intubation. We conclude that the increased stress response to insertion of a Combitube may represent a serious hazard to patients with cardiovascular disease.

Hemodynamic and Catecholamine Stress Responses to Insertion of the Combitube[registered sign], Laryngeal Mask Airway or Tracheal Intubation

In a prospective, randomized, and controlled trial, we compared the stress responses after insertion of the Combitube[registered sign] (CT; Kendall-Sheridan Catheter Corp., Argyle, NY), the laryngeal mask airway (LMA), or endotracheal intubation (ET). Seventy-five patients scheduled for routine urological or gynecological surgery were randomly allocated to one of three groups and were ventilated via either an ET, a LMA, or a CT. All three devices could be inserted easily and rapidly, providing adequate ventilation and oxygenation. Insertion of the CT was associated with a significant increase in mean maximal systolic arterial pressure (160 +/- 32 mm Hg) and diastolic arterial pressure (91 +/- 17 mm Hg) compared with ET (140 +/- 24, 78 +/- 11 mm Hg; P (Anesth Analg 1999;88:1389-94)

Nalbuphine by PCA-pump for analgesia following hysterectomy: bolus application versus continuous infusion with bolus application.

The analgesic properties of the partial agonist–antagonist nalbuphine in the postoperative period are well known. When used for patient‐controlled analgesia (PCA) the effectiveness of this substance is comparable to that of morphine or tramadol. However, the optimal programme for administration of nalbuphine in PCA‐pumps has not been investigated. In particular, the combination of bolus administration vs bolus administration plus continuous basal administration is disputable.

Direct Current Auditory Evoked Potentials During Wakefulness, Anesthesia, and Emergence from Anesthesia

Direct current auditory evoked potentials (DC-AEPs) are a sensitive indicator of depth of anesthesia in animals. However, they have never been investigated in humans. To assess the potential usefulness of DC-AEPs as an indicator of anesthesia in humans, we performed an explorative study in which DC-AEPs were recorded during propofol and methohexital anesthesia in humans. DC-AEPs were recorded via 22 scalp electrodes in 19 volunteers randomly assigned to receive either propofol or methohexital. DC-AEPs were evoked by binaurally presented 2-s, 60-dB, 800-Hz tones; measurements were taken during awake baseline, anesthesia, and emergence. Statistical analysis included analysis of variance and discriminant analysis of data acquired during these three conditions. About 500 ms after stimulus presentation, DC-AEPs could be observed. These potentials were present only during baseline and emergence—not during anesthesia. Statistically significant differences were found between baseline and anesthesia and between anesthesia and emergence. In conclusion, similar effects, as reported in animal studies of anesthetics on the DC-AEPs, could be observed in anesthetized humans. These results demonstrate that DC-AEPs are potentially useful in the assessment of cortical function during anesthesia and might qualify the method for monitoring anesthesia in humans. IMPLICATIONS This study demonstrates the potential of direct current auditory evoked potentials for monitoring depth of anesthesia in humans.

Automatic tube compensation in patients after cardiac surgery: Effects on oxygen consumption and breathing pattern

Objective To evaluate patients without prior pulmonary disease after cardiac surgery and to determine whether resistive unloading by automatic tube compensation, pressure support ventilation, and continuous positive airway pressure has different effects on oxygen consumption, breathing pattern, gas exchange, and hemodynamics. Design Prospective, randomized, controlled study. Setting Tertiary care, postoperative intensive care unit. Patients Twenty-one patients scheduled for open heart coronary artery bypass graft surgery. Interventions Each patient was ventilated with all three modes in random order. Measurements and Main Results Patients were ventilated in three modes, each applied for 30 mins according to computer-generated randomization: pressure support ventilation with 5 cm H2O, continuous positive airway pressure, and automatic tube compensation. Oxygen consumption was calculated by means of indirect calorimetry. The hypnotic state of the patients was monitored by Bispectral Index. For hemodynamic measurements, a fiberoptic pulmonary artery catheter was inserted. The main finding of our study was that oxygen consumption and breathing pattern (tidal volume and respiratory rate) did not differ significantly during automatic tube compensation and pressure support ventilation compared with continuous positive airway pressure (oxygen consumption, 170 ± 29 vs. 170 ± 26 vs. 174 ± 29 mL·min·m, respectively; tidal volume, 466 ± 132 vs. 484 ± 125 vs. 470 ± 119 mL, respectively; respiratory rate, 16 ± 4 vs. 15 ± 4 vs. 16 ± 4 breaths/min, respectively). Automatic tube compensation and pressure support ventilation had no clinical effects on gas exchange and hemodynamic variables compared with continuous positive airway pressure. None of the variables differed significantly during the three ventilatory settings. Conclusion In postoperative tracheally intubated patients with normal ventilatory demand, automatic tube compensation and pressure support ventilation with 5 cm H2O lead to identical oxygen consumption, breathing patterns, gas exchange, and hemodynamics. We, therefore, suggest that this group of patients does not need any additional positive pressure support from the ventilator to overcome the additional work of breathing imposed by the endotracheal tube during the weaning phase from mechanical ventilation.

Naloxone-Resistant Respiratory Depression and Neurological Eye Symptoms After Intrathecal Morphine

We describe a case of neurological symptoms after the intrathecal use of an opioid. These symptoms were not reversible by the use of an opioid-antagonist.

Transvenous, intracardial cardioversion for the treatment of postoperative atrial fibrillation.

Atrial fibrillation (AF) following cardiac surgery is an important factor contributing to postoperative morbidity. Transvenous, intracardial cardioversion (TIC) has been shown to be effective in the treatment of chronic AF, but is an invasive and cost-intensive procedure. However, TIC would definitely be a beneficial approach if recurrence of AF following TIC is low and pharmacological treatment could be avoided. Thus, we hypothesised that TIC would be superior to conventional treatment with amiodarone with respect to the conversion rate and recurrence of AF. We compared TIC and conventional amiodarone therapy in a prospective, randomised and controlled trial in patients who developed AF following cardiac surgery. Twenty-three patients developed AF out of a total of 76 patients who gave written informed consent. Eighteen of these AF patients could be randomised into two equally sized groups to receive either an ALERT pulmonary artery catheter and TIC, or a standard pulmonary artery catheter and treatment with amiodarone. Haemodynamic parameters were registered before intervention to exclude pulmonary hypertension or fluid overload. Rates of cardioversion were compared by a Likelyhood ratio test. Out of the nine ALERT patients, AF in five cases converted to sinus rhythm (SR) with a median of two shocks (6 J). After 24 hours however, only two patients remained in sinus rhythm. On the other hand, six of the nine patients treated with amiodarone were still in SR after 24 hours. Whereas no difference was detectable in the conversion rate, persistence of SR following TIC was low. Thus, TIC without antiarrhythmic treatment is not recommendable for the treatment of postoperative AF.