Normoxic cardiopulmonary bypass reduces oxidative myocardial damage and nitric oxide during cardiac operations in the adult.

OBJECTIVE: Hyperoxic cardiopulmonary bypass is widely used during cardiac operations in the adult. This management may cause oxygenation injury induced by oxygen-derived free radicals and nitric oxide. Oxidative damage may be significantly limited by maintaining a more physiologic oxygen tension strategy (normoxic cardiopulmonary bypass). METHODS: During elective coronary artery bypass grafting, 40 consecutive patients underwent either hyperoxic (oxygen tension = 400 mm Hg) or normoxic (oxygen tension = 140 mm Hg) cardiopulmonary bypass. At the beginning and the end of bypass this study assessed polymorphonuclear leukocyte elastase, nitrate, creatine kinase, and lactic dehydrogenase, antioxidant levels, and malondialdehyde in coronary sinus blood. Cardiac index was measured before and after cardiopulmonary bypass. RESULTS: There was no difference between groups with regard to age, sex, severity of disease, ejection fraction, number of grafts, duration of cardiopulmonary bypass, or ischemic time. Hyperoxic bypass resulted in higher levels of polymorphonuclear leukocyte elastase (377 +/- 34 vs 171 +/- 32 ng/ml, p = 0.0001), creatine kinase 672 +/- 130 vs 293 +/- 21 U/L, p = 0.002), lactic dehydrogenase (553 +/- 48 vs 301 +/- 12 U/L, p = 0.003), antioxidants (1.97 +/- 0.10 vs 1.41 +/- 0.11 mmol/L, p = 0.01), malondialdehyde (1.36 +/- 0.1 micromol/L,p = 0.005), and nitrate (19.3 +/- 2.9 vs 10.1 +/- 2.1 micromol/L, p = 0.002), as well as reduction in lung vital capacity (66% +/- 2% vs 81% +/- 1%,p = 0.01) and forced 1-second expiratory volume (63% +/- 10% vs 93% +/- 4%, p = 0.005) compared with normoxic management. Cardiac index after cardiopulmonary bypass at low filling pressure was similar between groups (3.1 +/- 0.2 vs 3.3 +/- 0.3 L/min per square meter). [Data are mean +/- standard error (analysis of variance), with p values compared with an oxygen tension of 400 mm Hg.] CONCLUSIONS: Hyperoxic cardiopulmonary bypass during cardiac operations in adults results in oxidative myocardial damage related to oxygen-derived free radicals and nitric oxide. These adverse effects can be markedly limited by reduced oxygen tension management. The concept of normoxic cardiopulmonary bypass may be applied to surgical advantage during cardiac operations.

Operative techniques in awake coronary artery bypass grafting.

BACKGROUND: Off-pump coronary artery bypass grafting was implemented to reduce trauma of surgical coronary revascularization by avoiding extracorporeal circulation. High thoracic epidural anesthesia further reduces intraoperative stress and postoperative pain. In addition, this technique even allows awake coronary artery bypass grafting, avoiding the drawbacks of mechanical ventilation and general anesthesia in high-risk patients. METHODS: Thirty-four patients underwent awake coronary artery bypass grafting with left internal thoracic artery to left anterior descending coronary artery by partial lower ministernotomy (n = 20), H-graft technique (n = 2), or rib cage-lifting technique (n = 2). In 9 cases we performed double bypass grafting, and in 1 case we performed triple-vessel coronary artery revascularization through complete median sternotomy. In addition to clinical outcomes, visual analog scale pain scores were recorded on days 1, 2, and 3 after surgery. RESULTS: Thirty-one patients remained awake throughout the whole procedure. Three patients required secondary intubation because of incomplete analgesia (n = 1) or pneumothorax (n = 2). Procedure time was 90 +/- 31 minutes, and recovery room stay was 4.2 +/- 0.6 hours. There were no in-hospital deaths or serious postoperative complications. In 1 case a graft occlusion was documented on predischarge angiography. Early postoperative pain was low (visual analog scale score of 30 +/- 6). CONCLUSION: These data demonstrate the feasibility and safety of various surgical coronary revascularization techniques without general anesthesia. Continuation of thoracic epidural analgesia provides good pain control and fast mobilization postoperatively. Surprisingly, the awake coronary artery bypass grafting procedure was well accepted by the patients.

[Preoxygenation with the NasOral((R)) system or the standard face mask?]. / Präoxygenierung mit NasOral((R))-System oder herkömmlicher Gesichtsmaske?

INTRODUCTION: Adequate preoxygenation of patients before onset of apnea for orotracheal intubation is of major importance in general anaesthesia. Various preoxygenation techniques are available but a face mask providing an oxygen supply via the circle absorber system of a mechanical respirator is most frequently used. Recently, a new device for preoxygenation - the NasOral((R)) system - has become available. The aim of the present study was to compare the efficacy of intrapulmonary oxygen storage with either the NasOral((R)) device or the standard face mask. METHODS: After informed and written consent and ethics committee approval was obtained, 40 elective patients (ASA I and II) undergoing surgical procedures of the neck and mouth area, were enrolled in this randomized, prospective study. In group A ( n=20), preoxygenation was performed using the NasOral((R)) system. Patients inhaled 100% oxygen through the nose and exhaled orally through unidirectional valves. In group B ( n=20), a conventional face mask with an O(2) flow of 15 l/min and an open airway pressure release valve was used for preoxygenation. In both groups preoxygenation lasted for 2.5 min. Induction of general anaesthesia was performed in a standardized manner. After intubation patients were not ventilated until the O(2) saturation in pulse oximetry (psaO(2)) dropped to 95%. This time of apnea was recorded in both groups and we determined the hemoglobin concentration (cHb) after beginning of ventilation. RESULTS: There were no significant differences with regard to demographic data and cHb. Time of apnea leading to a O(2) saturation of 95% was 6.0+/-2.1 min in group A and 6.3+/-2.1 min in group B (mean+/-SD, p>0.05). CONCLUSIONS: Both the NasOral((R)) system and the face mask are effective for intrapulmonary oxygen storage. In both systems the O(2) flow has to be adequately high and the masks have to be held tightly in order to avoid any contamination of the inhaled oxygen with nitrogen. Due to its unidirectional flow, the NasOral((R)) system additionally requires the patient to be cooperative. As the NasOral((R)) system is more expensive and has no clinical advantages without apneic oxygenation, we prefer the standard face mask for patient preoxygenation.

[Fiberoptic intubation during remifentanil propofol sedation]. / Bronchoskopische Intubation in Remifentanil-Propofol-Sedierung.

OBJECTIVE: Fiberoptic intubation for the management of the difficult airway is usually achieved with the patient under light sedation. The goal of the present study was to evaluate the combination of propofol and remifentanil for sedation during fiberoptic intubation. METHODS: Plans were made to use fiberoptic intubation in 40 patients with predictably difficult airways. After topical anaesthesia of the pharynx with lidocaine, oxygen was administered via nasal cannula. A capnograph was attached to determine the adequacy of ventilation and an infusion of remifentanil (0.05 microgram/kg/min) and propofol (2 mg/kg/h) was started. After the first signs of sedation, nasal fiberoptic intubation was carried out. The depth of sedation was guided by clinical observation and capnographic data and the remifentanil dose was adjusted as necessary. RESULTS: All patients, including some with very severe airway anomalies, were uneventfully intubated using the regimen we have described. Nasal capnography made it possible to monitor ventilation in all patients during bronchoscopy and intubation. The onset of hypoventilation was recognized in patients and appropriately treated by adjusting the narcotic dose. No subject became hypoxic or hypercarbic during the procedure. The changes of blood pressure and heart rate exceeded the 30% range in only one patient (a 37% blood pressure increase). Sedation was rated as good to very good in 35 patients. Coughing occurred only in 5 patients and 37 out of 40 patients had no recall that intubation had occurred. CONCLUSION: Our combination of remifentanil and propofol was shown to be a safe sedation regimen for fiberoptic intubation. Monitoring ventilation via nasal capnography and arterial oxygen saturation via pulse oximetry provided sufficient patient safety.

Prophylactically-administered rectal acetaminophen does not reduce postoperative opioid requirements in infants and small children undergoing elective cleft palate repair.

UNLABELLED: Rectal acetaminophen (Ac) is often administered prophylactically at anesthesia induction for postoperative pain management in small children and is thought to have an opioid-sparing effect. We assessed in this double-blinded, prospective, randomized study early opioid requirements after three doses of Ac (10, 20, and 40 mg/kg versus placebo) in 80 children (ASA physical status I, age 11.4 +/- 9.9 mo) undergoing cleft palate repair. Single Ac plasma concentrations were measured. Pain scores assessed in the postanesthesia care unit of > or = 4 of 10 resulted in the IV administration of 25 microg/kg piritramide, a popular European mu receptor agonist (lockout time, 10 min; maximum 0.125 mg/kg). There were no significant differences between groups with regard to the early postoperative pain scores and the overall cumulative IV opioid requirements. Maximal plasma concentrations achieved were only subtherapeutic (Ac 10 mg/kg: 8 microg/mL; Ac 20 mg/kg: 13 microg/mL; Ac 40 mg/kg: 21 microg/mL after 122, 122, and 121 min, respectively). We conclude that rectal Ac up to 40 mg/kg has no opioid-sparing effect, does not result in analgesic Ac plasma concentrations, and lacks proof of its efficacy in infants and small children undergoing cleft palate repair, whereas titrated IV opioid boluses produced rapid and reliable pain relief. IMPLICATIONS: Acetaminophen is widely used prophylactically for postoperative analgesia in children and is thought to have an opioid-sparing effect. We showed that rectal acetaminophen up to 40 mg/kg administered at anesthesia induction lacked proof of efficacy, whereas IV opioid boluses resulted in reliable pain relief in children undergoing cleft palate repair.

[Postoperative pain therapy in pediatrics. Results of a representative survey in Germany]. / Postoperative Schmerztherapie im Kindesalter. Ergebnisse einer repräsentativen Umfrage in Deutschland.

The last survey addressing postoperative pain management in Germany was published in 1987, special data concerning postoperative pain management in pediatric patients had not been presented previously. The goal of this survey is to present the standard of postoperative pain management in pediatric patients in Germany. A detailed questionnaire was mailed to all German anaesthesia departments and interdisciplinary intensive care units (n = 1,500) to determine the current management of postoperative pain management in pediatric patients. After eight weeks, 42.6% of the survey had been returned. Rectally administered acetaminophen is the standard drug regimen for postoperative analgesia in children. Compared to previous surveys, the use of opioids has increased in popularity. The routine use of non-steroid antiinflammatory drugs (NSAIDs) and spasmolytics as well as the application of regional anaesthesia techniques is uncommon in pediatric postoperative pain management. Compared to other European countries, patient- or parent-controlled analgesia is more popular in Germany. Despite modern concepts of organization and a great variety of drugs available today, 71.1% of the responding anesthesiologists in this survey still believe that pediatric postoperative pain management needs to be improved.

[Effect of halothane, enflurane and isoflurane on the pharmacodynamics of mivacurium in children]. / Einfluss von Halothan, Enfluran und Isofluran auf die Pharmakodynamik von Mivacurium bei Kindern.

INTRODUCTION AND OBJECTIVE: Mivacurium is a new non-depolarising muscle relaxant with a relatively rapid onset and short duration of action. In children, intravenous injection of 0.2 mg/kg produces satisfactory relaxation. Because inhalational anaesthetics have been found to enhance the potency of muscle relaxants we determined if onset or recovery times following mivacurium are influenced by inhalation of halothane (HAL), enflurane (ENF) or isoflurane (ISO). METHODS: After intramuscular induction, 36 surgical children (2-6 years, ASA I) were randomly assigned to inhale either HAL (n = 12); ENF (n = 12) or ISO (n = 12). The train-of four (TOF) response was determined electromyographically (Relaxograph, Datex) at 20-second time intervals. Following ten minutes of inhalation of either HAL, ENF or ISO (0,8; 1,2; 1,0 vol% respectively) in N2 O/O2 (2:1), 0.2 mg/kg of mivacurium was injected intravenously. Patients were intubated at maximal T1-suppression and the intubating conditions were judged according to a graded score. Upon recovery of T1 = 25%, six patients in each group were antagonised with 30 micrograms/kg of neostigmine and 15 micrograms/kg of atropine; the recovery indices were compared with those from non-antagonised patients. Differences between groups were tested with multifactorial analysis of variance (p < 0.05). RESULTS: Intubating conditions were graded as "excellent" or "good" in all patients but one who showed moderate breath holding following the tube passage. Onset times of mivacurium were not different between patients receiving HAL: 2.4 min +/- 0.52 (+/ SD); ENF: 2.4 min +/- 0.55 or ISO: 2.6 min +/- 0.68. Time to T1 = 25% was 7.6 min +/- 2.91 (HAL); 7.9 min +/- 1.55 (ENF) and 8.6 min +/- 2.30 (ISO). Recovery indices were not significantly different between groups. Total duration of action in non-antagonised patients was 13.0 min +/- 3.32 (HAL); 14.3 min +/- 4.01 (ENF) and 19.6 min +/- 5.17 (ISO), whereas antagonised duration of action was 13.4 min +/- 5.11 (HAL); 13.3 min +/- 1.97 (ENF) and 15.6 min +/- 4.25 (ISO). The shorter total duration of action in patients receiving neostigmine (average 0.5-2 minutes) was statistically insignificant. DISCUSSION AND CONCLUSION: Following injection of 0.2 mg/kg of mivacurium, no clinically relevant differences in onset or recovery times were found between children receiving halothane, enflurane or isoflurane. No differences in heart rate or blood pressure were found between groups. Compared to previous investigations with mivacurium, we noted a 30-60% longer mean onset time and a 30% shorter mean spontaneous recovery time. This may be explained by the lower mean age of our patients, which correlates with a relatively higher volume of distribution, resulting in lower plasma concentrations if the dose is calculated per kilogramme body weight. The reduction of the mean recovery time by 2 minutes following neostigmine injection seems to be clinically irrelevant. Similar to adult, a twofold ED95 produces satisfactory surgical muscle relaxation in children receiving mivacurium. Thus, its onset time is comparable to that of vecuronium or atracurium. The shorter duration of action offering a tighter control over relaxation may be of clinical advantage in this age group.

[Remifentanil-propofol for bronchoscopic fiber optic intubation under capnographic control]. / Remifentanil/Propofol zur bronchoskopischen Wachintubation unter Kapnographiekontrolle.

UNLABELLED: We report a case of a 41-years-old woman presenting for revision of a secondary reconstructive procedure using the modified Tagliacozzi upper arm flap after subtotal maxillectomy. Because of the pedicle flap the upper arm was fixed in a pre-facial position and so fiberoptic intubation was required. After routine pre-anesthetic preparations and topical anesthesia of the nares and nasopharynx a CO2 measuring catheter as well as a O2 catheter to administer 100% oxygen was inserted deeply into the left naris. At that time, a continuous infusion of 0.05 microgram/kg/min remifentanil and 2 mg/kg/h propofol was started. After 4 min, fiberoptic intubation was performed through the right nare without any technical difficulties in conscious sedation of the patient. During the entire fiberoptic intubation SaO2 was constant at 100% and capnogram tracings with etCO2 values ranging from 31 to 33 mmHg were displayed on the monitor. At the end of this second surgical procedure with fixed pre-facial upper arm position the patient was uneventfully extubated fully awake. For the time period of fiberoptic intubation the patient had complete amnesia. CONCLUSION: With the use of nasal capnography and capnometry in addition to simultaneous O2 administration during fiberoptic intubation under extreme conditions excellent analgosedation with propofol and remifentanil could be provided without compromising our patients' safety. The presented CO2 measuring and O2 administering device represents a simple and cheap expansion of standard anesthetic monitoring during fiberoptic intubation.

[Coronary bypass operation with complete median sternotomy in awake patients with high thoracic peridural anesthesia]. / Koronare Bypassoperation mit kompletter medianer Sternotomie am wachen Patienten in hoher thorakaler Periduralanästhesie.

OBJECTIVE: High thoracic epidural anesthesia (TEA) combined with general anesthesia is increasingly being used for coronary artery bypass grafting (CABG) with extracorporeal circulation. Recent developments in beating heart techniques have rendered the use of TEA alone in conscious patients possible and have been reported for single-vessel beating heart CABG via lateral thoracotomy. For multi-vessel revascularization the heart is usually approached via median sternotomy, therefore the use of TEA alone was applied in awake patients with multi-vessel coronary artery disease who underwent CABG via median sternotomy. METHODS: A total of 10 patients scheduled for awake coronary artery bypass grafting (ACAB) received TEA via an epidural catheter placed at T1/2 or T2/3. Total arterial myocardial revascularization was performed after median sternotomy. In addition to standard monitoring, anesthetic sensory and motor block levels were determined using an epidural scoring scale for arm movements (ESSAM). RESULTS: Except for one patient who required intraoperative endotracheal intubation due to a pneumothorax, all patients were awake and maintained spontaneous breathing during the entire procedure. Compared to baseline values, hemodynamic parameters, e.g. arterial blood pressure (SAP, MAP, DAP) and heart rate significantly declined during coronary anastomosis. No significant hypercarbia was observed. The intraoperative pain level was subjectively estimated by the patients as less than 20 out of 100 (median 10.95% confidence interval 4.2-21.6) using a visual analogue scale. All patients rated TEA as "good" or "excellent." Adverse effects associated with TEA were not observed. CONCLUSIONS: We could demonstrate that the use of TEA alone for CABG via median sternotomy was feasible and produced good results. High patient satisfaction in our small and highly selected cohort could be reported. Nevertheless, randomized controlled trials in large cohorts are mandatory to definitively evaluate the role of TEA alone in cardiac surgery.

[Total arterial bypass operations with complete sternotomy in the awake patient]. / Totalarterielle Bypassoperationen über komplette Sternotomie am wachen Patienten.

BACKGROUND: In minimally invasive coronary artery bypass surgery beating heart procedures and operations via limited incisions became more popular and are routinely performed in many centers. An additional approach to minimize general trauma is avoidance of general anesthesia endotracheal intubation. PATIENTS AND METHODS: Between March and June 2001, 14 spontaneously breathing patients underwent coronary artery bypass grafting on the beating heart without general anesthesia. Intra- and postoperative analgesia management was performed using continuous epidural infusion of local anesthetics at level Th2-Th3. Single (n = 8) as well as double (n = 5) and triple (n = 1) bypass grafting was performed with the off pump technique. Surgical access to the chest cavity was created via partial (n = 8) or complete sternotomy (n = 6). RESULTS: Twelve patients remained awake throughout the procedure; 2 patients required secondary intubation due to incomplete sensory block and pneumothorax. Operating time was 94 +/- 18 minutes. Intermediate care monitoring time amounted to 4.8 +/- 0.6 hours. No surgery-related complications or myocardial infarction occurred. Postoperative angiography reviewed good graft function in all patients. CONCLUSION: Our preliminary experience shows that complete surgical revascularization is safe and feasible without endotracheal intubation and general anesthesia. Thus, invasiveness in cardiac surgery is further reduced with less need for intensive care unit monitoring enabling faster mobilization and recovery.