The three-way stopcock may be a weak component of total intravenous anaesthesia.

BACKGROUND: An intravenous line is needed to administer anaesthesia, particularly when total intravenous anaesthesia (TIVA) is performed. A disadvantage of TIVA is that the intravenous concentration of anaesthetics cannot be easily measured compared with volatile anaesthetics. If a three-way stopcock is accidentally unscrewed, TIVA drugs cannot reach the patient's veins, thus resulting in inadequate anaesthesia levels, possibly resulting in awareness. We therefore measured the required torque to open five different brands of three-way stopcocks in an attempt to make an intravenous-line including all elements safer. METHODS: The torque required to open one, two or three three-way stopcocks being connected in a perpendicular manner was measured with a biaxial servo hydraulic material testing machine. RESULTS: The force required to open three-way stopcocks connected with an intravenous catheter ranged in five different stopcock models from 5.03+/-0.75 to 2.21+/-0.51 N respectively; with two three-way stopcocks from 2.68+/-0.42 to 1.31+/-0.59 N, respectively, and with three three-way stopcocks from 1.29+/-0.27 to 0.82+/-0.05 N, respectively. CONCLUSION: Turning a three-way stopcock to become loose with possibly leaking drugs requires minimal amounts of force and decreases significantly if not connected in-line.

[Anesthesia outside the core operating area]. / Anästhesie ausserhalb des Zentral-OP.

The number of diagnostic and surgical procedures being performed outside the core operating area is growing disproportionately. Due to the higher perioperative risk for such patients, anesthesia should only be provided by a very experienced anesthesiologist, even for supposedly small interventions. At these locations, timely and direct access to the anesthesia machine and/or the patient is often limited and if additional personnel or supplies are required, substantial time delays usually occur and should be allowed for. Standard operating procedures that are optimized to local requirements and providing a specially equipped anesthesia trolley for diagnostic and surgical procedures outside of the core operating area, may decrease the likelihood of complications induced by poorly equipped anesthesia workplaces. For electroconvulsive therapy (ECT), the standard drugs are methohexital in combination with short-acting opioids, such as remifentanil and succinylcholine. Significant variations in arterial blood pressure and heart rate are possible. Anesthesia induction in children with a known difficult airway or difficult intravascular access should initially be performed in a location with optimal infrastructure with subsequent transfer to the diagnostic or surgical suite outside the core operating area. Before entering the magnetic resonance imaging (MRI) suite, personal ferromagnetic items (e.g. pens, credit cards, stethoscopes, keys, telephones, USB sticks) should be removed to prevent injury and data loss; a MRI-compatible anesthesia machine and equipment is compulsory. Patients with cardiac pacemakers, cochlea implants, aneurysm or other clips, metallic-based tattoos or make-up are not normally compatible with MRI. General anesthesia should be preferred over conscious sedation for magnetic resonance imaging and ear protection is necessary for anesthetized patients. Gastroscopy in children should be performed under general anesthesia; and when concluding the procedure, air insufflated into the gastrointestinal tract should be suctioned in all patients. For angiography, maximum monitoring needs to be available to provide hemodynamically unstable patients with adequate anesthesia care; comprehensive radiation protection for patients and staff as well as temperature monitoring for prolonged diagnostic procedures is also necessary. Monitoring oxygen saturation and end-tidal carbon dioxide as well as employing visual and audible alarms is an essential requirement even during conscious sedation. In summary, the number of diagnostic and surgical procedures performed outside the core operating area should be reduced to a minimum and, whenever possible, diagnostic or surgical procedures should be performed within the core operating area.

Cardiac performance during vasopressin infusion in postcardiotomy shock.

OBJECTIVE: Arginine-vasopressin (AVP) might be a potent vasopressor agent in catecholamine-resistant postcardiotomy shock. However, its use remains experimental because of considerations about deleterious effects on the heart. We report on the effects of continuous AVP-infusion on cardiac performance, biomarkers of myocardial ischemia, and systemic hemodynamics in catecholamine-resistant postcardiotomy shock. DESIGN: Retrospective study. SETTING: Twenty-one-bed general and surgical intensive care unit. PATIENTS: Forty-one patients with catecholamine-resistant postcardiotomy shock. INTERVENTIONS: Continuous infusion of AVP. MEASUREMENTS AND RESULTS: Heart rate (HR), heart rhythm, mean arterial pressure (MAP), central venous pressure, mean pulmonary arterial pressure, cardiac index (CI), stroke volume index (SVI), left ventricular stroke work index (LVSWI), systemic vascular resistance (SVR) as well as milrinone and norepinephrine requirements were collected before and 1, 4, 12, 24, and 48 h after start of AVP infusion. Creatine kinase MB and troponin-I serum concentrations were measured daily. During AVP administration we observed a significant decrease in HR (-14.8%), milrinone (-17.5%), and norepinephrine requirements (-54.9%) as well as biomarkers of cardiac ischemia and a significant increase in LVSWI (+46.2%), MAP (+41.8%) and SVR (+60%). CI and SVI remained unchanged. Forty-five percent of postoperative new-onset tachyarrhythmias (TA) converted into sinus rhythm during AVP infusion. CONCLUSIONS: AVP was devoid of adverse effects on the heart in these patients with catecholamine-resistant postcardiotomy shock. The significant reduction in HR, vasopressor, and inotropic support suggest a substantial improvement in myocardial performance. These findings are supported by a significant decrease of cardiac enzymes and cardioversion of TA into sinus rhythm in 45.5% of patients with new-onset TA.

The effects of different mouth-to-mouth ventilation tidal volumes on gas exchange during simulated rescue breathing.

UNLABELLED: The American Heart Association recommends tidal volumes of 700 to 1000 mL during mouth-to-mouth ventilation, but smaller tidal volumes of 500 mL may be of advantage to decrease the likelihood of stomach inflation. Because mouth-to-mouth ventilation gas contains only 17% oxygen, but 4% carbon dioxide, it is unknown whether 500-mL tidal volumes given during rescue breathing may result in insufficient oxygenation and inadequate carbon dioxide elimination. In a university hospital research laboratory, 20 fully conscious volunteer health care professionals were randomly assigned to breathe tidal volumes of 500 or 1000 mL of mouth-to-mouth ventilation gas (17% oxygen, 4% carbon dioxide, 79% nitrogen), or room air control (21% oxygen, 79% nitrogen) for 5 min. Arterial blood gases were taken immediately before, and after breathing 5 min of the experimental gas composition. When comparing 500 versus 1000 mL of mouth-to-mouth ventilation tidal volumes with 500 mL of room air, 500 mL of mouth-to-mouth ventilation tidal volume resulted in significantly (P < 0.05) lower mean +/- SEM arterial oxygen partial pressure (70 +/- 1 versus 85 +/- 2 versus 92 +/- 3 mm Hg, respectively), and lower oxygen saturation (94 +/- 0.4 versus 97 +/- 0.2 versus 98 +/- 0.2%), but increased arterial carbon dioxide partial pressure (46 +/- 1 versus 40 +/- 1 versus 39 +/- 1 mm Hg, respectively). Sixteen of 20 volunteers had to be excluded from the experiment with 500 mL of mouth-to-mouth ventilation gas after about 3 min instead of after 5 minutes as planned because of severe nervousness, sweating, and air hunger. We conclude that during simulated mouth-to-mouth ventilation, only large (approximately 1000 mL), but not small (approximately 500 mL) tidal volumes were able to maintain both sufficient oxygenation and adequate carbon dioxide elimination. IMPLICATIONS: To provide efficient mouth-to-mouth ventilation, it is important to administer tidal volumes of 1000 mL; tidal volumes of 500 mL were not adequate.

The respiratory system during resuscitation: a review of the history, risk of infection during assisted ventilation, respiratory mechanics, and ventilation strategies for patients with an unprotected airway.

The fear of acquiring infectious diseases has resulted in reluctance among healthcare professionals and the lay public to perform mouth-to-mouth ventilation. However, the benefit of basic life support for a patient in cardiopulmonary or respiratory arrest greatly outweighs the risk for secondary infection in the rescuer or the patient. The distribution of ventilation volume between lungs and stomach in the unprotected airway depends on patient variables such as lower oesophageal sphincter pressure, airway resistance and respiratory system compliance, and the technique applied while performing basic or advanced airway support, such as head position, inflation flow rate and time, which determine upper airway pressure. The combination of these variables determines gas distribution between the lungs and the oesophagus and subsequently, the stomach. During bag-valve-mask ventilation of patients in respiratory or cardiac arrest with oxygen supplementation (> or = 40% oxygen), a tidal volume of 6-7 ml kg(-1) ( approximately 500 ml) given over 1-2 s until the chest rises is recommended. For bag-valve-mask ventilation with room-air, a tidal volume of 10 ml kg(-1) (700-1000 ml) in an adult given over 2 s until the chest rises clearly is recommended. During mouth-to-mouth ventilation, a breath over 2 s sufficient to make the chest rise clearly (a tidal volume of approximately 10 ml kg(-1) approximately 700-1000 ml in an adult) is recommended.

[The new international guidelines for cardipulmonary resuscitation: an analysis and comments on the most important changes]. / Die neuen internationalen Richtlinien zur kardiopulmonalen Reanimation. Eine Analyse und Kommentierung der wichtigsten Anderungen.

In August 2000, the American Heart Association and the European Resuscitation Council published the conclusions of the International Guidelines 2000 Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care which contains both the new recommendations and an in-depth review. The discussions and drafting began at a conference in March 1999, followed by a second conference in September 1999, both attended by approx. 250 participants and another conference in February 2000 which was attended by approx. 500 participants. Review of the current state of science, discussion and final consensus continued subsequently via email, conference calls, fax, and personal conversation. During the entire process, scientists and resuscitation councils from all over the world participated, with participants from the United States comprising approx. 60%, and scientists from outside of the United States comprising approx. 40%. In order to ensure that the CPR recomendations are not dominated by any given nation or resuscitation council, most topics were reviewed and interpretated by two scientists from the United States and two scientists from outside of the United States. Accordingly, changes in these new CPR recommendations are the result of an evidence-based review by worldwide experts. The most important changes in the recommendations according to the authors are discontinuation of the pulse-check for lay people, 500 ml instead of 800-1200 ml tidal volume during bag-valve-mask ventilation (FiO2 > 0.4) of a patient with an unprotected airway, verifying correct endotracheal intubation with capnography and an esophageal detector, employing mechanical devices such as interposed abdominal compression CPR, vest CPR, active-compression-decompression CPR, and the inspiratory threshold valve (ITV) CPR as alternatives or adjuncts to standard manual chest compressions, defibrillation with < 200 Joule biphasic instead of with 200-360 Joule monophasic impulses, vasopressin (40 units) and epinephrine (1 mg) as comparable drugs to treat patients with ventricular fibrillation, amiodarone (300 mg) for shock-refractory ventricular fibrillation and intravenous lysis for patients who have suffered a stroke.