CO2-Angiographie

With an increasing number of diagnostic and therapeutic vascular interventions the risk of contrast-induced renal or allergic complications grows. Magnetic resonance (MR) angiography has limitations for patients with pacemakers or renal insufficiency stage 4 or 5. Carbon dioxide angiography is an invasive method which can be used with similar or better results, except for intracerebral or coronary interventions, without the limitations of MR angiography. Technical requirements, risk and imaging quality are comparable to conventional angiography if the physical characteristics of CO₂ are taken into account.     

Zur Frage der CO2-Speicherung bei laparoskopischer Cholezystektomie mit CO2-Pneumoperitoneum

Methods. Two groups of 22 patients each were studied in a prospective, randomised fashion during laparoscopic cholecystectomy (LCh) and CO₂ pneumoperitoneum (PP) with regard to end-tidal and arterial PCO₂ and pulmonary elimination of CO₂ (ECO₂, Servoventilator with integrated CO₂-analyser 930, Siemens). In group 1 minute ventilation was kept constant, resulting in moderate hypercapnia during PP. paCO₂ increased by about 10?mmHg during up to 50?min PP. In group 2 paCO₂ was kept constant by a stepwise increase in minute ventilation (Fig.?1, Table?2). Results. Compared to values just before PP, ECO₂ increased in group 1 rather rapidly up to 20?min of PP and more slowly thereafter, reaching a mean value 35% above control at 45?min PP. In group 2 ECO₂ was significantly higher than in group 1 between 15 and 35?min PP. At 45?min PP, however, ECO₂ was identical in both observation groups (Fig.?2). Conclusions. Assuming a stable metabolic CO₂ production rate during the observation period and no differences in CO₂ absorption from the PP between the two study groups, differences in ECO₂ between groups would be a measure of CO₂ stored in group 1 patients during the increase in paCO₂ with PP (Fig.?3, Table?3). CO₂ storage rapidly increased between 0 and 15?min PP, more or less reached a plateau between 15 and 35?min PP, and ceased at 45?min PP. Storing capacity for CO₂ during the first 45?min PP amounted to a mean value of 1.20?ml CO₂/kg body weight and mmHg paCO₂, which agrees favourably with data from the literature and a computer model from Fahri and Rahn published in 1960 (Fig.?4, Table?4). If during LCh with CO₂-PP patients are ventilated with a constant minute ventilation, a moderate increase in paCO₂ of about 10?mm Hg can be expected. In this case, during the first 45?min PP a 70-kg patient will retain about 1000?ml CO₂ in blood and tissues, which must be eliminated after cessation of PP. If the paCO₂ is to be held constant during PP, minute ventilation has to be progressively increased by about 40%.     

Pathophysiological and clinical aspects of the CO2 pneumoperitoneum (CO2-PP)

Experimental studies demonstrated a severe cardiac load of the CO₂ pneumoperitoneum caused by an accelerated after- and a decreased preload. Patients displaying cardiovascular risks are therefore often rejected from laparoscopic surgery. Hence, the pathophysiological changes and the intraoperative risk of the CO₂ pneumoperitoneum in high-risk cardiopulmonary patients (NYHA II–III, n= 15) undergoing laparoscopic cholecystectomy are described. The changes in cardiac after- and preload seem to be due to the elevated intraabdominal pressure rather than transperitoneally resorbed CO₂ and are reversible by desufflation. In one patient conversion to open operation had to be performed because of a severe drop in cardiac output and right ventricle ejection fraction. Mixed oxygen saturation was predicting intraoperative worsening in this case. The described pathophysiological changes may seem to be well tolerated even in high-risk cardiac patients. Monitoring of hemodynamics should include an arterial catheter line and blood gas analyses. Pharmacologic interventions or pressureless laparoscopic procedures might not be necessary as long as laparoscopic cholecystectomy is performed. Received: 13 December 1996/Accepted: 8 January 1997     

CO2与脑循环

编者按 1998年Anesthesiology杂志第5期上刊出了Brian,JE所写的一文,内容较新,但十分噜,字数很多.为取其精华,特约定南京大学医学院硕士生嵇晴医师先试行译出,然后在指导人帮她不厌其烦地予以删节和理顺,经重复修改和誊抄5次后方才成当前的面貌.     

CO2-Laser in neurosurgery

Summary New technical tools in surgery are only beneficial if they offer real improvements compared to the traditional techniques or if they open absolute new indications in surgery. Therefore we have tried to find absolute indications for the use of the indifferent laser system.Due to the specific wavelength the CO₂-Laser is entirely absorbed at the surface. This specific performance allows one to use the CO₂-Laser as the most precise cutting and as a completely new vaporizing instrument. It has become an irreplaceable tool in surgery of central lesions and brain stem tumours and also for spinal cord tumours. In addition the CO₂-Laser is adaptable to the operating microscope.A gain of the same importance in the meantime is the Nd-YAG Laser, which works specially for coagulation, volume coagulation and endoscopic use.It is certain that laser surgery will evolve for beyond our imagination.     

CO2 embolism during hysteroscopy

During CO2 hysteroscopy the intracavitary pressure increases up to 80 mmHg. This can result in a CO2 embolism, especially after injury/lesion of the endometrium. A 49-year-old female Caucasian patient underwent curettage, and the following day while a hysteroscopy was being performed in general anesthesia a CO2 embolism occurred, with bradyarrhythmia, drop of arterial blood pressure, superior vena cava syndrome, metallic heartsound and hypercapnia. It was possible to achieve recompensation of the right heart failure with drug therapy. Other causes (lung embolism, hypoventilation, increased CO2 production, cardiac causes) could be excluded.     

Misleading end-tidal CO2 tensions

Purpose

The aim of this study was to determine if the literature supported the assumption that the values and changes in end-tidal PCO₂ (PetCO₂) during anaesthesia accurately reflect the values and changes in arterial PCO₂ (PaCO₂) is tenable.

Methods

The information was obtained by (a) a Medline literature search and the appropriate references quoted in the list generated; (b) appropriate abstracts in recent issues of the annual meeting supplements of Anesth Analg, Anesthesiology, Br J Anaesth and Can J Anaesth. We specifically sought information obtained during major operations, in sick patients, and reports of serial measurements. The information obtained is summarized in graphic form, with a discussion of the mechanisms and clinical implications.

Results

(1) Patients with systemic disease, or when placed in the lateral position, or with haemodynamic instability have an increased Pa-PetCO₂ gradient. The values during surgery are probably due to marked alterations of ventilation: perfusion relationships. (2) In a number of reports, the gradient varied widely during the procedure. (3) The gradient may be reduced due to an alteration of the configuration of the alveolar plateau. (4) The magnitude and direction of change in PaCO₂ andPetCO₂ can be disproportionate and in the opposite direction.

Conclusion

End-tidal PCO₂ is often not indicative of PaCO₂. Also, changes inPetCO₂ do not always accurately indicate the direction and extent of the change in PaCO₂.     

Perioperative control of CO2

Canadian Journal of Anesthesia/Journal canadien d'anesthésie - The importance and complexity of inter-relationships between alterations in systemic CO2 tension in acute illness states is...     

A versatile dual-channel carbon dioxide (CO2) insufflator for various CO2 applications

Background Carbon dioxide (CO₂), with its rapid absorptive nature, has been proven superior to atmospheric air as an insufflating agent in various clinical settings. However, CO₂ insufflation has not gained wide clinical acceptance, mainly because there has been no suitable feeding system. The authors therefore have developed a versatile “dual-channel” CO₂ insufflator that facilitates wider use of CO₂. The objectives of this study were to introduce the authors’ prototype insufflator, to evaluate its safety and performance, and to validate CO₂ application using the prototype. Methods The prototype insufflator provides one CO₂ inlet connected to a regular CO₂ gas cylinder and two CO₂ outlets positioned on the front and back of the device, respectively. The CO₂ gas fed from the cylinder is pressure-regulated and divided into two independent conduits inside the device. The front outlet feeds CO₂ gas for pneumoperitoneum at an electronically controlled pressure and flow rate. The back channel supplies CO₂ gas at a fixed flow rate, allowing manual control of insufflation for various purposes. The device was evaluated with canine models. Results The prototype was safe and performed well. The CO₂ application (colonoscopy in this series) using the back channel was feasible while intact CO₂ pneumoperitoneum was simultaneously maintained via the front channel. There were no device malfunctions. The serial abdominal x-rays indicated that intraluminal CO₂ insufflation such as that used for CO₂ colonoscopy caused less residual intestinal gas than conventional air insufflation. Conclusions The dual-channel CO₂ insufflator enabled two different modes of CO₂ insufflation at the same time from a single CO₂ cylinder. The authors are now improving the prototype to allow safer and wider usage of CO₂ in the operating room.     

Uvulopalatopharyngoplasty with CO2, contact ND-YAG or combined CO2 and ND-YAG laser beams

Three different surgical lasers, ie CO₂, contact Nd-YAG and Combolaser (combined simultaneous and co-axial CO₂+Nd-YAG laser beam), were used for 76 uvulopalatopharyngoplasty (UPPP) operations. The effects of different lasers on intra-operative bleeding, operation time and post-operative pain were compared. Sixty patients with obstructive sleep apnoea syndrome (OSAS) and 16 patients with socially disturbing snoring were operated on. The CO₂ laser was used in 24 patients, contact Nd-YAG was used in 27 patients and Combolaser was used in 25 patients. The Combolaser was associated with significantly less intra-operative bleeding and a shorter operation time. During the immediate recovery period, post-operative pain was most mild after operations with the CO₂ laser when graded according to need for analgesics, or by the patients' subjective evaluation. Concerning possible post-operative complaints or overall outcome of the UPPP operation, no differences were found between the lasers.     

二氧化碳气腹下行胆囊切除术对胃粘膜二氧化碳分压及pH的影响

目的：探讨腹腔镜二氧化碳气腹对胃粘膜二氧化碳分压（i-PCO2)及胃粘膜pH(i-pH)的影响。方法：选择20例二氧化碳气腹下胆囊切除术病人。采用胃管法，分别于气腹前，气腹20、40分钟，排气后30分钟抽取胃液3－5ml。分析胃液PCO2及PO2，同时在气腹前、后各时点监测动脉血PaCO2,PaO2,pH,HCO3^-和BE，并代入Henderson-Hasseibach公式，计算i-pH。结果：i-PCO2在气腹20分钟腹前有显著性升高（P＜0．05）（气腹40分钟，排气后30分钟与气腹前比较显著升高（P＜0．01），气腹20、40分钟，排气后，30分钟i-pH均较气腹前明显降低（P＜0．01）。气腹40分钟时，i-PCO2最高，而i-pH为最低。胃粘膜氧分压（i-PO2)气腹前、后无明显变化，PaCO3气腹40分钟、排气后30分钟均显著高于气腹前（P＜0．01），动脉血pH、BE气腹后各时点均较气腹前降低（P＜0．01）。动脉血PaO2,HCO3^-气腹前后变化不明显（P＞0．05）。结论：二氧化碳气腹下胃粘膜有缺血低灌注现象。随着气腹时间延长，胃粘膜低灌注，酸中毒的症状加重。