DNA adducts: effects of low exposure to ethylene oxide, vinyl chloride and butadiene

Dose-response relationships of genotoxic agents differ greatly depending on the agent and the endpoint being evaluated. Simple conclusions that genotoxic effects are linear cannot be applied universally. The shape of the molecular dose of DNA adducts varies from linear, to supralinear, to sublinear depending on metabolic activation and detoxication, and repair of individual types of DNA adducts. For mutagenesis and other genotoxicity endpoints, the dose-response reflects the molecular dose of each type of DNA adduct, cell proliferation, as well as endogenous factors that lead to mutagenesis such as the formation and repair of endogenous DNA adducts. These same factors are important when interpreting the shape of dose-response data for carcinogenesis of genotoxic agents, however, tumor background variability adds additional complexity. Endogenously formed DNA adducts may be identical to those formed by chemicals, as in the case of vinyl chloride and ethylene oxide, or they may be those associated with oxidative stress. Data presented in this paper demonstrate that the exogenous number of adducts induced by 5 days of exposure to 10 ppm vinyl chloride is only 2. 2-fold greater than that present as a steady-state amount in unexposed control rats. Similar data are shown for ethylene oxide. Extremely sensitive methods have been developed for measuring the molecular dose of genotoxins. These methods can detect DNA adducts as low as 1 per 10(9) to 10(10). However, in view of the high number of endogenous DNA adducts that are present in all cells, it is unlikely that causal relationships can be attributed to very low numbers of such DNA adducts. Effects of both exogenous and endogenous DNA adducts need to be factored into the interpretation of chemical exposures.

Impact of different intraoperative CO2 pressure levels (8 and 15 mmHg) during laparoscopic hysterectomy performed due to benign uterine pathologies on postoperative pain and arterial pCO2 : a prospective randomised controlled clinical trial

OBJECTIVE

To compare the effects of two different intraoperative CO₂ pressures (8 and 15 mmHg) during laparoscopic hysterectomy for benign uterine pathologies in terms of postoperative abdominal and shoulder pain, laparoscopy-mediated vegetative alterations, pain medication requirement, arterial CO₂ pressure (pCO₂ ), surgical parameters, and safety.

DESIGN

Prospective randomised controlled study.

SETTING

German university hospital.

POPULATION

Female patients undergoing laparoscopic hysterectomy for benign uterine pathologies.

METHODS

Patients were randomised to a standard pressure (SP; 15 mmHg, control) or low-pressure (LP; 8 mmHg, experimental) group.

MAIN OUTCOME MEASURES

Primary outcomes were postoperative abdominal and shoulder pain intensities, measured via numeric rating scale (NRS) and vegetative parameters (fatigue, nausea, vomiting, bloating) at 3, 24, and 48 hours postoperatively. Secondary outcomes were pain medication requirement (mg) and arterial pCO₂ (mmHg). Surgical parameters and intra- and postoperative complications were also recorded.

RESULTS

In total, 178 patients were included. Patients in the LP group (n = 91) showed significantly lower postoperative abdominal and shoulder pain scores, fewer vegetative alterations, lower pain medication requirements, a shorter postoperative hospitalization, and lower intra- and postoperative arterial pCO₂ values compared with the SP group (n = 87; P ≤ 0.01). No differences in intra- and postoperative complications were observed between groups.

CONCLUSIONS

Low-pressure laparoscopy seems to be an effective and safe technique for the reduction of postoperative pain and laparoscopy-induced metabolic and vegetative alterations following laparoscopic hysterectomy for benign indications.

TWEETABLE ABSTRACT

Low-pressure laparoscopy seems to be an effective and safe technique for reduction of pain following laparoscopic hysterectomy.

[PONV after strabismus surgery : Risk adapted prophylaxis?]

BACKGROUND

Following strabismus surgery, patients frequently develop variable degrees of postoperative nausea and vomiting (PONV). These symptoms cause discomfort and result in serious complications such as intramuscular bleeding and subconjunctival hemorrhage. In children long lasting PONV can lead to and electrolyte imbalance and dehydration. A prolonged course of recovery is the consequence. For the hospital, PONV can also involve negative economic impacts because of a damaged public reputation of the institution. There is still an ongoing debate on wether prophylaxis of PONV is necessary and how the prophylaxis of PONV should be performed. On one hand, there are proponents of a liberal prophylaxis. These intend to treat almost all patients regardless of their individual risk for PONV. On the other hand, opponents point out that every medication has to be indicated individually. In their view, risk scores should be the base of a risk-adapted approach.

OBJECTIVES

The aim of the study was to reduce the frequency of PONV by using an anesthetic technique adapted to the individual risk for PONV. Until now, all trials studying the efficiency of a score-based antiemetic prophylaxis were performed on adult patients. In this study, a risk-adapted approach was evaluated on children for the first time.

PATIENTS AND METHODS

In 92 patients, the incidence of PONV was analyzed after strabismus surgery. Before surgery we evaluated the risk factors for PONV according to the POVOC score in children (n = 45, 49 %) and the Apfel's score in adults (n = 47, 51 %). Patients with 0-2 risk factors received a balanced anesthesia (n = 47, 51 %). Those with 3-4 risk factors were operated in total IV anesthesia (TIVA) with propofol (n = 45, 49 %). In addition, as an antiemetic prophylaxis, 0.15 mg/kg dexamethason and 0.1 mg/kg ondansetron were applied in the latter patients. we documented the symptoms and severity of PONV 2, 6 and 24 h after surgery by means of a standardized questionnaire for PONV (Wengritzky-Score).

RESULTS

The incidence of PONV was 17 % (n = 16) in all of the patients. The incidence in low-risk patients receiving a BA without prophylaxis were 21 % in adults and 38 % in children. Of the patients at high risk for PONV receiving the multimodal antiemetic approach 8 % (adults) and 9 % (children) suffered from PONV. The combination of TIVA and antiemetics could reduce the incidence of PONV compared to the predicted values in a clinically relevant manner (OR = 0.26, KI: 0.76-0.87).

CONCLUSION

The overall incidence could be reduced to a level below 20 %. Particularly in patients with a high risk of PONV, TIVA could clearly reduce the incidence. However, the incidence in patients with 2 risk factors is still high (30-39 %). Therefore, it is important to reconsider the effort involved with risk screening and individually adapting anesthesia. Risk stratification means a pre- and perioperative effort. Therefore, we advocate a more liberal approach for PONV prophylaxis.

[Reduction of intraocular pressure and ocular pulse amplitude during general anesthesia]

AIM

Measurement of the intraocular pressure (IOP) is an important tool for glaucoma diagnostics in children or patients with impaired cooperation. General anesthesia (GA) may significantly influence the IOP. This study aimed to evaluate the reduction of IOP during GA.

PATIENTS AND METHODS

The IOP was measured in 229 patients in a recumbent position in the non-operated eye prior to and 5 min after the beginning of GA with a dynamic contour tonometer (DCT).

RESULTS

The average IOP decreased from 19.9 ± 3.7 mmHg prior to GA to 14.1 ± 3.5 mmHg 5 min after beginning GA (p < 0.0001, IOP decrease 30 %). The GA caused a decrease of up to 2 mmHg in 6.1 %, 2-4 mmHg in 18.8 %, 4-6 mmHg in 21.0 %, 6-8 mmHg in 36.6 %, 8-10 mmHg in 13.6 %, 10-12 mmHg in 2.2 % and more than 12 mmHg in 1.7 % of the eyes. The ocular pulse amplitude (OPA) decreased from a mean of 3.4 ± 1.5 mmHg to 1.9 ± 1.0 mmHg (p < 0.0001, OPA decrease 41 %) under GA.

CONCLUSION

A significant decrease of IOP (mean 6 mmHg) occurs during GA and under extreme conditions up to 13.8 mmHg. A decrease of OPA of 1.5 mmHg should be taken into consideration for patients under general anesthesia and under extreme conditions up to 7 mmHg.

[The Effect of Non-Depolarising Muscle Relaxants on Ocular Pulse Amplitude and Intraocular Pressure]

AIM

In general anaesthesia (GA) for ocular surgery the chosen non-depolarising muscle relaxant has a high influence on the fluctuations of intraocular pressure (IOP) and ocular pulse amplitude (OPA).

PATIENTS AND METHODS

In 229 patients, who needed GA for their ophthalmic surgery, OPA and IOP were measured with the dynamic contour tonometer (DCT) before and 5 minutes after intubation. For GA, three groups of non-depolarising muscle relaxants, namely, mivacurium (n = 71), atracurium (n = 91) and rocuronium (n = 67) were used.

RESULTS

The IOP decreased by about 4.0 ± 2.3 mmHg using mivacurium in GA, by about 6.1 ± 2.2 mmHg using atracurium and by about 7.4 ± 1.7 mmHg using rocuronium (p < 0.001). The relative decrease of the IOP was 20% for mivacurium, 31% for atracurium and 37% for rocuronium. For mivacurium the OPA decreased from 3.4 ± 1.5 mmHg to 2.2 ± 1.1 mmHg (p < 0.001) in contrast to atracurium (decrease from 3.6 ± 1.5 mmHg to 1.8 ± 0.8 mmHg; p < 0.001) and rocuronium (decrease from 3.1 ± 1.6 mmHg to 1.7 ± 0.9 mmHg; p < 0.001). Mean OPA reduction was lowest with mivacurium (1.3 mmHg) and the highest with atracurium (1.7 mmHg). The mean relative decrease of the OPA was 34% with mivacurium, 46% with atracurium and 43% with rocuronium (p < 0.001). There was no linear correlation between the relative OPA decrease and the relative IOP decrease.

CONCLUSION

Risks for ophthalmic surgery may be minimised by avoiding mivacurium in general anaesthesia. Due to its negative effects on IOP and OPA mivacurium does not seem to be suitable for operations with a large opening in the eye such as penetrating keratoplasty and block excision. Rocuronium can be used because it induces a favourised intraoperative decrease of the IOP.

[One stop surgery in pediatric surgery. Preliminary report]

The One-Stop Surgery (OSS) is a new method of Day Surgery, which combines preoperative evaluation and subsequent operation into one visit. This report describes the initial experience of the authors. Referring physicians were informed by fax about method and selected surgical procedures. Included form helped them to gain anamnestic data and to inform parents about preoperative fast. Form was then sent back by fax to the pediatric surgeon and anesthesiologist who determined the patient suitability and scheduled the day of the surgery. At hospital admission, if the diagnosis was confirmed and no anesthesiologic contraindications were discovered, the patient underwent the prescheduled surgical procedure and was discharged as a day case. Another form containing informations about home postoperative care and telephone numbers for emergency call was gave to the parents. From November 2000 through February 2001 43 patients, aged from 2 to 7 years, underwent one-stop surgical procedure: central venous catheter removal (n = 16), umbilical (n = 2) and inguinal (n = 10) hernia repair, prepuce dorsal slit (n = 15). Recovery of all patient was uneventful. None of them called during the period considered necessary for postoperative follow-up. Decreased costs and increased satisfaction of the patients and parents are the most important advantages of the OSS. Potential disadvantages are a not appropriate indication for the planned procedure and/or an anesthesiologic contraindication at hospital admission. It could involve a waste of human and financial resources and an useless psychologic stress for the family. Authors conclude it is not advisable the OSS use on a large scale without a sound experience in pediatric Day Surgery.