The validity of continuous automated fluid monitoring during endometrial surgery: luxury or necessity?

Safety and efficacy of manual syringe infusion of distending media for hysteroscopic procedures: a case-control study

OBJECTIVES

Adverse events associated with large volumes of distending media in hysteroscopic procedures can be life-threatening. The aim of this study was to evaluate the safety and efficacy of manual syringe infusion (MI) of distending media for hysteroscopic procedures.

STUDY DESIGN

Between January 2011 and December 2013, the medical records of all women who underwent hysteroscopic procedures using MI or the conventional pump-infusion method (PI, the control group) were reviewed. The Wilcoxon rank-sum test, the Chi-square test and the multivariate logistic regression analysis were employed for statistical analysis.

RESULTS

The MI group (n=82) had a significantly lower average volume of infused fluid (1117 ± 712 mL vs. 2216 ± 1502 mL, respectively; p<0.001), less operative time (22.2 ± 9.7 vs. 30.4 ± 9.8 min, respectively; p<0.001) and lower postoperative abdominal pain scores (0.6 ± 0.7 vs. 0.8 ± 0.7, respectively; p=0.04) than the PI group (n=58). Subgroup analysis of women who underwent hysteroscopic myomectomy revealed a significantly lower amount of infused fluid for the MI group than for the PI group (1737 ± 905 mL vs. 3441 ± 1952 mL, respectively; p=0.001). Infused fluid amount (coefficient=0.08, p<0.001) was the only significant independent factor affecting fluid deficit, with a constant of 76.1.

CONCLUSION

The MI method appears to be a safe and feasible method for delivering distending media during hysteroscopic procedures.

Fluid absorption in endoscopic surgery

Fluid absorption is an unpredictable complication of endoscopic surgery. Absorption of small amounts of fluid (1-2 litre) occurs in 5-10% of patients undergoing transurethral prostatic resection and results in an easily overlooked mild transurethral resection (TUR) syndrome. Large-scale fluid absorption is rare but leads to symptoms severe enough to require intensive care. Pathophysiological mechanisms consist of pharmacological effects of the irrigant solutes, the volume effect of the irrigant water, dilutional hyponatraemia and brain oedema. Other less widely known factors include absolute losses of sodium by urinary excretion and morphological changes in the heart muscle, both of which promote a hypokinetic circulation. Studies in animals, volunteers and patients show that irrigation with glycine solution should be avoided. Preventive measures, such as low-pressure irrigation, might reduce the extent of fluid absorption but does not eliminate this complication. Monitoring the extent of absorption during surgery allows control of the fluid balance in the individual patient, but such monitoring is not used widely. However, the anaesthetist must be aware of the symptoms and be able to diagnose this complication. Treatment should be based on administration of hypertonic saline rather than on diuretics. New techniques, such as bipolar resectoscopes and vaporizing instead of resecting tissue, result in a continuous change of the prerequisites for fluid absorption and its consequences.

Anaesthetic considerations for hysteroscopic surgery

Use of the hysteroscope in modern gynaecological practice continues to develop as a diagnostic and management tool for intrauterine disease. Operative hysteroscopy (OH) is now an accepted alternative to hysterectomy for women with menorrhagia. The advantages of OH are associated with its short operating time, rapid post-operative recovery and low morbidity. However, there are concerns about the potential serious complications which can occur during and following OH, and it is important that both surgeons and anaesthetists are aware of these--especially as many procedures take place as day-cases. Much has been written in the urological literature concerning complications of endoscopic surgery. Information gathered from patients with post-transurethral resection of the prostate (TURP) syndrome has been useful in the treatment of gynaecology patients. However, the techniques used in TURP are not entirely comparable to hysteroscopic surgery as the uterus has a very thick wall, which requires higher distension pressures. The main complications of OH are fluid overload, hyponatraemia, hypo-osmolality, haemorrhage, uterine perforation and, rarely, gas or air embolism. Fluid overload with hyponatraemia and hypo-osmolality occurs in up to 6% of cases and it can be fatal. Therefore, all possible measures should be taken to prevent it or to detect it and treat it early. There are no controlled studies comparing different anaesthetic techniques for OH. Regional anaesthesia may offer an advantage over general anaesthesia because it enables early detection of fluid overload. Great care should be taken when positioning the patient to prevent peripheral neuropathy.

Anesthesia for hysteroscopy

Hysteroscopy is becoming a more widely used technique. Diagnostic hysteroscopy is replacing conventional dilatation and curettage in the diagnosis of intrauterine pathologies. Transcervical endometrial resection is often the first-line surgical treatment for dysfunctional uterine bleeding and carries less associated morbidity and morality. Overall, the technique is extremely safe, but vigilance is required particularly for intravasation of irrigation media. Complications such as gas embolus and hypo-osmolar hyponatremia require prompt treatment to reduce associated morbidity and morality. Careful monitoring of fluid deficit is paramount in avoiding the latter problem. Regional or general anesthetic techniques can be used and, in the ambulatory or office-based setting, in which these procedures are increasingly performed, the need for "street readiness" can influence the choice of the agents used.

Sources of error when tracking irrigation fluids during hysteroscopic procedures

STUDY OBJECTIVE

To evaluate the ability of circulating nurses to estimate input and outgo of irrigating fluids used during hysteroscopic procedures in a hospital operating room.

DESIGN

Simulation of intraoperative measurements (Canadian Task Force classification II-1).

SETTING

Operating room. Intervention. Circulating nurses estimated fluid volumes under circumstances simulating actual conditions of hysteroscopic ablative or resection procedures.

MEASUREMENTS AND MAIN RESULTS

Three-liter glycine irrigation bags were overfilled by an average of 2.8% (62-125 ml). Estimates of fluid remaining in partially emptied bags were in error by an average ranging from 4% to 50%/bag (largest error 10-55%, 157-401 ml). Estimates of fluid in kick buckets were in error by an average of 10% to 39% (largest error 22-66%, 232-903 ml). Visual estimates of fluid on the operating room floor were in error by an average of 56% to 67% (largest error 65-81%, 182-840 ml). Estimates of fluid in suction canisters were consistent among nurses. The accuracy of measurements for partially filled suction canisters primarily depended on the accuracy of canister calibration. Volume contained in cascaded suction canisters from an actual surgical procedure was grossly different from rated capacity.

CONCLUSION

Accurate tracking of irrigation fluid during hysteroscopic procedures is difficult. Even with a mechanical measuring system, fluid lost on the floor can introduce sizable errors. Estimation errors can easily and quickly accumulate to clinically significant volumes. Use of an automated mechanical fluid-tracking system with devices to capture fluid lost from the surgical field is recommended.

Endometrial laser intrauterine thermotherapy: the first series of 100 patients observed for 1 year

OBJECTIVE

To describe a new instrument (GyneLase) that offers a new approach (endometrial laser intrauterine thermal therapy [ELITT]) to treatment of menorrhagia and to evaluate the efficacy of ELITT in the management of dysfunctional uterine bleeding.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENT(S)

100 premenopausal women with dysfunctional uterine bleeding were observed for 1 year.

INTERVENTION(S)

Intrauterine laser thermotherapy with a diode laser.

MAIN OUTCOME MEASUREMENT(S)

Amenorrhea rate after 1 year.

RESULT(S)

The amenorrhea rate after 1 year of follow-up was 71%, and the rate of amenorrhea/severe hypomenorrhea rate was >90%; these rates are much higher than those in the literature after such procedures as electrosurgery or intrauterine thermal balloon therapy. The ELITT procedure is an inherently safe and simple alternative, providing controlled and effective treatment of the entire endometrium. In contrast to traditional endometrial ablation using a neodymium yttrium-aluminum-garnet laser, the ELITT procedure does not require intensive training or hysteroscopic control; it is also far less risky, because the power used per unit area is 1,000 times lower.

CONCLUSION(S)

The ELITT procedure is a new nonhysteroscopic technique for endometrial ablation. The technique is very safe and offers the highest amenorrhea rate to date in the literature.

The development and validation of an algorithm for real-time computerised fetal heart rate monitoring in labour

OBJECTIVE

To develop and validate a computerised algorithm for the interpretation of the characteristics of fetal heart rate monitoring in labour.

DESIGN

Prospective observational study.

SETTING

Labour ward in a tertiary hospital.

SAMPLE

Intrapartum cardiotocograms from 24 pregnancies.

METHODS

A computerised algorithm was developed to assess the fetal heart baseline rate, variability, the number of accelerations and the number of decelerations. Twenty five minute segments of cardiotocograms were interpreted by the algorithm and also by seven expert reviewers independently. The reviewers were unaware of the outcome of labour. The reliability of the characteristics of cardiotocography and the validity of the computerised algorithm were assessed using the intraclass correlation coefficient and weighted kappa statistic for continuous and ordinal variables respectively.

RESULTS

The inter rater reliability of the baseline fetal heart rate and the number and type of decelerations was good (intraclass correlation coefficient 0.93, 0.93 and 0.79, respectively). The reliability of baseline variability (kappa = 0.27) and accelerations (intraclass correlation coefficient = 0.27) was poor. The computerised algorithm had good agreement with the reviewers for the baseline fetal heart rate (intraclass correlation coefficient 0.91 to 0.98) and the number of decelerations (intraclass correlation coefficient 0.82 to 0.91), but was less valid as regards the number of late decelerations (intraclass correlation coefficient 0.68 to 0.85) and the number of accelerations (intraclass correlation coefficient 0.06 to 0.80), and was invalid as regards baseline variability (kappa 0.00 to 0.34).

CONCLUSIONS

The high level of validity of the computerised algorithm for the estimation of the baseline fetal heart rate and the number of decelerations justifies its further technical development.

Endometrial laser intrauterine thermo-therapy (ELITT): a revolutionary new approach to the elimination of menorrhagia

Various non-hysteroscopic procedures have been developed in the attempt to treat dysfunctional uterine bleeding that fails to respond to medical treatment efficiently and easily. Among these procedures is low-dose laser radiation of the endometrium with the diode source, which is characterized by the highest incidence of amenorrhea.

Fatal postoperative pulmonary edema: pathogenesis and literature review

STUDY OBJECTIVES

Pulmonary edema is a known postoperative complication, but the clinical manifestations and danger levels for fluid administration are not known. We studied (1) 13 postoperative patients (11 adult, 2 pediatric) who developed fatal pulmonary edema, and (2) one contemporaneous year of inpatient operations at two university teaching hospitals to determine the clinical manifestations, causes, epidemiology, and guidelines for fluid administration.

DESIGN

Retrospective analysis of 13 patients with fatal postoperative pulmonary edema and one contemporaneous year of major inpatient surgery.

PATIENTS AND METHODS

Thirteen patients had net fluid retention of at least 67 mL/kg in the initial 24 postoperative hours and developed pulmonary edema. Ten were generally healthy while three had serious associated medical conditions.

MEASUREMENTS AND RESULTS

There was no measurement, laboratory value, or clinical finding predictive of impending pulmonary edema. The most common clinical manifestation following the onset of pulmonary edema was cardiorespiratory arrest (n = 8). Patients had metabolic acidosis (pH = 7.15 +/- .33), hypoxia (PO2 = 45 +/- 18 mm Hg), and normal electrolytes. The diagnosis of pulmonary edema was established by chest radiograph and confirmed by autopsy and pulmonary artery pressure (21 +/- 4 mm Hg). The mean net fluid retention was 7.0 +/- 4.5 L (90 +/- 36 mL/kg/d) and exceeded 67 mL/kg/d in all patients. Autopsy revealed pulmonary edema with no other cause of death. Among 8,195 major operations, 7.6% developed pulmonary edema with a mortality of 11.9%. Extrapolation to the 8.2 million annual major surgeries in the United States yields a projection of 8,000 to 74,000 deaths.

CONCLUSIONS

Pulmonary edema can occur within the initial 36 postoperative hours when net fluid retention exceeds 67 mL/kg/d. There are no known predictive warning signs and cardiorespiratory arrest is the most frequent clinical presentation. The monitoring systems currently in use neither detect nor predict impending pulmonary edema, and as yet, there are no known panic values for excessive fluid administration or retention.