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| CASE REPORT |
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| Year : 2018 | Volume
: 20
| Issue : 2 | Page : 159-161 |
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Postoperative visual disturbance: “A peril related to glycine toxicity”
Deepak Dwivedi, Saurabh Sud, Sadhan Sawhney, Ashutosh Gupta
Department of Anaesthesia and Critical Care, Command Hospital (Southern Command), Pune, Maharashtra, India
| Date of Submission | 10-Apr-2018 |
| Date of Acceptance | 13-Aug-2018 |
| Date of Web Publication | 10-Jan-2019 |
Correspondence Address:
Lt Col Saurabh Sud
Department of Anaesthesia and Critical Care, Command Hospital (Southern Command), Pune - 411 040, Maharashtra
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jmms.jmms_24_18
Hysteroscopic gynecological surgeries are now commonly employed in the clinical practice. It has the potential to increase morbidity due to the complication resulting from perforation of the uterus, air/gas embolism, and fluid with electrolyte imbalance. Glycine 1.5%, as an irrigating fluid, is being commonly used and on increased systemic absorption can lead to a wide array of complications. We present a case of transient visual loss after increased absorption of the irrigating fluid, thereby highlighting the factors governing in its genesis and prevention. Keywords: Glycine, hyponatremia, hysteroscopy, vision disorders
How to cite this article:
Dwivedi D, Sud S, Sawhney S, Gupta A. Postoperative visual disturbance: “A peril related to glycine toxicity”. J Mar Med Soc 2018;20:159-61 |
| Introduction | |  |
In the era of minimally invasive surgeries, more and more gynecological procedures are amicable to hysteroscopy approach. Glycine 1.5% is the commonest fluid being used as it has low viscosity, transparency, good optical properties, nonconductive, and low risk of hemolysis.[1] The incidence of perioperative visual loss in nonocular surgeries varies between 0.01% and 1%.[2] Etiology includes corneal abrasion, sclera injury, cortical blindness, retinal arterial occlusion, ischemic optic neuropathy, and acute glaucoma.[2] Transient loss of vision due to glycine toxicity is primarily due to the increased absorption of the irrigating fluid. This case report highlights the patient-, surgery-, and equipment-related factors which independently or in tandem govern the amount of absorption of irrigating fluid which in turn increases the perioperative morbidity manifold.
| Case Report | | |
We present the case of a 61-year-old female, weighing 55 kg, a case of polymenorrhagia for hysteroscopic transcervical resection of endometrium. The patient was accepted in the American Society of Anesthesiologists' physical status class I. Her preoperative serum sodium was 140 mmol/L. On receiving the patient in the operation theater (OT), standard monitors (noninvasive blood pressure [BP], pulse oximetry [SpO2], electrocardiography, end tidal carbon dioxide, and temperature) were attached. General anesthesia was induced with intravenous (IV) fentanyl 100 μg and propofol 100 mg. Airway was secured with 7.0 mm of internal diameter endotracheal tube (ETT) after administering 25 mg atracurium IV. Maintenance of anesthesia was done with nitrous/oxygen and sevoflurane (1%–2%) to maintain minimal alveolar concentration of 1.2% with controlled ventilation. A 7Fr Karl Storz™ (Germany) resectoscope was used for hysteroscopy and glycine 1.5% was used for distending the uterine cavity. The surgery lasted for 40 min and at the end of the surgery, the BP started to increase from 130/74 mmHg to 230/136 mmHg, heart rate decreased from 74 bpm to 50 bpm, and SpO2 dropped from 98% to 74%, with development of pulmonary edema associated with pink frothy secretions in ETT and increased airway pressures of 38 cmH2O [Figure 1]. On auscultation, crepitation were present with decreased air entry bilaterally in all lung fields. Arterial blood gas (ABG) analysis showed pH 7.31 with serum sodium of 107 mmol/L. Injection furosemide 80 mg IV in divided doses and infusion nitroglycerine were started at the rate of 0.5 μg/kg/min. Sodium chloride 3% was administered at the rate of 22.50 ml/h to target sodium level of 120 mmol/L. The patient was shifted to the Intensive Care Unit on Bain circuit and connected to Schiller ventilator on synchronized intermittent mandatory ventilation (volume control with pressure support) mode. Serial serum ammonia and serum sodium levels showed a rising trend. Serum ammonia increased to 234 μg/dl (normal range: 10–35 μg/dl) which normalized after 20 h (35 μg/dl). Serum sodium also stabilized over 10 h from 107 to 120 mmol/L. The pulmonary edema resolved and her vital parameters normalized. Post - extubation in the evening, the patient complained of blurring of vision. Intraocular pressure measured by Schiotz tonometer was normal, and the pupils were sluggishly reacting and mid dilated. Direct ophthalmoscopy revealed normal fundus. Gross visual acuity showed finger counting at 3 ft in both eyes which gradually improved to 6/6 after 6 h. | Figure 1: Nonhomogeneous opacity bilaterally in both the lung fields in the perihilar region
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| Discussion | | |
In the era of minimally invasive surgeries, hysteroscopy surgeries are associated with complication rates of 1%–3%.[3] The commonest complications associated with hysteroscopy are acute compartmental syndrome, cervical trauma, uterine perforation, air embolus, intraoperative bleeding, fluid overload, and electrolyte disturbances.[3] The irrigating fluids are rarely associated with significant complications.[4] Glycine, the commonly used irrigating fluid, is an inhibitory neurotransmitter in the retina which slows down the transmission of impulse from retina to cerebral cortex, leading to visual disturbances and transient loss of vision, which correlates with plasma glycine concentration of 5–8 mmol/L (normal plasma glycine 0.2–0.3 mmol/L).[5] Transient loss of vision normally resolves within 6–48 h following absorption of irrigating fluid as being observed in our case.[5] Ammonia is an intermediate product of glycine metabolism. Studies have shown that serial increase in blood ammonia levels corresponds well with the period of blindness after hysteroscopic surgeries.[5] In our patient, the increase in blood ammonia level correlated well with the period of blindness. The other causes of transient visual loss in a perioperative period were ruled out which could be due to surgical procedure or position related. The surgical procedures include cardiac bypass surgery, major vascular surgery, spine surgery, orthopedic surgery, and profound prolonged hypotension during these surgical procedures. It can also occur in prone position due to the central retinal artery occlusion causing perioperative transient loss of vision.
During the hysteroscopic procedures, large volume of irrigating fluid can get absorbed into the systemic circulation, the incidence can vary between 3% and 5%.[6] The absorption depends on the pressure of irrigation fluid which indirectly depends on the height at which irrigating fluid bag is placed from the operative field. The pressure delivered to the uterus is approximately 70–100 mmHg, when the distending fluid bag is hung at 100–150 cm above the operating field.[7] The normal recommended height of irrigating bag from operative field should be 60 cm as being described in an analogous situation during transurethral resection of prostrate.[8] The other factors responsible for rapid absorption of fluid are high intrauterine pressure of more than 75 mmHg (normal value 45–75 mmHg), low mean arterial pressure, increased depth of myometrial penetration, larger size of uterine cavity, increased duration of surgery (>60 min), and menopausal status.[6] Systemic absorption of 1000 ml of hypotonic fluid (glycine) and 2500 ml of isotonic fluid is enough to cause symptoms of fluid overload and electrolyte imbalance in young healthy women. In elderly patients or those having coexisting cardiovascular and renal disease, a 750 ml of hypotonic and 1500 ml of isotonic fluid is enough to cause symptoms.[6] The quantification of systemically absorbed fluids is a complex task as it is confounded by many factors. Inter - observer variability exists in calculating the volume of fluid that flows out of the uterus and the one spilling on the operating table and operating room floor. Discrepancy may exist in calculating fluid remaining in emptied or used fluid bags, as volume in a 3-L bag exceeds by about 2.8%–6.0% due to overfilling.[9]
In our elderly patient, a total of 25 L glycine 1.5% was used and the outflow fluid was 23 L. The serum sodium decreased from 140 to 107 mmol/L. According to the European Society for Gynaecological Endoscopy guidelines, the decrease of serum sodium by 10 mmol/L correlates with the absorption of 1000 ml of irrigating fluid.[6] This did not correspond to the drop in the sodium level in our case as the fluid absorbed was less and the drop-in serum sodium was more. After analyzing each factor by the anesthesia team, the root cause observed was the height of the IV stand. Routinely used IV stand which was precalibrated to the height of 60 cm was replaced with a new stand. The height of the bag was found to be at 150 cm which could have led to rapid systemic absorption of glycine under enhanced pressure (approximately 110 mmHg) and resulted in the blindness. Avoiding the morbidity and complications in the future, the IV stands slated to be used in gynecology (hysteroscopy) and urology OT have been ear marked and recalibrated to limit similar errors in the perioperative period.
To conclude, one needs to be cautious and vigilant while using glycine in patients, especially the elderly with coexisting cardiovascular and renal impairment as any discrepancy in estimating the fluid deficit will be catastrophic. Serum sodium level estimation by a point-of-care ABG machine in such a dynamic situation where fluid absorption depends on multiple factors will come handy in early recognition and management of electrolyte disturbances, thereby preventing morbidity. Time is ripe to replace the manual measurement technique of fluid absorption with automated fluid measurement systems facilitating the correct fluid deficit measurement.[6]
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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