Bhavna Gupta

Amlodipine toxicity complicated by concurrent medications

tion in patients with hypertension. Cases of amlodipine toxicity have been reported in literature. We report a rare case of 45 year old female with alleged history of suicide with amlodipine, and other medications which included sedatives, anti-hypertensives, oral hypoglycemic agents and thyroid medications. Our patient presented with atypical features of poisoning and hence was managed accordingly. The clinical picture at the time of presentation and management has been described in detail. Amlodipine is a type of dihydropyridine calcium channel blocker and is used in management of angina pectoris and essential hypertension. It is prescribed as a daily dose of 5–10 mg daily. There are reported cases of amlodipine toxicity in literature, however none described a case of amlodipine toxicity complicated with other concurrent medications. We report a well-managed case of severe amlodipine intoxication complicated by other medications. A 45-year-old woman with chronic hypertension, diabetes, hypothyroidism, coronary artery disease, and depression had been taking amlodipine 5 mg once daily (OD), telmisartan 40 mg OD, metformin 500 mg twice daily (BID), glimepiride 2 mg BID, levothyroxine 100 μg OD, and alprazolam 0.5 mg at bedtime. She was admitted in an unconscious state, with an alleged suicide attempt by taking ten 5-mg tablets of amlodipine in addition to her usual telmisartan, metformin, alprazolam, and levothyroxine tablets at bedtime. Her history was provided by her son, and an empty tablet container was retrieved. She was admitted to the emergency department in an unconscious, diaphoretic state, with frothing from the mouth and tongue biting. She was drowsy, with a weak pulse, heart rate of 35 beats/min, systolic blood pressure of 85 mmHg, peripheral oxygen saturation (SpO2) of 40%–50%, and bilateral basal crepitus. Pupils were equally reactive, and she had oliguria (urine output: 30 ml/h). Relatives reported she had an episode of vomiting, followed by rigidity of limbs and a possible seizure. A 7.5 Fr endotracheal tube was immediately inserted and gastric lavage was performed with activated charcoal via gastric tube. She was also administered a bolus of atropine. Her blood sugar was 60 mg/dl, and she was given 100 ml of 25% dextrose over 20 min. She was subsequently transferred to the intensive care unit (ICU). In the ICU, her pulse rate was 45 /min, with blood pressure of 100/70 mmHg and SpO2 of 96%. Calcium and magnesium levels, arterial blood gases, an electrocardiogram, creatine phosphokinase (CPK, total and MB) and troponin T levels, and a chest X-ray were obtained. She was empirically given a bolus of calcium gluconate (10%; 30 ml over 10 min), followed by a 10 ml/h infusion, and a loading dose of phenytoin was given. She had a normal blood count, and urea, creatinine, CPK-MB, and troponin T levels were negative. Fig. 1 shows the chest X-ray with a possible right lower lobe infiltrate. Ionized calcium and blood sugar levels were maintained in the reference range and monitored every hour. She was uneventfully extubated 12 h after poisoning and maintained normal consciousness, vital signs, and urine output. Her oliguria responded to fluid boluses. After extubation, she required highflow nasal oxygen to maintain saturation and had tachypnea of 35 breaths/min, with a resolution after 96 h. Echocardiography and non-contrast brain computed tomography were normal. Over a period of 5 days, her clinical condition improved, and she was moved to a ward and discharged after a few days. She has been followed in the psychiatric clinic for her suicidal behavior. Amlodipine is typically known to produce fewer side efLetter to the Editor

Anesthetic and Critical Care Considerations in Children with Abdominal Trauma

Unrecognized abdominal trauma is a common unrecognized life-threatening emergency on pediatric age group. As compared to adults, children have large solid organs; they have low subcutaneous fat and have no significantly low abdominal muscle mass to protect. Solid organ injuries are common in children due to blunt and penetrating trauma. Blunt trauma causes injury to solid organs such as the liver and spleen. The potentially life-threatening injuries are real challenge to the attending anesthesiologist as the children are not only anatomically and physiologically different from adult but also psychologically more difficult to deal with [1, 2].

Closed-loop monitoring by anesthesiologists—a comprehensive approach to patient monitoring during anesthesia

is the main determinant of patient safety during anesthesia. Monitoring is defined as observation of a patient by a physician and analysis of the quality of sedation or anesthesia over a time period. Administration of anesthesia requires continual assessment of the physiological state of the patient as well as the adequacy of anesthesia. Although monitoring of the patient using monitors supplements clinical observation, the former is by no means a substitute for the latter. Monitoring and recording may be performed using either automated computerized methods or manual measurement. Automated computerized methods have the advantage of saving the recorded information and observing trends over time. Association of Anaesthetist of Great Britan and Ireland standards of monitoring include the following [1]: 1. The presence of a qualified anesthetist, 2. Monitoring the patient’s oxygenation, ventilation, circulation, and temperature a) Ventilation: Assessed by measuring end-tidal carbon dioxide and inspired anesthetic gases. b) Oxygenation: Assessed by measuring peripheral oxygen saturation and inspired anesthetic gases. c) Temperature: Core temperature monitoring (e.g., tympanic membrane, distal esophagus, nasopharynx, etc.) is used to monitor intraoperative hypothermia, prevent over-heating, and facilitate detection of malignant hyperthermia. d) Circulation: Assessed by measuring heart rate and non-invasive blood pressure every five minutes, and through electrocardiogram analysis. Minimum basic standard monitoring during general anesthesia includes pulse oximetry, electrocardiogram, monitoring of non-invasive blood pressure, end-tidal carbon dioxide, and airway pressure. The use of a nerve stimulator is indicated whenever a muscle relaxant is used. During regional anesthesia and sedation procedures, appropriate monitoring should be performed using pulse oximetry, measurement of non-invasive blood pressure, and electrocardiography, at a minimum [1]. In principle, monitoring of physiological variables provides information and feedback on the body’s response to therapeutic interventions or changing clinical conditions. This allows fine-tuning of patient management to achieve optimal outcomes and minimization of complications. Clinical observation and assessment by a vigilant anesthetist are essential for safe patient care during anesthesia. Appropriate clinical observations include the color of the mucosa, sweating, lacrimation, movement of the patient, response to a surgical stimulus, excursions of the chest wall, and movements of reservoir bag/bellows etc. A simple palpation of the radial/carotid pulse can indicate the volume status of the patient. Other clinical monitoring parameters include measurement of urine output, blood loss, and auscultation of heart sounds and breath sounds. Standard monitoring requires that measurements be performed every 5 minutes. Changes in clinical signs often precede abnorLetter to the Editor

Is irrational use of intralipid emulsion justified in amlodipine toxicity

highlighting the importance of intra-lipid emulsion (ILE) in amlodipine toxicity, suggested for the management of a case of amlodipine toxicity with concurrent medications, published in the Korean Journal of Anesthesiology [2], we would like to highlight a few points related to the effectiveness of ILE in amlodipine toxicity. Intra-lipid 20% is an intravenous emulsion of fat, administered to patients requiring parenteral nutrition as a source of calories and essential fatty acids. Its role in management of life-threatening cardiac arrest because of local anesthetic (especially bupivacaine) toxicity is well-documented; however, its role in the management of toxicity due to other lipophilic drugs, such as non-local anesthetic drugs, amitriptyline, calcium channel blockers, and baclofen, is not well-established, and most of the literature is based on published case reports [3]. Amlodipine toxicity is associated with significant morbidity and mortality, and the recommended first line therapy for symptomatic patients with calcium channel blocker (CCB) toxicity includes intravenous calcium, high dose of insulin in case of myocardial dysfunction, nor-epinephrine or epinephrine for vasodilatory shock, dobutamine for cardiogenic shock, and atropine in case of symptomatic bradycardia or conduction disturbances. Intravenous calcium is the recommended first line treatment as it improves contractility and blood pressure, carries little risk, and is a readily available drug. High dose of insulin is also known to improve contractility, increase blood pressure, and improve survival, according to observational studies, case series, and animal studies [4]. Recommendation to use ILE is neutral in cases of cardiac arrest due to CCB toxicity (diltiazem, verapamil, and dihydropyridines); ILE should not be used as the first line therapy in life-threatening or non-life-threatening toxicity due to CCBs (level of recommendation: 2D) [3]. The rationale of not using ILE as first line in CCB toxicity is because of inconsistent reported outcomes, including sudden deaths as immediate response, observed in human case reports and animal experiments; therefore, no clear recommendation of its use exists [3]. There are frequent known adverse effects of ILE which occur as a result of contamination of intravenous lines and vein irritation, both of which are not life-threatening. However, less frequent immediate reactions have been reported, including dyspnea; cyanosis; allergic reactions; headache; increase in temperature; chest-pain; flushing; dizziness; and delayed reactions such as jaundice, thrombocytopenia, focal seizure, splenomegaly, and shock [3]. Its administration is contraindicated in patients with disturbance of normal fat metabolism, such as hyperlipidemia and lipoid nephrosis [4]. Moreover, it has been postulated that ILE can enhance intestinal absorption of other toxins, thereby enhancing their effects, as suggested by oral drug poisoning models [4]. Concern has also been raised that concurrent administration of ILE with extracorporeal assist devices interferes with resuscitative medications. A study has also demonstrated worse outcome with verapamil when ILE was administered [5]. Although ILE is not recommended as the first line therapy, it is reserved as rescue therapy in refractory cases which cannot be managed with supportive measures. Step-wise management in case of CCB toxicity is summarized in Fig. 1, as adapted from “Experts consensus recommendations for management of calcium channel blocker poisoning in adults” [4]. Administration Letter to the Editor

Significance of outer diameter of endotracheal tube: a parameter less known

by the French gauge system. Improper interpretation of these standards may lead to confusion between the users and catheter manufacturers. The outer diameter (OD) and inner diameter (ID) are generally measured in inches or millimeters. The size of various tracheal tubes is usually expressed as ID, unless specified otherwise. Though the ID measurements may be constant, both OD and ID may show a difference of 2–4 mm depending on different manufacturers. For selecting an appropriate tracheal tube, the American society for testing and materials does not include any recommendations for OD measurement, as opposed to the recommendations available for ID measurements [1]. The OD and ID measurements of endotracheal tubes are summarized in Table 1. Armored or flexo-metallic endotracheal tubes have a slightly thicker wall. The difference between OD and a standard ID is greater in an armored tube as compared to a regular endotracheal tube (0.2–0.3 mm). The size of a double lumen tube is decided by the size of the bronchus; this corresponds to the external diameter equivalent of a French catheter gauge, defined as 3 times that of the ID, hence the OD here is more important. The difference in the ODs of Univent and double lumen tubes as compared to that of a regular endotracheal tube is 2–3 mm. In a study published by Al-Mazrou et al. [2], the internal tracheal diameter (ITD) was measured at the level of the cricoid, using magnetic resonance images, and compared to the OD of a utilized endotracheal tube (ETT). The OD of the best fit ETT was less than the ITD measured at the level of the cricoid by 0.1–1.7 mm, and it was concluded that the correlation of OD of the best fit ETT was strongerirrespective of weight or height. In another study by Bernet et al. [3], it was observed that the external diameter of pediatric tracheal tube cuffs could easily expand in vitro, to produce ODs of more than twice the age-corresponding ITD, when over-inflated with air. It has been observed that if the ID is too small, it may result in a smaller OD, which increases the cuff pressure required to create a seal in the trachea. A smaller ID tube also increases the Letter to the Editor

Is irrational use of tranexamic acid justified in anesthesia practice

acid lysine, which binds to five lysine binding sites on the plasminogen molecule. It has been widely used in orthopedic, cardiac, gynecological, and neurosurgery, etc., to reduce bleeding and transfusion requirements. The intravenous dosage is typically 0.5–1 g, administered by slow injection three times per day. Alternatively, the initial dose can be followed by infusion of 25–50 mg/kg over 24 hours. Dosing should be reduced to 5–10 mg/kg in patients with renal failure. TA has also proven useful in emergency trauma victims to reduce bleeding, as demonstrated in the CRASH2 trial, in which patients at risk of bleeding given a loading dose of 1 g of TA over 10 minutes, followed by infusion of 1 g over 8 hours within 8 hours of trauma, were found to have less bleeding compared to those receiving placebo [1]. Although there is no consensus regarding the adequate dose of TA to prevent bleeding in various surgeries, there have been many reports highlighting the dosages required for the optimal effect. Sigaut et al. [2] used two doses of TA, 30 mg/kg and 10 mg/kg, and reported that the higher dose was more effective for reducing transfusion needs, blood loss, and the incidence of repeat surgery. There are various contraindications for the use of TA: in cases of active thromboembolic disease, e.g., deep venous thrombosis or pulmonary embolism, TA has been shown to have a procoagulant effect and can be unsafe in patients with thromboembolism, those in a hypercoagulable state, and those with thrombogenic vascular diseases. Sundström et al. [3] suggested that TA was associated with an increased risk of venous thromboembolism, although the risk estimate did not reach statistical significance. Hypersensitivity reactions to TA are not uncommon, and care should be taken during its slow, intravenous administration. Visual effects are known side effects of TA, and retinal arterial and venous occlusion have even been reported in the literature. When administered at a high dosage, TA is known to produce seizure in cases of cardiac surgery, where it is commonly used at a high dose, to ensure an effective concentration, secondary to gamma-aminobutyric acid (GABA) receptor inhibition. Murkin et al. [4] suggested the epileptogenic potential of TA at higher doses in susceptible individuals. They suggested that nonischemic seizure is associated with TA at doses of 61– 259 mg/kg [4]. After this review, dosing guidelines have been modified to a low dose of tranexamic acid as 30 mg/kg loading dose followed by 15 mg/kg/h as infusion [4]. Many authors have suggested that use of TA at doses exceeding 80 mg/kg should be avoided. However, one of the largest retrospective data analyses, of 4,883 cardiac surgical patients, indicated that even a moderate TA dose of 24 mg/kg was associated with almost double the rate of convulsions and in-hospital mortality in comparison to a reference group that did not receive the drug [5]. Extreme caution is required regarding the use of this drug in patients with disseminated intravascular coagulation requiring antifibrinolytic therapy. Even among patients with acute ureteral obstruction, clot formation has been reported in those with upper urinary tract bleeding. Concurrent administration of TA with oral contraceptives is not recommended, as the risk of thromboembolism is further increased. Concurrent administration with factor IX complexes or anti-inhibitor coagulant complexes is also not recommended, due to the risk of thrombosis. Cerebral infarction and edema have been reported in patients with subarachnoid hemorrhage receiving TA. Concurrent use of tretinoin with TA may exacerbate procoagulant effects. Accidental intrathecal injection of 500 mg of TA was reported to be associated with spinal myoclonus, and even death. TA is Letter to the Editor

Anesthesia for neurosurgery (Part II)

The central nervous system (CNS) deserves special consideration in the perioperative setting for several reasons for an anesthetist. An understanding of neuroanatomy is essential because neuro anesthesia continues to develop and evolution of neurosurgical practice is accompanied by new challenges for the anesthetist. Basic knowledge and expertise of the neuro-anesthetist can directly influence patient outcome. With the recent advancement in functional and minimally invasive procedures, there is an increased emphasis on the provision of optimal operative conditions, preservation of neurocognitive function, minimizing interference with electrophysiological monitoring, and a rapid, high-quality recovery. So, during neuro anesthesia, anesthesiologist needs to know physiology of CNS including cerebral metabolism and cerebral blood flow. Neuro anesthesia can be challenging, because sometimes apparently contradictory demands must be managed, for example, achieving optimal conditions for neurophysiological monitoring while maintaining sufficient anesthetic depth, or maintaining oxygen delivery to neuronal tissue and simultaneously preventing high blood pressures that might induce local bleeding. One of the peculiarities of neuro anesthesia has always been that as much importance is attached to wakening the patient as sending them to sleep. We have included the anesthesia for neurosurgery in two parts. In the first part, we had discussed cerebral anatomy, physiology and intracranial pressure, in the second part we have included anesthesia considerations for surgery for brain tumor, aneurysmal surgery, temporal lobe surgery, trans sphenoidal surgery and traumatic brain injury.xa0 n nKeywords: Anesthesia, Neurosurgery.

Anesthetic considerations for a parturient with pulmonary hypertension

Pulmonary hypertension is defined as persistent rise in mean pulmonary artery pressure of 25 mmHg or more with pulmonary occlusion pressure <15 mmHg. Most of the symptoms encountered in pulmonary hypertension overlap with that of normal pregnancy such as shortness of breath, weakness, fatigue, chest pain, syncope, and abdominal discomfort. Pulmonary hypertension in pregnant patients carries high mortality rates between 30% and 56% and is also the important cause of increased perioperative morbidity and mortality. Basic principles of management include maintaining right ventricular function and reducing pulmonary vascular resistance. Preoperative risk assessment and successful management of patients with pulmonary hypertension undergoing surgery are crucial and important and involve an understanding of the pathophysiology of the disease, analysis of preoperative and operative risk factors, thorough multidisciplinary planning, meticulous intraoperative management, and early recognition and treatment of postoperative complications. We searched PubMed and Google Scholar databases with the following key words: pulmonary hypertension, anesthesia concerns, and parturient female for literature search.