Sethuraman Manikandan

Severe seizures during propofol induction in a patient with syringomyelia receiving baclofen.

We report the occurrence of recurrent severe generalized seizures during induction of anesthesia with propofol in a patient with syringomyelia receiving baclofen for flexor spasms undergoing neurosurgery. We discuss the possible epileptogenic interaction between baclofen and propofol in our patient.

Airway problems caused by hypogonadism in male patients undergoing neurosurgery.

Unanticipated difficult endotracheal intubations can pose challenges for the anesthesiologist. Risks include airway injury, hypoxemia, and death. There is intubation difficulty in various conditions including Downs syndrome, achondroplasia, acromegaly, and dwarfism. We describe difficulty in intubating the trachea with an appropriate sized endotracheal tube in two young male patients with hypogonadism presenting for neurosurgical procedures under general anesthesia. We discuss the role of hypogonadism and the effects of gonadotropin hormones on pubertal laryngeal growth in male patients.

Cerebral vascular effects of loading dose of dexmedetomidine: A Transcranial Color Doppler study

Background: Dexmedetomidine has been widely used in critical care settings because of its property of maintaining stable hemodynamics and inducing conscious sedation. The use of dexmedetomidine is in increasing trend particularly in patients with neurological disorders. Very few studies have focused on the cerebral hemodynamic effects of dexmedetomidine. This study is aimed to address this issue. Methods: Thirty patients without any intracranial pathology were included in this study. Middle cerebral artery flow velocity obtained from transcranial color Doppler was used to assess the cerebral hemodynamic indices. Mean flow velocity (mFV), pulsatility index (PI), cerebral vascular resistant index (CVRi), estimated cerebral perfusion pressure (eCPP), and zero flow pressure (ZFP) were calculated bilaterally at baseline and after infusion of injection Dexmedetomidine 1 mcg/Kg over 10 min. Results: Twenty-six patients completed the study protocol. After administration of loading dose of dexmedetomidine, mFV and eCPP values were significantly decreased in both hemispheres (P < 0.05); PI, CVRi, and ZFP values showed significant increase (P < 0.05) after dexmedetomidine infusion. Conclusion: Increase in PI, CVRi, and ZFP suggests that there is a possibility of an increase in distal cerebral vascular resistance (CVR) with loading dose of dexmedetomidine. Decrease in mFV and eCPP along with an increase in CVR may lead to a decrease in cerebral perfusion. This effect can be exaggerated in patients with preexisting neurological illness. Further studies are needed to evaluate the effect of dexmedetomidine on various other pathological conditions involving brain like traumatic brain injury and vascular malformations.

Resolution of Airway Compression Induced by Transesophageal Echocardiography Probe Insertion in a Pediatric Patient After Repair of an Atrial Septal Defect and Partial Anomalous Pulmonary Venous Connection

S d RANSESOPHAGEAL ECHOCARDIOGRAPHY (TEE) is routinely used in the operating room to assess surgical epairs in children with congenital heart disease (CHD). In a tudy of TEE examinations involving 1,650 children, Stevenon1 described airway obstruction in 14 patients (1%), right ainstem advancement of the endotracheal tube (ETT) in 3 atients (0.2%), inadvertent tracheal extubation in 8 patients 0.5%), vascular compression in 10 patients (0.6%), and addiional complications in 4 patients (0.2%). In another intraopertive TEE study of 200 pediatric cardiac patients undergoing urgical repair of CHD, complications associated with probe nsertion occurred in 11 patients (5.5%) and included airway bstruction in 6, inability to pass the probe in 4, and vascular ompression in 1 patient.2 The authors now report resolution of airway compression rom a TEE probe after surgical closure of an atrial septal efect (ASD) and rerouting of partial anomalous pulmonary enous connection (PAPVC) in a child. The patient had shown igns of airway compression after TEE probe insertion that ecessitated its removal shortly after initial endotracheal intuation. The mechanisms and the risk factors associated with irway compression by TEE probe insertion are discussed.

The depth markings on Portex blue-line pediatric tracheal tubes need to be re-organized for enhanced safety.

1 Luthy CL, Collart L, Dayer P. The rate of administration influences the analgesic effects of paracetamol. Clin Pharm Ther 1993; 2: 171. 2 Anderson BJ, Holford NH, Woollard GA et al. Perioperative pharmacodynamics of acetaminophen analgesia in children. Anesthesiology 1999; 90: 411–421. 3 Ameer B, Divoll M, Abernethy DR et al. Absolute and relative bioavailability of oral acetaminophen preparations. J Pharm Sci 1983; 72: 955–958. 4 Anderson BJ, Woolard GA, Holford NH. Pharmacokinetics of rectal paracetamol after major surgery in children. Paediatr Anaesth 1995; 5: 237–242. 5 Montgomery CJ, McCormack JP, Reichert CC et al. Plasma concentrations after high-dose (45 mgÆkg) rectal acetaminophen in children. Can J Anaesth 1995; 42: 982–986. 6 Holmer Pettersson P, Jakobsson J, Owall A. Plasma concentrations following repeated rectal or intravenous administration of paracetamol after heart surgery. Acta Anaesthesiol Scand 2006; 50: 673–677.

Anesthetic management of a patient with polycythemia vera for neurosurgery

Polycythemia vera (PV) is a myeloproliferative disorder characterized by excess red cell clonality. The increased number of red blood cells can lead to increased viscosity of the blood and ultimately compromise the blood supply to the end organs. Thromboembolic and hemorrhagic complications can also develop. Patients with PV presenting with neurological diseases that require surgical intervention are at an increased risk due to various factors, such as immobility, prolonged surgical time, hypothermia and dehydration. We report anesthetic management of a patient with PV who underwent neurosurgical intervention for vestibular schwannoma excision.

Effect of Loading Dose of Dexmedetomidine on Dynamic Cerebral Blood Flow Autoregulation in Patients With Intracranial Glial Neoplasms.

Background: Dexmedetomidine has been widely used in neuroanesthesia and critical care settings. The effects of dexmedetomidine on cerebral vascular autoregulation and hemodynamics in patients with intracranial pathology are not well defined. This study is aimed to address this issue. Methods: Fifteen patients with unilateral supratentorial glial tumor (group S) and 15 patients without any intracranial pathology (group C) were included in this study. Transient hyperemic response testing was conducted bilaterally in both groups with transcranial color Doppler. Dynamic autoregulation was assessed with transient hyperemic response ratio (THRR) and strength of autoregulation (SA) at baseline and after infusion of inj. dexmedetomidine (1 mcg/kg) over 10 minutes. Results: THRR and SA values in the hemisphere that had tumor (group S) showed no difference from baseline after a loading dose of dexmedetomidine (P=0.914, 0.217). In the nontumor hemisphere of group S and in both the hemispheres of group C, significant reduction in THRR and SA values were observed (P<0.001) after administration of a loading dose of dexmedetomidine. THRR values were higher in the tumor hemisphere when compared with the nonpathologic hemispheres (P<0.001), suggesting the possibility of baseline hyperemia. Conclusions: In the hemisphere that had glial tumor, autoregulatory indices showed no significant change after dexmedetomidine. It can be because of abnormal vascular architecture and its altered reactivity to dexmedetomidine, or because of baseline hyperemia itself, but the exact mechanism needs to be elucidated. In the nonpathologic hemispheres, THRR and SA values were decreased, suggesting impaired autoregulation with the use of loading dose of dexmedetomidine.

Endotracheal tube fixation in neurosurgical procedures operated in prone position.

isoflurane group. Hemodynamic profile in propofol group was thus better than the isoflurane group. Regarding comparison of emergence, we compared the time for eye opening and time taken to reach an Aldrete score of 9. Aldrete score contains parameters like consciousness and motor activity. So, eye opening, consciousness, and motor activity are reasonably enough parameters to compare emergence. We used a single isoflurane vaporizer for all cases in control group. Isoflurane consumed per case was calculated by dividing total isoflurane used in the vaporizer with total number of cases anesthetized. Indeed, it was a rough estimate, but we could not find any better and more practical method to calculate the isoflurane dose. The surgery was performed by same neurosurgical team, time required was nearly identical (as shown in the relevant observations in the manuscript) in most cases. In propofol group, we calculated the cost of the propofol used. We did not consider the amount of propofol that remained in the syringe after operation, because that was used in next patient, after changing the connecting tubing to avoid wastage of the drug. We routinely use midazolam 30 mcg/kg intravenous 3 minutes before starting administration of propofol in all cases. We titrated the infusion dose of propofol according to bispectral index scores, which were kept in a range of 40 to 60.

Perioperative implications of retrograde flow in both the subclavian arteries in an adult undergoing surgical repair of coarctation of aorta

During surgical repair of coarctation of aorta (CoA), management of spinal cord ischemia and prevention of paraplegia is an important issue. The risk factors for paraplegia include level and duration of aortic-clamping, clamping of left subclavian artery (SCA), intraoperative temperature, variability of collateral circulation to the spinal cord, cerebrospinal fluid pressure, upper body arterial pressure, and aortic pressure beyond the aortic clamp. A short clamp time (<30 min), and distal aortic pressure>60 mmHg, minimizes the risks of spinal cord injury. In an adult patient during surgical repair of CoA, the arterial pressure in the femoral artery remained around 45 mmHg and repair took 83 min of aortic-clamping. Neurological assessment on regaining consciousness showed no deficit of lower limbs. Aortic root angiogram had shown retrograde filling of both SCAs. A unique situation in which clamping of SCAs would increase flow to the spinal cord as their clamping would stop stealing of blood and aortic-clamping proximal to CoA will further increase collateral flow; because of these reasons, the patient tolerated prolonged aortic-clamping despite low distal aortic pressure without neurological deficit. However, aortic-clamping increased left ventricular after-load and the patient developed worsening of mitral regurgitation and pulmonary hypertension during aortic clamping.

Origin of the Right Subclavian Artery Distal to a Coarctation of the Aorta: Anesthetic Implications

Problems associated with the presence of an aberrant right subclavian artery and its anesthetic implications were previously escribed by Gadhinglajkar et al in an adult patient.1 We now describe the anesthetic implications of the aberrant subclavian rtery in a child undergoing repair of coartation of the aorta. A 3-month-old male child (weight, 3.5 kg) presented to the uthors’ hospital with excessive crying and breathlessness. On cardiovascular examination, arterial pulses were felt in the pper limbs but not in the lower limbs. Preoperative noninvasive blood pressure (NIBP) measured in the right upper limb was 5/30 mmHg, and in the right thigh, it was 60/34 mmHg. Transthoracic echocardiography showed severe postductal oarctation (gradient 60 mmHg), hypoplastic distal aortic arch, small muscular ventricular septal defect (gradient 90 mHg), secundum atrial septal defect, and moderate pulmonary hypertension. The patient was scheduled for coarctation epair. After uneventful anesthetic induction and intubation, an invasive arterial catheter was attempted in the right radial rtery; however, it could not be cannulated. The right femoral artery was cannulated with a 22-G cannula, and, with an infant uff, NIBP was monitored in the right upper limb. After left thoracotomy, an anomalous origin of the right subclavian artery istal to the coarctation was found with the left subclavian artery above the level of coarctation (Fig 1). The NIBP cuff was ransferred to the left upper limb from the right side because the right subclavian artery was included in the aortic clamp. efore aortic cross-clamping, furosemide, 1 mg, and dexamethasone, 1 mg, were administered intravenously. The aortic ross-clamp time was 22 minutes. During the cross-clamping, the mean femoral artery pressure was 25 mmHg. Postoperaively, the child did not have any neurologic deficits. Anomalous origin of the right subclavian artery occurs in 0.86% of patients presenting with coarctation of the aorta.2 The nomalous right subclavian artery is derived from the right dorsal aorta and the right 7th intersegmental artery.2 It originates from he descending thoracic aorta and passes across the mediastinum in a retroesophageal position. Although it arises distal to the coarct egment, reports exist of origin from the precoarct segment.2 The anomalous origin of the subclavian artery may form a vascular ing and may cause dysphagia.3 The diagnosis is difficult with transthoracic echocardiography, and its presence is usually confirmed ith angiography. The anesthetic implications of anomalous origin of the right subclavian artery below the coarctation segment nclude the following: 1. Difficulty in cannulating the right radial artery and the absence of a pressure gradient between the upper and lower limbs: the proximal arterial pressure can be measured with left radial cannulation or NIBP in the left upper limb. If the left subclavian artery is included in the aortic cross-clamp, proximal pressure can be obtained by insertion of a cannula directly from the aorta by the surgeon.