Satyajeet Misra

The effect of gabapentin premedication on postoperative nausea, vomiting, and pain in patients on preoperative dexamethasone undergoing craniotomy for intracranial tumors.

Background: In patients undergoing craniotomy, the incidence of postoperative nausea and vomiting (PONV) is 55% to 70% and that of moderate to severe postoperative pain is 60% to 84%. We hypothesized that gabapentin plus dexamethasone would be superior, compared with placebo and dexamethasone in reducing the incidences of PONV and pain after craniotomy. Methods: Patients undergoing craniotomy received either placebo (group D) or gabapentin (600 mg) (group GD) premedication orally, 2 hours before induction of anesthesia. In addition, all patients received 4 mg of intravenous dexamethasone on the morning of surgery and continued receiving it after every 8 hours. The 24-hour incidence of nausea, emesis, or PONV (nausea, emesis, or both) (primary outcome) and postoperative pain scores (secondary outcome) were analyzed with the &khgr;2 test and the Wilcoxon rank-sum test as applicable. Results: A significant difference was observed between the groups in the incidence of nausea (odds ratio [OR], 0.23; 95% confidence interval [CI], 0.07, 0.80; P=0.02), PONV (OR, 0.3; 95% CI, 0.08, 0.8; P=0.02), and the requirement for antiemetics (OR, 0.30; 95% CI, 0.09, 0.9; P=0.03). The number of emetic episodes were also reduced in group GD, but this did not assume statistical significance (OR, 0.34; 95% CI, 0.10, 1.1; P=0.06). However, there was no significant difference in either the postoperative pain scores or the opioid consumption between the 2 groups. Conclusions: A dosage of 600 mg of gabapentin plus 4 mg of dexamethasone significantly reduced the 24-hour incidence of nausea and PONV. However, there was no reduction in either the postoperative pain scores or opioid consumption.

A review of the practice of sedation with inhalational anaesthetics in the intensive care unit with the AnaConDa® device

The intensive care unit (ICU) environment is often perceived to be hostile and frightening by patients due to unfamiliar surroundings coupled with presence of numerous personnel, monitors and other equipments as well as a loss of perception of time. Mechanical ventilation and multiple painful procedures that often need to be carried out in these critically ill patients add to their overall anxiety. Sedation is therefore required not only to allay the stress and anxiety, but also to allow for mechanical ventilation and other invasive therapeutic and diagnostic procedures to be performed. The conventional intravenous sedative agents used in ICUs suffer from problems of over sedation, tachyphylaxis, drug accumulation, organ specific elimination and often lead to patient agitation on withdrawal. All this tend to prolong the ventilatory as well as ICU and hospital discharge time, which increase the risk for infection and add to the overall increase in morbidity, mortality and hospital costs. In 2005, the anaesthetic conserving device (AnaConDa®) was marketed for ICU sedation with volatile anaesthetic agents. A number of trials have shown the effectiveness of using volatile anaesthetic agents for ICU sedation with the AnaConDa device. Compared with intravenous sedatives, use of volatile anaesthetic agents have resulted in shorter wake up and extubation time, lesser duration of mechanical ventilation and faster discharge from hospitals. This review shall focus on the benefits, technical pre-requisites and status of sedation with volatile anaesthetic agents in ICUs with the AnaConDa® device.

Changes in Left Ventricular Preload, Afterload, and Cardiac Output in Response to a Single Dose of Mannitol in Neurosurgical Patients Undergoing Craniotomy: A Transesophageal Echocardiographic Study

Background: Mannitol increases intravascular volume by withdrawing water from the brain and causes significant changes in stroke volume, cardiac output (CO), systemic vascular resistance, central venous pressure (CVP), and blood pressure. No previous studies have demonstrated changes in left ventricular (LV) preload, afterload, and CO using transesophageal echocardiography (TEE). Methods: Fifteen adult patients undergoing elective supratentorial craniotomy received 20% mannitol 1.0 gm/kg over 15 minutes before dural opening. The following hemodynamic and TEE-derived parameters were recorded before and after the administration of mannitol: heart rate (HR), mean arterial pressure (MAP), CVP, LV end diastolic area (EDA), end systolic area, fractional area change, stroke volume, and CO. Results: EDA and CVP significantly increased at 5 minutes (P=0.002 and <0.001) after mannitol infusion and remained insignificantly elevated till 15 minutes, thereafter returning to baseline values. CO also increased significantly at 5 and 15 minutes (P=0.001 and 0.013) and remained insignificantly elevated till 25 minutes, and thereafter returned to baseline values. A concomitant significant decline in systemic vascular resistance was observed at 5 and 15 minutes (P=0.002 and 0.008 at 5 and 15 min, respectively). Although EDA increased significantly at 5 minutes, there were no appreciable changes in MAP and HR throughout the study period. Conclusions: In conclusion, in patients undergoing craniotomy, TEE demonstrated that a single bolus dose of 20% mannitol (1.0 gm/kg) caused significant but short-duration alterations in LV preload, afterload, and CO without concomitant changes in hemodynamic variables (MAP/HR).

Gabapentin Premedication Decreases the Hemodynamic Response to Skull Pin Insertion in Patients Undergoing Craniotomy

BackgroundIn patients undergoing craniotomy, skull pin insertion produces significant increases in heart rate (HR) and blood pressure. We investigated whether premedication with gabapentin would prevent or attenuate this increase. MethodsForty-seven ASA I and II patients, 18 to 60 years, undergoing elective craniotomy for intracranial tumor surgery were recruited prospectively and randomly divided into 3 groups; L (oral placebo plus 2% lidocaine infiltration at pin sites; n=12), G (oral gabapentin 900 mg plus normal saline infiltration; n=21) and GL (oral gabapentin 900 mg plus 2% lidocaine infiltration; n=14). The oral medications were administered 2 hours before induction of anesthesia. Measurements were made at preinduction baseline, before skull pin insertion and at every 1 minute from pin insertion till end of 10 minutes. ResultsForty-three patients completed the study (L, n=11; G, n=20; GL, n=12). Premedication with gabapentin significantly attenuated the rise in systolic (SBP) and mean arterial pressure (MAP) after pin insertion when compared with placebo (for SBP, P<0.001 at 1 and 2 min and <0.05 at 3 to 5 min between L and G; P<0.001 at 1 to 4 min and <0.05 at 5 min between L and GL; for MAP, P<0.05 at 1 min, <0.001 at 2 min and <0.05 at 3 to 4 min between L and G; P<0.001 at 1 to 2 min and <0.05 at 3 to 5 min between L and GL). HR responses were also attenuated in patients premedicated with gabapentin; however, the responses were more variable in group G (P=0.03 between L and G at 4 min after pin insertion) as compared with group GL (P<0.05 at 1 min, <0.001 at 2 min and <0.05 at 3 to 10 min between L and GL). ConclusionIn conclusion, 900 mg of gabapentin, administered orally 2 hours before induction of anesthesia along with lidocaine scalp infiltration abolished the hemodynamic response after skull pin insertion. Premedication with gabapentin alone significantly attenuated the SBP and MAP; however, HR responses were more variable. A larger trial is required to corroborate the findings of the study before clinical recommendations would be warranted.

Echo rounds: False tendons and accessory papillary muscle in the left ventricle.

This report is presented after obtaining consent from the patient, a 72-year-old man who underwent coronary artery bypass graft surgery at our institution. Intraoperative transesophageal echocardiography revealed the presence of numerous false tendons in the left ventricle (LV). The false tendons were seen in multiple views (Fig. 1, A and B) (Video loops 1 and 2, see Supplemental Digital Content 1, http://links.lww.com/AA/A309). In addition, transgastric midpapillary short-axis and 2-chamber views of the LV revealed the presence of an accessory papillary muscle in the anterior free wall, just anterior to the anterolateral papillary muscle (Fig. 2) (Video loops 3 and 4, see Supplemental Digital Content 2, http://links.lww.com/AA/A310). False tendons could also be seen attached between the accessory papillary muscle and the LV wall, but there was no flow turbulence at the site of attachment of the accessory papillary muscle. There was no regional wall motion abnormality, no significant mitral valve regurgitation, or LV outflow tract obstruction. The patient made an uneventful recovery from the surgery. False tendons were first described as moderator bands at autopsy and have subsequently been described in several echocardiography series. Variably termed as anomalous and/or false chords, bands, and aberrant tendons, they are fibrous or fibromuscular structures and possibly share a common embryological origin with true chordae tendineae. However, unlike the true tendineae, which are inserted into the mitral valve, false tendons have no attachment to the valve and are connected to the papillary muscles, LV walls, or both. The incidence of false tendons detected by autopsy is approximately 45% to 55% in normal hearts, and 0.5% to 50% by 2-dimensional (2D) echocardiography. Twodimensional echocardiography is a highly sensitive and specific modality for the detection of false tendons (sensitivity 85% and specificity 82%). These structures may be better visualized when the LV dilates leading to their stretching and differentiation from the myocardium and, thus, better insonation by the ultrasound beam. On 2D echocardiography, the false tendons appear as echodense linear chord-like structures of varying length and thickness in the LV cavity and are usually seen in multiple views. False tendons have previously been misdiagnosed as subaortic membrane, hypertrophic obstructive cardiomyopathy, septal aneurysms, and flail aortic and mitral leaflets. However, with improvement and refinement of ultrasound technology, these tendons are easily recognized on 2D echocardiography. Occasionally, though, false tendons may be misdiagnosed as artifacts or LV thrombus. Because false tendons are considered to be a normal anatomical variant, absence of symptoms and demonstration of the tendons in 2 or more echocardiographic views are points in favor of their diagnosis. Additional points that help in diagnosing false tendons are a free intracavitary course, presence of echo-free space on either side of the tendon, constant motion of the tendon with the cardiac cycle, and absence of regional wall motion abnormalities adjacent to the site of attachment of the tendon. Various anomalies of the papillary muscles including accessory papillary muscles have also been described. Accessory papillary muscles may sometimes be misdiagnosed on 2D echocardiography as LV thrombus or tumors such as papillary fibroelastoma or hemangioma. The points in favor of LV thrombus include associated regional wall motion abnormality, frequent apical location of the thrombus, distinct thrombus margin with jagged edges, movement separate from the underlying endocardium, and a higher echo density as compared with the myocardium. Papillary muscle tumors such as fibroelastomas are usually asymptomatic and diagnosed as a hyperechoic mass on 2D echocardiography with a characteristic shimmer at the tumor-blood interface whereas hemangiomas have heterogeneous echogenicity and may occasionally be symptomatic depending on their location. In this case, an additional point in favor of accessory papillary muscle as compared with thrombus was the attachment of false tendons to the muscle. There is a wide variation in papillary muscle architecture. In an autopsy study of 100 human hearts, more than 1 belly was demonstrated in 33% of anterolateral and in 50% of posteromedial papillary muscles, with a variable pattern in the type and site of attachment of the muscles to the LV wall as well. Therefore, in defining a true accessory papillary muscle, it is important to demonstrate it in multiple views, so as to distinguish it from a papillary muscle with multiple bellies. Papillary muscles are usually well visualized at end-systole in the midesophageal commissural and 2-chamber as well as transgastric midpapillary short-axis and 2-chamber views. Adjusting the machine settings such as gain and contrast may improve the visualization of the endocardial borders thus better delineating the site of attachment of the papillary muscles. In conclusion, false tendons and accessory papillary muscles may be present in the LV and occasionally misdiagnosed by echocardiographers as thrombus or other pathologies. Awareness of the existence of these normal From the Department of Anesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Kerala, India.

Accuracy of a Chest X-Ray–Based Method for Predicting the Depth of Insertion of Endotracheal Tubes in Pediatric Patients Undergoing Cardiac Surgery

OBJECTIVES The incidence of endotracheal tube (ETT) malposition in children with various described methods is 15% to 30%. Chest x-ray (CXR) is the gold standard for confirming appropriate ETT position. The aim of this study was to measure the accuracy of a preoperative CXR-based method in determining depth of insertion of ETTs and to compare it with methods based on the intubation depth mark or formulae (age, height, and ETT internal diameter) in children undergoing cardiac surgery. DESIGN Prospective observational study. SETTING University-affiliated tertiary care hospital. PARTICIPANTS Sixty-six consecutive children scheduled for elective pediatric cardiac surgery. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The distance from carina to mid-trachea was measured for each child preoperatively on the CXR displayed as a computed radiography image in a picture archival and communications system computer. Following intubation, ETTs deliberately were pushed endobronchially and then pulled back to the carina; they were further withdrawn by the previously measured carina to mid-tracheal distance and secured. CXRs postoperatively were repeated to confirm ETT position. The ETT position was measured with other methods using the picture archival and communications system ruler on the postoperative CXR and compared with the CXR method. The proportion of appropriate ETT position with the CXR method was 98.5% (p≤0.001 v other methods). In children younger than 3 years, the appropriate proportion was 97.4%. CONCLUSION The appropriate positioning of ETTs in the trachea by the CXR method is superior to other methods.

Unexpected Air in the Left Ventricle after Aortic Cannulation in Two Patients with Severe Aortic Insufficiency: Possible Mechanisms and Clinical Implications

a fl l l l t ir bubbles are commonly seen in the heart on echocardiography after cardiac surgery and may lead to systemic air mbolism.1 The morbidity and mortality potential of air emboism to the coronary and cerebral circulation are described and ay affect the surgical outcome.2-5 Air embolism has been escribed both during initiation6 as well as termination7 of ardiopulmonary bypass (CPB). However, there are no reports of air entrained into the left entricle (LV) before the onset of CPB. The authors report 2 ases of aortic insufficiency in which air bubbles were seen nexpectedly in the LV just after aortic cannulation but before he initiation of CPB, and discuss the possible mechanisms and linical implications.

A Ring Artifact in the Left Ventricle on Transesophageal Echocardiography After Mitral Valve Replacement

A 48-year-old man, weighing 60 kg, underwent mitral valve replacement for severe mitral stenosis with a 29-mm St. Jude bileaflet mechanical prosthesis (St. Jude Medical, St. Paul, MN). We present the case after obtaining his consent. Transesophageal echocardiography (TEE) revealed that the mechanical prosthesis was working well after separation from cardiopulmonary bypass with minimal gradients and good ventricular function.

Embolization of Atrial Septal Occluder Device into the Pulmonary Circulation: Role of Transesophageal Echocardiography

(ECHOCARDIOGRAPHY, Volume 26, July 2009)

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.