Temperature-controlled spectral tuning of a single wavelength polymer-based solid-state random laser.

We demonstrate temperature-controlled spectral tunability of a partially-pumped single-wavelength random laser in a solid-state random laser based on DCM [4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran] doped PMMA (polymethyl methacrylate) dye. By carefully shaping the spatial profile of the pump, we first achieve a low-threshold, single-mode random lasing with an excellent side lobe rejection. Notably, we show how temperature-induced changes in the refractive index of the PMMA-DCM layer result in a blue shift of this single lasing mode. We demonstrate spectral tunability over an 8nm-wide bandwidth.

Right Atrial Strain in Pediatric Pulmonary Hypertension-A Prospective Observational Study.

Right ventricular (RV) afterload due to elevated pulmonary arterial (PA) pressure in pulmonary hypertension (PH) causes long-term right atrial (RA) remodeling and dysfunction. RA function has been shown to correlate with PA pressures and outcome in both adult and pediatric patients with PH. We studied the role of RA strain in estimating PA pressures in congenital heart disease (CHD)-associated PH. Children below 12 years undergoing elective repair of CHD with left-to-right shunts and echocardiographic evidence of PH were included. RA reservoir, conduit and contractile strain along with conventional measures of RV function and PA pressure were measured using transthoracic echocardiography after induction of anaesthesia. Pre-and post-repair invasive PA pressures were measured after surgical exposure. 51 children with a median age of 24 months (range 4-144 months) were included, most of whom were undergoing VSD closure. Contractile RA strain showed good correlation with pre-repair systolic PA pressure in mmHg (r = 0.59, 95%CI 0.37-0.75) or expressed as a percentage of SBP (r = 0.67, 95%CI 0.49-0.80). It also predicted persistent postoperative PH as well as pre-repair pulmonary artery acceleration time and right ventricular systolic pressure measured from tricuspid regurgitation jet. The trends of correlation observed suggest a possible prognostic role of RA strain in ACHD with PH and potential utility in its echocardiographic assessment. The observed findings merit deeper evaluation in larger cohorts.

Author Response.

How to cite this article: Niyogi SG, Naskar C, Singh A, Kumar B, Grover S. Author Response. Indian J Crit Care Med 2024;28(2):188.

Melatonin and Melatonin Agonists for Prevention of Delirium in the Cardiac Surgical ICU: A Meta-analysis.

Aim and Background: Delirium is highly prevalent in the immediate postoperative period following cardiac surgery and adversely impacts outcomes. Melatonin has been increasingly used in pharmacological prevention of delirium. We aimed to synthesize the available evidence concerning the role of melatonin and melatonin agonists in preventing delirium in patients after cardiac surgery. Materials and methods: PubMed, Google Scholar, and Web of Science databases were searched for relevant randomized and non-randomized trials in adults undergoing cardiac surgery investigating melatonin agonists to prevent delirium. Studies incorporating transplants, preoperative organ support, prophylactic antipsychotics, or children were excluded. Risk-of-bias was assessed using Cochrane ROB 2.0 and ROBINS-I tools. A systematic review and meta-analysis were conducted, calculating pooled odds ratio (OR) for the incidence of postoperative delirium using a random effects model with the Mantel-Haenszel method with restricted maximum-likelihood estimator. Trial sequential analysis was also carried out for the primary outcome. Results: Six randomized trials and one non-randomized trial involving 1,179 patients were included. Incidence of delirium was 16.7 and 29.6% in the intervention and comparator groups respectively, indicating a pooled OR of 0.44 [95% confidence interval (CI) 0.27 - 0.71, p = 0.04] favoring melatonin. Two studies had a high risk of bias, and I2 statistics indicated significant heterogeneity. However, publication bias was insignificant, and trial sequential analysis indicated the significance of the attained effect size. Conclusion: Based on available studies, perioperative melatonin use significantly decreases postoperative incidence of delirium after adult cardiac surgery. However, the available quality of evidence is low, and larger trials with standardization of nonpharmacological delirium prevention interventions, in high-risk cohorts, and exploring various dosages and regimens should be carried out. How to cite this article: Niyogi SG, Naskar C, Singh A, Kumar B, Grover S. Melatonin and Melatonin Agonists for Prevention of Delirium in the Cardiac Surgical ICU: A Meta-analysis. Indian J Crit Care Med 2023;27(11):837-844.

Utility of Transfontanelle Ultrasound in Predicting the Fluid Responsiveness in Children After Repair of Congenital Heart Diseases: A Prospective Observational Study.

OBJECTIVES: Postoperative fluid management in children undergoing cardiac surgery requires a balanced optimization. The blood flow velocity variation in the internal carotid artery (ΔICA) measured through transfontanelle ultrasound has been shown to predict fluid responsiveness during cardiac surgery. It may provide an excellent window to study fluid responsiveness in infants during the postoperative period when the intensivist is faced with the challenges of poor echocardiographic window. The authors aimed to observe the correlation between ΔICA measured on transfontanelle ultrasound with the respiratory variability of peak aortic blood flow velocity (ΔVpeak) on transthoracic echocardiography as a marker of fluid responsiveness in infants on mechanical ventilation during the postoperative period after cardiac surgery. DESIGN: A prospective observational study. SETTING: The postcardiac surgery intensive care unit (ICU) of a tertiary care hospital. PARTICIPANTS: Thirty infants undergoing congenital cardiac surgery. INTERVENTIONS: A fluid bolus of 10 mL/kg administered over 10 minutes at 1 and 6 hours after ICU admission. Patients were categorized into fluid responders and nonresponders based on >15% increase in the indexed stroke volume. MEASUREMENTS AND MAIN RESULTS: A total of 50 fluid boluses were administered in 30 patients. Among these, 22 (73.33%) were responders and 8 (26.67%) were nonresponders. There was moderate correlation between ΔICA and peak aortic blood flow velocity variation (ΔVpeak) (r = 0.59, p ≤ 0.001). The ΔVpeak >14.74% had 68% sensitivity and 75% specificity to predict fluid responsiveness (area under the receiver operating characteristic [AUROC], 0.749; p = 0.001; positive likelihood ratio, 2.71; negative likelihood ratio, 0.43). The ΔICA >9.85% could predict fluid responsiveness in infants (AUROC, 0.728; p = 0.003; 75% sensitivity; 60% specificity; positive likelihood ratio, 1.85; negative likelihood ratio, 0.42). Among children younger than 6 months, ΔICA >9.85% was a better predictor of fluid responsiveness (AUROC, 0.889; p = 0.009) than ΔVpeak >15% (AUROC, 0.778; p = 0.061). CONCLUSION: The ICA variability >9.85% measured via transfontanelle ultrasound is a good predictor of fluid responsiveness in infants, especially those younger than 6 months on mechanical ventilation after cardiac surgery.

Utility of Lung Ultrasound in the Estimation of Extravascular Lung Water in a Pediatric Population-A Prospective Observational Study.

OBJECTIVE: Lung ultrasound (LUS) is a promising bedside modality for the estimation of extravascular lung water index (EVLWI), but has not been validated against objective measures in children. This study aimed to investigate the correlation of LUS B-line scoring with EVLWI, thresholds indicating elevated EVLWI, and its outcome following pediatric cardiac surgery. DESIGN: Prospective observational study. SETTING: Cardiothoracic surgical intensive care unit in a tertiary care teaching hospital. PARTICIPANTS: Children younger than 12 years undergoing elective complete surgical correction of cyanotic or acyanotic congenital heart disease (Aristotle score ≤9), excluding neonates, those weighing <3.5 kg, and those with thoracic deformities, pulmonary pathology, and hemodynamic instability. INTERVENTIONS: Extravascular lung water index measurement by transpulmonary thermodilution, along with concurrent LUS B-line and Chest-X ray (CXR) scoring. MEASUREMENTS AND MAIN RESULTS: LUS B-line score had a moderate correlation with EVLWI (Pearson's correlation coefficient 0.57; 95% CI 0.44-0.69). LUS B-line scores showed acceptable discrimination only for higher thresholds of EVLWI (sensitivity 82% and 79%, respectively, for EVLWI >20 mL/kg v sensitivity and specificity 57% and 80% for EVLWI >10 mL/kg). Age, body surface area, vasoactive-inotropic score (VIS), chest X-ray score, and EVLWI but not LUS B-line score were significant predictors for duration of mechanical ventilation in this cohort. CONCLUSIONS: LUS B-line scoring has limited utility in semiquantitative estimation of EVLWI at lower thresholds of EVLWI in pediatric cardiac surgical patients. It may have better discrimination and acceptable sensitivity and specificity at higher thresholds of EVLWI. Contrasting with multiple reports of clinical utility, these results call for wider evaluation of LUS and its clinical modifiers like age, pathology, and pretest probability in estimation of EVLWI.

Role of Lung Ultrasound in the Detection of Postoperative Pulmonary Complications in Pediatric Patients: A Prospective Observational Study.

OBJECTIVE: To evaluate the incremental benefit of lung ultrasound (LUS) over clinical examination and chest x-rays (CXR) together (clinico-radiologic examination) for the diagnosis of postoperative pulmonary complications (PPC). DESIGN: Prospective observational study. SETTING: Tertiary care center. PARTICIPANTS: One hundred children after corrective congenital cardiac surgery with left-to-right shunts. INTERVENTION: Participants were independently evaluated with clinico-radiologic examination by the treating team, as well as LUS by an investigator at 12, 24, 48, and 72 hours after surgery. After recording the diagnoses, the LUS findings were disclosed to the treating team and a final diagnosis was made. CXR scores and LUS scores were evaluated for their ability to predict PPC. MEASUREMENTS AND MAIN RESULTS: A total of 34 cases of PPCs were observed. Of these, 32 each were detected by clinico-radiologic examination and LUS alone. Addition of LUS improved total number of PPCs detected in the early postoperative period but not in the late postoperative period. Preoperative and early postoperative LUS scores were superior to CXR scores in predicting occurrence of PPC (area under receiver operating characteristics curve [AUROC] 0.920 v 0.732; p < 0.001 preoperatively; AUROC 0.987 v 0.858, p = 0.001 at 12 hours postoperatively). Multivariate analysis suggested LUS score as an independent predictor of PPC, and LUS score along with aortic cross-clamp time as independent predictors of duration of mechanical ventilation and intensive care unit stay. CONCLUSIONS: LUS improves identification of PPC over clinico-radiologic examination in the early postoperative period. Preoperative LUS scores have better predictive ability than CXR scores for the occurrence of PPC.

Left Atrial Dissection and Rupture Following Excision of Left Atrial Myxoma: Role of Transesophageal Echocardiography.

Left atrial mass after excision of a left atrial myxoma may occur due to residual or additional masses, such as biatrial or multicentric myxomas and inverted left atrial appendage. In this E-challenge, the authors present a case where intraoperative transesophageal echocardiography allowed visualization of a left atrial mass after excision of a left atrial myxoma. Detailed examination demonstrated that the mass was due to left atrial dissection that progressed to rupture, allowing its early detection and repair. A high index of suspicion, as well as coordination between the surgeon and the perioperative echocardiographer, played a crucial role in the detection and management of this complication.

Dextrocardia, situs solitus, inlet ventricular septal defect (VSD), and iatrogenic tricuspid regurgitation (TR)-A surgical perspective.

Dextrocardia with situs solitus is a rare congenital anomaly, often associated with intra- or extracardiac malformations. A clear understanding of the spatial orientation of the chambers of the heart for planning surgical approach, is imperative. Access to the right side of the heart, especially for repair of the tricuspid valve can be challenging. We describe a case of dextrocardia, situs solitus, inlet ventricular septal defect (VSD) with iatrogenic tricuspid regurgitation (TR) in an adult patient, highlighting the surgical aspects essential for a successful outcome.

Absent right superior vena cava with left superior vena cava draining into unroofed coronary sinus with common atrium in a child with an atrioventricular septal defect.

The association of absent right superior vena cava and persistent left superior vena cava draining into unroofed coronary sinus with common atrium and the atrioventricular septal defect is an extremely rare form of the congenital cardiac disorder with only one case reported so far, hence, can be missed preoperatively if not carefully looked for. Failure to detect absent right superior vena cava beforehand may otherwise pose difficulties in carrying out invasive surgical or medical interventions.

Emergency valve preserving ascending aorta replacement following iatrogenic right coronary artery dissection: A life-saving procedure.

Iatrogenic aortocoronary dissection is a rare but potentially fatal complication of coronary catheterizations. Although the incidence is comparatively low, dissection often leads to procedure failure with increased risk of myocardial infarction and death. Iatrogenic aortocoronary dissection is principally caused by disruption of intima at the ostia of the right or left coronary artery during interventional procedures and appears as luminal filling defects, the persistence of contrast or intimal tear outside the coronary lumen. We present a case of right coronary artery dissection leading to type-A aortic dissection suffered during diagnostic coronary catheterization. This required emergency supracoronary replacement of the ascending aorta with an aortic interposition tube graft and venous grafts to coronary arteries.

The processing and heterostructuring of silk with light.

Spider silk is a tough, elastic and lightweight biomaterial, although there is a lack of tools available for non-invasive processing of silk structures. Here we show that nonlinear multiphoton interactions of silk with few-cycle femtosecond pulses allow the processing and heterostructuring of the material in ambient air. Two qualitatively different responses, bulging by multiphoton absorption and plasma-assisted ablation, are observed for low- and high-peak intensities, respectively. Plasma ablation allows us to make localized nanocuts, microrods, nanotips and periodic patterns with minimal damage while preserving molecular structure. The bulging regime facilitates confined bending and microwelding of silk with materials such as metal, glass and Kevlar with strengths comparable to pristine silk. Moreover, analysis of Raman bands of microwelded joints reveals that the polypeptide backbone remains intact while perturbing its weak hydrogen bonds. Using this approach, we fabricate silk-based functional topological microstructures, such as Mobiüs strips, chiral helices and silk-based sensors.

Effect of Continuous Paravertebral Dexmedetomidine Administration on Intraoperative Anesthetic Drug Requirement and Post-Thoracotomy Pain Syndrome After Thoracotomy: A Randomized Controlled Trial.

OBJECTIVES: To assess the effect of paravertebral administration of dexmedetomidine as an adjuvant to local anesthetic on the intraoperative anesthetic drug requirement and incidence of post-thoracotomy pain syndrome. DESIGN: Prospective, randomized, controlled, double-blind trial. SETTING: Single university hospital. PARTICIPANTS: The study comprised 30 patients who underwent elective thoracotomy and were assigned randomly to either the Ropin or Dexem group (n = 15 each). INTERVENTIONS: All patients received the study medications through paravertebral catheter. Patients in the Ropin group received a bolus of 15 mL of 0.75% ropivacaine over 3-to-5 minutes followed by an infusion of 0.2% ropivacaine at 0.1 mL/kg/hour. Patients in the Dexem group received 15 mL of 0.75% ropivacaine plus dexmedetomidine, 1 µg/kg bolus over 3-to-5 minutes followed by an infusion of 0.2% ropivacaine plus 0.2 µg/kg/hour of dexmedetomidine at 0.1 mL/kg/hour. MEASUREMENTS AND MAIN RESULTS: The primary outcome of the study was intraoperative anesthetic drug requirement. The secondary outcome was the incidence of post-thoracotomy pain syndrome 2 months after surgery. The amount of propofol required for induction of anesthesia was significantly less in the Dexem group (Dexem 49.33±20.51 v 74.33±18.40 in the Ropin group, p = 0.002). End-tidal isoflurane needed to maintain target entropy was significantly less in the Dexem group at all time points. Intraoperative fentanyl requirement was lower in the Dexem group (Dexem 115.33±33.77 v 178.67±32.48 in the Ropin group, p = 0.002). Postoperative pain scores and morphine consumption were significantly less in the Dexem group (p<0.001). The incidence of post-thoracotomy pain syndrome was comparable between the 2 groups (69.23% v 50%, p = 0.496). CONCLUSIONS: Paravertebral dexmedetomidine administration resulted in decreased intraoperative anesthetic drug requirement, less pain, and lower requirements of supplemental opioid in the postoperative period. However, it had no effect on the incidence of post-thoracotomy pain syndrome.

Utility of Sonoclot in Prediction of Postoperative Bleeding in Pediatric Patients Undergoing Cardiac Surgery for Congenital Cyanotic Heart Disease: A Prospective Observational Study.

OBJECTIVES: To assess the utility of Sonoclot in prediction of postoperative bleeding in pediatric patients undergoing cardiac surgery with cardiopulmonary bypass for congenital cyanotic heart disease. DESIGN: Prospective, observational study. SETTING: Single university hospital. PARTICIPANTS: Eighty-seven pediatric patients undergoing cardiac surgery for congenital cyanotic heart disease. INTERVENTIONS: Laboratory coagulation parameters (prothrombin time, international normalization ratio, activated partial thromboplastin time, fibrinogen, D-dimer) as well as point-of-care Sonoclot glass bead activation time, clot rate, and platelet function (gbPF) were done before induction of anesthesia and following heparin reversal after termination of cardiopulmonary bypass (CPB) in all patients. MEASUREMENTS AND MAIN RESULTS: Postoperative blood loss was monitored by the amount of chest tube drainage. The primary outcome was to define Sonoclot parameters for prediction of postoperative bleeding. Secondary outcomes studied were amount of postoperative blood loss, transfusion requirement of various blood products, incidence of surgical re-exploration, duration of postoperative mechanical ventilation, intensive care unit and hospital stay. Among studied subjects, 37.9% (33 of 87 patients) were designated as bleeders while 62.1% (54 of 87 patients) were non-bleeders. Lower age, D-dimer, and gbPF test after termination of CPB following heparin neutralization were predictive for postoperative bleeders. Among these, post-protamine gbPF had the highest area under the curve (0.725), 95% confidence interval (0.619-0.831) for prediction of postoperative bleeders. Duration of mechanical ventilation (26.41±36.44 v 8.25±6.36 h, respectively, p = 0.001), intensive care unit stay (7.36 ± 4.05 v 4.96 ± 2.49, p = 0.001), and hospital stay (11.69±4.82 v 8.63±3.48 p = 0.001) were higher in bleeders; however, incidence of re-exploration was comparable between both groups. CONCLUSION: Postoperative bleeders may be predicted independently by post-CPB gbPF, postoperative D-dimer, and lower age of patients. Among these, post-CPB gbPF has maximum predictive value.

Utility of transesophageal echocardiography in identifying spinal canal structures and epidural catheter position: a prospective observational study of intraoperative hemodynamics and postoperative analgesia.

PURPOSE: The aims of this study were to determine the utility of transesophageal echocardiography (TEE) for identifying spinal canal structures and epidural catheter position and to assess the effect of catheter position on intraoperative hemodynamics and quality of postoperative analgesia. METHODS: Twenty-six adult patients undergoing thoracic surgery were included in this prospective, observational study. An epidural catheter was inserted 7.5 cm or more into the thoracic epidural space using a midline approach and a loss-of-resistance technique. A pediatric TEE probe was inserted after induction of general anesthesia. It was used to identify the spinal canal structures, the catheter tip position in the epidural space, and the spread of injected local anesthetic. Intraoperative hemodynamics, postoperative visual analogue scale (VAS) pain scores, and the need for rescue epidural doses were recorded and compared between groups determined by their catheter position. RESULTS: Two subjects were excluded from the study because of an intrathecally positioned epidural catheter. The remaining 24 subjects were divided into two groups based on TEE-determined epidural catheter position: posterior (Gr-P) or lateral (Gr-L). Spinal canal structures and the epidural catheter was successfully identified in all patients. The epidural catheter was located posteriorly in 20 (83%) patients and laterally in four (17%) patients. The spread of the local anesthetic was bilateral in all Gr-P patients, whereas it was unilateral in all but one of the Gr-L patients. Compared to Gr-P patients, Gr-L patients had higher heart rates and blood pressures at various time points after local anesthetic administration until the end of surgery (P = 0.02 to < 0.001). Postoperative VAS scores (P = 0.02) and the median number of rescue analgesic doses required during the intraoperative and postoperative periods were also higher in Gr-L patients (P < 0.001). CONCLUSION: Transesophageal echocardiography reliably identified spinal canal structures and the position of epidural catheters in the epidural space in adult patients. Posteriorly located epidural catheters appear to provide better epidural analgesia than laterally situated catheters.

Comparative Effect of Levosimendan and Milrinone in Cardiac Surgery Patients With Pulmonary Hypertension and Left Ventricular Dysfunction.

OBJECTIVE: To compare the effects of levosimendan with milrinone in cardiac surgical patients with pulmonary hypertension and left ventricular dysfunction. DESIGN: A prospective, randomized study. SETTING: Tertiary care teaching hospital. PARTICIPANTS: The study included patients with valvular heart disease and pulmonary artery hypertension undergoing valve surgery. INTERVENTIONS: Forty patients were allocated randomly to receive either milrinone, 50 µg/kg bolus followed by infusion at a rate of 0.5 µg/kg/min (group 1), or levosimendan, 10 µg/kg bolus followed by infusion at a rate of 0.1 µg/kg/min (group 2) for 24 hours after surgery. MEASUREMENTS AND MAIN RESULTS: Hemodynamic parameters were measured using a pulmonary artery catheter, and biventricular functions were assessed using echocardiography. Mean pulmonary artery pressures and the pulmonary vascular resistance index were comparable between the 2 groups at several time points in the intensive care unit. Biventricular function was comparable between both groups. Postcardiopulmonary bypass right ventricular systolic and diastolic functions decreased in both groups compared with baseline, whereas 6 hours postbypass left ventricular ejection fraction improved in patients with stenotic valvular lesions. Levosimendan use was associated with higher heart rate, increased cardiac index, decreased systemic vascular resistance index, and increased requirement of norepinephrine infusion compared with milrinone. CONCLUSIONS: The results of this study demonstrated that levosimendan was not clinically better than milrinone. Levosimendan therapy resulted in a greater increase in heart rate, decrease in systemic vascular resistance, and a greater need for norepinephrine than in patients who received milrinone.

Comparative Effect of High-Frequency Nasal Cannula and Noninvasive Ventilation on the Work of Breathing and Postoperative Pulmonary Complication after Pediatric Congenital Cardiac Surgery: A Prospective Randomized Controlled Trial.

BACKGROUND: Various forms of commonly used noninvasive respiratory support strategies have considerable effect on diaphragmatic contractile function which can be evaluated using sonographic diaphragm activity parameters. OBJECTIVE: To compare the magnitude of respiratory workload decreased as assessed by thickening fraction of the diaphragm and longitudinal diaphragmatic strain while using high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) modes [nasal intermittent positive pressure ventilation (NIPPV) and bilevel positive airway pressure (BiPAP)] in pediatric patients after cardiothoracic surgery. METHODOLOGY: This prospective randomized controlled trial was performed at a tertiary care surgical intensive care unit in postcardiac surgery patients aged between 1 and 48 months, who were randomly allocated into three groups: 1) HFNC (with flows at 2 L/kg/min), 2) NIPPV via RAMS cannula in PSV mode (pressure support 8 cmH2O, PEEP 5 cmH2O), and 3) BiPAP in nCPAP mode (CPAP of 5 cmH2O). Measurements were recorded at baseline after extubation (R0) and subsequently every 12 hourly (R1, R2, R3, R4, R5) at 12, 24, 36, 48, and 60 hours respectively until therapy was discontinued. RESULTS: Sixty patients were included, with 20 patients each in the NIPPV group, HFNC group, and BiPAP group. Longitudinal strain at crura of diaphragm was lower in the BiPAP group as compared to HFNC group at R2-R4 [R2 (-4.27± -2.73 vs - 8.40± -6.40, P = 0.031), R3 (-5.32± -2.28 vs -8.44± -5.6, P = 0.015), and R4 (-3.8± -3.42 vs -12.4± -7.12, P = 0.040)]. PFR was higher in HFNC than NIPPV group at baseline and R1-R3[R0 (323 ± 114 vs 264 ± 80, P = 0.008), R1 (311 ± 114 vs 233 ± 66, P = 0.022), R2 (328 ± 116 vs 237 ± 4, P = 0.002), R3 (346 ± 112 vs 238 ± 54, P = 0.001)]. DTF and clinical parameters of increased work of breathing remain comparable between three groups. The rate of reintubation (within 48 hours of extubation or at ICU discharge) was 0.06% (1 in NIPPV, 1 in BiPAP, 2 in HFNC) and remain comparable between groups (P = 1.0). CONCLUSION: BiPAP may provide better decrease in work of breathing compared to HFNC as reflected by lower crural diaphragmatic strain pattern. HFNC may provide better oxygenation compared to NIPPV group, as reflected by higher PFR ratio. Failure rate and safety profile are similar among different methods used.