Kathirvel Subramaniam

Ketamine as Adjuvant Analgesic to Opioids: A Quantitative and Qualitative Systematic Review

Animal studies on ketamine and opioid tolerance have shown promising results. Clinical trials have been contradictory. We performed a systematic review of randomized, double-blind clinical trials of ketamine added to opioid analgesia. Thirty-seven trials with 51 treatment arms and 2385 patients were included. Studies were divided into 5 subgroups: IV ketamine as single dose (n = 11), continuous infusion (n = 11), patient-controlled analgesia (PCA) (n = 6), epidural ketamine with opioids (n = 8), and studies in children (n = 4). Outcome measures included pain scores, time to first request for analgesia, supplemental analgesics, and adverse events. Efficacy was estimated by statistical significance (P <0.05) of outcome measures as reported in studies and also by calculation of weighted mean difference for pain scores during the first 24 h after surgery. As compared to morphine alone, IV PCA with ketamine and morphine did not improve analgesia. Intravenous infusion of ketamine decreased IV and epidural opioid requirements in 6 of 11 studies. A single bolus dose of ketamine decreased opioid requirements in 7 of 11 studies. Five of 8 trials with epidural ketamine showed beneficial effects. Adverse effects were not increased with small dose ketamine. We conclude that small dose ketamine is a safe and useful adjuvant to standard practice opioid-analgesia.

Perioperative Risk and Management in Patients With Pulmonary Hypertension

Pulmonary hypertension (PH) is a known risk factor for perioperative complications. Unlike in the case of cardiac surgery, PH is currently not listed as an independent risk factor for postoperative complications in guidelines for the management of noncardiac surgery. Despite the paucity of data, though, patients with PH are often counseled against having elective procedures because early and sudden postoperative deaths have been reported. Patients with PH are unable to accommodate alterations in right ventricular (RV) preload or afterload induced by fluid shifts, medications, or changes in the autonomic nervous system precipitated by hypoxia or hypercapnia. These factors become magnified in situations of added stress such as surgical intervention. Systemic hypotension and arrhythmias may precipitate RV ischemia, further worsening RV function. Patient and surgical characteristics and choice of anesthetic technique are crucial factors in perioperative management. The two main principles of perioperative management are the prevention of systemic hypotension (risk of RV ischemia) and the prevention of acute elevations in pulmonary arterial pressure (risk of RV failure). Close monitoring, optimization of systemic BP, pain control, oxygenation and ventilation, avoidance of exacerbating factors, and use of vasopressors and pulmonary vasodilators as necessary are essential elements of management. Understanding the pathophysiology, cause, and severity of PH in the individual perioperative patient allows accurate risk assessment, optimization of PH and RV function prior to surgery, and appropriate intraoperative and postoperative management.

Management of Pulmonary Hypertension in the Operating Room

Pulmonary artery hypertension is defined as persistent elevation of mean pulmonary artery pressure > 25 mm Hg with pulmonary capillary wedge pressure < 15 mm Hg or elevation of exercise mean pulmonary artery pressure > 35 mm Hg. Although mild pulmonary hypertension rarely impacts anesthetic management, severe pulmonary hypertension and exacerbation of moderate hypertension can lead to acute right ventricular failure and cardiogenic shock. Knowledge of anesthetic drug effects on the pulmonary circulation is essential for anesthesiologists. Intraoperative management should include prevention of exacerbating factors such as hypoxemia, hypercarbia, acidosis, hypothermia, hypervolemia, and increased intrathoracic pressure; monitoring and optimizing right ventricular function; and treatment with selective pulmonary vasodilators. Recent advances in pharmacology provide anesthesiologists with a wide variety of options for selective pulmonary vasodilatation. Pulmonary hypertension is a major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement.

Preoperative Epidural Ketamine in Combination with Morphine Does Not Have a Clinically Relevant Intra- and Postoperative Opioid-Sparing Effect

In this prospective, randomized, and double-blinded clinical trial, we evaluated the efficacy of preincisional administration of epidural ketamine with morphine compared with epidural morphine alone for postoperative pain relief after major upper-abdominal surgery. We studied 50 ASA I and II patients undergoing major upper-abdominal procedures. These patients were randomly allocated to one of the two treatment groups: patients in Group 1 received epidural morphine 50 &mgr;g/kg, whereas those in Group 2 received epidural ketamine 1 mg/kg combined with 50 &mgr;g/kg of morphine 30 min before incision. Intraoperative analgesia was provided in addition, with IV morphine, and the requirement was noted. A blinded observer using a visual analog scale for pain assessment observed patients for 48 h after surgery. Additional doses of epidural morphine were provided when the visual analog scale score was more than 4. Analgesic requirements and side effects were compared between the two groups. There were no differences between the two groups with respect to age, sex, weight, or duration or type of the surgical procedures. The intraoperative morphine requirement was significantly (P = 0.018) less in Group 2 patients (median, 6.8 mg; range, 3–15 mg) compared with patients in Group 1 (median, 8.3 mg; range, 4.5–15 mg). The time for the first requirement of analgesia was significantly (P = 0.021) longer (median, 17 h; range, 10–48 h) in Group 2 patients than in Group 1 (median, 12 h; range, 4–36 h). The total number of supplemental doses of epidural morphine required in the first 48 h after surgery was comparable (P = 0.1977) in both groups. Sedation scores were similar in both groups. One patient in Group 2 developed hallucinations after study drug administration. None of the patients in either group developed respiratory depression. Other side effects, such as pruritus, nausea, and vomiting, were also similar in both groups. Although the addition of ketamine had synergistic analgesic effects with morphine (reduced intraoperative morphine consumption and prolonged time for first requirement of analgesia), there was no long- lasting preemptive benefit seen with this combination (in terms of reduction in supplemental analgesia) for patients undergoing major upper-abdominal procedures.

Evaluation of the safety and efficacy of epidural ketamine combined with morphine for postoperative analgesia after major upper abdominal surgery

STUDY OBJECTIVE To evaluate the efficacy of the combination of epidural ketamine and morphine compared with epidural morphine alone for postoperative pain relief following major upper abdominal surgery. STUDY DESIGN Prospective, randomized, double-blinded study. SETTING Tertiary care referral and teaching hospital. PATIENTS 46 ASA physical status I and II patients who underwent major upper abdominal procedures. INTERVENTIONS Patients were randomly allocated to one of the two treatment groups: patients in Group 1 received epidural morphine 50 microg/kg whereas patients in Group 2 received epidural ketamine 1 mg/kg combined with 50 microg/kg of morphine postoperatively. MEASUREMENTS A blinded observer using a visual analog scale (VAS) for pain assessment followed up patients for 48 hours postoperatively. Top-up dose of epidural morphine was provided when VAS was higher than 4. Analgesic requirements and side effects were compared between the two groups. RESULTS Only 40 patients completed the study. There were no differences between the two groups with respect to age, gender, weight, duration, or type of surgical procedure or intraoperative opioid requirements. Onset of analgesia was faster (p < 0.001) in Group 2 (11 min) than in Group 1 patients (25 min). The time for first requirement of analgesia was significantly (p < 0.01) longer (19.8 +/- 9.8 hours) in Group 2 patients than Group 1 (12.8 +/- 6.2 hours). Total number of supplemental doses of epidural morphine required in the first 48 hours postoperatively was also significantly less (p < 0.005) in Group 2 compared to Group 1. Patients in Group 2 had higher sedation scores than Group I patients for the first 2 hours postoperatively. None of the patients in either group developed hallucinations or respiratory depression. Other side effects such as pruritus, nausea, and vomiting were also similar in both groups. CONCLUSIONS The addition of epidural ketamine 1 mg/kg to morphine 50 microg/kg improved analgesia after major upper abdominal surgery without increasing side effects.

Extracorporeal membrane oxygenation support in acute coronary syndromes complicated by cardiogenic shock

Acute coronary syndrome (ACS) complicated by shock is associated with high mortality despite the use of percutaneous support devices. Extracorporeal membrane oxygenation (ECMO) offers cardiopulmonary support but its safety and efficacy in the ACS setting is still under investigation.

Pathophysiology of Cardiopulmonary Bypass: Current Strategies for the Prevention and Treatment of Anemia, Coagulopathy, and Organ Dysfunction.

The techniques and equipment of cardiopulmonary bypass (CPB) have evolved over the past 60 years, and numerous numbers of cardiac surgical procedures are conducted around the world using CPB. Despite more widespread applications of percutaneous coronary and valvular interventions, the need for cardiac surgery using CPB remains the standard approach for certain cardiac pathologies because some patients are ineligible for percutaneous procedures, or such procedures are unsuccessful in some. The ageing patient population for cardiac surgery poses a number of clinical challenges, including anemia, decreased cardiopulmonary reserve, chronic antithrombotic therapy, neurocognitive dysfunction, and renal insufficiency. The use of CPB is associated with inductions of systemic inflammatory responses involving both cellular and humoral interactions. Inflammatory pathways are complex and redundant, and thus, the reactions can be profoundly amplified to produce a multiorgan dysfunction that can manifest as capillary leak syndrome, coagulopathy, respiratory failure, myocardial dysfunction, renal insufficiency, and neurocognitive decline. In this review, pathophysiological aspects of CPB are considered from a practical point of view, and preventive strategies for hemodilutional anemia, coagulopathy, inflammation, metabolic derangement, and neurocognitive and renal dysfunction are discussed.

Intra‐ and Postoperative Very Low Dose Intravenous Ketamine Infusion Does Not Increase Pain Relief after Major Spine Surgery in Patients with Preoperative Narcotic Analgesic Intake

OBJECTIVE This study aims to demonstrate the analgesic efficacy and opioid-sparing effect of low dose ketamine in patients with preoperative narcotic intake undergoing major spine surgery. DESIGN The study used a prospective, randomized, double-blinded, and placebo-controlled clinical trial. SETTINGS AND PATIENTS We evaluated the analgesic efficacy and safety of low dose IV ketamine infusion after major spine surgery in patients with preoperative narcotic analgesic intake. Ketamine group received IV ketamine infusion (2 µg/kg/min) and saline group received saline intraoperatively and the first 24 hours postoperatively. In addition, all patients received IV patient-controlled hydromorphone and epidural bupivacaine. OUTCOME MEASURES Pain scores, narcotic requirement, and side effects were compared between the groups for 48 hours postoperatively. RESULTS Thirty patients completed the study (N = 15 in each group). No difference in pain scores at rest and movement was noted between the groups (P > 0.05). Patients in ketamine group received 40.42 ± 32.86 mg IV hydromorphone at 48 hours compared with 38.24 ± 26.19 mg in saline group (P = 0.84). Central nervous system side effects were observed in five (33%) ketamine group patients compared with nine (60%) in saline group (P = 0.29). CONCLUSION The addition of IV very low dose ketamine infusion regimen did not improve postoperative analgesia. Side effects were not increased with low dose ketamine.

Left Atrial Wall Hematoma/Dissection After Mitral Valve Replacement

A 63-year-old woman with a significant history of rheumatic mitral stenosis/regurgitation, tricuspid regurgitation, atrial fibrillation, and giant left atrium (LA; 90 mm in diameter) underwent mitral valve replacement with a mechanical valve, tricuspid annuloplasty, and LA appendage closure. The mitral valve was approached by a conventional left atriotomy from the right side of the LA. The postoperative course was uneventful initially, and the patient was extubated on postoperative day 1. On postoperative day 2, however, acute hemodynamic deterioration occurred that required reintubation and a high dose of inotropes. Transthoracic echocardiography showed a large mass in the LA that occupied almost the entire LA cavity (Figure …

Severe Functional Mitral Regurgitation Arising From Isolated Annular Dilatation

Functional mitral regurgitation or functional tricuspid regurgitation most commonly result from maladaptive remodeling due to ischemic heart disease or idiopathic dilatative cardiomyopathy. We report a case of significant functional mitral regurgitation and functional tricuspid regurgitation arising from isolated annular dilatation secondary to atrial fibrillation and associated atrial remodeling. The patient underwent successful mitral and tricuspid valve repair and a bi-atrial Maze procedure.