Targeted Temperature Management for Treatment of Cardiac Arrest.

PURPOSE OF REVIEW: Cardiac arrest is a common condition associated with high mortality and a substantial risk of neurological injury among survivors. Targeted temperature management (TTM) is the only strategy shown to reduce the risk of neurologic disability cardiac arrest patients. In this article, we provide a comprehensive review of TTM with an emphasis on recent trials. RECENT FINDINGS: After early studies demonstrating the benefit of TTM in out-of-hospital cardiac arrest due to a shockable rhythm, newer studies have extended the benefit of TTM to patients with a nonshockable rhythm and in-hospital cardiac arrest. A target temperature of 33 °C was not superior to 36 °C, suggesting that a lenient targeted temperature may be appropriate especially for patients unable to tolerate lower temperatures. Although early initiation of TTM appears to be beneficial, the benefit of prehospital cooling has not been shown and use of intravenous cold saline in the prehospital setting may be harmful. SUMMARY: There is substantial risk of neurological injury in cardiac arrest survivors who remain comatose. TTM is an effective treatment that can lower the risk of neurological disability in such patients and ideally delivered as part of a comprehensive, goal-directed post-resuscitation management by a multidisciplinary team in a tertiary medical center.

Plaque regression and improved clinical outcomes following statin treatment in atherosclerosis.

3-hydroxy-3-methylglutaryl-coenzymeA reductase inhibitors, or statins, represent an important class of agents that improve clinical outcomes in atherosclerotic cardiovascular disease. Aside from lowering total and low density lipoprotein cholesterol, statins have important pleiotropic effects that include anti-inflammatory, antioxidant, antithrombotic actions as well as mobilization of endothelial progenitor cells and modification of plaque cholesterol crystallization. These combined effects lead to atherosclerotic plaque stabilization that is both quantitative (slowing of plaque progression or plaque volume regression) as well as qualitative (reduced inflammation and amount of lipid rich necrotic plaque) in nature. Statins have been shown to reduce overall mortality when used for either primary or secondary prevention of cardiovascular disease in multiple randomized clinical trials, but such trials involve a large sample size, long treatment duration and enormous financial cost. Imaging of change in plaque burden by various means such as coronary angiography, intravascular and B mode ultrasound and magnetic resonance imaging represents a means of measuring surrogate endpoints by directly assessing statin effects on plaque regression. Multiple imaging studies have demonstrated plaque stabilization or regression with statin treatment that paralleled improvement in lipid profile and clinical outcomes, although it is unlikely that imaging modalities can replace hard clinical outcomes in assessing treatment efficacy.

Total intravenous anesthesia with ketamine for pediatric interventional cardiac procedures.

OBJECTIVE: To evaluate the safety and efficacy of ketamine in pediatric patients undergoing interventional cardiac procedures. DESIGN: A retrospective clinical study. SETTING: A single, tertiary referral center. PARTICIPANTS: Patients (n = 107) undergoing interventional cardiac procedures between July 1996 and July 1998. INTERVENTIONS: Each patient received a bolus of ketamine, 1 mg/kg intravenously, followed by an infusion of 50 to 75 microg/kg/min for the duration of the procedure. MEASUREMENTS AND MAIN RESULTS: Hemodynamic and respiratory parameters were noted. All patients were breathing spontaneously. Average infusion dose of ketamine was 51.40+/-3.54 microg/kg/min (mean +/- standard deviation). Increases in heart rate and mean arterial pressure by more than 20% from baseline values were seen in 10 and 9 patients, respectively. Transient apnea and excessive salivation were seen in two patients each. Excessive movement of extremities was seen in six patients. There were no episodes of unpleasant dreams or hallucinations. There were two deaths (1.9%) related to the interventional procedures. CONCLUSION: The technique described is a simple, safe, and effective method for anesthetizing children in the cardiac catheterization laboratory for interventional procedures.

Significant intraoperative right ventricular outflow gradients after repair for tetralogy of Fallot: to revise or not to revise?

BACKGROUND: This study was performed to define alternative parameters for the management of intraoperative residual right ventricular outflow obstruction (RVOTO) after transatrial repair of tetralogy of Fallot (ToF) in order to differentiate those requiring immediate revision from those who do not. METHODS: Since October 1995, 166 patients of ToF underwent transatrial repair. Postbypass residual RVOTO was assessed by surgeon's subjective impression, direct intracardiac pressure measurements, and intraoperative echocardiography (IOE). RVOTO was labeled "significant" whenever it exceeded a gradient of 40 mm Hg on IOE or right ventricular to left ventricular pressure ratio (pRV/LV) exceeded 0.85. Further, on IOE, significant RVOTO was defined "fixed", if there was no change in RVOT dimensions during the cardiac cycle, along with the presence of anatomic substrate for obstruction, and "dynamic" if RVOT dimensions increased appreciably in diastole. Postoperative course and follow-up echocardiograms of all patients were analyzed. RESULTS: Significant RVOTO was detected in 58 (35%) patients (mean gradient 54 mm Hg). Seven (12%) of them with fixed obstruction (mean 46 mm Hg) underwent immediate surgical revision, while the remaining 51 patients with mean gradient of 78 mm Hg (including 10 patients with pRV/LV ratio of > or = 1.0) with dynamic obstruction did not undergo revision. There were six (3.6%) early deaths. Operative mortality and postoperative morbidity were not related to higher residual gradients, although the first 15 such patients had longer intensive care stay and inotropic support, in which this was done electively. On follow-up (mean 18.5 months), outflow gradients declined sharply (mean 16 mm Hg) irrespective of the severity of intraoperative gradients (p < 0.001). There were no reoperations or late deaths. CONCLUSIONS: This study shows that: 1) existing parameters for immediate revision of residual RVOTO possibly need to be reviewed; 2) intraoperative echocardiography helps in differentiating "fixed" from "dynamic" obstruction and helps obviate needless revisions; and 3) dynamic RVOT gradients decline significantly irrespective of their severity after transatrial repair of ToF.

Comparison of intubating conditions and haemodynamic effects of rocuronium with vecuronium in patients with poor left ventricular ejection fraction undergoing coronary artery bypass graft surgery.

To compare the haemodynamic effects and intubating conditions of rocuronium and vecuronium, 20 patients of either sex with poor left ventricular function (ejection fraction <35%) scheduled for coronary artery bypass surgery were randomly divided into two equal groups. All patients were premedicated with lorazepam and morphine and induced with morphine, midazolam, thiopentone and either vecuronium (0.1 mg/kg) or rocuronium (0.6 mg/kg) as muscle relaxant. All patients were intubated after 3 minutes in the vecuronium group and 90 seconds in the rocuronium group by the same anaesthesiologist. Monitoring in all cases included neuromuscular (train of four- TOF), systemic and pulmonary arterial pressures, cardiac output and calculated haemodynamic variables. Demographic (age, sex and mean ejection fraction) and haemodynamic variables were comparable in both the groups. A significant suppression of the TOF in the vecuronium group was observed despite better intubating conditions in the rocuronium group. The heart rate at 3 minutes and mean arterial pressure at 1 minute was higher in the vecuronium group as compared to the rocuronium group. There were no other significant haemodynamic differences in both the groups. We conclude that rocuronium does provide better intubating conditions at 90 seconds than vecuronium at 3 minutes with no significant differences in the haemodynamic parameters between the two; however, the train of four response does not correlate with intubating conditions.

Sevoflurane for induction and intubation in children undergoing congenital cardiac surgery.

The induction and intubation characteristics of sevoflurane were studied prospectively in 23 children, aged 3 months to 6 years (mean 24 +/- 20.25), undergoing repair of congenital cardiac defects. After premedication with syrup chloral hydrate (75mg/kg orally), anaesthesia was induced with 8% sevoflurane and 50% nitrous oxide in oxygen. Nasal endotracheal intubation was performed once the pupils were small and central, without the use of neuromuscular blocking agents or opioids. Characteristics of induction and intubating conditions were recorded. Induction time (from application of face mask to loss of eyelash reflex) was 43.7 +/- 4.57 secs (mean +/- SD). Mean intubation time was 149.1 +/- 15.6 secs. Intubating conditions were excellent in 21 patients (91.3%) and good in 2 patients (80.7%). Haemodynamic parameters (heart rate, rhythm, and systolic blood pressure) were recorded at loss of eyelash reflex, immediately before intubation and at 1, 3 and 5 min after intubation. All children remained haemodynamically stable throughout induction and there were no adverse airway events.

Intraoperative echocardiography as a routine adjunct in assessing repair of congenital heart defects: experience with 300 cases.

Utility of intraoperative echocardiography (IOE) in perioperative management of congenital heart disease has been reported in literature. However, its consistent use as a monitoring tool has not yet been reported from our country. The aim of this study was to evaluate the role of routine use of IOE for intraoperative assessment of surgical repairs in terms of residual shunt, residual gradient, valvular insufficiency and ventricular function. Three hundred consecutive patients above 3 Kg body weight were included in this study. In 152 patients epicardial and in 148 patients transoesophageal echocardiography (TEE) was performed intraoperatively. Age ranged from 4 months to 52 years (median 5.8 yrs) and body weight from 3 Kg to 62 Kg (Median 12 Kg). IOE Doppler and Doppler colour flow imaging studies were performed before cardiopulmonary bypass (CPB) whenever feasible and after CPB in all patients. Pre-bypass examination yielded additional information in 17 (5.6%) patients. In 9 (3%) such patients it had an impact on surgery. In post CPB IOE studies, surgery was found to be 'perfect' in 210 (70%) patients and 'acceptable' residual defects in 70 (23.3%) patients. In 20 (6.6%) cases post CPB IOE found surgical repair 'unacceptable'. Ten of these patients required immediate surgical revision with excellent outcome, thus saving them from late reoperation or postoperative complications. No short term complications were encountered relating to the procedure. We conclude that intraoperative echocardiography is an inexpensive, accurate, valuable and safe addition to the perioperative care of patients and should be mandatory during all corrective surgical procedures for congenital heart disease. It is especially applicable in our country where the costs of reoperation for residual defects are prohibitive.

Comparison of caudal morphine and buprenorphine for post-operative analgesia in children.

Sixty five children aged from 1-10 years who underwent herniotomy, cystolithotomy or orchidopexy received either buprenorphine 4 micrograms kg-1 (n = 33) or morphine 50 micrograms kg-1 (n = 32) by the caudal epidural route; each thus received 0.5 ml kg-1 body weight. General anaesthesia was given for surgery. Post-operative pain and behaviour were assessed by an independent observer at 1, 4, 8, 16 and 24 h post-operatively. Caudal morphine and buprenorphine were equally effective for post-operative analgesia in children, but buprenorphine was better because of its longer duration of action and lower incidence of side effects.

Caudal buprenorphine for postoperative analgesia in children: a comparison with intramuscular buprenorphine.

This study was conducted on 44 children aged 1-10 years, who had undergone lower extremity orthopaedic surgery under general anaesthesia. Patients were divided into two groups: Group 1 (n = 23) received buprenorphine caudally and Group 2 (n = 21) received buprenorphine intramuscularly, at the completion of the surgery. The dose of buprenorphine used in both the groups was 4 micrograms.kg-1 body weight. The quality and duration of postoperative analgesia were evaluated by a single observer using a 5-point score for the first 24 h postoperatively. The time until the patient required postoperative analgesic was recorded. The duration of analgesia was significantly greater with caudal buprenorphine (median 20.20 h) than with intramuscular buprenorphine (median 5.20 h). Of the patients in the caudal group, 43% did not require any supplemental analgesia during the first 24 h, whereas all the patients in the intramuscular group required supplements within 10 h postoperatively. Caudal buprenorphine (4 micrograms.kg-1 body weight) provided 10.8 h to more than 24 h of analgesia in children, with fewer side effects.

Postoperative analgesia in children who have genito-urinary surgery. A comparison between caudal buprenorphine and bupivacaine.

A study conducted on 40 children, aged 1-11 years, who had genito-urinary surgery compared the quality and duration of analgesia after caudal blocks in two groups of patients. Group 1 (n = 20) received caudal bupivacaine 0.25% and group 2 (n = 20) caudal buprenorphine 4 micrograms/kg; each received 0.5 ml/kg body weight. Patients were operated on under general anaesthesia. Postoperative behaviour and severity of pain were measured on a 3-point scale. The results indicate that caudal buprenorphine provides excellent postoperative analgesia in children comparable to caudal bupivacaine in the early postoperative period. Buprenorphine proved better in the late postoperative period. Analgesia lasted from 20 hours to more than 24 hours after caudal buprenorphine with fewer side effects.

No cutaneous histamine release with buprenorphine?

Most narcotics cause histamine release, both systemic and cutaneous. Whether buprenorphine causes histamine release is not yet known. We conducted intradermal tests on 11 healthy adults with buprenorphine in dilutions of 1:10,000, 1:1000, 1:100 and 1:10 and with 0.9% saline and histamine 10(-3) mol/l. The size of dermal reaction was noted after 15 and 30 min. None of the volunteers showed any cutaneous reaction suggestive of histamine release with buprenorphine. The absence of histamine-releasing activity of buprenorphine may be due to the structure of the drug resulting in its decreased basicity or to the insufficient concentration of the drug achieved at mast cell membrane.