Danja S. Groves

Tracheostomy in the critically ill: indications, timing and techniques.

Purpose of reviewTracheostomy is one of the most common procedures performed in the intensive care unit. Indications, risks, benefits, timing and technique of the procedure, however, remain controversial. The decision of when and how to perform a tracheostomy is often subjective, but must be individualized to the patient. The following review gives an update on recent literature related to tracheostomy in the critically ill. Recent findingsSurprisingly, few data are available on the current practice of tracheostomy in the intensive care unit setting. Very few trials address this issue in a prospective, randomized fashion (randomized controlled trial). Most reports include small numbers representing a heterogeneous population, describing contrary results and precluding any definite conclusions. Evidence seems to suggest that early tracheostomy, however, might be preferable in selected patients. SummaryDue to increased experience and advanced techniques, percutaneous tracheostomy has become a popular, relatively safe procedure in the intensive care unit. The question of appropriate timing, however, has not been definitely answered with a randomized controlled trial. Instead, a number of retrospective studies and a single prospective study have shed some light on this issue. Most reports favor the performance of tracheostomy within 10 days of respiratory failure.

Systemic lidocaine decreased the perioperative opioid analgesic requirements but failed to reduce discharge time after ambulatory surgery.

BACKGROUND: In this randomized, blinded, placebo-controlled trial, we evaluated whether systemic lidocaine would reduce pain and time to discharge in ambulatory surgery patients. METHODS: Sixty-seven patients were enrolled to receive lidocaine or saline infusion perioperatively. RESULTS: Length of postanesthesia care unit (PACU) stay did not differ between groups. Intraoperative opioid use was significantly less in the lidocaine group, both in the PACU and during the total study period but not after discharge. In the PACU, patients in the lidocaine group reported less pain (visual analog scale score 3.1 ± 2.04 vs 4.5 ± 2.9; P = 0.043). There were no differences in postoperative nausea and vomiting. CONCLUSION: Perioperative systemic lidocaine significantly reduces opioid requirements in the ambulatory setting without affecting time to discharge.

The role of methylene blue in serotonin syndrome following cardiac transplantation: a case report and review of the literature.

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Pulmonary complications of cardiopulmonary bypass

Pulmonary complications after the use of extracorporeal circulation are common, and they range from transient hypoxemia with altered gas exchange to acute respiratory distress syndrome (ARDS), with variable severity. Similar to other end-organ dysfunction after cardiac surgery with extracorporeal circulation, pulmonary complications are attributed to the inflammatory response, ischemia-reperfusion injury, and reactive oxygen species liberated as a result of cardiopulmonary bypass. Several factors common in cardiac surgery with extracorporeal circulation may worsen the risk of pulmonary complications including atelectasis, transfusion requirement, older age, heart failure, emergency surgery, and prolonged duration of bypass. There is no magic bullet to prevent or treat pulmonary complications, but supportive care with protective ventilation is important. Targets for the prevention of pulmonary complications include mechanical, surgical, and anesthetic interventions that aim to reduce the contact activation, systemic inflammatory response, leukocyte sequestration, and hemodilution associated with extracorporeal circulation.

A brief review of innovative uses for local anesthetics.

Purpose of review Local anesthetics are drugs which have many potentially beneficial actions, especially when used as a continuous intravenous infusion. The following review gives an update on the most recent literature along with some interesting and promising areas where systemic local anesthetics are being implemented. Recent findings Surprisingly little research has been conducted with the use of systemic local anesthetics when considering their cost effectiveness, good side effect profile when used in low-dose infusions, and promising results in the available literature. The in-vivo studies, ranging from case reports to randomized controlled trials, have small sample sizes, yet most have found that low-dose systemic infusions are efficacious for various conditions. Summary Local anesthetics have many beneficial properties, and promising results have been seen when low-dose infusions are implemented. This review briefly describes the anti-inflammatory properties of local anesthetics and discusses the benefits seen when used systemically for neuroprotection, postoperative ileus, decompression sickness, and glaucoma.

Local anesthetic-induced inhibition of human neutrophil priming: the influence of structure, lipophilicity, and charge.

Background and Objectives Local anesthetics (LAs) are widely known for inhibition of voltage-gated sodium channels underlying their antiarrhythmic and antinociceptive effects. However, LAs have significant immunomodulatory properties and were shown to affect human neutrophil functions independent of sodium-channel blockade. Previous studies suggest a highly selective interaction between LAs and the &agr;-subunit of G protein–coupled receptors of the Gq/G11 family as underlying mechanism. Providing a detailed structure function analysis, this study aimed to determine the active parts within the LA molecule responsible for the effects on human neutrophil priming. Methods Human neutrophils were incubated with structurally different LAs for 60 minutes, followed by priming and activation using either platelet-activating factor or lysophosphatidic acid and N-formyl-methionyl-L-leucyl-L-phenylalanine. Superoxide anion generation was determined, using the cytochrome c reduction assay. Results Differences in priming inhibition of human neutrophils between LAs were smaller than expected, although significant. Ester-linked LAs blocked priming responses more effectively than did amide LAs. Furthermore, the inhibitory potency of LAs on priming decreased with an increase of their respective octanol-buffer coefficient, and inhibition did not correlate with sodium-channel–blocking potency. Charge was not crucially required for priming inhibition, yet it played a role in effect size. Conclusions Local anesthetics significantly attenuated G&agr;q-protein–mediated neutrophil priming. The most potent inhibition was achieved by ester compounds, inversely correlated with their octanol-buffer coefficient, and enhanced by permanent charges within the LA molecule. No correlation to their potency of blocking sodium channels was found.

The effect of the intrathoracic pressure regulator on hemodynamics and cardiac output.

The intrathoracic pressure regulator (ITPR) (CirQLator; Advanced Circulatory Systems Inc, Roseville, Minn) is a novel, noninvasive device intended to increase cardiac output and blood pressure in hypovolemic or cardiogenic shock by generating a continuous low-level intrathoracic vacuum in between positive pressure ventilations. Although there are robust data supporting the benefit of the ITPR in multiple animal models of shock, the device has not been used in humans. The goals of this study were to evaluate both the safety and efficacy of the ITPR in humans. Twenty patients undergoing coronary artery bypass graft surgery were enrolled in this phase 1 study. Intraoperative use of both pulmonary artery pressure monitoring and transesophageal echocardiography (TEE) was required for study inclusion. Hemodynamic variables as well as TEE measurements of left ventricular performance were collected at baseline and after the ITPR device was activated, before surgical incision. Thermodilution cardiac output increased significantly with the application of the ITPR (4.9 vs. 5.5 L/min; P = 0.017). Similarly, cardiac output was measured by TEE (5.1 vs. 5.7 L/min; P = 0.001). There were significant increases in pulmonary artery systolic blood pressures (35 vs. 38 mmHg; P < 0.001) and mean pulmonary artery pressures (24 vs. 26 mmHg; P = 0.008). There were no significant differences in systemic blood pressures, left ventricular volumes, stroke volume, or ejection fraction as measured by TEE. Using two different measurement techniques, application of the ITPR increased cardiac output in normovolemic anesthetized patients who underwent coronary artery bypass graft before sternotomy. These data suggest that the ITPR has the potential to safely and effectively increase cardiac output in humans.

HbA1c and Diabetes Predict Perioperative Hyperglycemia and Glycemic Variability in On-Pump Coronary Artery Bypass Graft Patients

OBJECTIVE Perioperative hyperglycemia and glycemic variability are considered independent predictors of morbidity and mortality in critically ill patients. The purpose of this study was to investigate the relation of HbA1c and/or a prior diagnosis of diabetes mellitus and intra- and postoperative hyperglycemia and glycemic variability. DESIGN A retrospective data analysis from a single-center database. SETTING A single university hospital. PARTICIPANTS Diabetic and nondiabetic patients undergoing isolated on-pump coronary artery bypass graft (CABG) surgery. MEASUREMENTS One hundred twenty patients undergoing isolated CABG surgery were evaluated. Glucose values were acquired pre-, intra-, and postoperatively on the day of surgery as well as on the first postoperative day. The extent of hyperglycemia within and between groups was compared using mean and maximum glucose values. As a measure of the patients individual intra- and postoperative glucose variability, the standard deviation (SD) and the coefficient of variation (CV) of glucose values were calculated. Outcomes were analyzed using a multiple logistic regression model. RESULTS Diabetics and/or patients with elevated HbA1c had higher postoperative glucose levels, a higher SD, and a higher CV of postoperative glucose values; however, higher glucose variability was not associated with higher rates of complication. Intraoperative glucose values and variation did not differ significantly between groups. Increased mean blood glucose values were associated with increased risk of infection. CONCLUSIONS Diabetic status and/or elevated HbA1c are predictors of postoperative glucose variability and hyperglycemia in CABG surgery patients. However, in the intraoperative period, these groups show similar glycemic responses to operative stress.

Local anesthetic effects on human neutrophil priming and activation.

Background: The anti-inflammatory effects of local anesthetics (LAs) are well documented. Local anesthetics in micromolar concentrations inhibit extracellular oxygen release in isolated neutrophils; the underlying mechanism seems to be an inhibition of leukocyte priming. It remains unclear, however, if first, these effects also can be observed in whole blood, and second, if the priming of other neutrophil functions is similarly attenuated by LAs. Furthermore, the effects of LAs on intracellular generation of oxidative species remain to be investigated. Methods: Whole-blood samples from healthy volunteers were incubated for 0, 1, or 3 hrs with different concentrations (10−7 to 10−4 M) of either lidocaine, ropivacaine, QX314, or NaCl 0.9% as control. Dihydroethidium was added to quantify oxidative burst. Samples were primed with platelet-activating factor (PAF, 10−5 M) and/or activated with formyl-methyl-leucyl-phenylalanine (10−5 M) for 15 mins each. After staining for CD11b and lysis of erythrocytes, samples were analyzed by flow cytometry. Results: Priming of leukocytes is a relevant mechanism in whole blood. Platelet-activating factor stimulates the priming of oxidative burst and CD11b expression. Lidocaine up to millimolar concentrations did not affect the PAF priming and formyl-methyl-leucyl-phenylalanine activation of oxidative burst. The priming of CD11b expression and the priming and activation of changes in cell morphology were significantly attenuated by lidocaine. Conclusions: The intracellular generation of reactive oxygen species remains largely unaffected by LAs in clinical concentrations. This suggests that the anti-inflammatory effects of LAs do not interfere with the host defense.

Systemic lidocaine decreases the Bispectral Index in the presence of midazolam, but not its absence ☆ ☆☆ ★

STUDY OBJECTIVE To evaluate the effects of intravenous (IV) lidocaine on the Bispectral Index (BIS) in the presence or absence of midazolam. DESIGN Prospective, randomized, double-blinded, placebo-controlled clinical study. SETTING Operating room of a university hospital. PATIENTS 96 ASA physical status 1, 2, and 3 patients undergoing general anesthesia. INTERVENTIONS Patients were assigned to one of 6 treatment groups to receive IV midazolam (0.03 mg/kg) or placebo, followed 5 minutes later by one of three IV preinduction doses of lidocaine: 0.5, 1.0, or 1.5 mg/kg. MEASUREMENTS BIS values were recorded before administration of lidocaine and at 30-second intervals afterwards for three minutes. The primary endpoint was the average BIS level recorded. MAIN RESULTS Baseline BIS values were lower in the midazolam group (94 ± 4 vs. 90 ± 7, P < 0.001). There was no significant decrease in BIS values in the placebo group for any of the three lidocaine doses. However, in the midazolam groups, significant decreases in BIS levels versus baseline values were measured. CONCLUSION IV lidocaine decreases BIS in the presence of midazolam, suggesting that the effect of lidocaine on BIS is not direct, but rather results from modulation by midazolam.