Yaacov Gozal

Use of ultrasound guidance in the insertion of radial artery catheters.

ObjectiveTo assess the role of a portable ultrasound device in the insertion of radial artery catheters. DesignProspective, randomized, comparative study. SettingTertiary university hospital. PatientsElective surgery patients requiring arterial catheter insertion for intraoperative monitoring. InterventionsA portable ultrasound device was used to visualize the radial artery at the wrist and to direct arterial catheter insertion. This new technique of arterial catheter insertion was compared with the classic palpation technique. Measurements and Main ResultsA total of 69 patients requiring an arterial catheter were randomized to either the ultrasound (34 patients) or palpation technique (35 patients). The time taken from skin puncture to successful arterial catheter insertion, the time taken per insertion attempt, the number of attempts required, and the number of cannulae used were recorded for each group. The arterial cannula was inserted on the first attempt in 21 (62%) cases using ultrasound vs. 12 (34%) cases by palpation (p = .03). Significantly fewer attempts were required for catheter insertion using ultrasound as compared with palpation (mean ± sd, 1.6 ± 1.0 vs. 3.1 ± 2.4;p = .003); however, the time taken for each successful attempt was longer (26.1 ± 2.0 vs. 17.3 ± 1.6 secs, p = .001). A trend toward shorter overall time required for catheter insertion was found for the ultrasound group (55.5 ± 63.8 vs. 111.5 ± 121.5 secs, p = .17). There were four failures in the ultrasound group and one in the palpation group (not significant). ConclusionsUltrasound is a useful adjunct to arterial catheter insertion and increases the rate of success at first attempt. The technique is easy to learn and may reduce the time taken to insert the catheter.

Hyperglycemia inhibits anesthetic-induced postconditioning in the rabbit heart via modulation of phosphatidylinositol-3-kinase/Akt and endothelial nitric oxide synthase signaling.

Hyperglycemia is known to inhibit ischemic and anesthetic preconditioning. We tested whether hyperglycemia inhibits anesthetic postconditioning with isoflurane and whether this effect is mediated via phosphatidylinositol-3-kinase/Akt and nitric oxide signaling. New Zealand white rabbits subjected to 40 minutes of myocardial ischemia, followed by 3 hours of reperfusion were assigned to the following groups: ischemia and reperfusion (I/R), isoflurane (1 minimal alveolar concentration) postconditioning, and isoflurane postconditioning with hyperglycemia (15% dextrose in water infusion). A control group of hyperglycemia + I/R was also included. Levels of MB fraction of creatine kinase (CK-MB) were assessed as an indicator of myocardial damage, and infarct size was evaluated. Akt, iNOS, and endothelial nitric oxide synthase (eNOS) expression was assessed by immunoblotting. Determination of nitrite and nitrate levels in the myocardium was also performed. Isoflurane postconditioning reduced infarct size compared with the I/R group: 25% ± 4% versus 49% ± 5% (P < 0.01). CK-MB concentrations in the postconditioned animals (124% ± 14% above baseline levels) were lower than those in the I/R group (236% ± 9% above baseline levels; P < 0.01). Hyperglycemia inhibited the cardioprotective effect of isoflurane: myocardial infarction size was 46% ± 4% and CK-MB increased to 241% ± 11% above baseline. Phosphorylated Akt and eNOS protein expression increased after isoflurane postconditioning compared with the I/R group. These effects were also inhibited by hyperglycemia. iNOS expression, however, did not change significantly within the various experimental groups. There were increased tissue levels of nitrite and nitrate (NOx) in the postconditioning group. This was also blocked by hyperglycemia. Our results suggest that hyperglycemia inhibits cardioprotection provided by isoflurane postconditioning. This effect seems to be mediated via modulation Akt and eNOS.

Appearance of white urine during propofol anesthesia.

Reference 6 addresses rotating the needle using postmortem dura mater that was “clamped so as to be flat but not stretched” prior to contact with the needle. The dura in this investigation is grossly dissimilar to the dura in the epidural space as seen in a clinical practice. In the epiduroscopy investigations (ref. 7, 14 autopsy subjects, and ref. 8, 10 patients), the Tuohy needle was not rotated. In the 10 patients the following resulted: 1) “A complete examination was possible in eight subjects.” 2) “In 2 of the 10 subjects a moderate bleeding impaired the view and made complete examination impossible.” 3) “Smaller bleeding occurred in three other subjects.” To hopefully prove that rotating a needle in the epidural is dangerous, Bromage appears to be “hanging his hat” on epiduroscopy. However, knowing the results in patients, is not conducting a prospective major clinical epiduroscopy investigation with statistical significant data minuscule? Would anesthesiologists volunteer for such an investigation or submit their patients to one simply to determine the outcome of rotating a needle in the epidural space? “What you don’t want done to yourself, do not do unto others” (Confucianism-Sixth Century B.C.). This is perhaps the oldest ethical proposition of mankind. To conclude, Bromage’s letter is resplendently cloaked with terms such as 1) “would seem to be true,” 2) “potential,” 3) “brings us very close,” 4) “perhaps,” 5) “may,” and 6) “it comes as close as one can get.” These reveal his letter to be speculation. Therefore, my statement about rotation of a needle in the epidural space, namely “All of us are theorizing,” (3) is still valid! Neither this response, the letter by Bromage, nor the letters of others (4,5) will alter an anesthesiologist’s technique of performing an epidural block. With or without rotating a needle in the epidural space, its bevel will occasionally enter a blood vessel, the subdural space, or the subarachnoid space, and the therapeutic dose of local anesthetic will be injected. Of greatest importance if these occur is that the anesthesiologist immediately recognizes the problem, treats it promptly and correctly, and thereby avoids a catastrophic sequela.

Ischemic preconditioning decreases the reperfusion-related formation of hydroxyl radicals in a rabbit model of regional myocardial ischemia and reperfusion: The role of KATP channels

The objective of this study was to assess the effects of ischemic preconditioning (IP) on hydroxyl free radical production in an in vivo rabbit model of regional ischemia and reperfusion. Another goal was to determine whether KATP channels are involved in these effects. The hearts of anesthetized and mechanically ventilated New Zealand White rabbits were exposed through a left thoracotomy. After IV salicylate (100u2009mg/kg) administration, all animals underwent a 30-min stabilization period followed by 40u2009min of regional ischemia and 2u2009h of reperfusion. In the IP group, IP was elicited by 5u2009min of ischemia followed by 10u2009min of reperfusion (prior to the 40-min ischemia period). Glibenclamide, a KATP channel blocker, was administered prior to the preconditioning stimulus. Infarct size was measured by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. We quantified the hydroxyl-mediated conversion of salicylate to its 2,3 and 2,5-dihydroxybenzoate derivatives during reperfusion by high performance liquid chromatography coupled with electro-chemical detection. IP was evidenced by reduced infarct size compared to control animals: 22% vs. 58%, respectively. Glibenclamide inhibited this cardioprotective effect and infarct size was 53%. IP limited the increase in 2,3 and 2,5-dihydroxybenzoic acid to 24.3 and 23.8% above baseline, respectively. Glibenclamide abrogated this effect and the increase in 2,3 and 2,5-dihydroxybenzoic acid was 94.3 and 85% above baseline levels, respectively, similar to the increase in the control group. We demonstrated that IP decreased the formation of hydroxyl radicals during reperfusion. The fact that glibenclamide inhibited this effect, indicates that KATP channels play a key role in this cardioprotective effect of IP.

Epidural clonidine, bupivacaine and methadone as the sole analgesic agent after thoracotomy for lung resection*

Thoracic epidural analgesia can effectively relieve post‐thoracotomy pain but may also adversely affect pulmonary function. This randomised, prospective study compared the effects on pulmonary function of three different epidural analgesics (clonidine, bupivacaine and methadone). Forty‐seven patients undergoing thoracotomy were treated postoperatively for 72 h with one of the study drugs. Doses were titrated to maintain visual analogue pain scale values below 4 out of 10. Throughout the postoperative period, reductions of up to 70% of the pre‐operative value were observed in forced expiratory volume in 1u2003s, forced vital capacity and peak expiratory flow rate. Patients who received clonidine showed significantly faster recovery rates of forced expiratory variables compared to other patients, and by the third postoperative day significantly higher spirometry values (10–15%) were recorded in this group. As clonidine was the most effective drug in terms of preservation of pre‐operative lung function, it may be clinically advantageous in post‐thoracotomy patients.

Myocardial Metabolism Altered by Ischemic Preconditioning and Enflurane in Off-Pump Coronary Artery Surgery

OBJECTIVEnDuring off-pump coronary artery bypass (OPCAB) surgery, the heart is subjected to ischemia and reperfusion. The authors hypothesized that the volatile anesthetics are as effective as ischemic preconditioning (IPC) in preserving myocardial function during off-pump cardiac surgery, and this effect is because of multiple mechanisms of action. Therefore, the effects of enflurane with its calcium inhibition and antioxidative properties were compared with mechanical IPC in preserving myocardial cellular markers.nnnDESIGNnA prospective, randomized, controlled, and partly blinded study.nnnSETTINGnA tertiary care university hospital.nnnPARTICIPANTSnTwenty-five patients undergoing elective single-graft OPCAB surgery.nnnINTERVENTIONSnPatients were randomized into 3 groups: (1) control (n = 8), (2) a single 5-minute ischemia/reperfusion interval of IPC before coronary occlusion (n = 9), and (3) 1.6% enflurane anesthesia 15 minutes before and during graft attachment (n = 8). Arterial and coronary sinus venous blood were analyzed for biochemical indices of ischemia and hydroxyl radical generation.nnnMEASUREMENTS AND MAIN RESULTSnAlthough the hemodynamic changes were small, myocardial lactate production in the control group increased by 120%, whereas in the enflurane group it decreased significantly (p < 0.01) compared with the control and IPC groups. Oxygen utilization in the control group was 44% higher (p < 0.03), and there was also a larger release of the hydroxyl radical-dependent adduct 2,3-dihydroxybenzoic acid (225% increase, p < 0.05) compared with both study groups. During reperfusion, initial anterior wall hypokinesis by TEE was observed, with slow recovery during reperfusion compared with early recovery in both study groups.nnnCONCLUSIONSnCoronary occlusion during OPCAB surgery results in increased production of ischemia-related metabolic products. The application of methods such as IPC or volatile anesthesia appears to reduce the metabolic deficit, free-radical production, and physiologic changes.

Anesthesiologists' ability in calculating weight-based concentrations for pediatric drug infusions: an observational study.

STUDY OBJECTIVESnTo assess the ability of anesthesiologists to calculate weight-specific drug concentrations for continuous drug administration in children, and to evaluate the acceptance of an inhouse-developed, computer-based application for calculating drug infusions for pediatric cardiac surgery.nnnDESIGNnObservational study.nnnSETTINGnAnesthesiology department of a tertiary-care medical center in Israel.nnnPARTICIPANTSn45 anesthesiology department staff members (attendings and residents).nnnMEASUREMENTSnAnesthesiologists were asked to calculate the weight-based amount of drug and the corresponding amount in mL to be drawn from a standard vial and added to a 50-mL syringe in order to reach an infusion rate, where 1 mL/hr corresponds to 1 μg x kg(-1) x min(-1). The time it took to reach the result was measured. Staff members were also asked to rate the user-friendliness and usability of the program.nnnMAIN RESULTSn41 of the original 42 participants returned the completed questionnaire. Only 6 (15%) of 41 anesthesiologists provided all the correct answers. The mean calculation time required was 205 (±53) seconds. There was no difference in success rate between attendings and residents. Incorrect calculations ranged from a drug concentration 50 times too low up to 56 times too high. Most staff members believed that the computer-based application to perform these calculations reduced errors (65%) and workload (81%), and improved patient treatment (71%). This application was rated as very user-friendly.nnnCONCLUSIONSnAnesthesiologists have difficulty calculating pediatric drug concentrations for continuous drug infusions. The correct calculations are time-consuming. Incorrect calculations may lead to dangerously high or low doses. A computer-based application to calculate drug concentrations was rated as very useful and user-friendly.

Anesthetic management of prophylactic cervical cerclage: a retrospective multicenter cohort study

ObjectivesCervical incompetence complicates approximately 1 in 500 pregnancies and is the most common cause of second-trimester spontaneous abortion and preterm labor. No prospective or large retrospective studies have compared regional and general anesthesia for cervical cerclage.Study designFollowing IRB approval, we performed a retrospective study in the two main medical centers over an 8-year period to assess the association of anesthesia choice with anesthetic and obstetric outcomes. Anesthetic and perioperative details were retrospectively collected from fails of all patients undergoing cervical cerclage from 01/01/2005 until 31/12/2012. Details included demographic data, anesthetic technique, PACU data and perioperative complications.ResultsWe identified 487 cases of cervical cerclage in 327 women during the study period. The most commonly used anesthetic technique was general anesthesia (GA) (402/487; 82.5xa0%) compared with regional anesthesia (RA) (85/487; 17.5xa0%). When GA was performed, facemask was the most commonly used technique (275/402; 68.4xa0%), followed by intravenous deep sedation (61/402; 15.2xa0%); LMA (51/402; 12.7xa0%) and tracheal intubation (13/402; 3.2xa0%). There were no significant differences in demographic characteristics between women receiving general and regional anesthesia. Average duration of suturing the cervix among the GA group was 9.8xa0±xa01.6 and 10.6xa0±xa02.1xa0min in the RA group (pxa0<xa00.001). Average length of stay in the operating room in the GA group was 20.5xa0±xa03.9 and 23xa0±xa04.6xa0min in the RA group (pxa0<xa00.001). Patients receiving GA received in the PACU more opioids (6.2 versus 1.2xa0%; pxa0<xa00.05) and more non-opioids analgesics (36.8 versus 9.4xa0%; pxa0<xa00.001). Duration of PACU stay was shorter after GA (49.5xa0±xa018xa0min) than after RA (62.4xa0±xa028xa0min; pxa0<xa00.001). There were no other differences in anesthetic or perioperative outcome between groups. This study was not designed to provide evidence that RA reduces the risk of pulmonary aspiration, airway complications or adverse fetal neurological effects from maternal anesthetic exposure.ConclusionsBoth regional and general anesthesia were safely used for the performance of cerclage. Patients after general anesthesia had a shorter recovery time but a higher demand for opioids and non-opioids analgesia.

Effect of thrombocytopenia on mode of analgesia/anesthesia and maternal and neonatal outcomes

Abstract Objectives: The purpose was to correlate the use of regional analgesia/anasthesia among women with different degrees of thrombocytopenia relative to women with normal platelet counts, and note maternal and neonatal outcome, and mode of delivery. Methods: A case-control paradigm was developed based on women who delivered during 2007–2011 with platelet counts ≤80u2009000/mm3. For each woman in this “severe” thrombocytopenic group, an age- and parity-matched control was found who delivered a singleton within the same year but whose platelets were either 81u2009000–150u2009000/mm3 (“moderate” thrombocytopenia) or ≥151u2009000/mm3 (normal platelet counts). Results: 168 women were identified for each group; mean maternal age (28.4 years), mean gravidity (4.3), mean parity (3.7), mean gestational age (39.2 weeks) and mean birth weight (3283u2009g) were comparable. However, only in the severe thrombocytopenic women were there very early preterm deliveries, lowest birth weight, lowest Apgar scores, the greatest number with serious post-partum hemorrhage (>500u2009ml); use of regional analgesia/anesthesia was lowest, and percent cesarean sections highest. Conclusions: This study highlights potential for adverse maternal outcome of post-partum hemorrhage and adverse neonatal outcomes of prematurity, low birth weight, and low Apgar scores (but not neonatal death), and limited regional analgesia/anesthesia in women who present at delivery with severe (≤80u2009000/mm3) thrombocytopenia.

Ischaemic preconditioning but not isoflurane prevents post-ischaemic production of hydroxyl radicals in a canine model of ischaemia–reperfusion

Background and objective: Isoflurane has been shown to mimic ischaemic preconditioning (IPC). The protective effect of IPC, or applying isoflurane or perfusion with the ‘push‐pull’ complex zinc‐desferrioxamine (Zn‐DFO) in the canine heart, was investigated. Methods: Thirty minutes after salicylate administration (100 mg kg−1) the heart was exposed. All dogs were subjected to a 10 min left anterior descending artery occlusion followed by 2 h of reperfusion. In Group I (n = 9) isoflurane (2.5%) was administered 10 min prior to and during ischaemia. In Group II (n = 8), IPC was elicited by 5 min coronary artery occlusion, followed by 5 min of reperfusion, prior to the 10 min ischaemia. In Group III (n = 9) Zn‐DFO (2.5 mg kg−1) was given 10 min prior to ischaemia. The effects of these interventions were compared to control (n = 10). Coronary sinus blood concentrations of salicylate, 2,3‐dihydroxybenzoic acid (DHBA), lactate, pH and oxygen content were monitored. Results: In the control group, 2,3‐DHBA increased by 32% above the pre‐ischaemic value (P < 0.05). In contrast, in the IPC hearts, a significant decrease in the production of 2,3‐DHBA was observed (40% lower than baseline, P < 0.01). In the isoflurane group only a 13% (and non‐significant) decrease was noticed. In the Zn‐DFO group a 33% decrease was found (P < 0.01). The increase in lactate concentrations in the IPC and Zn‐DFO groups was significantly smaller than that of control and isoflurane groups. Conclusions: IPC protected the heart against the deleterious effects of reperfusion, possibly by amelioration of the level of oxygen‐derived reactive species, and the complete inhibition of reactive hydroxyl radical production. Isoflurane did not prove to be as effective in reducing the free radical damage.