Hyun Joo Ahn

Bupivacaine-sparing effect of fentanyl in spinal anesthesia for cesarean delivery.

Background and Objectives: Visceral pain decreases in cesarean patients under spinal anesthesia when the dose of local anesthetic is increased. However, larger doses of local anesthetic are associated with higher sensory blocks. We hypothesized that the addition of fentanyl could reduce the dose of bupivacaine necessary to achieve adequate surgical anesthesia. Methods: Two double‐blinded, sequential, prospective studies were performed on 120 patients. In the preliminary study, the patients received 8, 10, or 12 mg of 0.5% hyperbaric bupivacaine intrathecally. In the second, main study, they received each bupivacaine dose with 10 μg of fentanyl. Each group consisted of 20 patients, and the groups were identified as B8, B10, B12, BF8, BF10, and BF12. Sensory and motor block, intraoperative pain defined by visual analogue scale (VAS), muscle relaxation, and side effects were assessed. We also measured the sensory and motor recovery and the onset of pain in the postanesthesia care unit (PACU). Results: Maximal block level and incidence of high block (≥T1) were higher in the 12‐mg groups. There was intraoperative pain in 35% of the B8 patients and 20% of the B10 patients, but none in the B12 patients and all fentanyl groups. Incidences of other side effects were not different. The addition of fentanyl to bupivacaine significantly delayed the onset of postoperative pain and sensory recovery, but motor recovery time did not change with additional fentanyl. Conclusions: The optimal dose of hyperbaric bupivacaine to produce surgical anesthesia was 12 mg, which was accompanied by high sensory block. With the addition of 10 μg of fentanyl, the dose of bupivacaine could be reduced to 8 mg in spinal anesthesia for cesarean delivery.

Arteriovenous Malformations of the Body and Extremities: Analysis of Therapeutic Outcomes and Approaches According to a Modified Angiographic Classification

Purpose: To propose a modified angiographic classification for peripheral arteriovenous malformations (AVMs) and to determine its value for assessing therapeutic outcomes and approaches to ethanol embolization of AVMs in the body and extremities. Methods: AVMs of the trunk and extremities were categorized according to the angiographic morphology of the nidus: type I (arteriovenous fistulae), type II (arteriolovenous fistulae), type IIIa (arteriolovenulous fistulae with non-dilated fistula), and type IIIb (arteriolovenulous fistulae with dilated fistula). Sixty-six patients (41 women; mean age 28.3 years, range 5–53) with inoperable AVMs in the body and extremities who underwent staged ethanol embolizations were retrospectively analyzed. Therapeutic outcomes and approaches were evaluated according the above classification system. Results: The 66 AVMs were composed of 30 (45%) type IIIb, 13 (20%) type II, 12 (18%) mixed types IIIa and IIIb, 9 (14%) mixed types II and IIIb, and 2 (3%) type IIIa. Ethanol embolization was most effective for type II (100%), and more effective for type IIIb (83%) than for type IIIa or mixed types (≤50%). Despite the use of the transarterial approach, direct puncture and transvenous approaches were more relevant for treating type II AVMs. Only the transarterial approach was used for treating type IIIa; both direct puncture and transarterial approaches were used for treating the other types. Conclusion: The described angiographic classification provides considerable information concerning the characteristics of AVMs in the body and extremities, the optimal therapeutic approach, and the likely therapeutic outcome.

Does a Protective Ventilation Strategy Reduce the Risk of Pulmonary Complications After Lung Cancer Surgery? : A Randomized Controlled Trial

BACKGROUND Protective ventilation strategy has been shown to reduce ventilator-induced lung injury in patients with ARDS. In this study, we questioned whether protective ventilatory settings would attenuate lung impairment during one-lung ventilation (OLV) compared with conventional ventilation in patients undergoing lung resection surgery. METHODS One hundred patients with American Society of Anesthesiology physical status 1 to 2 who were scheduled for an elective lobectomy were enrolled in the study. During OLV, two different ventilation strategies were compared. The conventional strategy (CV group, n=50) consisted of FIO2 1.0, tidal volume (Vt) 10 mL/kg, zero end-expiratory pressure, and volume-controlled ventilation, whereas the protective strategy (PV group, n=50) consisted of FIO2 0.5, Vt 6 mL/kg, positive end-expiratory pressure 5 cm H2O, and pressure-controlled ventilation. The composite primary end point included PaO2/FIO2<300 mm Hg and/or the presence of newly developed lung lesions (lung infiltration and atelectasis) within 72 h of the operation. To monitor safety during OLV, oxygen saturation by pulse oximeter (SpO2), PaCO2, and peak inspiratory pressure (PIP) were repeatedly measured. RESULTS During OLV, although 58% of the PV group needed elevated FIO2 to maintain an SpO2>95%, PIP was significantly lower than in the CV group, whereas the mean PaCO2 values remained at 35 to 40 mm Hg in both groups. Importantly, in the PV group, the incidence of the primary end point of pulmonary dysfunction was significantly lower than in the CV group (incidence of PaO2/FIO2<300 mm Hg, lung infiltration, or atelectasis: 4% vs 22%, P<.05). CONCLUSION Compared with the traditional large Vt and volume-controlled ventilation, the application of small Vt and PEEP through pressure-controlled ventilation was associated with a lower incidence of postoperative lung dysfunction and satisfactory gas exchange. TRIAL REGISTRY Australian New Zealand Clinical Trials Registry; No.: ACTRN12609000861257; URL: www.anzctr.org.au.

Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients

BACKGROUND This study was performed to assess whether intubation is more difficult in obese patients and to assess the ability of a new index: the ratio of the neck circumference to thyromental distance (NC/TM), to predict difficult intubation in obese patients. METHODS The incidence of difficult tracheal intubation in 123 obese (BMI≥27.5 kg m(-2)) and 125 non-obese patients was compared. Difficult intubation was determined using the intubation difficulty scale (IDS≥5). The NC/TM ratio was calculated and its ability to predict difficult intubation in obese patients was compared with that of established predictors including high BMI, the Mallampati score, the Wilson score, NC, width of mouth opening, sternomental distance, TM, and a previous history of difficult intubation. RESULTS Difficult intubation was more frequent in obese patients than in non-obese patients (13.8% vs 4.8%; P=0.016). Multivariate analysis revealed that the Mallampati score, the Wilson score, and NC/TM independently predicted difficult intubation in obese patients. Among these three indices, NC/TM showed the highest sensitivity and a negative predictive value, and largest area under the curve on an ROC curve. CONCLUSIONS Difficult intubation was more common in obese patients and the NC/TM was a better method for predicting difficult intubation than other established indices.

The changes in coagulation profile and epidural catheter safety for living liver donors: A report on 6 years of our experience

The use of epidural catheters has been a subject of active debate in living liver donors because of the possible postoperative coagulation derangement and the subsequent risk of epidural hematoma. The aim of this study was to evaluate the safety of epidural catheters in relation to the changes in coagulation profile based on a review of previously published literature and the results of our 360 donors. In both the literature and in our cases, platelet count, prothrombin time (PT), and activated partial thromboplastin time (aPTT) in cases of heparin administration showed significant changes (P < 0.05), especially after right lobectomy. Platelet count reached its nadir on postoperative day (POD) 2–3, while PT and aPTT reached their peaks on POD 1–2 and at the end of the operation, respectively. In our donors, the ranges of platelet count, PT, and aPTT for the first 3 PODs were 54–359 ×10/μL, 0.99–2.38 international normalized ratio (INR), and 25.9–300 seconds, respectively, and of note, 5 donors (1.4%) had a platelet count of <80 × 10/μL and 9 donors (2.5%) had a PT of >2.0 INR. Epidural catheterizations were performed in 242 donors, and the catheters were removed on POD 3–4 in 177 donors (73.1%). Mean (range) of platelet count, PT, and aPTT on the day of catheter removal were 168.4 ± 42.9 (82–307) × 10/μL, 1.33 ± 0.18 (0.99–1.93) INR, and 40.9 ± 4.8 (32.0–70.6) seconds, respectively. No epidural hematoma was observed in this study. In conclusion, the discreet use of epidural catheters in live liver donors, in spite of postoperative coagulation derangements, appears to be safe regardless of the type of hepatectomy performed. Liver Transpl 13:62–70, 2007.

Synergistic anti-cancer effect of phenformin and oxamate.

Phenformin (phenethylbiguanide; an anti-diabetic agent) plus oxamate [lactate dehydrogenase (LDH) inhibitor] was tested as a potential anti-cancer therapeutic combination. In in vitro studies, phenformin was more potent than metformin, another biguanide, recently recognized to have anti-cancer effects, in promoting cancer cell death in the range of 25 times to 15 million times in various cancer cell lines. The anti-cancer effect of phenformin was related to complex I inhibition in the mitochondria and subsequent overproduction of reactive oxygen species (ROS). Addition of oxamate inhibited LDH activity and lactate production by cells, which is a major side effect of biguanides, and induced more rapid cancer cell death by decreasing ATP production and accelerating ROS production. Phenformin plus oxamate was more effective than phenformin combined with LDH knockdown. In a syngeneic mouse model, phenformin with oxamate increased tumor apoptosis, reduced tumor size and 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography compared to control. We conclude that phenformin is more cytotoxic towards cancer cells than metformin. Furthermore, phenformin and oxamate have synergistic anti-cancer effects through simultaneous inhibition of complex I in the mitochondria and LDH in the cytosol, respectively.

A Korean Predictive Model for Postoperative Nausea and Vomiting

Postoperative nausea and vomiting (PONV) is one of the most common and distressing complications after surgery. An identification of risk factors associated with PONV would make it easier to select specific patients for effective antiemetic therapy. We designed a case-controlled study to identify the risk factors for PONV in 5,272 surgical patients. At postoperative 2 and 24 hr, patients were visited and interviewed on the presence and severity of PONV. Thirty nine percent of patients experienced one or more episodes of nausea or vomiting. Five risk factors were highly predictive of PONV: 1) female, 2) history of previous PONV or motion sickness, 3) duration of anesthesia more than 1 hour, 4) non-smoking status, and 5) use of opioid in the form of patient controlled analgesia (PCA), in the order of relevance. The formula to calculate the probability of PONV using the multiple regression analysis was as follows: P (probability of PONV)=1/1+e-Z, Z=-1.885+0.894 (gender)+0.661 (history)+0.584 (duration of anesthesia)+0.196 (smoking status) +0.186 (use of PCA-based opioid) where gender: female=1, male=0; history of previous PONV or motion sickness: yes=1, no=0; duration of anesthesia:more than 1 hr=1, less than or 1 hr=0; smoking status: no=1, yes=0; use of PCA-based opioid: yes=1, no=0.

Incidence of severe ventricular arrhythmias during pulmonary artery catheterization in liver allograft recipients

Liver allograft recipients may develop a hyperdynamic circulation and cardiac electrophysiologic abnormalities. The incidence of severe ventricular arrhythmias in liver allograft recipients during pulmonary artery (PA) catheterization was determined. One hundred five liver allograft recipients were studied prospectively; 5 of the patients with preexisting valvular heart disease, ischemic heart disease, or arrhythmias were excluded. Severe ventricular arrhythmia, defined as 3 or more consecutive ventricular premature beats occurring at a rate of >100 per minute, was observed in 37.0% of the patients during insertion of the catheter and in 25.0% of the patients during removal of the catheter. Two patients developed ventricular tachycardia, and 2 developed ventricular fibrillation; the arrhythmias in these 4 patients did not respond to appropriate pharmacological treatment but resolved promptly after removal of the PA catheter. The catheter transit time from the right ventricle to the pulmonary capillary wedge position was longer in patients with severe ventricular arrhythmia than in those without this arrhythmia (91.6 ± 103.6 s versus 53.3 ± 18.4 s, P < 0.05). In conclusion, patients undergoing liver transplantation have a high risk of developing a ventricular arrhythmia during PA catheterization. Liver Transpl 13:1451–1454. 2007.

Intrathecal morphine combined with intravenous patient‐controlled analgesia is an effective and safe method for immediate postoperative pain control in live liver donors

The healthy condition of living donors makes their tolerance to pain particularly low, and clinicians are often challenged to come up with an analgesic technique that is effective yet ensures donor safety. This study compared, in donor right hepatectomy, the efficacy and safety of preoperative intrathecal morphine (ITM) combined with intravenous patient‐controlled analgesia (IV‐PCA) with IV‐PCA alone. Forty adult patients were randomly allocated into 2 groups: ITM+IV‐PCA group (n = 20) and IV‐PCA‐only group (n = 20). Patients in the ITM+IV‐PCA group received morphine sulfate (400 μg). The visual analog scale (VAS) at rest and when coughing and supplementary meperidine and IV‐PCA (fentanyl) consumption were assessed at 2, 4, 6, 8, 10, 12, 18, 24, 30, 36, 42, 48 56, 64, and 72 hours after surgery. Also, side effects such as sedation, dizziness, nausea, vomiting, pruritus, and respiratory depression were evaluated. The ITM+IV‐PCA group showed significantly less pain at rest and when coughing for up to 30 hours and 24 hours, respectively. Cumulative postoperative consumption of meperidine and IV‐PCA (fentanyl) were significantly less in the ITM+IV‐PCA group. The incidence of side effects were comparable between the 2 groups except for pruritus; its incidence was significantly higher in the ITM+IV‐PCA group during the first 24 hours, but no treatment was required due to its mild severity. The results of our study suggest that preoperative ITM combined with IV‐PCA may be considered as an effective and safe pain management regimen in living liver donors who have characteristics of low tolerance to pain and postoperative coagulation derangement. Liver Transpl 15:381–389, 2009.

Reactive oxygen species by isoflurane mediates inhibition of nuclear factor κB activation in lipopolysaccharide-induced acute inflammation of the lung.

BACKGROUND:Although anesthetic-induced inhibition of lipopolysaccharide (LPS)-induced lung injury has been recognized, the underlying mechanism is obscure. Some studies suggest that reactive oxygen species (ROS) by isoflurane play a crucial role for anesthetic-induced protective effects on the brain or the heart; however, it still remains controversial. In this study, we examined the role of isoflurane-derived ROS in isoflurane-induced inhibition of lung injury and nuclear factor &kgr;B (NF&kgr;B) activation in LPS-challenged rat lungs. METHODS:Male Sprague-Dawley rats were subjected to inhalation of 1.0 minimum alveolar concentration of isoflurane for 60 minutes, and intratracheal LPS 0.1 mg was administered 60 minutes later. In some cases, ROS scavenger, 2-mercaptopropinyl glycine or N-acetylcysteine was given 30 minutes before isoflurane. ROS generation was measured by fluorometer before LPS challenge and 4 hours after. Isoflurane’s preconditioning effect was assessed by histologic examination, protein content, neutrophil recruitment, and determination of tumor necrosis factor (TNF)-&agr;, interleukin (IL)-1&bgr;, and IL-6 levels in bronchoalveolar lavage fluid and lung tissue. Western blotting measured phosphorylation of inhibitory &kgr;B &agr; (ser 32/36), NF&kgr;B p65, and inducible nitric oxide synthase (iNOS). TNF-&agr; and IL-6 mRNA expression and immunofluorescence staining for iNOS were also assessed. RESULTS:Isoflurane preconditioning reduced inflammatory lung injury and TNF-&agr;, IL-1&bgr;, and IL-6 release in the lung. Isoflurane upregulated ROS generation before LPS but inhibited a ROS burst after LPS challenge. ROS scavenger administration before isoflurane abolished the isoflurane preconditioning effect as well as isoflurane-induced inhibition of phosphorylation of inhibitory &kgr;B&agr;, NF&kgr;B p65, iNOS activation, and mRNA expression of TNF-&agr; and IL-6 in acute LPS-challenged lungs. CONCLUSIONS:This study suggests a crucial role of upregulated ROS generation by isoflurane for modification of inflammatory pathways by isoflurane preconditioning in acute inflammation of the lung.