The effect of dietary fiber supplement on prevention of gestational diabetes mellitus in women with pre-pregnancy overweight/obesity: A randomized controlled trial

Objective: To investigate the effect of dietary fiber intake during pregnancy on the prevention of gestational diabetes mellitus (GDM) in women who are overweight/obese prior to pregnancy.

Methods: This randomized controlled trial was conducted in Shanghai General Hospital from June 2021 to March 2022. A total of 98 women who reported BMI≥24 kg/m² prior to pregnancy were recruited before their 20th gestational week, and randomly (simple random allocation) assigned to the fiber supplement group (12 g of dietary fiber power twice daily) and the control group (standard prenatal care) from 20 to 24⁺⁶ gestational weeks. Both groups received nutrition education and dietary advice during the study. GDM diagnosis was performed by an oral glucose tolerance test (OGTT) at 25–28 weeks’ gestation. Data are presented as means with SD, as medians with IQR, or as counts with percentages as appropriate. Comparisons were conducted using a t-test, Mann-Whitney U test, and χ² test, respectively.

Results: The incidence of GDM was significantly reduced in the fiber supplement group compared with the control group: 8.3 vs. 24.0% (χ² = 4.40, p = 0.036). At OGTT, the mean fasting plasma glucose in the fiber supplement group was significantly lower than before the intervention (4.57 ± 0.38 mmol/L vs. 4.41 ± 0.29 mmol/L, p < 0.01) but not in the control group (4.48 ± 0.42 mmol/L vs. 4.37 ± 0.58 mmol/L, p = 0.150). Compared with the control group, the TG and TG/HDL-C ratio levels in the intervention group were significantly higher than those in the control group (2.19 ± 0.54 mmol/L vs. 2.70 ± 0.82 mmol/L and 1.19 ± 0.49 vs.1.63 ± 0.63, respectively, all P＜0.05). The body weight gain was significantly lower in the fiber supplement group than the control group (1.99 ± 1.09 kg vs. 2.53 ± 1.20kg, p = 0.022). None of the women randomized to the fiber supplement group experienced preterm birth (<37 weeks gestation) compared with 12.0% in the control group (p = 0.040). Excessive weight gain (total weight gain >11.5 kg for overweight, and >9.0 kg for obesity) occurred in 46.7% of women in the fiber supplement group compared with 68.0% in the control group (p = 0.035). There were no differences in other maternal and neonatal outcomes.

Conclusion: Increased dietary fiber intake in pregnant women who were overweight/obese prior to pregnancy may reduce the risk of GDM, excessive weight gain, and preterm birth, but it did not improve blood lipids.

Insulin Treatment of Hypertriglyceridemia During Pregnancy

Objective: This study aims to investigate the efficiency of insulin on the reduction of gestational lipid profiles and try to propose a real-world approach to assist clinicians.

Methods: A retrospective, single-centered cohort study of 35 cases was conducted from October 2018 to July 2021 in Shanghai General Hospital. SPSS version 25.0 was performed to analyze the whole data. For continuous variables, a paired-sample t test was carried out on each variable to make a comparison between before and after treatment.

Results: The average pre-pregnancy TGs and TCs of these patients were about 3.96 ± 1.42 mmol/L and 4.78 ± 1.18 mmol/L, respectively. The maximum of TG before insulin treatment was up to 64.62 and TC 20.43 mmol/L, which decreased to 17.34 and 4.92 mmol/L after intervention of the insulin drip. TG was noticed to fall by 77% and 12.71% of TG, respectively. The difference of TG and TC between pre-treatment and post-treatment were statistically significant (p < 0.01), while this difference has not been found in the other laboratory tests reports. The outcomes of newborns and mothers with management of insulin were proven to be improved.

Conclusion: The use of insulin in the management of gestational hypertriglyceridemia is safe and efficient, and insulin may become a mainstream in the near future to mitigate serum TG and TC levels in the pregnancy period besides regulating the blood glucose level.

Associations of Thyroid Function Tests with Lipid Levels and Adverse Pregnancy Outcomes During the First Trimester

OBJECTIVE

The present study aims to evaluate the relationship of thyroid function during the first trimester of pregnancy with lipid levels and pregnancy outcomes.

METHODS

Women who delivered babies at the Shanghai General Hospital between March 2019 and December 2019 with a known pregnancy outcome and complete data were included in the present study (n = 1779). A retrospective cohort study of all subjects with available first-trimester thyroid function testing and lipid levels data was conducted, and the relationship of thyroid function with lipid levels and pregnancy outcomes was evaluated. The data were analyzed using the SPSS software for statistical correlation.

RESULTS

The proportion of caesarean sections was higher in women with hypothyroxinemia (HIA) and hypothyroidism than in women with euthyroidism. Hypothyroidism was shown to be related with polyhydramnios, preterm labor and hypertriglyceridemia. HIA was correlated with increased rates of gestational diabetes mellitus (GDM), preeclampsia, gestational hypertension and hypertriglyceridemia. Compared with the euthyroidism group, the hypothyroidism group had a higher apolipoprotein A1 (Apo A1) level and apolipoprotein B level; the subclinical hypothyroidism group had a higher total cholesterol (TC) level and low-density lipoprotein cholesterol level; the HIA group had higher triglyceride, high-density lipoprotein cholesterol levels and lower TC, Apo A1 levels. TC levels were positively correlated with the thyroid-stimulating hormone level and negatively correlated with free thyroxine (FT4) level, and free triiodothyronine and FT4 levels were positively correlated with GDM occurrence.

CONCLUSION

Thyroid function in early pregnancy is associated with dyslipidemia and pregnancy outcomes; conventional screening of thyroid diseases in early pregnancy may help improve lipid levels and decrease adverse pregnancy outcomes.

Effect of exposure to antibiotics on the gut microbiome and biochemical indexes of pregnant women

INTRODUCTION

Exposure to antibiotics (ABX) during pregnancy can have a systematic effect on both fetal and maternal health. Although previous biomonitoring studies have indicated the effects on children of extensive exposure to ABX, studies on pregnant women remain scarce. To explore the effect on pregnant women of environmental exposure to ABX through accidental ingestion and identify potential health risks, the present study investigated 122 pregnant women in East China between 2019 and 2020.

RESEARCH DESIGN AND METHODS

The presence of six categories of ABX (quinolones, sulfonamides, lincosamides, tetracyclines, amide alcohol ABX, and β-lactams) in plasma samples taken from the pregnant women was investigated using an ABX kit and a time-resolved fluorescence immunoassay.

RESULTS

All six ABX were detected in the plasma, with a detection rate of 17.2%. It was discovered that the composition of intestinal flora in pregnant women exposed to ABX was different from that of pregnant women who had not been exposed to ABX. The intestinal flora of pregnant women exposed to ABX also changed at both the phylum and genus levels, and several genera almost disappeared. Furthermore, the metabolic levels of glucose and insulin and the alpha diversity of pregnant women exposed to ABX were higher than those of pregnant women not exposed to ABX.

CONCLUSION

Pregnant women are potentially at higher risk of adverse microbial effects. Glucose metabolism and insulin levels were generally higher in pregnant women exposed to ABX than in unexposed women. Also, the composition and color of the gut microbiome changed.

The characteristics of intestinal flora in overweight pregnant women and the correlation with gestational diabetes mellitus

OBJECTIVE

To investigate the characteristics of intestinal flora in overweight pregnant women and the correlation with gestational diabetes mellitus (GDM).

METHODS

A total of 122 women were enrolled and divided into four groups according to their pre-pregnancy BMI and the presence of GDM: group 1 (n = 71) with a BMI <24 kg/m2, without GDM; group 2 (n = 27) with a BMI <24 kg/m2, with GDM; group 3 (n = 17) with a BMI ≥24 kg/m2, without GDM; and group 4 (n = 7) with a BMI ≥24 kg/m2 with GDM. Feces were collected on the day that the oral glucose tolerance test was conducted. The V3-V4 variable region of 16S rRNA was sequenced using the Illumina Hiseq 2500 platform, and a bioinformatics analysis was conducted.

RESULTS

There were differences between the four groups in the composition of intestinal flora, and it was significantly different in group 4 than in the other three groups. Firmicutes accounted for 36.4% of the intestinal flora in this group, the lowest among the four groups, while Bacteroidetes accounted for 50.1%, the highest among the four groups, making ratio of these two bacteria approximately 3:5, while in the other three groups, this ratio was reversed. In women with a BMI <24 kg/m2, the insulin resistance index (homeostatic model assessment for insulin resistance (HOMA-IR)) in pregnant women with GDM was higher than in those without (P3 = 0.026).

CONCLUSION

The composition of the intestinal flora of pregnant women who were overweight or obese before pregnancy and suffered from GDM was significantly different than women who were not overweight or did not suffer from GDM.

Corrigendum: The Role of High-Content Complex Dietary Fiber in Medical Nutrition Therapy for Gestational Diabetes Mellitus

[This corrects the article DOI: 10.3389/fphar.2021.684898.].

Alterations of gut microbiota in gestational diabetes patients during the second trimester of pregnancy in the Shanghai Han population

BACKGROUND

The causes of gestational diabetes mellitus (GDM) are still unclear. Recent studies have found that the imbalance of the gut microbiome could lead to disorders of human metabolism and immune system, resulting in GDM. This study aims to reveal the different gut compositions between GDM and normoglycemic pregnant women and find the relationship between gut microbiota and GDM.

METHODS

Fecal microbiota profiles from women with GDM (n = 21) and normoglycemic women (n = 32) were assessed by 16S rRNA gene sequencing. Fasting metabolic hormone concentrations were measured using multiplex ELISA.

RESULTS

Metabolic hormone levels, microbiome profiles, and inferred functional characteristics differed between women with GDM and healthy women. Additionally, four phyla and seven genera levels have different correlations with plasma glucose and insulin levels. Corynebacteriales (order), Nocardiaceae (family), Desulfovibrionaceae (family), Rhodococcus (genus), and Bacteroidetes (phylum) may be the taxonomic biomarkers of GDM. Microbial gene functions related to amino sugar and nucleotide sugar metabolism were found to be enriched in patients with GDM.

CONCLUSION

Our study indicated that dysbiosis of the gut microbiome exists in patients with GDM in the second trimester of pregnancy, and gut microbiota might be a potential diagnostic biomarker for the diagnosis, prevention, and treatment of GDM.

The Role of High-Content Complex Dietary Fiber in Medical Nutrition Therapy for Gestational Diabetes Mellitus

Objectives: A controlled open clinical study was conducted to evaluate the role of Ricnoat, a high-content complex dietary fiber powder produced by Zhuhai Aimed Biotechnology Co. Ltd., in medical nutrition therapy (MNT) to treat gestational diabetes mellitus (GDM). The study aimed to investigate glycemic control, lipid control, weight control, and pregnancy outcomes (neonatal weight) in patients with GDM, as well as evaluate the clinical safety of Ricnoat.

Methods: A total of 120 patients with GDM who were admitted to three hospitals in Shanghai between January 2019 and January 2020 were enrolled. Ricnoat was used for intervention for patients in the experimental group. Using a χ² test and t-test, respectively, comparisons were conducted between the measurement data and countable data of the demographics and baseline disease characteristics of the experimental group and control group.

Results: Fasting blood glucose, 2-h postprandial blood glucose, glycated hemoglobin, total cholesterol, triglycerides, low-density lipoprotein, maternal gestational weight gain, neonatal weight, serum creatinine, glutamate transaminase, and aspartate aminotransferase were lower in the experimental group than in the control group, whereas high-density lipoprotein was higher in the experimental group than in the control group. Ricnoat intervention resulted in satiety higher than the expected 80% and more common occurrence of type 4 (smooth and soft, like salami or a snake) and type 5 (a soft mass with clear edges) stools.

Conclusion: Ricnoat intervention had a significant effect on glycemic control, lipid control, weight control, and pregnancy outcomes (neonatal weight) in patients with GDM by enhancing maternal satiety and improving the stool features of pregnant women. It was also found to be safe for application during pregnancy.

Computerized analysing system using the active contour in ultrasound measurement of carotid artery intima-media thickness

BACKGROUND AND PURPOSE

B-mode measurement of the carotid intima-media (IM) thickness (T) based on manual tracing (MT) procedures are dependent on the subjectivity of the reader and the existing automatic tracing procedures often fail to detect the IM boundaries accurately. The purpose of this study was to compare the tracing results of the IM boundaries of the carotid wall with a new automatic identification (AI) procedure, based on an active contour model, and computer-assisted manual tracing (MT).

METHODS

The detection of the IM boundaries was performed with both procedures in 126 ultrasound images [63 each of the common carotid artery (CCA) and carotid bulb] along the far wall of the distal CCA and the carotid bulb. Intra- and inter-reader variability for mean and maximum IMT with AI and MT and accuracy of identification of both IM boundaries were evaluated.

RESULTS

Using MT the intra- and inter-reader variability amounted to 0.01-0.03 and 0.03-0.07 mm, respectively. The variability was slightly higher in the carotid bulb than in the CCA. Using AI the variability was almost eliminated. Mean and maximum IMT were measured systematically lower by AI compared with MT in all regions by 0.01 mm. The accuracy of identification was similar for both IM boundaries, but lower in the carotid bulb region than in the CCA.

CONCLUSIONS

The new AI procedure identifies both IM boundaries in the region of the far wall of the CCA and carotid bulb with high precision, and eliminates most of the intra- and inter-reader variability of the IMT measurement using MT.

Clinical and echocardiographic diagnoses disagree in patients with unexplained hemodynamic instability after cardiac surgery

PURPOSE

To investigate 1) if clinical indications match diagnostic findings from urgent transesophageal echocardiography (TEE) in hemodynamically unstable patients after cardiac surgery and 2) the clinical impact of the TEE findings.

METHODS

Retrospective review of all postcardiac surgical intensive care patients who received an urgent TEE over a three- year period from July 1(st) 1997 until June 30(th) 2000. The clinician's presumed diagnosis based on hemodynamic and clinical evaluation was compared to TEE diagnosis. Surgical and medical interventions based on TEE results and the associated mortality were correlated.

RESULTS

A hundred and thirty TEEs were performed for hemodynamic instability or suspected intracardiac vegetation or thrombus, all category I indications according to ASA guidelines. In 41.5% of patients the echocardiographic finding matched the presumed diagnosis. Patient management was significantly changed as a result of TEE findings in 58.5% of patients; 43.3% had changes in pharmacological therapy and 15.3% had a surgical intervention. Mortality was significantly lower in those who received a surgical intervention when compared to those who had changes in drug treatment (P <0.05).

CONCLUSIONS

The results of urgent TEE in hemodynamically unstable patients or patients with thromboembolic phenomena in the postcardiac surgical intensive care unit are unpredictable in over half of cases. Inappropriate management decisions may result without the information obtained from TEE examination. Clinical management is often modified as a result of TEE findings. TEE is essential in the management of hemodynamically unstable postcardiac surgical patients.

The efficacy and resource utilization of remifentanil and fentanyl in fast-track coronary artery bypass graft surgery: a prospective randomized, double-blinded controlled, multi-center trial

We compared (a) the perioperative complications; (b) times to eligibility for, and actual time of the following: extubation, less intense monitoring, intensive care unit (ICU), and hospital discharge; and (c) resource utilization of nursing ratio for patients receiving either a typical fentanyl/isoflurane/propofol regimen or a remifentanil/isoflurane/propofol regimen for fast-track cardiac anesthesia in 304 adults by using a prospective randomized, double-blinded, double-dummy trial. There were no differences in demographic data, or perioperative mortality and morbidity between the two study groups. The mini-mental status examination at postoperative Days 1 to 3 were similar between the two groups. The eligible and actual times for extubation, less intense monitoring, ICU discharge, and hospital discharge were not significantly different. Further analyses revealed no differences in times for extubation and resource utilization after stratification by preoperative risk scores, age, and country. The nurse/patient ratio was similar between the remifentanil/isoflurane/propofol and fentanyl/isoflu-rane/propofol groups during the initial ICU phase and less intense monitoring phase. Increasing preoperative risk scores and older age (>70 yr) were associated with longer times until extubation (eligible), ICU discharge (eligible and actual), and hospital discharge (eligible and actual). Times until extubation (eligible and actual) and less intense monitoring (eligible) were significantly shorter in Canadian patients than United States' patients. However, there was no difference in hospital length of stay in Canadian and United States' patients. We conclude that both anesthesia techniques permit early and similar times until tracheal extubation, less intense monitoring, ICU and hospital discharge, and reduced resource utilization after coronary artery bypass graft surgery.

IMPLICATIONS

An ultra-short opioid technique was compared with a standard fast-track small-dose opioid technique in coronary artery bypass graft patients in a prospective randomized, double-blinded controlled study. The postoperative recovery and resource utilization, including stratification of preoperative risk score, age, and country, were analyzed.

Ultra-fast-track anesthetic technique facilitates operating room extubation in patients undergoing off-pump coronary revascularization surgery

OBJECTIVE

To determine if implementation of ultra-fast-track anesthetic (UFTA) technique facilitates operating room extubation in patients undergoing off-pump coronary artery bypass graft (CABG) surgery.

DESIGN

Retrospective review.

SETTING

Referral center for cardiovascular surgery at a university hospital.

PARTICIPANTS

Thirty-seven patients undergoing off-pump CABG surgery.

INTERVENTIONS

Two groups represented UFTA (n = 10) and standard anesthetic (controls, n = 27) techniques. Anesthesia was conducted with propofol, remifentanil, vecuronium, and thoracic epidural analgesia in the UFTA group and thiopental, fentanyl, pancuronium, and isoflurane in the control group. Active temperature control was an integral part of the UFTA technique but not the standard technique. The active temperature control included intravenous fluid warmer, prewarmed skin preparation, humidified inspired gases, a circulating water warming blanket, and a forced-air warmer, along with the maintenance of the operating room temperature at 24 degrees C. The control group was managed with an intravenous fluid warmer, and the ambient temperature remained constant (20 degrees C). Patients who did not satisfy extubation criteria within 30 minutes from the end of surgery were sedated and transferred to the intensive care unit (ICU).

MEASUREMENTS AND MAIN RESULTS

All patients in the UFTA group and 2 in the control group were extubated in the operating room immediately after surgery. None of the patients required reintubation. There was no significant difference in postextubation PaO(2) and PaCO(2) between the groups. Nasopharyngeal temperature decreased from 36.7 +/- 0.4 degrees C to 36.4 +/- 0.3 degrees C in the UFTA group and from 36.6 +/- 0.5 degrees C to 35.6 +/- 0.4 degrees C in the control group (p < 0.0001). Bradycardia occurred significantly more often in the UFTA group but there was no difference in episodes of hypotension. There were no perioperative deaths. Patients who were extubated in the operating room required lower nurse-to-patient acuity ratio (1:2) in the ICU. No difference was found in ICU and hospital length of stay.

CONCLUSIONS

Implementation of UFTA technique provided adequate hemodynamic control and facilitated operating room extubation in all patients. The impact of UFTA on earlier patient discharge and actual cost savings within a fully integrated post-cardiac surgery unit requires further evaluation.

Safety and efficacy of o-raffinose cross-linked human hemoglobin (Hemolink) in cardiac surgery

PURPOSES

There are currently two major classes of oxygen therapeutics: hemoglobin based oxygen carriers (HBOCs) and synthetic perfluorocarbons (PFCs). This review focuses on the use of o-raffinose cross-linked human hemoglobin (Hb raffimer) in cardiac surgery.

SOURCE

The literature on HBOCs was reviewed and the development and clinical trials on Hb raffimer were outlined.

PRINCIPAL FINDING

The benefits of HBOCs include avoidance of known viruses, pathogens and cross-matching; increased stability and storage time; and efficient oxygen delivery to tissues. The limitations of HBOCs include binding the endogenous vasodilator, nitric oxide, thereby resulting in transient hypertension, esophageal dysfunction and abdominal discomfort. The short half-lives of these products makes them best suited to situations of acute anemia. Hb raffimer is prepared from outdated red blood cells, cross-linked with o-raffinose, a polyaldehyde obtained through the oxidation of the trisaccharide raffinose. The Hb is covalently cross-linked (beta-beta) within the 2,3 DPG binding pocket to form a stable 64 kDa tetramer. At this time, a total of over 500 patients have been enrolled and more than 300 patients have been treated with Hb raffimer. Preliminary analysis of data from recent Phase II & III clinical trials of Hb raffimer in routine coronary artery bypass grafting surgery suggest that the product is well tolerated and may facilitate avoidance of allogeneic blood product transfusion in this surgical setting.

CONCLUSION

The converging evidence from clinical studies with HBOCs has demonstrated that these products have the potential to provide hemoglobin and oxygen carrying capacity to tissues in times of acute anemia during surgery. It is anticipated that Hb raffimer will be used to facilitate intraoperative autologous donation and emerge as an important alternative to allogeneic blood transfusion during cardiac surgery.

The effect of insulin cardioplegia on atrial fibrillation after high-risk coronary bypass surgery: a double-blinded, randomized, controlled trial

Atrial fibrillation after coronary bypass (CABG) surgery is an important cause of morbidity and increased resource utilization. Insulin-enhanced cardioplegia may reduce postoperative arrhythmias by improving aerobic myocardial metabolism and mitigating the deleterious effects of ischemia. We performed a double-blinded, randomized, controlled clinical trial to determine if insulin-enhanced cardioplegia decreases the risk of post-CABG atrial fibrillation in a high-risk patient population. We randomized 501 patients undergoing urgent CABG to receive insulin-enhanced (Humulin R 10 IU/L, Insulin group, n = 243) or standard (Control group, n = 258) blood cardioplegia during cardiopulmonary bypass. Patients were monitored by using continuous electrocardiography for a minimum of 3 days postoperatively. All standard cardiac medications, including beta-adrenergic blockers, were continued postoperatively. Insulin-enhanced cardioplegia did not result in a significant reduction in postoperative atrial fibrillation. Furthermore, we failed to detect a difference in the incidence of conduction defects, ventricular tachycardia, or pacemaker requirements between insulin and placebo patients. Atrial fibrillation was the most common arrhythmia, occurring in 31% of all patients. Independent predictors of atrial fibrillation were elderly age, preoperative atrial fibrillation, and renal insufficiency. Right bundle branch block was the most common conduction abnormality. Predictors of right bundle branch block were elderly age, female sex, and circumflex coronary artery disease. The incidence of postoperative ventricular tachycardia, left bundle branch block, and permanent pacemaker requirement was small. We conclude that insulin-enhanced cardioplegia does not reduce the incidence of postoperative atrial fibrillation in high-risk CABG patients.

IMPLICATIONS

We conducted a double-blinded, randomized, placebo-controlled trial of insulin-enhanced cardioplegia in 501 patients undergoing urgent coronary bypass surgery. Insulin did not decrease the incidence of postoperative atrial fibrillation when compared with placebo. We also failed to demonstrate a difference in the incidence of other postoperative arrhythmias between the two groups of patients.

Postoperative intensive care in cardiac surgery

Postoperative intensive care in cardiac surgery is a growing area, fuelled by the increase in the number of cardiac surgical procedures performed. An increase in the number of patients has resulted in increased resource utilization. Much of the recent research in this field is concerned with the early extubation of cardiac surgical patients, reducing the length of stay in the intensive care unit and predicting which patients will have delayed extubation and a prolonged length of stay. A number of recent studies have been published advocating 'off pump' cardiac surgery as a way of reducing the physiological insult of cardiopulmonary bypass and thereby improving the postoperative course. There is still insufficient evidence that this approach reduces morbidity and intensive care unit length of stay in multi-vessel off-pump coronary artery bypass surgery. The traditional design of post-cardiac surgical intensive care units and high dependency units has also recently been challenged. More flexible integrated units improve cost control and are more suited to modern cardiac surgery.

Fast-track cardiac anaesthesia in the elderly: effect of two different anaesthetic techniques on mental recovery

Elderly patients may be considered for 'fast-track' cardiac anaesthesia, but can suffer psychological complications and slow recovery of mental function after surgery, which can interfere with recovery. Reduced metabolism and changed distribution of anaesthetic and sedative agents can cause poor recovery. We made a prospective randomized comparison of mental function, haemodynamic stability and extubation and discharge times in elderly patients (65-79 yr) receiving two premedication, anaesthetic and sedative techniques. Patients received either propofol (n=39) (fentanyl 10-15 microg kg(-1) and propofol 2-6 mg kg(-1) intraoperatively and a propofol infusion for 3 h postoperatively) or premedication with lorazepam followed by midazolam for anaesthesia (n=39) (fentanyl 10-15 microg kg(-1) and midazolam 0.05-0.075 mg kg(-1) intraoperatively and a midazolam infusion for 3 h postoperatively). Impairment of mental function was noted in 41% of patients in the propofol group and 83% in the lorazepam and midazolam group (P=0.001) 18 h after extubation. Patients in the propofol group were extubated earlier [1.4 (SD 0.6) vs 1.9 (0.8) h, P=0.02]; and reached standard intensive care unit discharge criteria [7.6 (4.6) vs 14.2 (13) h, P=0.02] and hospital discharge criteria [4.3 (1.0) vs 4.9 (1.1) days, P=0.04) sooner than patients in the lorazepam and midazolam group, but actual discharge times did not differ between the groups. Haemodynamic values were stable in both groups.

Non-steroidal anti-inflammatory drugs in treatment of postoperative pain after cardiac surgery

PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) are used as analgesic in postoperative pain to reduce opioid side effects, such as drowsiness and nausea. However, NSAIDs have not been used extensively in cardiac surgical patients due to the fear of untoward effects on gastric, renal, and coagulation parameters. This study will evaluate the efficacy and safety of three NSAIDs for pain control in CABG patients.

METHODS

One hundred and twenty patients scheduled for elective CABG surgery were enrolled in randomized, double blind, controlled study. Standardized fast track cardiac anesthesia was used. One dose of drug (75 mg diclofenac, 100 mg ketoprofen, 100 mg indomethacin, or placebo) was given pr one hour before tracheal extubation and a second dose 12 hr later. Pain was treated with morphine iv and acetaminophen po. Visual analogue pain scores were recorded at baseline, 3, 6, 12 and 24 hr after the first dose of drug.

RESULTS

There were no differences among the groups in pain scores. Only patients who received diclofenac required less morphine than patients in the control group (P < 0.05). When the total amounts of pain medications were computed to morphine equivalents, only patients in the diclofenac group received less pain medications than the placebo group (P < 0.05). Proportion of patients with postoperative increase of creatinine level (20% and over) did not differ between placebo and drug groups.

CONCLUSION

Non-steroidal anti-inflammatory drugs may be used for analgesia management post CABG surgery in selected patients. Diclofenac appears to have the best analgesic effects by reducing the morphine and other analgesic requirement postoperatively.

Acute graded hypercapnia increases collateral coronary blood flow in a swine model of chronic coronary artery obstruction

OBJECTIVE

To evaluate the effect of acute hypercapnia on regional myocardial blood flow in a swine model of chronic, single-vessel coronary artery obstruction. Permissive hypercapnia is being used frequently in critical care settings. One possible detrimental effect of hypercapnia is the initiation of coronary "steal" in patients with coronary artery disease. The effects of hypercapnia on collateral coronary blood flow in the setting of coronary obstruction have not been defined.

DESIGN

Prospective controlled experimental study.

SETTING

Institutional animal research facility.

SUBJECTS

Eight juvenile swine weighing 25-30 kg.

INTERVENTIONS

Collateral coronary circulation was induced in eight piglets by banding the proximal left anterior descending coronary artery for 8-10 wks followed by total ligation. Graded hypercapnia (mean Paco2, 81 torr [10.80 kPa; Paco2 = 81 torr] and 127 torr [16.93 kPa; Paco2 = 127 torr]) was induced by increasing inspiratory carbon dioxide under isoflurane anesthesia (1 minimum alveolar concentration).

MEASUREMENTS AND MAIN RESULTS

Animals were attached to instruments to measure pulmonary and systemic hemodynamics, regional myocardial blood flow, and cardiac output. Regional myocardial blood flow was determined using radiolabeled microspheres. Cardiac output, mean arterial pressure, and coronary perfusion pressure were unchanged at both levels of hypercapnia compared with baseline values. Heart rate was increased at Paco2 [HI] (p < .05). Regional blood flow was increased at both levels of hypercapnia in the collateral-dependent and normally perfused myocardium (p < .05; as high as 56% for subendocardium and as high as 106% for subepicardium at Paco2 [HI]). The intercoronary blood flow ratio remained unaltered. The transmural flow ratio was reduced at Paco2 [HI] (P < .05). During hypercapnia, regional lactate extraction remained unaltered, and regional oxygen extraction was unchanged or reduced despite the increase in oxygen consumption.

CONCLUSIONS

In this swine model of chronic single-vessel coronary artery obstruction, acute hypercapnia does not induce coronary steal from collateral-dependent myocardium, but it does increase global coronary blood flow.

Risk factors of delayed extubation, prolonged length of stay in the intensive care unit, and mortality in patients undergoing coronary artery bypass graft with fast-track cardiac anesthesia: a new cardiac risk score

BACKGROUND

Risk factors of delayed extubation, prolonged intensive care unit (ICU) length of stay (LOS), and mortality have not been studied for patients administered fast-track cardiac anesthesia (FTCA). The authors' goals were to determine risk factors of outcomes and cardiac risk scores (CRS) for CABG patients undergoing FTCA.

METHODS

Consecutive CABG patients undergoing FTCA were prospectively studied. Outcome variables were delayed extubation > 10 h, prolonged ICU LOS > 48 h, and mortality. Univariate analyses were performed followed by multiple logistic regression to derive risk factors of the three outcomes. Simplified integer-based CRS were derived from logistic models. Bootstrap validation was performed to assess and compare the predictive abilities of CRS and logistic models for the three outcomes.

RESULTS

The authors studied 885 patients. Twenty-five percent had delayed extubation, 17% had prolonged ICU LOS, and 2.6% died. Risk factors of delayed extubation were increased age, female gender, postoperative use of intraaortic balloon pump, inotropes, bleeding, and atrial arrhythmia. Risk factors of prolonged ICU LOS were those of delayed extubation plus preoperative myocardial infarction and postoperative renal insufficiency. Risk factors of mortality were female gender, emergency surgery, and poor left ventricular function. CRSs were modeled for the three outcomes. The area under the receiver operating characteristic curve for the CRS-logistic models was not significantly different: 0.707/0.702 for delayed extubation, 0.851/0.855 for prolonged ICU LOS, and 0.657/0.699 for mortality.

CONCLUSION

In CABG patients undergoing FTCA, the authors derived and validated risk factors of delayed extubation, prolonged ICU LOS, and mortality. Furthermore, they developed a simplified CRS system with similar predictive abilities as the logistic models.

Structural models for intermediate care areas

OBJECTIVE

To describe structural models of intermediate care units used for critically ill patients.

DATA SOURCES

Three multidisciplinary units with varying structures and functions of intermediate care areas (ICAs) are described.

DATA SYNTHESIS

Advantages and limitations for each of the three models are outlined. The structural models described are the conventional isolated ICA model, the parallel model, and the integrated model of ICA.

CONCLUSION

Each structural model has advantages and limitations. Selection of the appropriate ICA model for an institution depends on the specific circumstances and needs of the institution. Each of the three models can facilitate improved utilization of critical care resources.

Fast-track cardiac anesthesia in patients with sickle cell abnormalities

We conducted a retrospective review of 10 patients with sickle cell trait (SCT) and 30 patients (cohort control) without SCT undergoing first-time coronary artery bypass graft surgery with cardiopulmonary bypass. Demographic, perioperative management, and outcome data were collected. Both groups were matched according to age, weight, duration of surgery, and preoperative hemoglobin (Hb) concentration. Distribution of gender, medical conditions, pharmacological treatment, and preoperative left ventricular function were similar between the groups. The comparisons were analyzed in respect to postoperative blood loss and transfusion rates, as well as duration of intubation, intensive care unit, and hospital length of stay (LOS). All patients underwent fast-track cardiac anesthesia. A combination of cold crystalloid and blood cardioplegia was used. The lowest nasopharyngeal temperature was 33 degrees C. There were no episodes of significant hypoxemia, hypercarbia, or acidosis. None of the patients had sickling crisis during the perioperative period. The postoperative blood loss was 687 +/- 135 vs 585 +/-220 mL in the SCT and control groups, respectively. The trigger for blood transfusion during cardiopulmonary bypass was hematocrit <20% and Hb <75 g/L postoperatively. Three SCT patients (30%) and 10 control patients (33%) received a blood transfusion. Median extubation time was 4.0 vs 3.9 h; intensive care unit LOS was 27 vs 28 h; and hospital LOS was 6.0 vs 5.5 days in the SCT and control groups, respectively. There were no intraoperative deaths. One patient in the SCT group died from multiorgan failure 2 mo after surgery.

IMPLICATIONS

Fast-track cardiac anesthesia can be used safely in patients with sickle cell trait undergoing first-time coronary artery bypass graft surgery. Extubation time and intensive care unit and hospital length of stay are comparable to those of matched controls, and blood loss and transfusion requirements are not increased. A hematocrit of 20% seems to be a safe transfusion trigger during cardiopulmonary bypass in these patients.

Gas exchange and hemodynamics in experimental pleural effusion

OBJECTIVE

To investigate the cardiorespiratory effects of graded bilateral pleural effusions in the anesthetized pig.

DESIGN

Prospective, randomized, controlled, laboratory study.

SETTING

Animal laboratory.

SUBJECTS

Eleven male Yorkshire pigs.

INTERVENTIONS

Animals were anesthetized using inhaled isoflurane. Orotracheal intubation was followed by mechanical ventilation. Bilateral chest tubes were inserted, and graded increasing pleural effusions were created using saline of 0, 20, 40, and 80 mL/kg, divided equally between each side. At each pleural volume, intravascular volume was randomly altered (by phlebotomy or transfusion of colloid) to normal (unchanged), low (decreased by 10 mL/kg), or high (increased by 10 mL/kg).

MEASUREMENTS AND MAIN RESULTS

Hemodynamic parameters, intrapleural pressures, hemoglobin, and blood gases were measured. At the lowest volume of pleural fluid, PaO2 was reduced by approximately 50% vs. baseline, whereas systemic hemodynamics were unchanged. PaO2 was reduced in a dose-dependent fashion as pleural volume increased but was not affected by alterations in intravascular volume. Intrapulmonary shunt was increased both by intrapleural volume in a dose-dependent fashion and by increases in intravascular volume at high levels of pleural volume. Cardiac output and systemic mean arterial pressure increased with elevated intravascular volume but were not influenced by lower levels of intrapleural volume. Mean pulmonary arterial pressure, central venous pressure, and pulmonary artery occlusion pressure were increased by elevations in both intrapleural volume and intravascular volume. Intrapleural pressure and pulmonary vascular resistance were related to intrapleural volume only.

CONCLUSIONS

Hypoxemia occurs as an early event in acute bilateral pleural effusions and precedes hemodynamic decompensation. Oxygenation is independent of intravascular filling pressures, but hemodynamics are preserved with elevated filling pressures. Clinical studies should be undertaken to examine the risks/benefits of careful removal of pleural fluid in patients with pleural effusions, when oxygenation is impaired during mechanical ventilation.

Morbidity outcome in patients with hypertrophic obstructive cardiomyopathy undergoing cardiac septal myectomy: early-extubation anesthesia versus high-dose opioid anesthesia technique

OBJECTIVE

Anesthetic management of patients with hypertrophic obstructive cardiomyopathy (HOCM) undergoing septal myectomy is challenging. The morbidity outcome of early-extubation anesthesia (EEA), or fast tracking, versus high-dose opioid (HDO) anesthesia was studied.

DESIGN

Retrospective study.

SETTING

University teaching hospital.

PARTICIPANTS

One hundred seventy-five cardiac septal myectomy patients (EEA, n = 53; HDO, n = 122).

INTERVENTIONS

EEA technique consisted of low-dose fentanyl, 10 to 15 microg/kg; propofol infusion; midazolam; and inhalation agent. HDO technique consisted of fentanyl, 50 to 100 microg/kg, and benzodiazepines, with or without an inhalation agent. Demographic data, preoperative symptoms, and data on anesthesia management and postoperative complications were recorded.

MEASUREMENTS AND MAIN RESULTS

There were no differences between the groups (EEA v HDO, respectively) regarding age, sex, preoperative symptoms (dyspnea, 89% v 79%; palpitations, 28% v 26%; angina, 47% v 61%; syncope, 47% v 41%), redo surgery, or combined surgery. Mean +/- standard deviation time to tracheal extubation was 7.2 +/- 5.3 hours in EEA versus 19.4 +/- 10.5 hours in HDO patients (p < 0.0001). Intensive care unit (ICU) stay was significantly shorter in EEA versus HDO patients (2.2 v 3.0 days; p < 0.005), with the trend toward earlier hospital discharge (9.7 v 11.3 days; p = 0.09). There was a high requirement for temporary pacing in both groups immediately postoperatively (EEA, 60% v HDO, 48%; p > 0.08). Permanent pacemaker insertion postoperatively was required in 7 of 53 patients (13%) in the EEA group and 11 of 122 patients (9%) in the HDO group (p > 0.25). Atrial arrhythmias occurred postoperatively in 25% of EEA patients versus 34% of HDO patients (p > 0.08).

CONCLUSION

EEA facilitates earlier tracheal extubation by 12 hours in patients with HOCM undergoing septal myectomy, significantly shortening ICU stay by 1 day without increasing perioperative cardiac morbidity or mortality.

Impact of early tracheal extubation on hospital discharge

Economic realities of the continuing increased utilization of cardiac surgery in the 1990s have led to the practice of early tracheal extubation and shortening of the length of intensive care unit and hospital stays. In this era of cost-containment and physician report cards, we are held accountable for patients' outcome in terms of mortality, morbidity, quality of life, length of stay, and cost of care. This report outlines the factors that influence costs of cardiac surgery. These include patient risk, anesthesia, surgical, intensive care unit, and health care systems or hospital factors. The current literature on outcome, utilization, and cost implications of early tracheal extubation in cardiac surgery is summarized and discussed. It has been demonstrated that early extubation anesthesia is safe and cost-effective and can improve resource utilization in cardiac surgery, but to achieve a maximum cost benefit from fast-track or early extubation anesthesia in cardiac patients, team organization of a fast-track cardiac surgery program must be implemented. A perioperative clinical pathway management in fast-track cardiac surgery is presented.

The effect of three different doses of tranexamic acid on blood loss after cardiac surgery with mild systemic hypothermia (32 degrees C)

OBJECTIVE

Prophylactic administration of tranexamic acid (TA), an antifibrinolytic agent, decreases bleeding after cardiac surgery with systemic hypothermia (25 degrees C to 29 degrees C). Warmer systemic temperatures during cardiopulmonary bypass (CPB) may reduce bleeding and thus alter the requirement for TA. The effect of three different doses of TA on bleeding after cardiac surgery with mild systemic hypothermia (32 degrees C) is evaluated.

DESIGN

Double-blind, prospective, randomized study.

SETTING

University hospital.

PARTICIPANTS

One hundred fifty adult patients undergoing aortocoronary bypass or valvular cardiac surgery.

INTERVENTIONS

Patients received TA, 50 (n = 50), 100 (n = 50), or 150 (n = 50) mg/kg intravenously before CPB with mild systemic hypothermia.

MEASUREMENTS AND MAIN RESULTS

Blood loss through chest drains over 6, 12, and 24 hours after surgery and total hemoglobin loss were measured. Autotransfused blood, transfused banked blood and blood products, and coagulation profiles were measured. Analysis of variance on log-transformed data for blood loss and confidence intervals (CIs) of 0.95 were calculated and transformed to milliliters of blood. No patient was re-explored for bleeding. Blood loss at 6 hours was statistically greater in the 50-mg/kg group compared with the other two groups (p = 0.03; p = 0.02). Total hemoglobin loss was statistically greater in the 50-mg/kg group compared with the 150-mg/kg group (p = 0.04). There was no statistical difference in blood tranfusion rate or coagulation profiles among the three groups. However, preoperative hemoglobin level was statistically lower in the 150-mg/kg group compared with the other two groups (p = 0.01).

CONCLUSION

Of the three doses of TA studied, the most efficacious and cost-effective dose to reduce bleeding after cardiac surgery with mild hypothermic systemic perfusion is 100 mg/kg.

Intraoperative awareness in fast-track cardiac anesthesia

BACKGROUND

Fast-track cardiac anesthesia, using low-dose narcotics combined with short-acting anesthetic and sedative agents, facilitates early tracheal extubation after cardiac surgery. The incidence of awareness with this anesthetic technique has not been investigated previously. The purpose of this study was to prospectively investigate the incidence of intraoperative awareness with explicit memory of events during fast-track cardiac anesthesia.

METHODS

Data were collected prospectively over a 4-month period from 617 consecutive adult patients undergoing cardiac surgery at a university hospital. All patients received a fast-track cardiac anesthetic regimen. Patients underwent a structured interview by a research nurse 18 h after extubation. A standard set of questions was asked during this interview to determine if the patient had explicit memory of any event from induction of anesthesia to recovery of consciousness.

RESULTS

Nine patients did not complete a postoperative interview because of death (n = 7) or postoperative confusion (n = 2). The last memory before surgery reported in 420 (69.1%) patients was waiting in the holding area at the operating suite, and in the remaining 188 (30.9%) patients it was lying on the operating table before induction of anesthesia. Two patients (0.3%) had explicit memory of intraoperative events. One of the two patients also had explicit memory of pain. Neither patient reported adverse psychological sequelae.

CONCLUSIONS

The authors report an incidence of awareness in fast-track cardiac anesthesia of 0.3%. This is the lowest incidence of awareness currently reported during cardiac surgery. This low incidence of awareness may be related to the use of a balanced anesthetic technique involving the continuous administration of volatile (isoflurane) or intravenous (propofol) anesthetic agents before, during, and after cardiopulmonary bypass.

Epidural bupivacaine-morphine analgesia versus patient-controlled analgesia following abdominal aortic surgery: analgesic, respiratory, and myocardial effects

BACKGROUND

The efficacy and effects of epidural analgesia compared with patient-controlled analgesia (PCA) have not been reported in patients undergoing major vascular surgery. We compared the effects of epidural bupivacaine-morphine with those of intravenous PCA morphine after elective infrarenal aortic surgery.

METHODS

Forty patients classified as American Society of Anesthesiologists physical status 2 or 3 received general anesthesia plus postoperative PCA using morphine sulfate (group PCA; n = 21) or general anesthesia plus perioperative epidural morphine-bupivacaine (group EPI; n = 19) during a period of 48 h. During operation, EPI patients received 0.05 mg/kg epidural morphine and 5 ml 0.25% bupivacaine followed by an infusion of 0.125% bupivacaine with 0.1% morphine (0.1 mg/ ml); group PCA received 0.1 mg/kg intravenous morphine sulfate. Continuous electrocardiographic monitoring (V4 and V5 leads) was performed from the night before surgery until 48 h afterward. Respiratory inductive plethysmographic data were recorded after tracheal extubation. Visual analog pain scores at rest and after movement were performed every 4 h after extubation.

RESULTS

Nurse-administered intravenous morphine and time to tracheal extubation were less in group EPI, as were visual analog pain scores at rest and after movement from 20 to 48 h. Complications and the duration of intensive care unit and hospital stay were comparable. There was a similar, low incidence of postoperative apneas, slow respiratory rates, desaturation, and S-T segment depression.

CONCLUSIONS

Epidural morphine-bupivacaine is associated with reduced early postoperative intravenous opioid requirements, more rapid tracheal extubation, and superior analgesia after abdominal aortic surgery, with comparable respiratory effects.

Fast-track cardiac surgery: economic implications in postoperative care

Economics is the main driving force in changing health care delivery in the 90s. The motto is to "do more with less." Cost containment and efficient resource utilization swing the pendulum back to the debate of early tracheal extubation in cardiac surgical patients. Recently, it has been confirmed that fast-track cardiac anesthesia is both safe and cost-effective. This article describes the economic implications in postoperative care of fast-track cardiac surgery. First, the developments of early extubation postcardiac surgery and the factors that influence costs of cardiac surgery are reviewed. Second, the morbidity outcome, utilization, and cost implications of early extubation in cardiac surgery are summarized. The perioperative cost analysis in fast-track cardiac surgery, including the cost of complications and resource utilization, is outlined. Lastly, it is important to realize that early extubation does not necessarily mean earlier intensive care unit or hospital discharge. To achieve a maximum cost benefit from early extubation, team organization of a fast-track cardiac surgery program for the perioperative management of these patients is detailed.

Comparison of lorazepam alone vs lorazepam, morphine, and perphenazine for cardiac premedication

PURPOSE

To compare the effects of two premedication regimens on cardiorespiratory variables, sedation, and anxiety in patients scheduled for coronary artery bypass graft (CABG) surgery.

METHODS

This was a prospective randomized, double-blind clinical trial. Sixty-eight patients were monitored for 1.5 hr before and 2.0 hr after premedication with lorazepam (0.03 mg.kg-1 sl), morphine (0.15 mg.kg-1 im), and perphenazine (0.05 mg.kg-1 im) [Group 1], or with lorazepam (0.03 mg.kg-1 sl) and saline (1.5 ml im) [Group 2]. All were continuously monitored with a 12-lead ECG ST monitors, respiratory inductive plethysmography (RIP), digital pulse oximetry, intra-arterial blood pressure, and arterial blood gas analysis. Sedation and anxiety scores were also recorded.

RESULTS

The incidence and duration of myocardial ischaemia was low and similar in Groups 1 and 2. Patients in Group 1, but not in Group 2, had a greater number of events (P < 0.04) and duration (P < 0.02) of O2 desaturation; higher PaCO2 (P < 0.001), and more haemodynamic events (P < 0.006) after premedication when compared with baseline. There was no difference in RIP or ECG variables between the two groups. Following premedication, both groups reported reduced anxiety scores and elevated sedation scores (P < 0.01), with sedation greater in Group 1 than in Group 2 (P < 0.01).

CONCLUSION

In CABG patients, premedication with lorazepam provides adequate anxiolysis and sedation, and the addition of morphine and perphenazine results in elevated PaCO2, arterial haemoglobin desaturation, and potentially adverse haemodynamic changes.

Early tracheal extubation after coronary artery bypass graft surgery reduces costs and improves resource use. A prospective, randomized, controlled trial

BACKGROUND

Economics has caused the trend of early tracheal extubation after cardiac surgery, yet no prospective randomized study has directly validated that early tracheal extubation anesthetic management decreases costs when compared with late extubation after cardiac surgery.

METHODS

This prospective, randomized, controlled clinical trial was designed to evaluate the cost savings of early (1-6 h) versus late tracheal extubation (12-22 h) in patients after coronary artery bypass graft (CABG) surgery. The total cost for the services provided for each patient was determined for both the early and late groups from hospital admission to discharge home. All costs applicable to each of the services were classified into direct variables, direct fixed costs, and overhead (an indirect cost). Physician fees and heart catheterization costs were included. The total service cost was the sum of unit workload and overhead costs.

RESULTS

One hundred patients having elective CABG who were younger than 75 yr were studied. Including all complications, early extubation (n = 50) significantly reduced cardiovascular intensive care unit (CVICU) costs by 53% (P < 0.026) and the total CABG surgery cost by 25% (P < 0.019) when compared with late extubation (n = 50). Forty-one patients (82%) in each group were tracheally extubated within the defined period. In the early extubation group, the actual departmental cost savings in CVICU nursing and supplies was 23% (P < 0.005), in ward nursing and supplies was 11% (P < 0.05), and in respiratory therapy was 12% (P < 0.05). The total cost savings per patient having CABG was 9% (P < 0.001). Further cost savings using discharge criteria were 51% for CVICU nursing and supplies (P < 0.001), 9% for ward nursing and supplies (P < 0.05), and 29% for respiratory therapy (P < 0.001), for a total cost savings per patient of 13% (P < 0.001). Early extubation also reduced elective case cancellations (P < 0.002) without any increase in the number of postoperative complications and readmissions.

CONCLUSIONS

Early tracheal extubation anesthetic management reduces total costs per CABG surgery by 25%, predominantly in nursing and in CVICU costs. Early extubation reduces CVICU and hospital length of stay but does not increase the rate or costs of complications when compared with patients in the late extubation group. It shifts the high CVICU costs to the lower ward costs. Early extubation also improves resource use after cardiac surgery when compared with late extubation.

Cocaine toxicity and isoflurane anesthesia: hemodynamic, myocardial metabolic, and regional blood flow effects in swine

OBJECTIVES

Increasing numbers of people use cocaine recreationally and may require anesthesia care, having recently abused the drug. However, no data currently exist concerning potential interactions between toxic levels of cocaine and volatile anesthetic agents. This study investigated the effects of cocaine infusion on systemic hemodynamics, myocardial metabolism, and regional organ blood flow in relation to depth of isoflurane anesthesia.

DESIGN

Prospective, randomized, controlled trial.

SETTING

A laboratory at a university medical center.

PARTICIPANTS

Twelve miniature pigs.

INTERVENTIONS

An open-chest swine model was used. Isoflurane (ISO) was the sole anesthetic, administered at 0.75 and 1.5 minimum alveolar concentration (MAC), and cocaine was infused (n = 6) at a rate of 0.5 mg/kg/min. Control animals (n = 6) received an equivalent amount of normal saline.

MEASUREMENTS AND MAIN RESULTS

Systemic and pulmonary arterial pressures and thermodilution cardiac output data were collected at 0.75 MAC and 1.5 MAC ISC. Regional myocardial and blood flows to other organs were measured using radiolabeled microspheres. Arrhythmias and altered ventricular conduction were noted only in the cocaine group, along with significant elevations in diastolic arterial pressure, coronary perfusion pressure, and systemic vascular resistance. Increased subendocardial blood flow occurred during cocaine infusion (p = 0.03); subepicardial perfusion was unchanged. Cerebral (p < 0.01) and spinal cord (p < 0.05) blood flows were reduced in animals receiving cocaine. Other organ blood flows were unchanged with depth of anesthesia or cocaine administration, with the exception of splenic blood flow (p < 0.04).

CONCLUSIONS

Moderately toxic cocaine levels occurring during isoflurane at 0.75 MAC and 1.5 MAC are associated with hemodynamic abnormalities, a marked increase in systemic vascular resistance, and a tendency to produce cardiac arrhythmias. A reversal of endo/epicardial myocardial perfusion ratio occurs associated with cocaine infusion during ISO anesthesia. This is probably not related to a primary redistribution of subendocardial blood flow and may be related to a combination of increased myocardial oxygen demand and epicardial coronary vasoconstriction. The reductions in cerebral and spinal cord perfusion observed may explain, in part, the neurologic sequelae of cocaine toxicity.

Morbidity outcome in early versus conventional tracheal extubation after coronary artery bypass grafting: a prospective randomized controlled trial

INTRODUCTION

We undertook a prospective, randomized, controlled clinical trial to evaluate morbidity outcomes and safety of a modified anesthetic technique to provide shorter sedation and early extubation (1 to 6 hours) than those of the conventional anesthetic protocol used for prolonged sedation and extubation (12 to 22 hours) in patients after coronary artery bypass grafting.

METHODS

One hundred twenty patients undergoing elective coronary artery bypass grafting were prospectively assigned randomly to either an early extubation group (n = 60; 15 micrograms.kg-1 fentanyl and 2 to 6 mg.kg-1.hour-1 propofol and isoflurane) or to a conventional extubation group (n = 60; 50 micrograms.kg-1 fentanyl and 0.1 mg.kg-1 midazolam and isoflurane). Cardiac morbidity (postoperative myocardial ischemia, postoperative myocardial infarction, and perioperative sympathoadrenal stress response), respiratory morbidity (postextubation apnea, alveolar-arterial oxygen gradient, pulmonary shunting, oxygen consumption, atelectasis, and reintubation), hemodynamic values and vasoactive medication requirements, intraoperative awareness, postoperative cognitive function, 30 day mortality, and intensive care unit and hospital lengths of stay were compared between the two groups.

RESULTS

Fifty-one of the 60 patients in each group (85%) were extubated within the defined time period. Postoperative extubation time and intensive care unit and hospital lengths of stay were significantly shorter in the early group. At 48 hours after operation, there were no significant differences between the two groups in myocardial ischemia incidences, ischemia burdens, or creatine kinase isoenzyme MB levels. Four patients in the conventional group, but not in the early group, had postoperative myocardial infaction. The extubation anesthetics used were effective in suppressing the perioperative plasma catecholamine stress response in both groups. Postextubation apnea characteristics were similar between the groups. Intrapulmonary shunt fraction improved significantly in the early group at 4 hours after extubation. The incidences and degree of atelectasis did not differ significantly between the two groups. The incidences of treated postoperative complications were comparable between the two groups, but three patients in the conventional group died as a result of stroke or postoperative myocardial infarction.

CONCLUSION

Early extubation after coronary artery bypass grafting is safe and does not increase perioperative morbidity. There is an improvement in postextubation intrapulmonary shunt fraction and a reduction in intensive care unit and hospital lengths of stay.

Comparison of nifedipine and metoprolol on collateral coronary blood flow in a swine model of chronic coronary obstruction and acute ischaemia during isoflurane anaesthesia

PURPOSE

This study compared the effects of nifedipine and metoprolol on collateral-dependent myocardial blood flow in a swine model of chronic coronary obstruction and acute ischaemia during isoflurane anaesthesia.

METHODS

Collateral coronary circulation was induced in 15 three-week-old piglets by banding of the proximal left anterior descending coronary artery (LAD). After 8-10 wk, the distal LAD was ligated and the open-chest pigs were randomized to receive infusions of either saline, nifedipine (5 micrograms.kg-1.min-1) or metoprolol (10 micrograms.kg-1.min-1) for 30 min during isoflurane anaesthesia (2%). Transient ischaemia was induced by 30 sec occlusion of the left circumflex artery. Arterial blood pressures, heart rate and regional myocardial blood flow (radiolabelled microspheres technique) were measured at the end of drug infusion (baseline) and one minute after transient ischaemia.

RESULTS

No differences in the blood flow to the collateral-dependent (CD) myocardium or haemodynamic variables were observed at baseline among the three groups. Following transient ischaemia, in the nifedipine but not in the metoprolol group, blood flow to the CD myocardium was reduced by 28 +/- 24% in the epicardium (P < 0.05) and 56 +/- 20% in the endocardium (P < 0.01), resulting from intercoronary and transmural steal. This was associated with a moderate increase (10%, P < 0.05) in the heart rate in the nifedipine group.

CONCLUSIONS

In a swine model of chronic coronary obstruction and acute ischaemia during isoflurane anaesthesia, the collateral coronary blood flow was maintained in the presence of metoprolol, but reduced in the presence of nifedipine following transient ischaemia due to intercoronary and transmural steal.

Pro: early extubation after cardiac surgery decreases intensive care unit stay and cost

The recurrent or new trends of early extubation after cardiac surgery are here to stay in the 1990s. The preoperative status does not necessarily predict the postoperative course and prolonged mechanical ventilation following cardiac surgery should not be uncritically considered as routine. All patients should be assessed for tracheal extubation at the earliest opportunity when the criteria are met in the ICU. Early extubation post-cardiac surgery does reduce ICU and hospital length of stay and costs. It also allows early ICU discharge and reduces case cancellations without any increase in postoperative complications and readmission. These studies have emphasized that the change in the process of care to early extubation can affect patient outcome as well as costs in cardiac patient care. The substantial difference in cost savings per cardiac case between "criteria discharge" and "actual discharge" points out the importance of the organization of the process of care being delivered. To achieve maximum cost benefit from early extubation in cardiac patients, the organization of the perioperative management of these patients must be optimized. This process of care includes intraoperative anesthetic modification; organization of ICU and staff expertise; postoperative early extubation and management; acute pain service; ICU discharge policy; utilization of step-down unit and surgical ward; and communication among cardiac patient management teams (cardiovascular surgeon, cardiac anesthesiologist, ICU staff, nurses, respiratory therapists, physiotherapists, and social workers), which are all vital to the success of such a program.

A prospective randomized double-blinded study of the effect of intravenous fluid therapy on adverse outcomes on outpatient surgery

This study investigated the impact of perioperative fluid status on adverse clinical outcomes in ambulatory surgery. Two hundred ASA grade I-III ambulatory surgical patients were prospectively randomized into two groups to receive high (20 mL/kg) or low (2 mL/kg) infusions of isotonic electrolyte solution over 30 min preoperatively. A standardized balanced anesthetic was used. A minimal amount of fluid was given during the intraoperative and postoperative periods. Adverse outcomes were assessed by an investigator blinded to the fluid treatment group at 30 and 60 min after surgery, at discharge, and the first postoperative day. The incidence of thirst, drowsiness, and dizziness was significantly lower in the high-infusion group at all intervals. We recommend perioperative hydration of 20 mL/kg for patients undergoing general anesthesia for short ambulatory surgery.

Amrinone therapy for severe pulmonary hypertension and biventricular failure after complicated valvular heart surgery

We report two cases in which amrinone was used effectively, in addition to the conventional sympathomimetic drug, for the emergence from cardiopulmonary bypass following complicated valvular heart surgery in patients who had severe pulmonary hypertension and biventricular failure. Amrinone was used in combination with isoproterenol in one and dopamine in the other case. The clinical changes were brought about by a 21.5 percent and 53.5 percent decrease in pulmonary blood pressure and pulmonary vascular resistance, respectively. Concomitantly, the mean systemic blood pressure was increased by 50 percent, whereas heart rate decreased by 17.5 percent. This report demonstrates that amrinone can be life-saving in patients with biventricular failure and severe pulmonary hypertension not responding to conventional beta-adrenergic and vasodilator drug therapy.

Anaesthesia for non-cardiac surgery in heart-transplanted patients

This review documents the anaesthetic management, haemodynamic function and outcome in 18 of 86 heart-transplanted recipients, who returned for 32 non-cardiac surgical procedures at the Toronto Hospital from 1985 to 1990. General anaesthesia was administered in eight of the 27 elective operations and four of the five emergency operations. Induction medications included thiopentone (2-4 mg.kg-1), fentanyl (1-7 micrograms.kg-1) and succinylcholine (1-1.5 mg.kg-1). Anaesthesia was maintained with a combination of oxygen/nitrous oxide and isoflurane or enflurane. Muscle relaxation was maintained with vecuronium or pancuronium. No delayed awakening or unplanned postoperative ventilation was observed. Neurolept-anaesthesia was administered to 63.0% and 20.0% of the elective and emergency operations, respectively. The anaesthetics included fentanyl (25-100 micrograms) and midazolam (0.5-1.5 mg) or diazemuls (2.5-5.0 mg). Spinal anaesthesia (75 mg lidocaine) was administered to only two of the 27 elective operations. No important haemodynamic changes were observed in any anaesthetic group, but lower systolic BP was found after induction and during maintenance periods in the patients who received general anaesthesia than in those who received neurolept-anaesthesia. However, no anaesthesia-related morbidity or mortality was noted. This suggests that general, neurolept- and spinal anaesthesia do not affect haemodynamic function or postoperative outcome in heart-transplanted recipients undergoing subsequent non-cardiac surgery.

Supplemental oxygen does not reduce myocardial ischemia in premedicated patients with critical coronary artery disease

This randomized, prospective clinical study investigated the effects of supplemental inspired oxygen on arterial hemoglobin desaturation and myocardial ischemia in premedicated patients who have critical coronary artery stenosis, identified predictors for these adverse events, and examined the temporal relationship between hemoglobin desaturation and myocardial ischemia. Before elective coronary artery bypass surgery, 104 patients were monitored continuously by using a real-time electrocardiogram (V4 and V5 leads) recorder and a digital pulse oximeter. After a 2-h baseline monitoring period (Interval A), patients were given sublingual lorazepam 0.03 mg/kg, and were randomized to receive continuous supplemental inspired oxygen by nasal catheters [4 L/min (Oxygen Group, n = 52)] or to receive no supplemental inspired oxygen (Control Group, n = 52) (Interval B). One hour later, all patients received intramuscular morphine 0.15 mg/kg with perphenazine 0.05 mg/kg (Interval C). Interval C lasted 1 h, and the study was terminated. In the Oxygen Group, the incidence of desaturation was 25% before premedication and 11.5% after premedication (NS). In the Control Group after premedication, the incidence of desaturation increased from 25% to 56.9% (P < 0.001). There was no significant difference in the incidence of myocardial ischemia before or after premedication within or between the two groups. Arterial hemoglobin desaturation was not associated temporally with myocardial ischemia at any time. Predictors of desaturation after premedication included absence of supplemental O2, increased weight, age, and occurrence of desaturation before premedication. There were no identifiable predictors for myocardial ischemia after premedication. During Intervals A and C, episodes of hemoglobin desaturation were associated with small but statistically significant increases in mean heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-response relationship of isoflurane and halothane versus coronary perfusion pressures. Effects on flow redistribution in a collateralized chronic swine model

The authors studied the redistribution of myocardial blood flow in a collateral-dependent (CD) zone as a function of coronary perfusion pressure (CPP) during isoflurane and halothane anesthesia. A swine model with CD myocardium distal to a chronically occluded left anterior descending coronary artery was developed and studied. Sixteen piglets were allowed to grow for 8-10 weeks after banding of the left anterior descending coronary artery. They were randomly anesthetized with either isoflurane (n = 8) or halothane (n = 8) as the sole anesthetic, which was used to regulate specific CPP. The resultant regional myocardial blood flows were measured using radiolabeled microspheres. Four randomly allocated CPPs, of 30, 40, 45, and 55 mmHg, were studied in each animal. Four additional collateralized animals were anesthetized with alpha-chloralose, and the same CPPs were obtained using an intravenous adenosine infusion (1-5 microM kg-1) to validate this model. There was a proportional decrease in heart rate and blood pressure in both the isoflurane and and the halothane group with CPP. Cardiac output was significantly decreased in the halothane group at 30 mmHg when compared to 55-mmHg CPP, but it was maintained in the isoflurane group. Systemic vascular resistance was significantly lower in the isoflurane group at 30 and 40 mmHg when compared to 55-mmHg CPP. Both the isoflurane and the halothane group showed a proportional and significant decrease in endo-, mid-, and epicardial blood flows at 30-mmHg CPP when compared to baseline. In both CD and normal perfusion zones, isoflurane consistently sustained a higher endocardial blood flow than halothane (5.7-41.1%).(ABSTRACT TRUNCATED AT 250 WORDS)

Postoperative haemodynamic and pharmacological responses in patients with positive technetium pyrophosphate single-photon emission computed tomography following CABG

The aim of this prospective study was to evaluate the postoperative haemodynamic variables and medication requirements in patients with perioperative myocardial infarction (PMI), following elective coronary artery bypass graft (CABG) surgery, as documented by technetium pyrophosphate scintigraphy using single-photon emission computed tomography (TcPPi-SPECT). A high-dose fentanyl anaesthetic technique was applied. Twelve of 58 patients (21%) developed PMI with an infarcted myocardial mass of 35.7 +/- 3.9 g. Over the 48 hr postoperative period, patients with positive TcPPi-SPECT (n = 12) did not differ from those with negative TcPPi-SPECT (n = 46) in mean heart rate (below 100 bpm), systolic blood pressure (100-120 mmHg) or central venous pressure (8-16 mmHg). However, patients with positive TcPPi-SPECT had higher pulmonary artery diastolic pressures at 5-8 hr after surgery. No differences were found in the incidence and dosage requirements for postoperative sedative or vasoactive drugs (morphine, diazepam, propranolol, lidocaine, nitroglycerin and nitroprusside) between the two groups. There was no difference in the incidence of dopamine requirement between the groups (positive-scan: 16.7%, negative-scan: 13.0%). However, the dopamine dosage for inotropic support was higher in the positive TcPPi-SPECT group over 24 hr (318.5 +/- 125.2 mg vs 71.2 +/- 24.7 mg, P less than 0.05) and 48 hr (869.1 +/- 19.0 mg vs 142.3 +/- 49.4 mg, P less than 0.001) periods after surgery. We postulate that careful control of postoperative haemodynamic variables did not prevent but may limit the extent of PMI in elective CABG patients.

Analgesic and pulmonary effects of continuous intercostal nerve block following thoracotomy

This study examined the beneficial effects and potential systemic toxicity from continuous intercostal nerve block by repeated bolus injections of bupivacaine. In this double-blind, randomized study, 20 post-thoracotomy patients were assigned to receive four doses of either: 20 ml 0.5% bupivacaine with epinephrine 5 micrograms.ml-1 (bupivacaine group, n = 10), or 20 ml preservative-free saline (placebo group, n = 10) through two indwelling intercostal catheters every six hours. Patients receiving intercostal bupivacaine injections had greater decreases in visual analogue pain scores (VAS) (P less than 0.05) and lower 24 hr morphine requirements, 16.6 +/- 4.6 mg vs 35.8 +/- 7.2 mg, than patients in the placebo group (P less than 0.05). Higher post-injection values of forced expiratory volume in one second, forced vital capacity and peaked expiratory flow rate were also observed in the bupivacaine group (P less than 0.01). Repeated intercostal bupivacaine administration did lead to systemic accumulation, but the peak bupivacaine level after 400 mg was low at 1.2 +/- 0.2 microgram.ml-1. Thus, the technique of continuous intercostal nerve block described in this study is an effective treatment for the control of post-thoracotomy pain.

Differential effect of oncotic pressure on cerebral and extracerebral water content during cardiopulmonary bypass in rabbits

To study the effect of oncotic pressure on brain water content during cardiopulmonary bypass (CPB), 14 anesthetized New Zealand White rabbits underwent 60 min of nonpulsatile CPB at normothermia. Animals were grouped according to the composition of the circuit priming fluid. Group 1 animals (n = 7) received a priming fluid (6.5% hydroxyethyl starch in 0.72 N NaCl; 323 +/- 13 mOsm/kg [mean +/- SD]) that maintained normal colloid oncotic pressure (COP) during CPB (19.0 +/- 1.5 mmHg). Group 2 animals (n = 7) received a priming fluid (0.9 N NaCl; 324 +/- 23 mOsm/kg) that led to a hypooncotic state (COP = 6.2 +/- 1.2 mmHg). Blood chemistries and hemodynamics were recorded every 15 min during CPB. Animals were given additional priming fluid and sodium bicarbonate during CPB to maintain a circuit flow of 85 ml.kg-1.min-1 and arterial pH greater than 7.35. There were no significant differences between groups 1 and 2 with respect to temperature, central venous pressure, mean arterial pressure, PaO2, PaCO2, plasma sodium concentration, or osmolality at any time during CPB, although osmolality increased in both groups. After 60 min of bypass, animals were killed and organ water contents were determined by wet/dry weight ratios. A separate group of nine similarly prepared and anesthetized animals that did not undergo cannulation or CPB also underwent measurement of plasma chemistries and tissue water contents and served as nonbypass controls (group 3). Brain and kidney water contents were unaffected by oncotic pressure, whereas duodenum and skeletal muscle had significantly greater water content (P = 0.003 and P = 0.008, respectively) after hypooncotic CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Low-dose sufentanil and lidocaine supplementation of general anaesthesia

This randomized double-blind study compared the effects of: (1) saline infusion (C); (2) sufentanil alone (1.0 micrograms.kg-1) (S); and (3) low-dose sufentanil (0.5 micrograms.kg-1) in combination with lidocaine (1.5 mg.kg-1) (LS): on the cardiovascular responses to tracheal intubation and on postoperative ventilation as monitored by respiratory inductive plethysmography in day-care surgical procedures of approximately 60 min duration. Thirty healthy, unpremedicated patients were studied. Thiopentone requirements were reduced by 40 and 28 per cent in the S and LS groups respectively compared with control (P less than 0.001). Both treatments suppressed HR and BP responses (P less than 0.005) to intubation. Postoperatively, PaCO2 was elevated (P less than 0.05) in group S. Dose-related respiratory depression was observed. The incidence of postoperative apnoea was significantly higher in both S and LS groups than compared with control (P less than 0.05). However, only patients in group S showed higher apnoea index and mean apnoea duration over the initial 10-20 min after surgery compared with control (P less than 0.005). In addition, group S showed slower respiratory frequency and prolonged expiratory time (P less than 0.005). In conclusion, an induction dose of sufentanil (1 microgram.kg-1) used in balanced anaesthesia of less than 70 min duration was associated with significant respiratory depression, particularly during the initial 10-20 min after surgery, whereas low-dose sufentanil (0.5 micrograms.kg-1) with lidocaine (1.5 mg.kg-1) had minimal postoperative respiratory depression and comparable attenuation of pressor responses to intubation.

A randomized comparison of midazolam and diazepam injectable emulsion in cataract surgery

The purpose of this study was to compare the psychomotor recovery of patients sedated with either midazolam or Diazemuls using the digit symbol substitution test and the Trieger test. Sixty patients were allocated in random double-blind fashion to receive either midazolam or diazepam in oil emulsion (Diazemuls) as intravenous sedation for cataract surgery. Both groups received fentanyl 0.5 micrograms.kg-1 IV. Tests of cognition were performed by the patients prior to sedation and at half-hourly intervals for three hours after cataract surgery. In a dose ratio of 1:4, midazolam was found to produce better sedation but more prolonged recovery than Diazemuls. Anterograde amnesia was comparable in the two groups, while more patients in the Diazemuls group developed episodes of apnoea and venous irritation.

Postoperative myocardial infarction documented by technetium pyrophosphate scan using single-photon emission computed tomography: significance of intraoperative myocardial ischemia and hemodynamic control

The aim of this prospective study was to document postoperative myocardial infarction (PMI) by technetium pyrophosphate scan using single-photon emission computed tomography (TcPPi-SPECT) in 28 patients undergoing elective coronary bypass grafting (CABG). The relationships of intraoperative electrocardiographic myocardial ischemia, hemodynamic responses, and pharmacological requirements to this incidence of PMI were correlated. Radionuclide cardioangiography and TcPPi-SPECT were performed 24 h preoperatively and 48 h postoperatively. A standard high-dose fentanyl anesthetic protocol was used. Twenty-five percent of elective CABG patients were complicated with PMI, as documented by TcPPi-SPECT with an infarcted mass of 38.0 +/- 5.5 g. No significant difference in demographic, preoperative right and left ventricular function, number of coronary vessels grafted, or aortic cross-clamp time was observed between the PMI and non-PMI groups. The distribution of patients using preoperative beta-adrenergic blocking drugs or calcium channel blocking drugs was found to have no correlation with the outcome of PMI. As well, no significant differences in hemodynamic changes or pharmacological requirements were observed in the PMI and non-PMI groups during prebypass or postbypass periods, indicating careful intraoperative control of hemodynamic indices did not prevent the outcome of PMI in these patients. However, the incidence of prebypass ischemia was 39.3% and significantly correlated with the outcome of positive TcPPi-SPECT, denoting a 3.9-fold increased risk of developing PMI. Prebypass ischemic changes in leads II and V5 were shown to correlate with increased CPK-MB release (P less than 0.05) and tends to occur more frequently with lateral myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)