The effects of intrathecal morphine on patients undergoing minimally invasive direct coronary artery bypass surgery

OBJECTIVE: To evaluate the effects of intrathecal morphine (ITM) on the perioperative use of opiates and the fast-track pathway in patients undergoing minimally invasive direct coronary artery bypass grafting (MIDCAB). DESIGN: Retrospective cohort study. SETTINGS: University teaching hospital. PARTICIPANTS: Twenty-two elective consecutive patients who underwent MIDCAB surgery. INTERVENTIONS: Eleven patients received an intrathecal injection of morphine, 7 microg/kg (ITM group, n=11), and the control group (n=11) received standard anesthesia care. MEASUREMENTS AND MAIN RESULTS: The intraoperative dose of fentanyl was 0.55+/-0.2 mg in the ITM group and 1.1+/-0.2 mg in the control group (p<0.0001). Four patients in the ITM group and none in the control group were extubated in the operating room. Extubation time was 3.2+/-4.7 hours in the ITM group and 6.3+/-3.4 hours in the control group (p=0.016). Morphine requirements in 24 hours after surgery were 2.0+/-3.5 mg in the ITM and 16.1+/-4.8 mg in the control group (p<0.0001). There were no differences in ischemic time, intraoperative fluid requirements, postoperative blood loss, and duration of surgical procedure. Hospital length of stay was shorter in the ITM group compared with the control group (3.9+/-1.7 days v 4.9+/-1.4 days, respectively, p=0.047). CONCLUSIONS: ITM has to be considered in MIDCAB surgery as an effective component of the perioperative analgesia. The safety and effects of ITM in the patients recovery after MIDCAB surgery should be evaluated in further prospective studies.     

The use of pre-operative intrathecal morphine for analgesia following coronary artery bypass surgery

With the emergence of rapid extubation protocols following cardiac surgery, providing adequate analgesia in the early postoperative period is important. This prospective randomised double-blind study investigated the benefits of pre-operative intrathecal administration of low dose morphine in patients undergoing coronary artery bypass graft surgery. Postoperative analgesia, pulmonary function, stress response and postoperative recovery profile were assessed. Thirty patients were allocated into two groups, receiving either 500 mug of morphine intrathecally prior to anaesthesia and intravenous patient-controlled analgesia with morphine postoperatively following tracheal extubation, or only postoperative intravenous patient-controlled analgesia. In the intrathecal group, the total consumption of intravenous morphine following surgery was significantly reduced by 40% and patients reported lower pain scores at rest, during the first 24 h following extubation. Peak expiratory flow rate was greater and postoperative catecholamine release was significantly lower. Patients in the control group had a higher incidence of reduced respiratory rate following extubation.     

Does intrathecal morphine alter the stress response following coronary artery bypass grafting surgery?

PURPOSE: Intrathecal morphine administered prior to coronary artery revascularization (CABG) surgery was studied to determine its effects on the stress response. METHODS: In a single centre, open, randomized clinical trial, first time elective CABG surgery patients, < 75 yr, were studied. Control subjects (n=12) received a standardized anesthetic consisting of fentanyl (maximum cumulative dose of 35 microg x kg(-1)), propofol, and pancuronium. In addition, spinal subjects (n=13) received 1.0 mg (age > 60 yr) or 1.5 mg (age < or = 59 yr) intrathecal morphine prior to induction of anesthesia. Control subjects received continuous i.v. morphine at 2 mg x hr(-1) on arrival in the ICU with i.v. bolus morphine supplementation as required while spinal subjects received bolus i.v. morphine as required. Changes in plasma cortisol and catecholamine concentrations were measured preoperatively, poststernotomy, on admission to ICU, following tracheal extubation, at 0800 hr on the first postoperative day, and 24 and 48 hr after ICU admission. RESULTS: No differences between groups were detected for demographic variables. The percent change in cortisol concentration relative to preoperative values (control vs spinal; (38 (87) vs -41 (46)%: P < 0.05)) was lower in the spinal group on admission to ICU. The percent change in plasma epinephrine levels (control vs spinal) on admission to ICU (285 (337) vs -10 (37)%) and 0800 hr after surgery (314 (341) vs -4 (37)%) was also significantly different. CONCLUSION: Intrathecal morphine only partially attenuated the postsurgical stress response in CABG surgical patients.     

Combination of intrathecal morphine and remifentanil infusion for fast-track anesthesia in off-pump coronary artery bypass surgery

OBJECTIVE: The purpose of this study was to assess the combination of intrathecal morphine and remifentanil infusion with isoflurane in off-pump coronary artery surgery, with a focus on postoperative analgesia and fast-tracking. DESIGN: Prospective, randomized, controlled, blinded clinical study. SETTING: University hospital. PARTICIPANTS: Forty-six patients who underwent elective off-pump coronary artery bypass grafting. INTERVENTIONS: Patients were randomly assigned to receive remifentanil infusion alone (control group, n = 23) or remifentanil infusion plus 10 microg/kg of intrathecal morphine (ITM group, n = 23). Induction and maintenance anesthesia were the same in both groups. Maintenance therapy was remifentanil infusion (0.25-1 microg/kg/min) and 0.5% to 1.5% isoflurane, with adjustments according to hemodynamics. After extubation, intravenous patient-controlled analgesia with morphine (1-mg bolus and 5-minute lockout) was administered, and Wilson sedation scores, visual analog pain scores (scale, 0-100 mm) at rest and during coughing, and cumulative morphine consumption were assessed at 1, 2, 4, 8, 12, 24, and 48 hours. Examiners were unaware of patients' group identities. Anesthetic recovery parameters and opioid-related, spinal anesthesia-related, and cardiac complications were recorded. MEASUREMENTS AND MAIN RESULTS: There were no differences between the groups' intraoperative hemodynamic or anesthetic recovery findings. Pain scores and morphine consumption were significantly lower in the ITM group at all time points after extubation (p = 0.0001-0.05). Group frequencies of opioid-related and cardiac complications were similar. No patient had central neuroaxial hematoma or post-spinal tap headache. CONCLUSION: In the setting of isoflurane anesthesia for off-pump coronary artery bypass grafting, ITM combined with remifentanil infusion provides better postoperative analgesia than does remifentanil infusion alone, and does not improve or negatively affect fast-tracking.     

Postoperative radial artery angiography for coronary artery bypass surgery.

OBJECTIVE: To compare radial artery (RA) patency with internal mammary artery (IMA) patency for coronary artery bypass surgery in our early experience. METHODS: Symptomatic as well as asymptomatic patients with > or =1 RA coronary graft underwent postoperative angiography. Each anastomosis was considered separately. A string sign referred to a diffusely narrowed conduit, which did not fill the grafted coronary artery, as well as all occluded conduits. The raw value of P was adjusted for the testing of multiple hypotheses (P'). The patency data for each conduit was divided into two parts. 'Cut-off' stenosis for a conduit was the lowest dividing coronary stenosis at which a difference in patency rate with P< or =0.05 occurred. RESULTS: One-hundred-and-twenty-nine patients had 137 radial arteries and 157 angiograms. Only the most recent angiogram was analyzed for each patient at 13+/-0.7 months (n=129). Overall patency for arterial conduit 91% (n=404) was not different from venous conduit 91% (n=42) and patency for RA 90% (n=226) was not different from IMA 92% (n=178), (P'=0.999). Cut-off stenosis for RA was 70% and IMA was 40%. Patent arterial conduit had a mean coronary stenosis of 85% and non-patent conduit 64%, (P'<0.001). Right coronary territory patency was 82 vs. 94% for other territories (P'=0.022). No overall differences in patency were noted for patients with sequential anastomoses, symptoms or coronary disease at the anastomosis at the time of surgery. Reversible ischaemia was detected in the distribution of only two of 14 string signs in patients undergoing sestamibi exercise protocol following angiogram. CONCLUSION : There were no differences in patency between radial artery and internal mammary artery at 13 months post-operative. Lower coronary stenosis and right coronary territory predicted lower patency. The clinical importance of a string sign remains to be determined.     

Postoperative atrial fibrillation: a comparison of off-pump coronary artery bypass surgery and conventional coronary artery bypass graft surgery

OBJECTIVE: To compare the incidence and pattern of onset of postoperative atrial fibrillation (AF) in patients undergoing coronary artery bypass graft (CABG) surgery with and without cardiopulmonary bypass (CPB). DESIGN: Retrospective, cohort-controlled study. SETTING: University hospital and tertiary referral center. PARTICIPANTS: A group of 108 consecutive patients who underwent primary off-pump coronary artery bypass (OP-CAB) surgery and a control group of 100 patients who underwent CABG surgery with CPB. All patients underwent surgery between January and September 1999. INTERVENTIONS: Patients in the OP-CAB surgery group were operated on by either of 2 surgeons. The CABG surgery group was drawn from the general pool of patients operated on by 1 of 10 surgeons. All patients underwent median sternotomy and received standard anesthesia and intensive care unit management for this institution. MEASUREMENTS AND MAIN RESULTS: Data from 99 OP-CAB surgery patients (data incomplete in 9 patients) were compared with data from 100 CABG surgery patients. General demographics were similar except the CABG surgery group received a higher mean number of distal anastomoses (3.3 v 3.0; p = 0.028) The incidence of AF was similar in both groups (OP-CAB surgery, 25% v CABG surgery, 18%; p = 0.228). The peak incidence of AF was postoperative day 2 in both groups. The median hospital length of stay was increased in patients developing AF. CONCLUSION: Avoiding CPB does not seem to reduce the incidence of postoperative AF in CABG surgery. The similar time distribution of onset of AF in OP-CAB surgery patients and CABG surgery patients may point toward a common cause.     

Antinociceptive effect of low-dose intrathecal neostigmine combined with intrathecal morphine following gynecologic surgery

BACKGROUND: The purpose of this study was to determine whether combination of 1-5 microg intrathecal neostigmine would enhance analgesia from a fixed intrathecal dose of morphine. METHODS: A total of 60 patients undergoing gynecologic surgery were randomized to one of five groups. Patients received 15 mg bupivacaine plus 2 ml of the test drug intrathecally (saline, 100 microg morphine, or 1-5 microg neostigmine). The control group received spinal saline as the test drug. The morphine group received spinal morphine as test drug. The morphine + 1 microg neostigmine group received spinal morphine and 1 microg neostigmine. The morphine + 2.5 microg neostigmine group received spinal morphine and 2.5 microg neostigmine. Finally, the morphine + 5 microg neostigmine group received spinal morphine and 5 microg neostigmine. RESULTS: The groups were demographically similar. The time to first rescue analgesic (minutes) was longer for all patients who received intrathecal morphine combined with 1-5 microg neostigmine (median, 6 h) compared with the control group (median, 3 h) (P < 0.02). The morphine group (P < 0.05) and the groups that received the combination of 100 microg intrathecal morphine combined with neostigmine (P < 0.005) required less rescue analgesics in 24 h compared with the control group. The incidence of perioperative adverse effects was similar among groups (P > 0.05). CONCLUSIONS: The addition of 1-5 microg spinal neostigmine to 100 microg morphine doubled the duration to first rescue analgesic in the population studied and decreased the analgesic consumption in 24 h, without increasing the incidence of adverse effects. The data suggest that low-dose spinal neostigmine may improve morphine analgesia.     

Postoperative hyperthermia following off-pump versus on-pump coronary artery bypass surgery

OBJECTIVE: Hyperthermia is common in the first 24 hours following coronary artery bypass graft surgery (CABG) with cardiopulmonary bypass (CPB). An inflammatory response to CPB is often implicated in the pathophysiology of this fever. Unlike CABG with CPB, the temperature pattern after off-pump CABG (OPCAB), where CPB is avoided, has not yet been described. The purpose of this study was to describe the postoperative temperature pattern following OPCAB and to compare it with that following on-pump cardiac surgery. DESIGN: Retrospective, observational study. SETTING: Tertiary care university hospital. PARTICIPANTS: Consenting patients undergoing CABG or OPCAB procedures. INTERVENTIONS: Observational. MEASUREMENTS AND MAIN RESULTS: Of the CABG patients, 89% had temperature elevations above 38 degrees C, versus 44% of the OPCAB patients (P = 0.04). Peak body temperature was higher in the on-pump patients (CABG 38.5 degrees C +/- 0.4 degrees C versus OPCAB 37.9 degrees C +/- 0.5 degrees C; P = 0.002), as was the area under the curve for temperatures greater than 38 degrees C (CABG 1.6 +/- 1.7 degrees C/hr versus OPCAB 0.4 +/- 1.2 degrees C/hr; P = 0.02). CONCLUSIONS: Off-pump CABG surgery patients experience less hyperthermia compared with on-pump CABG patients. The reasons for a lower incidence and severity of hyperthermia after OPCAB surgery are not known, but may be related to a reduced inflammatory response.     

Effects of low-dose adenosine on myocardial performance after coronary artery bypass surgery

The effect of a non-hypotensive dose of adenosine infusion on myocardial performance after coronary artery bypass surgery was examined. Upon arrival at the intensive care unit, 16 patients (14 males, 2 females; mean age 64.5, range 46–71) were randomized to a blinded infusion of either low-dose adenosine (n = 8) or placebo (n = 8). The infusion continued at a rate corresponding to 30 μg. kg^-1. min^-1 of adenosine into the right ventricle over 4 h. Data were collected from the arterial line, thermodilution pulmonary artery catheter, transoesophageal echocardiogram (TEE), and 12-lead ECG on six occasions: before infusion, hourly during the infusion, and 1 h after terminating the infusion. Mean arterial blood pressure did not differ between the adenosine and placebo groups at any measurement point. Heart rate increased by approximately 15% during the first hour of adenosine infusion. Cardiac index increased by approximately 50% during infusion of adenosine and cardiac index remained higher while systemic vascular resistance remained lower in the adenosine-treated group during infusion. The E/A ratio (ratio between peak left ventricular inflow blood velocities during early filling and atrial contraction) was significantly higher in the adenosine-treated group after treatment for 1 h while the area injection fraction did not differ between groups at any time. The number of patients with ischaemic events as judged from ECG and from left ventricular regional wall motion abnormalities (RWMA) as visualized by TEE did not differ between groups (ECG: one patient in the adenosine group and one patient in the placebo group - RWMA: four patients in the adenosine group versus three in the placebo group). According to enzyme determinations, three patients (two in the adenosine group and one in the placebo group) developed a perioperative myocardial infarction. In conclusion, adenosine could be infused at a rate that induced peripheral vasodilation and improved cardiac output, without affecting arterial blood pressure. The echo Doppler indices area ejection fraction and E/A ratio revealed no signs of impaired ventricular function during the infusion of adenosine.     

The effects of single-dose tramadol on post-operative pain and morphine requirements after coronary artery bypass surgery

AIM: To investigate the effects of a single dose of tramadol administered prior to extubation on post-operative pain and morphine consumption after coronary artery bypass surgery. METHODS: Patients were randomized post-operatively into two groups (group T, n= 30; group P, n= 30). The technique of anaesthesia was standardized for all patients. The patients in group T received intravenous tramadol, 1 mg/kg, and the patients in group P received 2 ml of saline 0.9%, both approximately 1 h before extubation. After extubation, all patients were allowed to use the morphine patient-controlled analgesia (PCA) device for 24 h post-operatively. Post-operative data were recorded in the cardiac intensive care unit at 30 min, 1 h, 2 h, 4 h, 12 h and 24 h after extubation by the same anaesthesiologist, who had no knowledge of the groups, and the side-effects were also evaluated. RESULTS: In group P, the visual analogue scale (VAS) scores were found to be higher 30 min (P < 0.01), 1 h (P < 0.01), 2 h (P < 0.01) and 4 h (P < 0.05) after extubation. The patient comfort scores were higher in group T 30 min (P < 0.01), 1 h (P < 0.05), 2 h (P < 0.01) and 4 h (P < 0.01) after extubation. The total morphine consumption was higher in group P at all evaluation times (P < 0.01), and the numbers of PCA demands and boluses were also higher in group P (P < 0.01). CONCLUSIONS: The study demonstrated that a single dose of tramadol administered prior to extubation following coronary artery bypass surgery is associated with a decrease of up to 25% in morphine consumption, a decrease in the VAS scores and an improvement in patient comfort within the first 4 h post-operatively.     

Effect of low-dose ketamine on inflammatory response in off-pump coronary artery bypass graft surgery

Background: Off-pump coronary artery bypass graft surgery (OPCAB) is stillassociated with a marked systemic inflammatory response. Theaim of this study was to investigate whether pre-emptive, lowdose of ketamine, which has been reported to have anti-inflammatoryactivity in on-pump coronary artery bypass surgery, could reduceinflammatory response in low-risk patients undergoing OPCAB. Methods: In this prospective randomized-controlled trial, 50 patientswith stable angina and preserved myocardial function undergoingOPCAB were randomly assigned to receive either 0.5 mg kg^–1of ketamine (Ketamine group, n=25) or normal saline (Controlgroup, n=25) during induction of anaesthesia. Inflammatory markersincluding C-reactive protein (CRP), interleukin (IL)-6, tumournecrosis factor- (TNF-), and cardiac enzymes were measured previousto induction (T1), 4 h after surgery (T2), and the first andsecond days after the surgery (T3 and T4). Results: There were no significant intergroup differences in the serumconcentrations of the CRP, IL-6, and TNF- and cardiac enzymes.Pro-inflammatory markers and cardiac enzymes, except TNF-, wereall increased after the surgery compared with baseline valuesin both groups. Conclusions: Low-dose ketamine administered during anaesthesia inductiondid not exert any evident anti-inflammatory effect in termsof reducing the serum concentrations of pro-inflammatory markersin low-risk patients undergoing OPCAB.     

Haemodynamic effects of nifedipine in patients undergoing coronary artery bypass surgery

Forty patients scheduled for elective aortocoronary bypass surgery were entered in a double-blind study set up to compare the haemodynamic effects of 20 mg nifedipine (n = 20) and placebo (n = 20), both administered with the premedication. Global left ventricular function was normal in all patients. Anaesthesia was induced and maintained with standardized doses of fentanyl, flunitrazepam, and pancuronium together with 50% N2O. Cardiovascular responses to anaesthesia, intubation, skin incision, sternal retraction, and aortic manipulation were investigated. Throughout the study nifedipine produced a marked decrease in systemic vascular resistance. The reduction of left ventricular afterload was associated with an increase in cardiac index. In contrast to other reports, we observed no severe hypotension after nifedipine administration. Mean arterial pressure in patients from the nifedipine group was lower than in the placebo group only prior to anaesthesia. Since no negative drug interactions between nifedipine and the anaesthetic agents were observed, we conclude that the established cardiovascular benefit of nifedipine should be continued during anaesthesia.