Rafael Miguel

A Multicenter Evaluation of Total Intravenous Anesthesia with Remifentanil and Propofol for Elective Inpatient Surgery

Remifentanil is a mu-opioid receptor agonist with a context sensitive half-time of 3 min and an elimination half-life <or=to10 min. This study sought to evaluate the efficacy of remifentanil and propofol total intravenous anesthesia (TIVA) in 161 patients undergoing inpatient surgery. Remifentanil 1 micro gram/kg was given intravenously (IV) followed by one of two randomized infusion rates: small dose (0.5 micro gram centered dot kg-1 centered dot min-1) or large dose (1 micro gram centered dot kg-1 centered dot min-1). Propofol (0.5-1.0 mg/kg IV bolus and 75 micro gram centered dot kg-1 centered dot min-1 infusion) and vecuronium were also given. Remifentanil infusions were decreased by 50% after tracheal intubation. End points included responses (hypertension, tachycardia, and somatic responses) to tracheal intubation and surgery. More patients in the small-dose than in the large-dose group responded to tracheal intubation with hypertension and/or tachycardia (25% vs 6%; P = 0.003) but there were no other differences between groups in intraoperative responses. Recovery from anesthesia was within 3-7 min in both groups. The most frequent adverse events were hypotension (systolic blood pressure [BP] < 80 mm Hg or mean BP < 60 mm Hg) during anesthesia induction (10% small-dose versus 15% large-dose group; P = not significant [NS]) and hypotension (27% small-dose versus 30% large-dose group; P = NS), and bradycardia (7% small-dose versus 19% large-dose group; P = NS) during maintenance. In conclusion, when combined with propofol 75 micro gram centered dot kg-1 centered dot min-1, remifentanil 1 micro gram/kg IV as a bolus followed by an infusion of 1.0 micro gram centered dot kg-1 centered dot min-1 effectively controls responses to tracheal intubation. After tracheal intubation, remifentanil 0.25-4.0 micro gram centered dot kg-1 centered dot min-1 effectively controlled intraoperative responses while allowing for rapid emergence from anesthesia. (Anesth Analg 1996;83:279-85)

Preemptive Ketamine Decreases Postoperative Narcotic Requirements in Patients Undergoing Abdominal Surgery

The aim of this study was to determine if preemptive administration of systemic ketamine decreases postoperative pain when compared with postwound closure administration of ketamine.Patients undergoing abdominal procedures were randomized into a preemptive or postwound closure ketamine administration group. Before surgical incision, patients in the preemptive group (n = 20) were given 0.5 mg/kg ketamine followed by a ketamine infusion of 10 micro g [centered dot] kg-1 [centered dot] min-1, which was discontinued at abdominal closure. The patients in the postwound closure (n = 20) group were given 0.5 mg/kg of ketamine immediately after abdominal closure. Postoperatively, all patients received intravenous (IV) morphine in the postanesthesia care unit (PACU) and were started on IV morphine patient-controlled analgesia after discharge from the PACU. Postoperative pain was assessed by measuring morphine consumption and visual analog scale (0-100 mm) pain scores at rest. Patients in the preemptive group had significantly lower morphine consumption on postoperative Days 1 and 2. No significant intergroup differences were seen in the pain scores throughout the study period. Preemptive ketamine decreased postoperative opioid requirements, which was observed long after the normal expected duration of ketamine. (Anesth Analg 1997;84:1086-90)

The efficacy and safety of pain management before and after implementation of hospital-wide pain management standards: is patient safety compromised by treatment based solely on numerical pain ratings?

Inadequate analgesia in hospitalized patients prompted the Joint Commission on Accreditation of Healthcare Organizations in 2001 to introduce standards that require pain assessment and treatment. In response, many institutions implemented treatment guided by patient reports of pain intensity indexed with a numerical scale. Patient safety associated with treatment of pain guided by a numerical pain treatment algorithm (NPTA) has not been examined. We reviewed patient satisfaction with pain control and opioid-related adverse drug reactions before and after implementation of our NPTA. Patient satisfaction with pain management, measured on a 1–5 scale, significantly improved from 4.13 to 4.38 (P < 0.001) after implementation of an NPTA. The incidence of opioid over sedation adverse drug reactions per 100,000 inpatient hospital days increased from 11.0 pre-NPTA to 24.5 post-NPTA (P < 0.001). Of these patients, 94% had a documented decrease in their level of consciousness preceding the event. Although there was an improvement in patient satisfaction, we experienced a more than two-fold increase in the incidence of opioid over sedation adverse drug reactions in our hospital after the implementation of NPTA. Most adverse drug reactions were preceded by a documented decrease in the patients level of consciousness, which emphasizes the importance of clinical assessment in managing pain.

Capnography accurately detects apnea during monitored anesthesia care

Apnea and airway obstruction are common during monitored anesthesia care (MAC). Because their early detection is essential, we sought to measure the efficacy of capnography as an indicator of apnea during MAC at a variety of oxygen flow rates compared with thoracic impedance. Anesthesia care providers using standard American Society of Anesthesiologists monitors were blinded to capnography and thoracic impedance monitoring. Ten (26%) of the 39 patients studied developed 20 s of apnea; none was detected by the anesthesia provider, but all were detected by capnography and impedance monitoring. There was no difference in detection rates between the two methods. Higher oxygen flow rates decreased the amplitude of the capnograph but did not interfere with apnea detection. This pilot study revealed that apnea of at least 20 s in duration may occur in every fourth patient undergoing MAC. Although these episodes were undetected by the anesthesia provider, they were reliably detected by both capnography and respiratory plethysmography. Monitoring of nasal end-tidal CO2 is an important way to improve safety in patients undergoing MAC.

A multicenter evaluation of remifentanil for early postoperative analgesia

We evaluated the use of an infusion of remifentanil to provide postoperative analgesia during recovery from total intravenous anesthesia (TIVA) with remifentanil and propofol.One hundred fifty-seven patients from seven medical centers underwent abdominal, spine, joint replacement, or thoracic surgery. Remifentanil was titrated in an effort to limit pain to 0 or 1 on a 0-3 scale. At the end of the 30-min titration period, 78% of infusion rates were in the range of 0.05 to <or=to0.15 micro g [centered dot] kg-1 [centered dot] min-1, 5% were <0.05 micro g [centered dot] kg (-1) [centered dot] min-1, and 17% were >0.15 micro g [centered dot] kg-1 [centered dot] min-1. Pain scores were 0 or 1 in 64% of patients. Nausea occurred in 35% and emesis in 8% of patients; the peak incidence of nausea followed discontinuation of the remifentanil infusion at the time of administering morphine. Respiratory adverse events (oxygen saturation by pulse oximetry [SpO2] <90% or respiratory rate <12) affected 29% of patients. Apnea occurred in 11 patients (7.0%). There was a large variation in the incidence of respiratory depression between the centers, ranging from 0 to 75%. The explanation for the large variability in respiratory outcome was not evident. (Anesth Analg 1996;83:1292-7).

Interventional treatment of cancer pain: the fourth step in the World Health Organization analgesic ladder?

BACKGROUND For most patients with cancer pain, the World Health Organizations three-step analgesic ladder provides adequate management with oral or transdermal options. However, some cancer patients are not well palliated with these approaches. METHODS The author reviews interventional options that include nerve blocks, spinal administration of local anesthetics, opioids, alpha-2 agonists, spinal cord stimulation, and surgical interventions. RESULTS Numerous interventional options are readily accessible and most can be performed on an outpatient basis. They can be used as sole agents for the control of cancer pain or as useful adjuncts to supplement analgesia provided by opioids, thus decreasing opioid dose requirements and side effects. CONCLUSIONS Cancer-related pain can be controlled with several interventions when oral or transdermal opioids are inadequate. A risk:benefit ratio should be considered before implementing invasive analgesic methods.

A comparison of remifentanil and morphine sulfate for acute postoperative analgesia after total intravenous anesthesia with remifentanil and propofol

Background:The transition from remifentanil intraoperative anesthesia to postoperative analgesia must be planned carefully due to the short duration of action (3–10 min) of remifentanil hydrochloride, a potent, esterase-metabolized micro-opioid agonist. This study compared the efficacy and safety of

A prospective, randomized, double-blind comparison of epidural and intravenous sufentanil infusions.

BackgroundThe site of action (spinal vs. central) of epidurally administered lipid-soluble opioids has been the subject of controversy. We compared the efficacy, plasma concentration and side effects of epidural and intravenously administered sufentanil for postoperative pain relief. MethodsUsing a double-blind, prospective design, 50 patients scheduled for intraabdominal operations during combined epidural-general anesthesia were randomized into one of two groups. Patients in group 1 (n = 24) received a 1-μg/ml sufentanil infusion epidurally at 0.2 μg · kg−1. h−1 and a saline infusion intravenously at the same rate. Patients in group 2 (n = 26) received a 1-μg/ml sufentanil infusion intravenously at 0.2 μg · kg−1. h−1 and a saline infusion epidurally at the same rate. Intravenous morphine sulfate was available in 2-mg increments to all patients in the postanesthesia care unit until visual analogue scale (0–100 mm) pain score was ≤30. Then, a patient-controlled intravenous pump providing morphine on demand (1 mg with a 10-min lockout) was begun. Blood samples were drawn for sufentanil plasma levels and patients were assessed for pain, sedation and nausea for the 48 h after commencement of the infusions. ResultsSimilar visual analogue pain, sedation, and nausea scores were found between the patients in the two groups. No differences were found in supplemental morphine requirements and plasma sufentanil concentrations between the patients in the two groups. A higher incidence of excessive sedation requiring infusion decrease was infusion decrease was found in the intravenous group (six vs. one, P < 0.05). ConclusionsMany clinical similarities were found when epidural and intravenous sufentanil infusions were compared. The higher incidence of excessive sedation in the patients receiving intravenous sufentanil could not be explained on the basis of plasma sufentanil concentrations alone. This study indicates that little clinical difference exists between epidural and intravenous administration of sufentanil.

The effect of sentinel node selective axillary lymphadenectomy on the incidence of postmastectomy pain syndrome.

BACKGROUND Postmastectomy pain syndrome (PMPS) has been reported following procedures involving complete lymph node dissection (CLND). Since the triggering event is probably related to nerve injury, sentinel lymph node dissection (SLND) should decrease the incidence of PMPS. The purpose of this report is to determine the impact of SLND on the number of patients referred to the pain clinic for PMPS treatment. METHODS The records of all breast surgical patients with a diagnosis of PMPS referred to the Moffitt Cancer Center pain clinic were reviewed. The criterion for diagnosis of PMPS was a history of postoperative pain in the upper anterior chest wall, upper extremity, axilla, and/or shoulder in the absence of recurrent disease. RESULTS A total of 55 patients with a diagnosis of PMPS were seen in the pain clinic since 1991. Treatments included local anesthetics/corticosteroid injection, stellate ganglion block, and tricyclic antidepressants. A decrease from 15 patients in 1991 to 3 in 1998 was observed. All but one of the 55 patients with PMPS had CLND, and none referred to the pain clinic had undergone SLND. CONCLUSIONS PMPS is a complication of CLND. The increased use of SLND in our center has reduced the number of referrals to the pain clinic for treatment of PMPS. This benefit of SLND reduces suffering in the postoperative breast patient.

Epidural Air Associated With Multiradicular Syndrome

Epidural opioids injected through permanently implanted epidural catheters are used increasingly to control intractable pain. Not surprisingly, complications are also occurring with increasing frequency. The epidural space is relatively large at the lumbar level, but becomes markedly smaller cephala