Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2001
Randomized Controlled Trial Comparative Study Clinical TrialColloids versus crystalloids and tissue oxygen tension in patients undergoing major abdominal surgery.
The effects of intravascular volume replacement regimens on tissue oxygen tension (ptiO(2)) are not definitely known. Forty-two consecutive patients scheduled for elective major abdominal surgery were prospectively randomized to receive either 6% hydroxyethyl starch (HES) (mean molecular weight 130 kd, degree of substitution 0.4, n = 21) or lactated Ringer's solution (RL, n = 21) for intravascular volume replacement. Fluids were administered perioperatively and continued for 24 h on the intensive care unit to keep central venous pressure between 8 and 12 mm Hg. The ptiO(2) was measured continuously in the left deltoid muscle by using microsensoric implantable partial pressure of oxygen catheters after the induction of anesthesia (baseline, T0), 60 min (T1) and 120 min thereafter (T2), at the end of surgery (T3), and on the morning of the first postoperative day on the intensive care unit (T4). HES 130/0.4 2920 +/- 360 mL and 11,740 +/- 2,630 mL of RL were given to the patients within the study period. Systemic hemodynamics and oxygenation (PaO(2), PaCO(2)) did not differ significantly between the two volume groups throughout the study. From similar baseline values, ptiO(2) increased significantly in the HES-treated patients (a maximum of 59% at T4), whereas it decreased in the RL group (a maximum of -23% at T4, P < 0.05). The largest differences of ptiO(2) were measured on the morning of the first postoperative day. We conclude that intravascular volume replacement with 6% HES 130/0.4 improved tissue oxygenation during and after major surgical procedures compared with a crystalloid-based volume replacement strategy. Improved microperfusion and less endothelial swelling may be responsible for the increase in ptiO(2) in the HES 130/0.4-treated patients. ⋯ In patients undergoing major abdominal surgery, a colloid-based (with hydroxyethyl starch [HES] 130/0.4) and a crystalloid-based (with lactated Ringer's solution [RL]) volume replacement regimen was compared regarding tissue oxygen tension (ptiO(2)) measured continuously by microsensoric implantable catheters. The ptiO(2) increased in the HES-treated (+59%) but decreased in the RL-treated (-23%) patients. Improved microcirculation may be the mechanism for the better ptiO(2) in the HES group.
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Anesthesia and analgesia · Aug 2001
Randomized Controlled Trial Clinical TrialIpsilateral shoulder pain after thoracotomy with epidural analgesia: the influence of phrenic nerve infiltration with lidocaine.
Patients receiving effective thoracic epidural analgesia for postthoracotomy pain may still complain of severe ipsilateral shoulder pain. The etiology of this pain is unclear. In this randomized, double-blinded, placebo-controlled study, we investigated the effect of phrenic nerve infiltration with lidocaine or saline on postoperative shoulder pain in 48 patients. After completion of a lung resection, patients received either 10 mL of 1% lidocaine or 10 mL of 0.9% saline infiltrated into the periphrenic fat pad at the level of the diaphragm. Shoulder pain was experienced by 33% of patients receiving lidocaine, compared with 85% of patients receiving saline (P < 0.008). Overall pain scores were lower with lidocaine (P < 0.05). PaCO(2) values were not significantly higher with lidocaine in the first 2 h. We conclude that pain transmitted via the phrenic nerve and referred to the shoulder is the most likely explanation for the ipsilateral shoulder pain experienced by patients receiving epidural analgesia for postthoracotomy pain. ⋯ Ipsilateral shoulder pain after thoracotomy is common and may be severe, even in the presence of a functioning thoracic epidural. We have shown that infiltration of the phrenic nerve with local anesthetic significantly and safely reduces this shoulder pain, potentially allowing the ideal goal of a pain-free thoracotomy.
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We determined the performance of the vaporizer of the ADU machine (Anesthesia Delivery Unit; Datex-Ohmeda, Helsinki, Finland). The effects of carrier gas composition (oxygen, oxygen/N(2)O mixture, and air) and fresh gas flow (0.2 to 10 L/min) on vaporizer performance were examined with variable concentrations of isoflurane, sevoflurane, and desflurane across the whole range of each vaporizer's output. In addition, the effects of sudden changes in fresh gas flow and carrier gas composition, back pressure, flushing, and tipping were assessed. Vaporizer output depended on fresh gas flow, carrier gas composition, dial settings, and the drug used. Vaporizer output remained within 10% of dial setting with fresh gas flows of 0.3-10 L/min for isoflurane, within 10% of dial setting with fresh gas flows of 0.5-5 L/min for sevoflurane, and within 13% of dial setting with fresh gas flows of 0.5 to 1 L/min for desflurane. Outside these fresh gas flow ranges, output deviated more. The effect of sudden changes in fresh gas flow or carrier gas composition, back pressure, flushing, and tipping was minimal. We conclude that the ADU vaporizer performs well under most clinical conditions. Despite a different design and the use of complex algorithms to improve accuracy, the same physical factors affecting the performance of conventional vaporizers also affect the ADU vaporizer. ⋯ The ADU vaporizer performs well under most clinical conditions. Despite a different design and the use of complex algorithms to improve accuracy, the same physical factors affecting the performance of conventional vaporizers also affect the ADU vaporizer.
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Anesthesia and analgesia · Aug 2001
The pharmacokinetics of cisatracurium in patients with acute respiratory distress syndrome.
Continuous neuromuscular blockade is often necessary in patients being treated for acute respiratory distress syndrome (ARDS) to optimize oxygenation. In this study, neuromuscular blockade (no response to two responses at the train-of-four stimulation at the orbicularis oculi muscle) was achieved in six patients with ARDS by a continuous infusion of cisatracurium. The plasma concentration of cisatracurium during the infusion averaged 1.00 (0.25-1.45) microg/mL, expressed as median (range). The clearance and half-life were 6.5 (3.3-7.6) mL. min(-1). kg(-1) and 25 (16-48) min, respectively. The laudanosine plasma concentrations were 0.70 (0.12-1.20) microg/mL. The pharmacokinetic variables of cisatracurium are similar to those of patients without organ failure undergoing elective surgery. Plasma laudanosine levels always remained well less that those associated with seizure activity in animal models. Long-term infusion of cisatracurium was not associated with any side effects. Cisatracurium is a suitable muscle relaxant when deep and continuous levels of muscle relaxation are required in patients treated for ARDS. ⋯ We studied the pharmacokinetics of cisatracurium in six patients treated for respiratory distress syndrome by continuous muscle relaxation. A deep degree of neuromuscular blockade corresponding to abolition of two responses at the orbicularis oculi to train-of-four stimulation was obtained in all patients. The pharmacokinetic variables observed in these severely ill patients were similar to those of anesthetized patients. No accumulation of laudanosine was seen. Cisatracurium appears to be suitable when continuous muscle relaxation is required in critically ill patients.
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Anesthesia and analgesia · Aug 2001
The effect of large-dose intrathecal opioids on the autonomic nervous system.
Decreases in blood pressure after the spinal injection of opioids suggest that intrathecal (IT) opioids may have a sympatholytic effect similar to that of local anesthetic drugs. We compared two groups of patients aged 10-16 yr (n = 10 in each group). Group One (IT group) received IT opioids. Group Two (Epidural group) received 0.5% bupivacaine epidurally. The sympathetic effects of IT opioids and epidural bupivacaine were monitored by the changes in toe relative to calf temperature and by the changes in pulse wave gradients with digital plethysmography. Changes in temperature gradients comparing calf to toe and increases in pulse amplitude indicate vasodilatation caused by sympathetic blockade in this model. Calf to toe temperature gradients (Deltacalf-Deltatoe) were evaluated by subtracting the two measurements. Pulse wave plethysmography was recorded before and after spinal and epidural injection at intervals of 10 min for 40 min. All patients demonstrated changes in their calf to toe gradients after IT and epidural injections (-3.2 +/- 1.6). Systolic blood pressure decreased from a mean of 70 +/- 15 mm Hg to 55 +/- 10 mm Hg. Pulse wave plethysmography amplitude increased after the intrathecal opioid and epidural bupivacaine injection similarly. We conclude that the increases in pulse wave amplitude and decreases in calf-toe gradients indicate a sympatholytic effect after IT opioids similar to that of local anesthetics. ⋯ The sympatholytic effects of neuraxial opioids were compared with those of local anesthetics. Two groups of patients were assigned to receive a neuraxial opioid or bupivacaine. Our results demonstrate that opioids cause hypotension and peripheral vasodilatation similar to bupivacaine. This finding suggests that neuraxial opioids have a sympatholytic effect comparable to that of local anesthetic drugs.