Pulmonary gas exchange is well preserved during robot assisted surgery in steep Trendelenburg position.

INTRODUCTION: During robot assisted hysterectomies and prostatectomies, surgical exposure demands the application of a CO2 pneumoperitoneum with a very steep Trendelenburg position (40 degrees). The extent to which oxygenation and ventilation might be compromised intra-operatively remains poorly documented. METHODS: Dead-space ventilation and venous admixture were determined in 18 patients undergoing robot assisted hysterectomy (n = 6) or prostatectomy (n = 12). Anesthesia was maintained with desflurane in O2 or O2/air, with the inspired O2 fraction left at the discretion of the attending anesthesiologist. Controlled mechanical ventilation was used, but 15 min after assuming the Trendelenburg position and up until resuming the supine position pressure controlled ventilation was used. Dead-space ventilation and venous admixture were determined using Bohr's formula and Nunn's iso-shunt diagram, respectively, at the following 7 stages of the procedure: 15 min after induction; 5 min after applying the CO2 pneumoperitoneum (intra-abdominal pressure 12 mm Hg) but while still supine; 5, 60, and 120 min after assuming the Trendelenburg positioning; and 5 and 15 min after reassuming the supine position. RESULTS: Venous admixture did not change. Dead-space ventilation increased after Trendelenburg positioning, and returned to baseline values after resuming the supine position. However, individual patterns varied widely. DISCUSSION: The lung has a remarkable yet incompletely understood capacity to withstand the effects of a CO2 pneumoperitoneum and steep Trendelenburg position during general anesthesia. While individual responses vary and should be monitored, effects on dead-space ventilation and venous admixture are small and should not be an obstacle to provide optimal surgical exposure during robot assisted prostatectomy or hysterectomy.

Prevention of postoperative hypotension following spinal anesthesia for TURP: a double-blind randomized controlled trial comparing ephedrine with placebo.

Spinal hypotension (SH) is a common side effect of spinal anesthesia and may also occur after the surgical procedure. In this double-blinded, placebo-controlled, randomised clinical trial fifty patients undergoing transurethral prostatectomy under spinal anesthesia received 10 mg of ephedrine IV before being transferred from the operating table into their bed after the procedure, whereas fifty controls received saline IV. The number of per- and postoperative hypotensive episodes and vasopressor use, time delay between the administration of the study medication and the first hypotensive episode, level of spinal blockade at the start of surgery, pre- and postoperative hemoglobine and sodium concentration, cardiovascular co-morbidity and chronic medication were registered. There was no statistically significant difference in the incidence of postoperative hypotension between the two groups, but Poisson regression of the expected number of postoperative hypotensive episodes per patient showed a protective effect of ephedrine (p < 0.05). The occurence of peroperative hypotension was a risk factor for developing postoperative hypotension (p < 0.05). There was no statistically significant relation between age, level of spinal blockade, cardiovascular co-morbidity or biochemical parameters and the risk of developing per- or postoperative hypotension, except for a correlation between preoperative alpha-receptor blocking drugs and peroperative hypotension (p < 0.05). Postoperative hypotension (recorded incidence 31%) was almost as common as peroperative hypotension (recorded incidence 37%) and occurred as late as 190 minutes after the end of surgery. Ephedrine IV at the end of surgery reduced the number of postoperative hypotensive episodes per patient but did not reduce the overall incidence of postoperative SH.

Effect of sufentanil on minimum local analgesic concentrations of epidural bupivacaine, ropivacaine and levobupivacaine in nullipara in early labour.

BACKGROUND: The aim was to assess the effect of epidural sufentanil on relative analgesic potencies of epidural bupivacaine, ropivacaine and levobupivacaine by determining the minimum local analgesic concentrations during labour. METHODS: In a randomised, double-blind study, 171 parturients were allocated to one of six groups receiving a 10-mL bolus of bupivacaine, ropivacaine or levobupivacaine alone or with sufentanil 0.75 microg/mL. The concentration of local anaesthetic was determined by the response of the previous parturient using up-down sequential allocation starting at a concentration of 0.13% wt/vol with a testing interval of 0.01%. Effective analgesia was defined as a visual analogue pain score < or = 15/100 mm within 30 min and lasting for 30 min. Median effective concentrations were estimated and two-sided P < 0.05 was significant. RESULTS: Local anaesthetic concentration, use of sufentanil and local anaesthetic drug were independent significant predictors of effective and ineffective analgesia. Bupivacaine was significantly more potent than levobupivacaine and ropivacaine. The relative potency ratios without sufentanil of 0.77:0.83:1.00 were reduced to 0.36:0.38:1.00 by the addition of sufentanil. The major factor influencing local anaesthetic requirements was the addition of sufentanil, which reduced overall requirements by a factor of 4.2 (95% CI 3.6-4.8); this effect was proportionately more enhanced for bupivacaine. CONCLUSIONS: Local anaesthetic requirements for bupivacaine, levobupivacaine and ropivacaine follow an analgesic potency hierarchy. Any potency differences are small when compared to the effect of sufentanil, which resulted in a four-fold reduction in local anaesthetic requirements. Sufentanil may also enhance the potency differences between bupivacaine and the two S-enantiomer agents.

A randomized trial comparing low-dose combined spinal-epidural anesthesia and conventional epidural anesthesia for cesarean section in severe preeclampsia.

BACKGROUND AND OBJECTIVES: A prospective, randomized study was designed to compare the maternal and neonatal effects of conventional epidural anesthesia and combined spinal epidural anesthesia (CSE) for Cesarean section in severe preeclamptic patients. Additionally, two strategies in the prophylactic management of hypotension in severe preeclamptic patients were evaluated: fluid preloading or prophylactic ephedrine. METHODS: Thirty nonlaboring women with severe preeclampsia (PET), scheduled for an elective Cesarean section, were randomised into three groups: epidural anesthesia with prophylactic fluid loading (EA-F), combined spinal epidural anesthesia with prophylactic fluid loading (CSE-F), or combined spinal epidural anesthesia with prophylactic ephedrine (CSE-V). Hemodynamic data were recorded prior and after induction of regional anesthesia at five-minute intervals. The total amount of intravenous administered fluid and the total dose of vasopressors were recorded. RESULTS: Hemodynamic data were similar between the three groups. The incidence and duration of hypotension was similar in all three groups. Significantly more ephedrine was used in the CSE-V group as compared to the CSE-F group. More lactated Ringer's solution was used in the CSE-F group as compared to the CSE-V group. There were no hypertensive episodes and none of the patients developed pulmonary edema. The time period from induction until the start of surgery and the duration of surgery were significantly shorter in both CSE-groups. Neonatal outcome was comparable between the three groups. CONCLUSION: Our results confirm that combined spinal and epidural anesthesia (CSE) is a safe alternative to conventional epidural anesthesia in severe preeclamptic women and that the prophylactic use of ephedrine is effective and safe to prevent and treat spinal hypotension after combined spinal and epidural anesthesia for Cesarean section in severe preeclamptic women.

Long-chain triglycerides improve recovery from myocardial stunning in conscious dogs.

OBJECTIVES: Free fatty acid (FFA) oxidation is depressed in the postischaemic stunned myocardium and recovers in parallel with the normalization of contractile performance. Assuming a causal role for this metabolic disturbance in the pathogenesis of stunning, we questioned whether exogenous administration of high dose triglycerides during reperfusion of postischaemic myocardium, could improve its functional recovery. METHODS: Thirteen dogs were chronically instrumented to measure global and regional haemodynamics and to produce a 10 min episode of regional myocardial ischaemia. In 7 dogs, Intralipid 20% was administered i.v. during the reperfusion phase. Contractile recovery of stunned myocardium was compared with control saline treatments. The series were repeated in another 6 animals, but oxfenicine (CPT I inhibitor) preceeded Intralipid during reperfusion. RESULTS: Contractile recovery of stunned myocardium was faster and more extensive when Intralipid was administered during reperfusion than with saline treatment (wall thickening fraction 86 +/- 6% of preischaemic controls versus 52 +/- 11% at 90 min post-reperfusion; P < 0.05). Oxfenicine pretreatment completely abolished this beneficial effect. CONCLUSIONS: Exogenous administration of triglycerides during reperfusion of postischaemic myocardium improves functional recovery from stunning. This beneficial effect most likely operates through enhanced FFA availability and/or oxidation since it could be abolished by selective inhibition of the carnitine palmitoyl I enzyme.

Cardioprotective effects of lidoflazine in extensive aorta-coronary bypass grafting.

The cardioprotective effects of lidoflazine, a calcium entry blocker, were tested in patients undergoing multiple aorta-coronary bypass grafting (at least four grafts). Intermittent aortic cross-clamping at 25 degrees to 28 degrees C was used. Mean cross-clamp time was 11 minutes for one distal anastomosis. Patients were randomized into three groups: a control group (I), a group (II) pretreated with 0.5 mg . kg-1 lidoflazine intravenously before cardiopulmonary bypass (CPB), and a group (III) pretreated with 1 mg . kg-1 lidoflazine intravenously. The following markers of ischemia are used: (1) adenosine triphosphate (ATP), creatine phosphate (CP) and glycogen determined in transmural left ventricular biopsy specimens taken at the beginning and end of CPB; (2) ultrastructure in a similar pair of specimens; and (3) hemodynamic recovery 15 minutes after cessation of CPB. At the end of the intervention, ATP decreased to 73% in Group I but remained unchanged in Groups II (98%) and III (88%). CP decreased to 82% in Group I and remained unaltered in Groups II (100%) and III (110%). Glycogen decreased in Group I (to 44%) and in Group II (78%) but remained unchanged in Group II (138%). Ultrastructural study showed better preservation of the glycocalyx and sarcolemma in Group III than in Group I. Left ventricular stroke work index remained unaltered after CPB in Group III but decreased in Groups I and II to about 60% of its initial value. Thus lidoflazine pretreatment protects the myocardium in a dose-dependent manner against deterioration of myocardial function and structure.

Comparison of intramuscular buprenorphine and a buprenorphine/naloxone combination in the treatment of post-operative pain.

The analgesic efficacy and tolerance of a single intramuscular injection of either buprenorphine (0.3 mg) or a buprenorphine (0.3 mg)/naloxone (0.2 mg) combination was compared in 70 patients suffering from moderate to severe pain after abdominal surgery. Patients in both treatment groups experienced good analgesia which was apparent within 10 minutes of administration and lasted for approximately 12 hours. The most frequently reported unwanted effects were drowsiness and/or sleepiness and nausea and/or vomiting which were of mild or moderate severity in most cases. No significant differences were seen between the two treatment groups with regard to the overall assessments of efficacy and tolerance.

Fetal heart rate abnormalities after regional analgesia for labor pain: the effect of intrathecal opioids.

BACKGROUND AND OBJECTIVES: Intrathecal opioids used to relieve labor pain have been associated with uterine hyperactivity and nonreassuring fetal heart rate abnormalities. We retrospectively evaluated all charts of singleton, term, vertex-presenting parturients in active labor requesting neuraxial pain relief during a 1-year period for the occurrence of nonreassuring fetal heart rate tracings. METHODS: Three different strategies to relieve labor pain were routinely used in our department: conventional epidural using 10 mL bupivacaine 0.125% and sufentanil 0.75 microg/mL; combined spinal and epidural (CSE) using intrathecal sufentanil (7.5 microg); and CSE using intrathecal bupivacaine (2.5 mg) and sufentanil (1.5 microg). Charts (n = 1,293) were evaluated for nonreassuring fetal heart tracings and uterine hyperactivity as well as for neonatal and labor outcome. RESULTS: Intrathecal sufentanil (7.5 microg) produced significantly more nonreassuring tracings and uterine hyperactivity. However, this did not result in more cesarean deliveries or detrimental neonatal outcome. CONCLUSION: Based on this retrospective analysis, we conclude that intrathecal sufentanil in a dose of 7.5 microg has the potential to result in more nonreassuring fetal heart rate tracings compared with both intrathecal analgesia using a bupivacaine (2.5 mg)/sufentanil (1.5 microg) mixture and epidural analgesia using bupivacaine, sufentanil, and epinephrine. Reg Anesth Pain Med 2001;26:257-262.

Is there an evolution in the epidemiology and follow-up of carbon monoxide poisoning victims?

A retrospective study was conducted to investigate for potential changes in the epidemiology of acute carbon monoxide (CO) poisoning and to evaluate the recommendations within the emergency department (ED) on therapy and neurological and social follow-up of these patients. One hundred and sixty-seven patients with a non-intentional CO poisoning in the time period from 1995 to 1997 were reviewed and compared with data of a similar patient population between 1988 and 1990. Both patient groups were matched for age, sex and comorbidity. Comparing the epidemiological data of the two groups, three main evolutions were observed: (1) there is a global reduction in ED admissions for CO poisoning; (2) the number of young victims has a tendency to decrease; (3) the most common CO source has become an insufficiently functioning stove instead of a defective gas water heater. Regarding treatment and follow-up strategies three conclusions could be drawn: (1) the recommendations for hyperbaric-oxygen therapy were strictly followed; (2) the neurological follow-up was poor and has to be ameliorated and revisited; (3) the systematic follow-up by the social worker on the other hand resulted in immediate actions to prevent a second CO poisoning. This recently elaborated protocol for social evaluation emphasizes the important function of the social worker in the ED and the importance of transmural follow-up organized by the ED.

Continuous spinal analgesia for labor pain in a parturient with aortic stenosis.

Aortic stenosis in pregnancy carries a high fetal and maternal morbidity and mortality. Spinal analgesia/anesthesia is considered by many to be contraindicated in these patients. The rapid onset of sympathetic block induces hypotension, which can result in myocardial hypoperfusion and myocardial ischemia. We describe a case of moderate to severe aortic stenosis, diagnosed during pregnancy, in which pain relief during labor and delivery was managed using a continuous spinal catheter. Pure intrathecal opioid analgesia was used initially to maintain hemodynamic stability. However after two bolus administrations of sufentanil, analgesia was further maintained using ropivacaine and sufentanil. A spinal catheter was chosen to provide reliable anesthesia, which could be extended rapidly for cesarean section.

General anaesthesia with target controlled infusion of propofol for planned caesarean section: maternal and neonatal effects of a remifentanil-based technique.

The present case series evaluated maternal and neonatal effects of remifentanil, combined with propofol, during general anaesthesia for caesarean delivery. Following written informed consent, ten patients scheduled for semi-elective caesarean section were recruited to this prospective, unblinded trial. All patients with non-reassuring fetal status were excluded. A 0.50-micrograms/kg bolus of remifentanil was given intravenously, followed by a continuous infusion of 0.20 micrograms.kg(-1)min(-1). Anaesthesia was induced using propofol target controlled infusion set at a blood concentration of 5 micrograms/mL, 45 s after the remifentanil bolus. Following tracheal intubation the propofol target was reduced to 2.5 micrograms/mL and remifentanil maintained at 0.20 micrograms.kg(-1)min(-1). Mean arterial pressure remained stable throughout anaesthesia. Two patients experienced episodes of hypotension (mean arterial pressure decrease >20%). Although neonatal depression occurred in six babies and assisted mask ventilation was required briefly, recovery was rapid without the need for naloxone or tracheal intubation. Umbilical artery pH was >7.20 in all infants. We conclude that the results of the present case series using a remifentanil/propofol-based technique of general anaesthesia for caesarean section provide a basis to study the safety of this technique in a larger population. Under the conditions of the present trial, this anaesthetic technique seems safe for mother and infant, provided adequate precautions are taken to manage brief, self-limiting infant respiratory depression. At the moment we cannot advise the routine use of this technique, especially since it has not been studied in situations of fetal compromise.

Accidental epidural administration of a high dose of sufentanil.

Epidural sufentanil infusions are routinely used for post-operative analgesia after high-abdominal and thoracic surgery in our hospital. The erroneous administration of a bolus of 250 micrograms of sufentanil epidurally was followed by a 24 hour episode of deep analgesia and respiratory depression. The recovery from respiratory depression over a 27 hour period is described.

Nonsurgical extraction of intracardiac double-knotted pulmonary artery catheter.

A 75-year-old patient was admitted to the operating room for an emergency laparotomy for leaking abdominal aortic aneurysm. A pulmonary artery catheter (PAC) was inserted through the right internal jugular vein but it was impossible to advance the catheter lip into the pulmonary artery. We tried to withdraw the catheter but this was also impossible. A postoperative chest radiograph revealed a catheter knot in the right atrium. We succeeded in removing the PAC through a 14-French sheath introducer placed in the femoral vein via fluoroscopy.

Propofol does not inhibit hypoxic pulmonary vasoconstriction in humans.

The influence of increasing doses of propofol (from 6 to 12 mg/kg/h by continuous infusion) on hypoxic pulmonary vasoconstriction was studied in 10 patients prior to thoracic surgery. All patients were intubated with a left-sided double-lumen endobronchial tube. Initial anesthesia and muscle relaxation were accomplished by administering fentanyl, droperidol, and pancuronium. After 100% oxygen ventilation of both lungs for 20 min in a lateral decubitus position, the nondependent lung was deflated and one-lung ventilation was started. The dependent lung was continuously ventilated with 100% oxygen. Twenty minutes after the start of one-lung ventilation, propofol at an IV infusion rate of 6 mg/kg/h was added to the anesthetic technique. Thirty minutes later it was increased to 10 mg/kg/h and another 15 min later to 12 mg/kg/h. Then the propofol infusion was stopped. Thirty minutes later, two-lung ventilation was restarted to compare initial values. No changes in venous admixture or PaO2 were observed during propofol infusion. There was no change in any respiratory or circulatory variables except systemic vascular resistance, which decreased significantly immediately after the propofol infusion commenced but returned to control values 15 min later for the rest of the observation period. After reestablishing two-lung ventilation, all variables did not differ from control values. In all patients, the hypoxic pulmonary vasoconstriction reflex was present after institution of one-lung ventilation and was not abolished after administration of propofol in doses from 6 to 12 mg/kg/h.

Interaction of antibiotics on pipecuronium-induced neuromuscular blockade.

STUDY OBJECTIVE: To measure the interaction of two antibiotics (clindamycin and colistin) on neuromuscular blockade induced by pipecuronium bromide (a new long-acting, steroidal, nondepolarizing neuromuscular blocking drug). DESIGN: Prospective, randomized, placebo-controlled study. SETTING: Inpatient gynecologic and gastroenterologic service at a university medical center. PATIENTS: Three groups of 20 ASA physical status I and II patients with normal kidney and liver function, taking no medication, and undergoing elective surgery under general anesthesia. INTERVENTIONS: Anesthesia was induced with propofol and alfentanil intravenously (IV) and maintained with a propofol infusion and 60% nitrous oxide in oxygen. Pipecuronium bromide 50 micrograms/kg was administered after reaching a stable baseline of single-twitch response. At 25% recovery of pipecuronium-induced neuromuscular blockade, patients received one of two antibiotics, clindamycin 300 mg or colistin 1 million IU, or a placebo. MEASUREMENTS AND MAIN RESULTS: The recovery index (RI, defined as time from 25% to 75% recovery of neuromuscular blockade) was measured using the single-twitch response of the adductor pollicis muscle with supramaximal stimulation of the ulnar nerve at the wrist. RI after administration of an antibiotic (given at 25% recovery) was measured and compared with RI of the control group using Student's unpaired t-test. Statistical analyses of the results showed a significant prolongation of the recovery time (from 25% to 75% recovery) of 40 minutes for colistin. CONCLUSIONS: When this type of antibiotic is used during anesthesia with pipercuronium as a muscle relaxant, one must be aware of a significant prolongation of an already long-acting neuromuscular blockade and (although not observed in this study) possible problems in antagonism.

No decisive break-through yet for general anesthesia combined with locoregional anesthesia!

Although on theoretical grounds locoregional anesthesia, because of the claimed suppression of stress response and the ease with which prolonged analgesia can be achieved, seems preferable to general anesthesia, the shortcomings and drawbacks are such that its use is restricted to well chosen indications. The hope that combination anesthesia can overcome the limitations of both techniques remain to be proven whereas the problems that can arise during the combined technique could pose a major threat to the patient.

A comparative study between midazolam and thiopental alone or with analgesic and neuroleptic as intravenous induction agents in general anesthesia.

We compared midazolam with thiopental both in association with saline, fentanyl and fentanyl with droperidol for induction of anesthesia. Our data show that the administration of fentanyl or fentanyl and droperidol before midazolam improves the induction to reach almost the quality of a thiopental induction. No difference in cardiocirculatory effects between midazolam and thiopental was found.

Postanesthetic care unit (P.A.C.U.). A necessity for every hospital.

It is of primary importance that all patients awaking from anesthesia are followed in a recovery room. A number of recent publications show clearly that approximately 10% of all anesthetic accidents occur in the recovery period. The most recent study from Buck, Devlin and Lunn shows that most postoperative complications occur during "off hours". Because of inadequate staffing in a great number of hospitals the recovery room is closed at noon and it is not possible to bring all the patients who will then be operated upon to the intensive care unit postoperatively. Besides that, during the last years there is an enormous increase in the number of more serious surgery and also in the number of older and sicker patients. This results in an increasing number of patients requiring postoperative ventilation as medication to support their circulation. Furthermore there is also a new trend for postoperative pain control with continuous epidural administration of local anesthetics and narcotics. This very efficient method of pain control demands closer observation since respiratory depression can occur. In most hospitals, the number of intensive care beds is too small to accommodate the increasing number of those patients. Therefore the original recovery room is gaining a new dimension. It must function now as an intensive care unit setting for short stays. The name "recovery room" is changed into "postanesthetic care unit" (P.A.C.U.).

Anesthetic management of aortic trauma.

Most of the increasing number of ruptures of the thoracic aorta are caused by traffic accidents. Only a minority arrive sufficiently in time at the hospital to receive medical attention. The diagnosis is very difficult to make both on clinical and radiologic findings alone. An aortography is necessary when there is the slightest suspicion of aortic lesion. The lesions are mostly found in the isthmic region of the descending aorta. This and other localisations are easily explained when some specific anatomic, mechanical and congenital factors are considered. Surgical repair should be carried out in all cases as fast as possible. During repair attention must be directed toward the prevention of kidney and spinal cord injury and equally to prevent proximal hypertension and overload during clamping of the aorta.

Anesthesia for trauma.

Anesthesia of polytraumatized patients represents a considerable risk for them. The proper treatment of a polytraumatized patient comprises the rapid stabilisation of all his vital functions. At the same time, the attempt must be made to achieve a complete picture of all his injuries in order to be able to select a reliable and safe anesthetic procedure. Over and beyond this, a continuation of all intensive care measures, in particular the optimalization of blood volume, the maintenance of gas exchange, the support of the cardiac, and the balancing of the acid-base and electrolytes, is of the greatest importance for an effective treatment of the polytraumatized patient.