An evidence-based approach to airway management: is there a role for clinical practice guidelines?

Complications arising out of airway management represent an important cause of anaesthesia-associated morbidity and mortality. Anaesthetic practice itself can lead to preventable harm, a particular example being persistent attempts at direct laryngoscopy, that results in delay in employing alternative strategies (or devices) when intubation is difficult. When patients are injured, expert review is called upon and often concludes that airway management provided by the anaesthetists was substandard. Many training programmes do not offer their trainees structured or organised teaching in airway management and many trainees probably enter practice with limited skills to deal with difficult airways. The literature on the management of the difficult airway in anaesthesia practice (especially as it relates to new technology and salvage strategies) is expanding rapidly. New technologies and practised response algorithms may be helpful in the management of the difficult airway, reducing the potential for adverse patient outcomes. Specialist societies and national interest groups can play an important role by critically reviewing and then applying the evidence base to generate clinical practice guidelines. The recommendations contained in such guidelines should be based on the most current evidence and they should be reviewed regularly for their content and continued relevance.

Anesthesia for laparoscopic adrenalectomy (pheochromocytoma) in an anemic adult Jehovah's Witness.

PURPOSE: To report the anesthetic management of an anemic Jehovah's Witness patient presenting for laparoscopic adrenalectomy for pheochromocytoma. CLINICAL FEATURES: A 49-yr-old woman presented with hemodynamic instability progressing to cardiogenic shock and subsequent acute renal failure. Her course was complicated by anemia. An adrenal pheochromocytoma was diagnosed. Preoperatively, alpha- and beta-adrenergic blockade was instituted with phenoxybenzamine and metoprolol therapy and her anemia was treated with erythropoietin. She underwent laparoscopic resection of the adrenal tumour. A cell saver device was employed and attached to the laparoscopic suction-irrigation apparatus to provide salvage capability in the event of a major hemorrhage. The surgical intervention was uneventful and well tolerated. The patient was discharged home and well on follow-up. CONCLUSIONS: Cell salvage is the only mechanism currently acceptable to Jehovah's Witnesses which will allow for perioperative salvage and replacement of blood loss. Its use is encouraged in all situations in which surgical hemorrhage is anticipated.

The epidural blood patch. Resolving the controversies.

PURPOSE: To review the literature regarding epidural blood patch (EBP) to generate conclusions relating to the controversial issues surrounding its application. SOURCE: A Medline search was made for relevant publications using keywords epidural blood patch, prophylactic epidural blood patch, dural puncture, and postdural puncture headache. Bibliographies of retrieved articles were hand-searched for relevant articles. Case series and comparative trials were emphasized in the analyses. These were culled and those deemed relevant were reviewed. PRINCIPAL FINDINGS: The majority of the literature consists of observational reports: there are few comparative studies. Headache most likely results from cerebrospinal fluid (CSF) loss leading to intracranial content shift and traction on pain sensitive structures; cerebrovascular alterations may be implicated. An EBP with 10-15 ml blood is indicated and effective therapy for severe headache after dural puncture. There is conflicting evidence regarding larger volume blood injections or delaying EBP for 24 hr or more after the diagnosis of postdural puncture headache (PDPH). Efficacy of EBP is related to a "patch effect" as well as transmission of increased epidural space pressure to the CSF space. Previous estimates of EBP efficacy were overgenerous; persistent symptomatic relief can be expected in 61-75% of patients with initial EBP. Patching with non-blood solutions, although initially effective, is associated with a high incidence of headache recurrence. Prophylactic injection of saline or blood decreases the incidence of severe headache after dural puncture. CONCLUSION: Blood-patching is an effective treatment of PDPH but further research is required regarding its mechanisms and prophylaxis.

The unanticipated difficult airway with recommendations for management.

PURPOSE: To review the current literature and generate recommendations on the role of newer technology in the management of the unanticipated difficult airway. METHODS: A literature search using key words and filters of English language and English abstracted publications from 1990-96 contained in the Medline, Current Contents and Biological Abstracts databases was carried out. The literature was reviewed and condensed and a series of evidence-based recommendations were evolved. CONCLUSIONS: The unanticipated difficult airway occurs with a low but consistent incidence in anaesthesia practice. Difficult direct laryngoscopy occurs in 1.5-8.5% of general anaesthetics and difficult intubation occurs with a similar incidence. Failed intubation occurs in 0.13-0.3% general anaesthetics. Current techniques for predicting difficulty with laryngoscopy and intubation are sensitive, non-specific and have a low positive predictive value. Assessment techniques which utilize multiple characteristics to derive a risk factor tend to be more accurate predictors. Devices such as the laryngeal mask, lighted stylet and rigid fibreoptic laryngoscopes, in the setting of unanticipated difficult airway, are effective in establishing a patient airway, may reduce morbidity and are occasionally lifesaving. Evidence supports their use in this setting as either alternatives to facemask and bag ventilation, when it is inadequate to support oxygenation, or to the direct laryngoscope, when tracheal intubation has failed. Specifically, the laryngeal mask and Combitube have proved to be effective in establishing and maintaining a patent airway in "cannot ventilate" situations. The lighted stylet and Bullard (rigid) fibreoptic scope are effective in many instances where the direct laryngoscope has failed to facilitate tracheal intubation. The data also support integration of these devices into strategies to manage difficult airway as the new standard of care. Training programmes should ensure graduate physicians are trained in the use of these alternatives. Continuing medical education courses should allow physicians in practice the opportunity to train with these alternative devices.

Obstetrical anaesthesia for a parturient with preeclampsia, HELLP syndrome and acute cortical blindness.

PURPOSE: To report the management of a multigravida presenting with preeclampsia, HELLP syndrome and acute cortical blindness for Caesarean section. CLINICAL FEATURES: A 39-yr-old woman, with three past uncomplicated pregnancies presented at 33 wk with acute cortical blindness. Based on clinical and laboratory assessment, a diagnosis of preeclampsia with HELLP syndrome was made. A CT scan of her head demonstrated ischaemic lesions of her basal ganglia, extending superiorly to involve both posterior parietal and occipital regions. Infusions of magnesium sulphate and hydralazine were started and an urgent Caesarean section was performed under subarachnoid anaesthesia after insertion of an arterial line and intravenous hydration. The course of anaesthesia and surgery was uneventful and she delivered a live 1540 g female infant. By the following morning, she had recovered some vision and visual recovery was complete by 72 hr postpartum. She underwent an MRI with angiography on the first postpartum day. Ischaemic lesions were confirmed in the same sites identified on CT scan but all major cerebral vessels were patent and no significant vascular abnormality was noted. Her postoperative course was uneventful and she was discharged home seven days postpartum after being prescribed labetalol for continued hypertension. CONCLUSION: The anaesthetic management of a parturient with acute cortical blindness and HELLP syndrome is modeled on the underlying preeclamptic condition. Invasive monitoring is not routinely indicated but is specifically indicated in some cases. Provided that it is not contraindicated because of prohibitive risk to the mother, regional anaesthesia has particular advantage in these patients. In particular, the use of spinal anaesthesia, which has been discouraged by some for this patient population, should be re-evaluated.

North American survey of the management of dural puncture occurring during labour epidural analgesia.

PURPOSE: To document the range and the most common strategies for the management of the parturient with inadvertent dural puncture (DP) during labour epidural analgesia. METHODS: A confidential survey form was mailed to 46 academic units in Canada and USA. The responses were compiled into Canadian, US and joint North American databases. RESULTS: Thirty-six centres (78%) responded, representing 137,250 annual deliveries. The reported incidence of DP was 0.04-6%. The most common initial response to DP was resiting the catheter at another level. Most centres made little change in routine practice regarding epidural top-ups and infusion rates after DP. Unrestricted mobilisation was advocated by 86% of centres following delivery; enhanced oral hydration was encouraged by 61%. Prophylactic epidural blood patch (PEBP) was recommended by 37% of centres, with twice as many US as Canadian centres doing so. In the presence of PDPH, EBP was offered most commonly at or within 24 hr of diagnosis. Complications were common after EBP: 86% of centres reported patch failures; 44% reported persistent headache after > or = 2 EBP. Despite this, centres remained optimistic about EBP success, quoting cure rates > 90% in 58% of centres. CONCLUSION: There is little difference between the practices reported by Canadian or US centres. The expressed optimism regarding the efficacy of EBP is not supported by the evidence available and may be unwarranted. More research is needed to define the issue better.

Lumbosacral plexopathy from iliopsoas haematoma after combined general-epidural anaesthesia for abdominal aneurysmectomy.

PURPOSE: To report a case of iliopsoas haematoma after resection of an abdominal aortic aneurysm which resulted in a lumbosacral plexopathy. CLINICAL FEATURES: An 81-yr-old man presented with an abdominal aortic aneurysm for aneurysmectomy and tube grafting. An epidural catheter was placed at the L1-2 spinal level and combined epidural-general anaesthesia was provided for surgery. The surgery was complex and a suprarenal clamp was necessary to obtain proximal control. A continuous infusion of demerol through the epidural catheter was prescribed for postoperative analgesia. On the first postoperative day, examination revealed a paretic, pulseless right leg and he was returned to the operating room for femoral-femoral bypass. By the following day, the motor and sensory impairment had progressed to complete paralysis with loss of all deep tendon reflexes and absent sensation below L1, despite palpable pulses in the leg. A CT of the abdomen demonstrated a right iliopsoas haematoma. There was no evidence of either disc herniation or an epidural haematoma. A diagnosis of lumbosacral plexopathy secondary to a iliopsoas haematoma was made. CONCLUSION: Iliopsoas haematoma is a rare cause of postoperative neurological deficit following aortic vascular surgery. The haematoma results in compression of the lumbosacral neural elements and typically presents as a femoral neuropathy. The diagnosis is clinical and can be readily validated with computed tomography.

Treatment of intrathecal morphine-induced pruritus following caesarean section.

PURPOSE: To compare both the efficacy and cost of nalbuphine and diphenhydramine in the treatment of intrathecal morphine-induced pruritus following Caesarean section. METHODS: Eighty patients, undergoing elective Caesarean section under spinal anaesthesia, were randomized, in a prospective, double-blind trial, to receive either nalbuphine (Group NAL) or diphenhydramine (Group DIP) for the treatment of SAB morphine-induced pruritus. All patients received an intrathecal injection of 10-12 mg hyperbaric bupivacaine 0.75% and 200 micrograms preservative free morphine. Postoperative pruritus was assessed, using a visual analogue scale (VAS), for 24 hr. Pruritus treatment was administered upon patient request and by a nurse blinded to the treatment given. Patients who failed to respond to three doses of the study drug were deemed treatment failures. Patient satisfaction was assessed with a questionnaire given 24 to 48 hr after surgery. Direct drug costs were calculated based on the pharmacy provision costs as of April 1996. RESULTS: Eighty patients were enrolled and 45 requested treatment for pruritus. Patients treated with NAL (n = 24) were more likely to achieve a VAS score of zero with treatment (83% vs 43%, P < 0.01), had a higher delta VAS following treatment (4 +/- 2 vs 2 +/- 2, P < 0.003), and experienced fewer treatment failures (4% vs 29%, P < 0.04), than those treated with DIP (n = 21). Group NAL patients were also more likely to rate their pruritus treatment as being good to excellent (96% vs 57%, P < 0.004). Direct drug costs were higher for NAL than for DIP ($6.4 +/- 3.1 vs $1.7 +/- 0.7, respectively, P < 0.0001). CONCLUSION: Nalbuphine is more effective than diphenhydramine in relieving pruritus caused by intrathecal morphine and the cost differences are small.

Electrocardiographic "pacemaker pseudo-spikes" and radio frequency interference.

PURPOSE: To present a case of apparent interference of an ECG monitor by radiofrequency interference (RFI) and to provide a brief review of RFI issues to critical care medicine. CLINICAL FEATURES: A 74-yr-old woman, with an implanted pacemaker, underwent major spinal surgery. In the post-anaesthesia care unit, the cardiac monitor demonstrated graphic evidence of pacemaker malfunction but there was no apparent effect on the patient. Investigation by the hospital's biomedical personnel led to the conclusion that RFI was being interpreted by the monitor as abnormal pacemaker activity. CONCLUSION: With the emergence of portable, battery-operated communication devices, there is an increased risk of RFI within hospitals. Antennas and repeaters are required to receive and boost the signal levels of these devices to improve signal quality. They are located throughout hospitals and may be situated near patient care areas. Patient monitors may receive these signals, misinterpret them as being patient-generated and output erroneous information. In the case described, the monitor was presented with RFI signals and interpreted as pacemaker spikes, generating a tracing suggestive of pacemaker malfunction. Troubleshooting strategies and minimizing the potential impacts of RFI on patient monitors are discussed.

Airway and respiratory management following non-lethal hanging.

PURPOSE: To review the literature on airway and respiratory management following non-lethal (suicidal) hanging and to describe the anatomy, injury and pathophysiological sequelae and their impact on patient care. SOURCE: A Medline literature search of English-language and English-abstracted papers for 1990-96. Keywords were hanging; strangulation; airway obstruction; pulmonary oedema. Filters were applied to limit the search to relevant citations. (i.e., keywords = pulmonary oedema; filters = postobstructive, neurogenic). Citations were then hand-culled to obtain current and relevant papers about an unusual cohort of patients. A hand search of the bibliographies of relevant papers supplemented the Medline search. A review of our experience at the University of Ottawa adult hospitals over the last decade was also undertaken to determine the relevance of the literature to our clinical experiences. PRINCIPAL FINDINGS: Most victims are young men and survivors are uncommon. Laryngo-tracheal injuries, although reported in 20-50% of postmortem examinations, are infrequent in survivors and have little impact on airway management. Spinal injuries are rare in survivors but should be excluded. Pulmonary complications including pulmonary oedema and bronchopneumonia are implicated in most in-hospital deaths. Pulmonary oedema is likely due to neurogenic factors or negative intrathoracic pressure. Although neurological injury determines outcome following hanging, initial neurological presentation is of limited prognostic value: a poor initial condition does not exclude a good recovery. CONCLUSION: Airway injuries severe enough to interfere with airway management are uncommon after attempted suicide by hanging. Irrespective of the initial neurological assessment, aggressive and early resuscitation to optimize cerebral oxygenation is recommended.

Continuous epidural infusion of ropivacaine for the prevention of postoperative pain after major orthopaedic surgery: a dose-finding study.

PURPOSE: A dose-finding study to investigate the use of epidural infusions of ropivacaine for postoperative analgesia following orthopaedic surgery. METHODS: This was a randomized, double-blind study. Surgery was performed using a combination of a lumbar epidural block utilizing ropivacaine 0.5% and a standardized general anaesthetic. Postoperatively, an epidural infusion of the study solution (saline, ropivacaine 0.1%, 0.2% or 0.3%) was started at the rate of 10 ml.hr-1 and continued for 21 hr after arrival in the PACU. Analgesia was supplemented with PCA morphine (dose = 1.0 mg, lock-out = 5 min). RESULTS: Forty-four patients completed the study. The ropivacaine 0.1%, 0.2%, 0.3% groups required less morphine over the 21 hr than the saline group (P < 0.01). The VAS pain scores were also lower in the three ropivacaine groups (P < 0.001). The ropivacaine groups maintained sensory anaesthesia to pinprick when compared with saline (P < 0.05). The motor block in the 0.3% group was significantly higher than the saline group at all times (P < 0.05), and higher than the 0.1% group at eight hours (P < 0.01), while the 0.2% group had higher Bromage scores than saline at 4 and 21 hr (P < 0.05). CONCLUSIONS: The use of continuous epidural infusions of ropivacaine 0.1%, 0.2% and 0.3% at 10 ml.hr-1 improved postoperative pain relief and decreased PCA morphine requirements in patients undergoing major orthopaedic surgery. The 0.1% and 0.2% concentrations produced similar sensory anaesthesia with less motor blockade than the 0.3% concentration.

Routine predeposit of autologous blood is not warranted before breast reduction surgery.

OBJECTIVE: To assess perioperative blood losses and transfusion requirements in patients who undergo breast reduction surgery and to gauge the impact of an autologous blood program on homologous transfusion requirements. DESIGN: A chart review of patients who underwent breast reduction surgery between 1988 and 1992. SETTING: The Ottawa General Hospital, a teaching hospital with a surgical training program but with no plastic surgery program. PATIENTS: Included in the review were all 153 patients who had breast reduction surgery during the study period. Twenty patients were excluded because either the predonation or the final hemoglobin concentration was not available. The remaining 133 patients were divided into three groups: group 1--patients who had not predonated blood (63); group 2--patients who predonated blood and received a transfusion (55); and group 3--patients who had predonated blood but did not receive a transfusion (15). MAIN OUTCOME MEASURES: The mean final hemoglobin concentrations, the number of patients who lost more than 30 g/L of hemoglobin and the requirements for homologous transfusions. RESULTS: The rate of homologous transfusion was 1% whether the patients had predonated blood or not. If a more restricted pattern of transfusion been used this rate would have been lower. The final hemoglobin concentration was similar in all three groups. More patients in group 3 (60%) lost more than 30 g/L of hemoglobin compared with the initial hemoglobin value than either group 1 (23%) or group 2 (20%) (p < 0.01). CONCLUSION: The routine inclusion in autologous blood programs of patients scheduled to undergo breast reduction surgery is not warranted.

Epidural sufentanil does not attenuate the central haemodynamic effects of caesarean section performed under epidural anaesthesia.

The effect of sufentanil 30 micrograms added to the epidural local anaesthetic solutions used for anaesthesia during elective Caesarean section on central haemodynamic variables was studied. Haemodynamic measurements made by thoracic electrical bioimpedance (TEB) monitoring were compared in 21 healthy parturients undergoing Caesarean section under epidural anaesthesia with and without the addition of epidural sufentanil. The patients were randomized to control (Group C) and study (Group S) groups. Following iv prehydration, an epidural catheter was placed at the L2-3 or L3-4 interspace. After a negative test dose, in a double-blinded protocol, patients in Group S received sufentanil 30 micrograms (0.6 ml) in 4.4 ml lidocaine carbonate 2% with 5 micrograms.ml-1 epinephrine and those in Group C received 5 ml lidocaine carbonate 2% with epinephrine. Lidocaine carbonate 2% with 5 micrograms.ml-1 epinephrine was then titrated to establish an anaesthetic level of T4. Haemodynamic variables (heart rate, mean arterial blood pressure, cardiac index, ejection fraction and end-diastolic index) were measured non-invasively, continuously throughout the perioperative period. There were no differences noted in haemodynamic measurements between the groups at any time perioperatively. However, differences occurred within the groups when compared with baseline values. Heart rate was increased in both groups intraoperatively. Cardiac index was increased throughout the intraoperative period in Group S but was less frequently elevated in Group C. Ejection fraction was increased throughout the perioperative period in Group S but not in Group C. End-diastolic index increased following iv preloading in both groups and returned to baseline with induction of epidural block.(ABSTRACT TRUNCATED AT 250 WORDS)

Maternal positioning affects fetal heart rate changes after epidural analgesia for labour.

Adverse fetal heart rate (FHR) changes suggestive of fetal hypoxia are seen in patients with normal term pregnancies after initiation of epidural block for labour analgesia. It was our hypothesis that, in some parturients, these changes were a consequence of concealed aortocaval compression resulting in decreased uterine blood flow. We expected that the full lateral position compared with the wedged supine position would provide more effective prophylaxis against aortocaval compression. To test our hypothesis we studied the role of maternal positioning on FHR changes during onset of epidural analgesia for labour. Eighty-eight ASA Class I or II term parturients were randomized into two groups: those to be nursed in the wedged supine position and those to be nursed in the full lateral position during induction of an epidural block. External FHR monitoring was employed to assess the fetal response to initiation of labour epidural analgesia. Epidural catheters were sited with the parturients in the sitting position and the patients then assumed the study position. After a negative test dose, a standardized regimen of bupivacaine 0.25% was employed to provide labour analgesia. The quality and efficacy of the block were assessed using VAS pain scores, motor block scores and sensory levels. The results demonstrated that there was no difference in the quality of analgesia provided nor in the incidence of asymmetric blocks. There was no difference in the observed incidence of FHR changes occurring during the initiation of the epidural block.(ABSTRACT TRUNCATED AT 250 WORDS)