Incidence and related factors for intraoperative failed spinal anaesthesia for lower limb arthroplasty.

BACKGROUND: Spinal anaesthesia is the preferred choice for total hip- and knee arthroplasty (THA/TKA), due to the claimed superior outcome profile, relative simple technique and without the need for advanced airway support. However, choosing and informing about spinal anaesthesia should also include the risk for intraoperative failed spinal anaesthesia with associated pain, discomfort and suboptimal settings for airway management. Small-scale studies suggest incidences from 1 to 17%; however, no multi-institutional large data exists on failed spinal incidence and related factors during THA/TKA, hindering evidence-based information and potential anaesthesia stratification. METHODS: In a sub-analysis, data from a prospective study on spinal anaesthesia for THA/TKA were examined for incidence of intraoperative conversion to general anaesthesia. Potential perioperative factors (age, gender, American Society of Anaesthesiologist (ASA) score, height, weight, BMI, procedure, bupivacaine dosage and duration of time from spinal administration until end of surgery) were analysed with logistic regression for relation to failed spinal anaesthesia. RESULTS: In all, 1451 patients were included for analysis, whereof 57 (3.9%) had failed spinal anaesthesia. Spinal failure patients were significantly younger (61 vs. 67 years, P = 0.003), and operation time longer in the failed spinal group vs no-failure, respectively (133 vs. 89 min, P < 0.001). No significant differences were found with regard to bupivacaine volume, gender, ASA-score, height, weight, BMI or THA vs. TKA. CONCLUSION: Failed spinal anaesthesia for THA and TKA is a relatively frequent occurrence and identification of risk patients is not feasible. These results should be considered when choosing anaesthesia and included in the information to patients.

A randomized trial of the effect of low dose epinephrine infusion in addition to tranexamic acid on blood loss during total hip arthroplasty.

BACKGROUND: Total hip arthroplasty (THA) is associated with both intraoperative and postoperative blood loss resulting in anaemia and, in some patients, transfusion of red blood cells. Epinephrine enhances coagulation by several mechanisms. We evaluated the effect of intraoperative low dose infusion of epinephrine on intraoperative and early postoperative blood loss. METHODS: After consent, 106 subjects undergoing THA under spinal anaesthesia were randomly assigned to receive an i.v. infusion of either epinephrine 0.05 µg kg(-1) min(-1) or placebo (saline 0.9%) during the entire surgical procedure. Intraoperative tranexamic acid (TXA) was administered to all subjects. The primary outcome was intraoperative blood loss directly measured by drains and weighing swabs. Secondary outcome was total blood loss at 24 h postoperatively calculated using the Gross formula. RESULTS: Of 106 subjects randomized, 6 were excluded, leaving 100 subjects for analyses. Mean duration of surgery was 58 (21) min. Intraoperative blood loss was 343 (95% CI 300-386) ml in the epinephrine group compared with 385 (353-434) ml in the placebo group, P = 0.228. 24 h blood loss was 902 (800-1004) ml in the epinephrine group compared with 1080 (946-1220) ml in the placebo group, P = 0.038. CONCLUSION: In subjects also receiving TXA, intraoperative low dose epinephrine infusion did not reduce intraoperative blood loss in THA but calculated 24 h blood loss was reduced by 180 ml compared with placebo. Further studies on low dose epinephrine in patients at high risk of significant bleeding are warranted. CLINICAL TRIAL REGISTRATION: NCT 01708642.

Reduced arterial O2 saturation during supine exercise in highly trained cyclists.

Performance of intense dynamic exercise in highly trained athletes is associated with a reduced arterial haemoglobin saturation for O2 (SaO2) and lower arterial PO2 (PaO2). We hypothesized that compared with upright exercise, supine exercise would be accompanied by a smaller reduction in SaO2 because of a lower maximal O2 uptake (VO2max) and/or a more even ventilation-perfusion distribution. Eight elite bicyclists completed progressive cycle ergometry to exhaustion in both positions with concomitant determinations of ventilatory data, arterial blood gases and pH. During upright cycling VO2max averaged 75 +/- 1.6 mL O2 min-1 kg-1 (+/-SEM) and it was 10.6 +/- 1.7% lower during supine cycling (P < 0.001). Also the maximal pulmonary and alveolar ventilation were lower during supine cycling (by 15 +/- 2% and 21 +/- 3%, respectively; P < 0.001) which related to a 0.8 +/- 0.1 L lower tidal volume (P < 0.001). In all subjects and independent of work posture PaO2 and SaO2 decreased from rest to exhaustion (from 99 +/- 3 to 82 +/- 2 Torr and 98.1 +/- 0.2 to 95.2 +/- 0.4%, respectively; P < 0.001); alveolar-arterial PO2 difference increased from 6 +/- 2 to 37 +/- 3 Torr in both body positions. At exhaustion arterial PCO2 was lower in upright than in supine (33.4 +/- 0.6 vs. 35.9 +/- 0.9 Torr; P < 0.01), suggesting a greater relative hyperventilation in upright. Arterial pH was similar in upright and supine at rest (both 7.41 +/- 0.01) and at exhaustion (7.31 +/- 0.01 vs. 7.32 +/- 0.01, respectively). We conclude that despite a lower Vo2max and supposedly an improved ventilation-perfusion distribution, altering body position from upright to supine does not influence arterial O2 desaturation during intense exercise.

[Midazolam and lorazepam as premedication. A randomized double-blind study]. / Midazolam og lorazepam som praemedicinering. En randomiseret dobbeltblind undersøgelse.

Oral administration of midazolam and lorazepam as premedication was compared in a double-blind randomized clinical trial. Eighty patients scheduled for minor gynaecological surgery in general anaesthesia and 80 patients scheduled for hip arthroplasty in spinal anaesthesia were included. Assessments were: 1. patients subjective evaluation of the premedication, 2. sedation scale, 3. recovery of cognitive function assessed by Simple Paper-and-Pencil test and Postbox test, 4. amnesic effects. In the general anaesthesia group midazolam caused less postoperative sedation, less postoperative amnesia and cognitive function returned more rapidly. In the spinal anaesthesia group cognitive function returned more rapidly after midazolam. Midazolam should be preferred for premedication if rapid recovery is desired.

[Poisoning with petroleum preparations--again!]. / Forgiftning med petroleumspraeparater--igen!

Accidentally occurring hydrocarbon poisoning during early childhood is a frequent and in most cases benign event. Nevertheless there is a potential risk of more serious consequences. We describe such a case. Respiratory symptoms are of the greatest concern. They include cough, tachypnoea, and in the more serious cases cyanosis and respiratory failure. Moreover, symptoms from the gastrointestinal tract are common. Treatment includes prevention of aspiration, symptomatic treatment and in more serious cases respiratory support.

[Fasting times, ventricular aspiration and use of antacids and H2 blockaders at Danish departments of anesthesiology]. / Fastetider, ventrikelaspiration samt brug af antacida og H2-blokkere på danske anaestesiafdelinger.

In a questionnaire sent to 58 anaesthetic departments in Denmark (1992/93), we assessed fasting guidelines, preoperative gastric emptying and the use of pharmacological aspiration prophylaxis. Replies were obtained from 51 departments (88%). Most departments (90%) fast adults for at least six hours prior to elective surgery. However, 14 departments (27%) plan to change their guidelines to allow the intake of clear liquid on the day of surgery. Eighteen departments (35%) hardly ever use preoperative gastric emptying prior to emergency surgery. The other departments differ as to when gastric emptying should be performed. Only few departments (25%) employ pharmacological prophylaxis.

Sore throat after endotracheal intubation.

Nitrous oxide can diffuse into the cuff of an endotracheal tube during tracheal intubation, and the cuff pressure against the tracheal wall may cause mucosal damage. An endotracheal tube has been developed (Brandt Anesthesia Tube) that effectively limits nitrous oxide-related intracuff pressure increases. We determined whether the incidence of postoperative sore throat could be reduced by using this tube. Forty-eight female patients, 18-50 yr of age, were included in the study. Endotracheal intubation was performed with either a Brandt Anesthesia Tube or a Mallinckrodt endotracheal tube. All patients were interviewed postoperatively after 20-30 h by individuals who did not know which tube was used. In the Mallinckrodt group, 12 of 20 patients had a sore throat and 10 patients had intracuff pressures greater than 25 mm Hg. Only 3 of 20 patients in the Brandt group had a sore throat. We found that the incidence of sore throats after intubation could be significantly reduced by using the Brandt Anesthesia Tube (P less than 0.005).

[Capnometry. Technique and clinical use in anesthesia and emergency medicine]. / Kapnometri. Teknik og klinisk anvendelse inden for anaestesi og akut medicin.

By capnometry is understood measurement of carbon dioxide in the expiratory air. The concentration can be determined by various forms of spectometry. A new acoustic principle of measurement is more sensitive than the methods hitherto employed. Capnometry registers rapid intubation of the oesophagus. Sudden changes in expired carbon dioxide may be signs of malignant hyperthermia or pulmonary embolism. In addition, capnometry is a valuable aid in the regulation of mechanical ventilation. Recent investigations suggest that capnometry can be employed to confirm or refute clinical suspicion of pulmonary embolism and that measurement of expired carbon dioxide may be of prognostic value in resuscitation. It has not yet be elucidated whether nasal measurements in patients who are not intubated can provide reliable values.