Peter H. Norman

A randomized, double-blind comparison of the NK1 antagonist, aprepitant, versus ondansetron for the prevention of postoperative nausea and vomiting

BACKGROUND: Antiemetics currently in use are not totally effective. Neurokinin-1 receptor antagonists are a new class of antiemetic that have shown promise for chemotherapy-induced nausea and vomiting. This is the first study evaluating the efficacy and tolerability of the neurokinin-1 receptor antagonist, aprepitant, for the prevention of postoperative nausea and vomiting. METHODS: In this multicenter, double-blind trial, we randomly assigned 805 patients receiving general anesthesia for open abdominal surgery to a preoperative dose of aprepitant 40 mg orally, aprepitant 125 mg orally, or ondansetron 4 mg IV. Vomiting, nausea, and use of rescue therapy were assessed over 48 h after surgery. Treatments were compared using logistic regression. RESULTS: Incidence rates for the primary end point (complete response [no vomiting and no use of rescue] over 0–24 h after surgery, tested for superiority of aprepitant) were not different across groups (45% with aprepitant 40 mg, 43% with aprepitant 125 mg, and 42% with ondansetron). The incidence of no vomiting (0–24 h) was higher with aprepitant 40 mg (90%) and aprepitant 125 mg (95%) versus ondansetron (74%) (P < 0.001 for both comparisons), although between-treatment use of rescue and nausea control was not different. Both aprepitant doses also had higher incidences of no vomiting over 0–48 h (P < 0.001). No statistically significant differences were seen among the side effect profiles of the treatments. CONCLUSIONS: Aprepitant was superior to ondansetron for prevention of vomiting in the first 24 and 48 h, but no significant differences were observed between aprepitant and ondansetron for nausea control, use of rescue, or complete response.

Nitrous oxide in early labor: Safety and analgesic efficacy assessed by a double-blind, placebo-controlled study

BackgroundIntermittent self-administered nitrous oxide has long had widespread use as an analgesic in labor, but its efficacy has not been adequately established. Questions about its effect on maternal oxygenation between labor contractions also have been raised. MethodsTwenty-six women were recrulted to participate in a randomized, double-blind, cross-over, placebo-controlled study to assess the effect of intermittent nitrous oxide inhalation on labor pain and maternal hemoglobin oxygen saturation (SpO2) during the first stage of labor. Visual analog scale pain scores for each of five consecutive labor contractions were measured after administration of either nitrous oxide or compressed air. ResultsMean visual analog scale pain scores for five contractions were 5.1, 5.2, 5.7, 5.2, and 5.6 (nitrous oxide) and 4.9, 5.2, 6.1, 5.6, and 5.7 (compressed air). There were no statistically significant differences in pain when nitrous oxide as compared with compressed air was administered. Pain scores did not differ significantly over time as a function of inhaled substance (F = 0.41, P = 0.53). The mean lowest SpO2 observed between these contractions after self-administration of nitrous oxide and air were 97, 97, 97, 97, and 97% (nitrous oxide) and 97, 96, 96, 96, and 96% (compressed air). SpO2 was significantly higher after nitrous oxide administration (F = 8.8, P = 0.007). ConclusionsWhile intermittent self-administered 50% nitrous oxide in oxygen does not appear to predispose parturient women to hemoglobin oxygen desaturation, its analgesic effect has yet to be clearly demonstrated.

Preemptive analgesic effects of ketorolac in ankle fracture surgery

BackgroundPreemptive analgesia has been difficult to show in human experiments. If ketorolac has preemptive effects, then there may be an advantage to administering it at the beginning of surgery despite the potential for increased blood loss. MethodsThe authors performed a randomized, double-blind, controlled trial of 48 patients scheduled for ankle fracture surgery in a county trauma hospital. Anesthesia management was standardized and included adequate opioid analgesia (5 &mgr;g/kg fentanyl and 0.1 mg/kg morphine). Intravenous 30 mg ketorolac was administered to 23 patients before tourniquet inflation and to 25 patients after tourniquet inflation. Visual analog scale pain scores, morphine patient-controlled analgesia consumption, nausea–vomiting, and postoperative bleeding were measured. ResultsThe 23 patients given ketorolac before tourniquet inflation had no increase in pain postoperatively compared with their preoperative baseline (P = 0.280). The 25 patients who received ketorolac minutes later after tourniquet inflation had significant increases in their postoperative pain compared with their preoperative baseline (P = 0.00116). This effect was short-lived, and by 6 h the pain score in this group was not significantly more than it was preoperatively. Intergroup comparison showed a lower visual analog scale score at 2 (P = 0.0203) and 4 h (P = 0.00549) in the preemptive group and lower nausea scores at hour 6 (P = 0.00704). There was no difference in patient-controlled analgesia consumption between groups. ConclusionsIntravenous 30 mg ketorolac appears to have preemptive analgesic effects in patients undergoing ankle fracture repair. Ketorolac administered before tourniquet inflation prevents postoperative pain being perceived as more intense than preoperative pain.

Hypoxaemia in adults in the post-anaesthesia care unit

Continuous pulse oximetry was performed on 173 adults after general anaesthesia for elective inpatient surgery, throughout their post-anaesthesia care unit (PACU) stay. Supplemental oxygen was administered for ≥30 min after arrival and subsequently discontinued before discharge to the ward. The mean and minimum oxyhaemoglobin saturation (SpO2) after discontinuing oxygen were lower than those values achieved during oxygen administration and preoperatively (P < 0.001). At least one hypoxaemic episode (SpO2 ≤90% for ≥15 sec) occurred in 70 subjects (41%) and 45 of these had a moderatesevere episode (SpO2 ≥90% for ≤2 min or SpO2 ≤85%). The hypoxaemic episodes began 20 ±20 min (range 1–100; median 15) after discontinuing supplemental oxygen. Cyanosis was detected in only four of the 70 patients who desaturated. Factors associated with hypoxaemia were: ASA physical status class; surgical duration ≥90 min; and preoperative mean SpO2 <95%. Factors not associated with hypoxaemia were: age, sex, % ideal body weight, smoking history, preoperative minimum SpO2, premedication and type of surgery. In conclusion, after discontinuing supplemental oxygen in the PACU, hypoxaemia was common, difficult to detect clinically, and associated with ASA class, surgical duration and preoperative mean SpO2.RésuméNous avons monitoré continuellement la saturation artérielle en oxygène par oxymétrie pulsée en salle de réveil chez 173 adultes hospitalisés pour une intervention chirurgicale élective. Les patients respiraient un supplément d’oxygène pendant les 30 premières minutes de leur séjour en salle de réveil. Les valeurs minimales el moyennes en oxyhémoglobine enregistrées après l’arrêt du supplément en oxygène diminuaient en dessous de celles de la période précédente el de eelles mesurées avant l’intervention chirurgicale. Au moins un épisode d’hypoxémie (SpO2 ≤90% durant au moins 15 sec) est survenu chez 70 patients (41%) el l’hypoxemie était importante (SpO2 ≤90% pendant au moins 2 min ou SpO2 ≥85%) chez 45 d’entre eux. Elle apparaissait de 1 à 100 minutes après l’arrêt du supplément en oxygène, moyenne: 20 min, écart-rype: 20 min, médiane: 15 min. Seuls quatre des patients qui désaturaient arboraient de la cyanose. Les facteurs associés à la survenue de l’hypoxémie étaient la classe ASA, un intervention chirurgicale de plus de 90 min el une SpO2 moyenne <95% avant l’intervention. L’âge, le sexe, le poids des patients de même qu’une histoire de tabagisme, la SpO2 minimale préopératoire, la prémédication et le type d’intervention chirurgicale n’influencaient pas l’incidence d’hypoxémie en salle de réveil.

Obstruction due to retained carbon dioxide absorber canister wrapping

Proper functioning of every item of anesthetic equipment is of utmost importance in ensuring the safety of modern-day anesthesia. Accordingly, guidelines have been developed by several regulatory agencies for the safe manufacturing and use of most equipment used in anesthesia. As well, the Food and Drug Administration (FDA) has developed recommendations to test the integrity of all anesthetic apparatus prior to use (1). However, mishaps due to equipment failure still occur. Here we describe a case of breathing circuit obstruction due to failure to remove the packaging from a CO, absorber canister.

A Retrospective Evaluation of the Use of Video-Capable Double-Lumen Endotracheal Tubes in Thoracic Surgery

OBJECTIVE The objective of this study was to evaluate whether the use of a video double-lumen tube reduced the need for fiberoptic bronchoscopy for (1) verification of initial tube placement and for (2) reverification of correct placement after repositioning for thoracotomy. DESIGN A single-center retrospective study. SETTING Thoracic surgery in a medical university hospital. PARTICIPANTS & INTERVENTIONS After institutional review board approval, 29 patients who underwent thoracic surgical procedures using video double-lumen tubes were included in the final retrospective analysis. MEASUREMENTS AND MAIN RESULTS For 27 (93.2%) patients, the use of fiberoptic bronchoscopy was not needed either for initial placement or for verification of correct video double-lumen tube placement upon final positioning of the patient. However, for two patients, fiberoptic bronchoscopy was needed: for (1) one patient with severe left mainstem bronchus distortion as a result of a large left upper lobe tumor, and (2) a second patient with secretions that were difficult to clear. CONCLUSION This study demonstrates that the video double-lumen tube requires significantly less (6.8%) fiberoptic use for both initial placement and verification of final position, in stark contrast to standard practice in which bronchoscopy is always used to verify final positioning of the double-lumen tube. As opposed to intermittent bronchoscopy, the continuous visualization offered by an embedded camera may confer an added measure of safety.

Retrospective but Not Rigorous

To the Editor:—We read with much interest the article by Biki et al. regarding the effect of anesthetic technique and postoperative analgesia on the cancer recurrence rate after open radical prostatectomy. The results suggesting that epidural anesthesia/analgesia lowers the rate of recurrence are certainly intriguing; however, we are concerned with the lack of detailed information presented in various parts of this retrospective study. Not only does this diminish the quality of the publication, but it also raises questions about the validity of the results. Most areas where detailed information is omitted are located within the Materials and Methods section. The primary rationale for presenting methodology in any scientific publication is to allow the reader to determine the applicability of the study conditions to their own circumstances/practice and/or to replicate the study if desired. As such, meticulous and accurate reporting of details is essential. This may be particularly relevant for retrospective studies, as the most appropriate use of such studies is to generate hypotheses for the development of future clinical trials, the design of which will depend to a large extent on the methods used in the retrospective study. The most important example of incomplete information relates to the epidural anesthetic/analgesic. There is an almost complete lack of information regarding the intraoperative and postoperative epidural management, and, most significantly, the type and quantity of local anesthetic are mentioned nowhere. Certainly, “not all epidurals are created equal,” and knowing the type and quantity of medication administered via this route is of major relevance from both a research and clinical perspective. The authors also fail to provide data regarding the quantity of potent inhalational anesthetics or opioids actually administered in the perioperative period. Both types of agents inhibit natural killer cell activity, and may thus potentially increase the risk of cancer recurrence after surgery. Although the authors state in the Discussion section that “it is highly plausible that patients in the epidural group . . . required considerably less volatile anesthetic” and those receiving epidural anesthesia/analgesia “presumably required little opioid, whereas those given general anesthesia alone surely required considerable amounts of opioid,” they present no data to support these statements. Indeed, when the authors describe the general anesthetic as “most typically” consisting of a list of drugs, volatile anesthetics are not even included. Slightly more information is presented for opioids (fentanyl 1–2 g/kg is included in the list of “most typically” used intraoperative drugs; morphine 0.1–0.15 mg/kg is merely reported as having been “given for postoperative pain;” and the postoperative morphine patient-controlled anesthesia settings are stated for the general anesthesia–postoperative opioids group), but the quantity actually received by patients in the two groups is not reported. One further example of incomplete methodological information is not only deficient, but also inaccurate. The term “sizable minority” is used to describe the percentage of patients who received general anesthesia– postoperative opioids; however, this contradicts the actual numbers of patients in each group: 123 patients received general anesthesia–postoperative opioids whereas 102 received epidural anesthesia/analgesia. No explanation is given for this discrepancy. The above discussion leads to a more general issue: The standard of reporting expected for retrospective studies. Although some information may not be available, every attempt must be made to achieve the same standard of rigorous reporting as for clinical trials and laboratory investigations. Indeed, with the inherent drawbacks of retrospective studies, one could argue that the presentation of the information that is available should reach an even higher standard than that used for other types of scientific articles. Furthermore, if important data are not available, this calls into question whether the study should even be performed, as its validity may be suspect. As computerized recordkeeping and databases are increasingly used, it is quite possible that retrospective studies will become more and more common. To provide meaningful information, these studies should strive to achieve the same high standards expected of other scientific publications.

Pancuronium added to intravenous regional anesthesia: systemic weakness after prolonged tourniquet inflation time.

To the Editor: Neuromuscular blockers (NMBs) may be added to intravenous regional anesthesia (IVRA) to enhance both the motor and sensory blockade.1 , 2Most reports indicated lack of systemic effects with these agents but we encountered a case of weakness upon tourniquet deflation with the use of pancuronium despite a tourniquet inflation time of 89 min. A healthy 41-yr-old, 81 kg man presented for repair of a lacerated right extensor pollicis longus tendon and IVRA was performed with 40 lidocaine ml 0.7% plus 2 mg pancuronium. This quantity of pancuronium was inadvertently administered instead of the 1 mg dose typically used at our institution. The block was performed in the standard manner, with exsanguination of the arm and inflation of a double-cuffed tourniquet to 300 mmHg. The tourniquet was deflated after 89 min. Three minutes later the patient experienced diplopia and was unable to lift his head. Intravenous administration of 2.5 mg neostigmine (with 0.5 mg glycopyrrolate) terminated the diplopia and allowed a sustained head lift for > 5 sec. The apparent systemic release of a substantial quantity of NMB in this case is in contrast to that of local anesthetics, in which one would expect no systemic effects after deflation of a tourniquet which had been inflated for 89 min. The differences probably relate to the lesser extremity tissue binding with NMBs due to their greater ionization and lower lipid solubility. Clinicians who add NMBs to IVRA should be aware of the potential for systemic weakness, even after prolonged tourniquet inflation.

Oxygenation and Ventilation Characteristics of Thoracic Surgical Patients the Night Before Surgery

Studies of the respiratory effects of perioperative analgesic and anesthetic agents are complicated by evidence that healthy subjects and those with COPD may have abnormalities of oxygenation and ventilation during sleep. This report thus characterizes respiration during sleep preoperatively in a population frequently examined in postoperative analgesia studies. Sixty-two thoracic surgical patients were monitored by continuous respiratory inductive plethysmography, 49 of whom also had continuous pulse oximetry and bi-hourly blood gas measurements. The mean respiratory rate (RR) at each hour during sleep was similar to the awake RR (P > 0.06). The minimum RR during sleep was 7.6 +/- 2.1 (2.6-9.8; median 7.9). At least 1 apnea (tidal volume < 100 mL for > or = 15 sec) occurred in 77% of subjects, and 32% had > or = 1 slow respiratory rate (SRR; 5-min RR < 10 beats/min) episode. The mean SpO2 for hours 2 to 4 was significantly less than while awake (P < 0.0015), but the differences were < or = 1.1%. The minimum SpO2 was 88 +/- 7% (62-97; 89) and 40% of subjects had > or = 1 desaturation (DESAT90; SpO2 < 90% for > or = 15 sec) episode. The pH at hours 2 and 4 was significantly (P < 0.0009) less than while awake, but the differences were only 0.02. Other bi-hourly pH, PaCO2, and PaO2 values were similar to the awake values (P > 0.02). Interpatient variability was high, especially for episodic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)