Volume 3, Issue 9 S A M B A T A L K S - PAGE 3 February, 2004

FROM THE LITERATURE: - TOP


ANESTHESIA AND ANALGESIA - TOP

Administration of 100% Oxygen Before Removal of the Laryngeal Mask Airway Does Not Affect Postanesthetic Arterial Partial Pressure of Oxygen
Markus Renner, MD, Matthias Hohlrieder, MD, Thomas Wölk, MD, Friedrich Pühringer, MD, Axel T. Kleinsasser, MD, Christian Keller, MD, and Arnulf Benzer, MD
Anesth Analg. 2004;98:257-259

Breathing 100% oxygen at the end of general anesthesia has been shown to worsen postoperative pulmonary gas exchange when an endotracheal tube is used. Counter measures, such as high positive end-expiratory pressure or the vital-capacity maneuver, may limit this effect. Such strategies, however, may be impracticable, or even contraindicated, when the laryngeal mask airway (LMA) is used. Because of the vast differences in design between the LMA and endotracheal tube, we examined postanesthetic blood gas tensions in patients after emergence from anesthesia breathing oxygen via LMA. Sixty-four ASA physical status I-II patients undergoing general anesthesia for 60 min with LMA were randomly assigned to receive either 100% or 30% oxygen during emergence from anesthesia and removal of LMA. Postoperative blood gas measurements were taken at 30 and 60 min after removal of the LMA. At either measurement, patients treated with 100% oxygen essentially had the same arterial partial pressure of oxygen (60-min measurement: 83 ± 8 versus 85 ± 7 mm Hg [mean ± SD], P = 0.14) as those treated with 30% oxygen. We conclude that breathing 100% oxygen at the end of general anesthesia does not worsen postoperative pulmonary gas exchange when an LMA is used.
IMPLICATIONS: The endotracheal tube and laryngeal mask airway are substantially different artificial airways used to ventilate the lungs of anesthetized patients. Breathing 100% oxygen before removing the endotracheal tube results in lung function defects. This study shows that oxygen breathing before removing the laryngeal mask airway has no effect on pulmonary function.

Spinal 2-Chloroprocaine: A Comparison with Lidocaine in Volunteers
Mary E. Kouri, MD, and Dan J. Kopacz, MD
Anesth Analg 2004;98:75-80

Subarachnoid lidocaine has been the anesthetic of choice for outpatient spinal anesthesia. However, its use is associated with transient neurologic symptoms (TNS). Preservative-free formulations of 2-chloroprocaine are now available and may compare favorably with lidocaine for spinal anesthesia. In this double-blinded, randomized, crossover study, we compared spinal chloroprocaine and lidocaine in 8 volunteers, each receiving 2 spinal anesthetics: 1 with 40 mg 2% lidocaine and the other with 40 mg 2% preservative-free 2-chloroprocaine. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation and thigh tourniquet, motor strength, and a simulated discharge pathway were assessed. Chloroprocaine produced anesthetic efficacy similar to lidocaine, including peak block height (T8 [T5-11] versus T8 [T6-12], P = 0.8183) and tourniquet tolerance (46 ± 6 min versus 38 ± 24 min, P = 0.4897). Chloroprocaine anesthesia resulted in faster resolution of sensory (103 ± 13 min versus 126 ± 16 min, P = 0.0045) and more rapid attainment of simulated discharge criteria (104 ± 12 min versus 134 ± 14 min, P = 0.0007). Lidocaine was associated with mild to moderate TNS in 7 of 8 subjects; no subject complained of TNS with chloroprocaine ( P = 0.0004). We conclude that the anesthetic profile of chloroprocaine compares favorably with lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects make chloroprocaine an attractive choice for outpatient spinal anesthesia.
IMPLICATIONS: The spinal anesthetic profile of chloroprocaine (40 mg) compares favorably with the same dose of spinal lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects and without signs of transient neurological symptoms make chloroprocaine an attractive choice for outpatient spinal anesthesia.

Spinal 2-Chloroprocaine: A Dose-Ranging Study and the Effect of Added Epinephrine
Kristin N. Smith, MD, Dan J. Kopacz, MD, and Susan B. McDonald, MD
Anesth Analg 2004;98:81-88

With the availability of preservative- and antioxidant-free 2-chloroprocaine (2-CP), there may be an acceptable short-acting alternative to lidocaine for spinal anesthesia. We examined the safety, dose-response characteristics, and effects of epinephrine with spinal 2-CP. Six volunteers per group were randomized to receive 30, 45, or 60 mg of spinal 2-CP with and without epinephrine. Intensity and duration of sensory and motor blockade were assessed. When 11 of the 18 volunteers complained of vague, nonspecific flu-like symptoms, breaking of the blind revealed that all spinal anesthetics associated with the flu-like symptoms contained epinephrine. There were no complaints of flu-like symptoms in the volunteers who received 2-CP without epinephrine. No further spinal anesthetics containing epinephrine were administered, resulting in 29 anesthetics (11 with epinephrine, 18 without epinephrine.) Plain 2-CP demonstrated a dose-dependent increase in peak block height and duration of effect at all variables except time to 2-segment regression and time to regression to T10. Time to complete sensory regression with plain 2-CP was 98 ± 20, 116 ± 15, and 132 ± 23 min, respectively. 2-CP with epinephrine produced times to complete sensory regression of 153 ± 25, 162 ± 33, and 148 ± 29 min, respectively. Preservative and antioxidant free 2-CP can be used effectively for spinal anesthesia in doses of 30-60 mg. Epinephrine is not recommended as an adjunct because of the frequent incidence of side effects.
IMPLICATIONS: Hyperbaric spinal 2-chloroprocaine is effective and has an anesthetic profile appropriate for use in the surgical outpatient over the dose range of 30-60 mg without signs of transient neurologic symptoms. The addition of epinephrine is not recommended because of the frequent incidence of side effects.

Spinal 2-Chloroprocaine: The Effect of Added Fentanyl
Julie S. Vath, MD, and Dan J. Kopacz, MD
Anesth Analg 2004;98:89-94

Chloroprocaine is being investigated as a possible replacement for spinal lidocaine. Adding fentanyl to lidocaine increases the quality of spinal anesthesia without prolongation of block. We report the characteristics of 2-chloroprocaine (2-CP) spinal anesthesia with or without fentanyl in 8 volunteers receiving 40 mg 2-CP with saline or 20 µg fentanyl in a double-blinded, randomized, crossover manner. Spinal anesthesia was successful for all subjects with complete block regression, ambulation, and void by 110 min. Itching occurred in all subjects receiving fentanyl, though medication was not required. No subject reported signs of transient neurological symptoms. Peak block with fentanyl averaged T5 (T3-7) and without fentanyl T9 (L1-T4) ( P = 0.005). Regression to L1 was 78 ± 7 min with fentanyl and 53 ± 19 min without fentanyl ( P = 0.02). Tourniquet was tolerated for 51 ± 8 min with fentanyl and for 34 ± 14 min without fentanyl ( P = 0.02). Complete regression of block occurred at 104 ± 7 min with fentanyl and by 95 ± 9 min without fentanyl ( P = 0.02). We conclude that 2-CP spinal anesthesia provides rapid onset and adequate potency, giving it a positive profile for ambulatory surgery. The addition of fentanyl lengthens regression to L1 and tourniquet tolerance while minimally lengthening block duration.
IMPLICATIONS: Spinal 2-chloroprocaine (40 mg) provides rapid onset and reliable blockade without signs of transient neurological symptoms, giving it a positive profile for ambulatory surgical settings. The addition of fentanyl appears to lengthen the regression to L1 dermatome and tourniquet time while minimally lengthening duration of block.

Spinal 2-Chloroprocaine: The Effect of Added Dextrose
Daniel T. Warren, MD, and Dan J. Kopacz, MD
Anesth Analg 2004;98:95-101

Spinal 2-chloroprocaine is being investigated as an alternative short-acting spinal anesthetic to replace lidocaine for outpatient surgery. Adding dextrose increases the baricity of solutions and alters the characteristics of spinal anesthesia. In this study, we compared 2-chloroprocaine spinal anesthesia performed with or without the addition of dextrose (1.1%). Eight volunteers underwent 2 spinal anesthetics, receiving 40 mg 2-chloroprocaine (2 mL, 2%) with 0.25 mL saline with one and 0.25 mL 10% dextrose with the other in a double-blinded, randomized, balanced crossover manner. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation, and tourniquet, motor strength measurements, and time to ambulation and void were assessed. Postvoid residual bladder volume was measured via ultrasound. Spinal anesthesia was successful in all subjects and regressed within 110 (80-110) min. There was no significant difference in peak height T4 (T7-C6), time to achieve peak block height (14 ± 6 min), time for 2-segment regression (44 ± 9 min), regression to L1 (66 ± 12 min), tolerance of tourniquet (43 ± 9 min), or return of motor function (81 ± 14 min). Mean postvoid residual volume was larger with dextrose (74 ± 67 mL versus 16 ± 35 mL; P = 0.02). No subject reported signs of transient neurologic symptoms (TNS). In conclusion, spinal 2-chloroprocaine provides adequate potency with reliable regression, seemingly without TNS. Adding dextrose does not significantly alter spinal block characteristics but increases residual bladder dysfunction. Therefore, the addition of glucose to 2-chloroprocaine for spinal anesthesia is not necessary.
IMPLICATIONS: Spinal chloroprocaine provides adequate potency with reliable regression, seemingly without concerns of transient neurologic symptoms, and hence an appealing profile for outpatient surgery. The addition of dextrose does not alter peak block height or tolerance of thigh tourniquet, and increases the degree of residual bladder dysfunction.

CANADIAN JOURNAL OF ANESTHESIA - TOP

A risk adapted approach reduces the overall institutional incidence of postoperative nausea and vomiting
Andreas Biedler, MD, Julius Wermelt, MD, Oliver Kunitz, MD, Andrea Müller, MD, Wolfram Wilhelm, MD, Jürgen Dethling, MD and Christian C. Apfel, MD
Canadian Journal of Anesthesia 51:13-19 (2004)

Purpose: Routine prophylactic antiemetic treatment of surgical patients appears justified only in case of an increased risk of postoperative nausea and vomiting (PONV). The objective of this investigation was to assess the feasibility and efficacy of a dichotomized risk score adapted management of PONV based on ondansetron prophylaxis and treatment with respect to the overall institutional rate of PONV.
Methods: After estimating the individual PONV risk by a simplified score, 162 adult patients scheduled for elective surgery received either 4 mg ondansetron intravenously (two to four risk factors = high-risk) or no prophylaxis (zero to one risk factor = low-risk). For antiemetic treatment ondansetron was given intravenously and orally. Incidence of PONV was recorded during the first 24 hr after recovery.
Results: Data from 159 subjects were analyzed with 44 patients classified as low-risk and 115 patients classified as high-risk. Nine low-risk and 58 high-risk patients experienced PONV. The expected institutional PONV incidence of 47% was reduced to 36%. Treatment with ondansetron was necessary in seven low-risk and 37 high-risk patients with a complete response rate of 71% (low-risk) and 43% (high-risk).
Conclusion: Providing antiemetic prophylaxis with ondansetron to high-risk patients strictly based on a simplified risk score can reduce the overall institutional rate of PONV. However, classifying patients into two groups while using ondansetron as the single antiemetic in the high-risk group appears to be of limited efficacy as the incidence of PONV in high-risk patients is still double that of low-risk patients.

Remifentanil provides better analgesia than alfentanil during breast biopsy surgery under monitored anesthesia care
John A. Dilger, MD, Juraj Sprung, MD PhD, Walter Maurer, MD and John Tetzlaff, MD
Canadian Journal of Anesthesia 51:20-24 (2004)

Purpose: To compare the analgesic effects of remifentanil and alfentanil during breast biopsy under monitored anesthesia care (MAC).
Methods: Sixty patients received sedation with propofol (50 µg.kg^-1.min^-1 ). After receiving a loading dose of opioid (either remifentanil 0.5 µg.kg^-1 , or alfentanil 2.5 µg.kg^-1), an infusion was initiated (remifentanil 0.05 µg.kg^-1.min^-1 or alfentanil 0.25 µg.kg^-1.min^-1), and this was supplemented with local anesthetic infiltration. The pain was evaluated with a ten-point visual analogue scale (VAS) during local anesthetic infiltration and deep tissue dissection. Inadequate analgesia, defined as VAS scores 5, was treated first with boluses of opioid (remifentanil group 10 µg or alfentanil group 50 µg) and if inadequate after two treatments with additional local anesthetic. Postoperative times were recorded including the times until discharge criteria were achieved and patient's actual discharge.
Results: The pain scores were similar between the two groups during the initial injections of local anesthetic in the breast, however, patients in the remifentanil group had lower mean pain scores during deep tissue dissection (2.3 vs 4.3, P < 0.01). Patients in the remifentanil group required fewer rescue doses of opioid (1.9 vs 3.6, P < 0.03) and local anesthetic (5 vs 15, P < 0.006). The two study groups had comparable speed of recovery.
Conclusion: Remifentanil was a better opioid choice than alfentanil for breast biopsy under MAC at the doses studied, but it did not increase the rapidity in which patients recovered posto peratively.

Midazolam causes less sedation in volunteers with red hair
Marlene V. Chua, MD, Kentaro Tsueda , MD and Anthony G. Doufas, MD PhD
Canadian Journal of Anesthesia 51:25-30 (2004)

Purpose: We studied sedation, cognition, and mood during midazolam infusion in volunteers with red and non-red (blond or brown) hair, to test the hypothesis that patients with red hair may require more drugs to attain desired levels of sedation.
Methods: Twenty red and 19 non-red hair subjects were studied in a randomized, placebo-controlled cross-over design. Subjects were studied during placebo and midazolam at 30 ng.mL^-1 target effect site concentration. Sedation was assessed using the observer's assessment of alertness/sedation (OAA/S) scale, the drowsiness visual analogue scale (VAS), and the bispectral index; cognition was assessed using the Repeatable Battery for Assessment of Neuropsychological Status; and mood was assessed using the bipolar form of the Profile of Mood States (POMS).
Results: Red hair volunteers showed significantly higher OAA/S ( P < 0.01) and lower drowsiness VAS ( P < 0.05) scores compared to non-red hair subjects during midazolam infusion. Visuospatial score was significantly higher in subjects with red compared to non-red hair during placebo and midazolam trials. Delayed memory score was significantly higher during midazolam infusion in subjects with red compared to non-red hair. There were no group differences in POMS during either trials.
Conclusion: Midazolam appears to cause significantly less sedation and cognitive impairment in red haired subjects.

Children with severe OSAS who have adenotonsillectomy in the morning are less likely to have postoperative desaturation than those operated in the afternoon
Albert Koomson, MD, Isabelle Morin, MSC, Robert Brouillette, MD and Karen A. Brown, MD
Canadian Journal of Anesthesia 51:62-67 (2004)

Purpose: To determine, in a subset of children previously reported, if the time of day when adenotonsillectomy for severe obstructive sleep apnea syndrome (OSAS) was performed affected the incidence of postoperative respiratory complications.
Clinical features: Children having adenotonsillectomy were included if they had a polysomnographic diagnosis of severe OSAS within six months prior to operation. Patients who met the inclusion criteria were grouped by the occurrence of postoperative desaturation into a saturated (SAT) and desaturated (deSAT) group. The charts of children in group deSAT were reviewed. The clock time of the surgical procedure was recorded and categorized as morning (AM) or afternoon (PM).
Results: Eighty-eight patients met the inclusion criteria. There were 31 girls and 57 boys. The mean ± SD age (yr) and weight (kg) were 4.6 ± 2.9 yr and 20.8 ± 14.5 kg respectively. There were 63 children in the SAT group and 25 in the deSAT group. Differences in age, weight and gender were not significant. The preoperative oxygen saturation (SaO₂) nadir for the SAT and deSAT groups was 80.8 ± 10.2% and 67.6 ± 17.5% ( P < 0.05) respectively. The preoperative obstructive apnea and hypopnea index was 15.8 ± 10.2 and 35.7 ± 34.6 events.hr^-1 ( P < 0.05), respectively. Surgery in 63 (71.6%) children was performed in the AM. Univariate logistic regression identified PM surgery [odds ratio (OR) 4.6, 95% confidence interval (CI) 1.7 to 12.6, P = 0.002] and a preoperative SaO₂ nadir < 80% (OR 3.6, 95% CI 1.4 to 9.4, P = 0.009) as risk factors predicting postadenotonsillectomy desaturation.
Conclusion: Children with severe OSAS whose surgery is performed in the AM are less likely to desaturate following adenotonsillectomy than children whose surgery is performed in the PM.

Obstructive sleep apnea and tonsillectomy: do we have a new indication for extended postoperative observation? (EDITORIAL)
Charles J. Coté and Stephen H. Sheldon
Canadian Journal of Anesthesia 2004 51:6-12

No abstract available.

ACTA ANAESTHESIOLOGICA SCANDINAVICA - TOP

Bier's block; 100 years old and still going strong!
S. Brill ; W. Middleton ; G. Brill ; A. Fisher
Acta Anaesthesiologica Scandinavica Volume: 48 Number: 1 Page: 117 -- 122

Abstract: In August 1908 Karl August Bier, Professor of Surgery in Berlin , described a new method of producing analgesia of a limb which he named 'vein anesthesia'. Bier first presented his new method of intravenous regional anesthesia (IVRA) at the 37th Congress of the German Surgical Society on 22 April, 1908 , only 10 years after his significant communication on spinal anesthesia. His method, which now bears his name, consisted of occluding the circulation in a segment of the arm with two tourniquets and then injecting a dilute local anesthetic through a venous cut-down in the isolated segment. Bier had the good fortune to use procaine, the first safe injectable local anesthetic that had been synthesized by Einhorn in 1904.

BRITISH JOURNAL OF ANAESTHESIA - TOP

Outcome of ASA III patients undergoing day case surgery
G. L. Ansell and J. E. Montgomery
Br J Anaesth 2004; 92 : 71-4

Background. Day case surgery is becoming more acceptable, even for patients with complex medical conditions. Current recommendations suggest that patients who are graded as American Society of Anaesthesiologists physical status (ASA) III may be suitable for this approach. There is only a small amount of published data available to support this. We present a retrospective review of ASA III patients who had undergone day surgical procedures in our unit.
Methods. We carried out a retrospective case controlled review of 896 ASA III patients who had undergone day case procedures between January 1998 and June 2002 using the existing computerized patient information system. The system records admission rates, unplanned contact with healthcare services and post-operative complications in the first 24 h after discharge.
Results. We demonstrated no significant differences in unplanned admission rates, unplanned contact with health care services, or post-operative complications in the first 24 h after discharge between ASA III and ASA I or II patients.
Conclusion. With good pre-assessment and adequate preparation ASA III patients can be treated safely in the day surgery setting.

ANESTHESIOLOGY - TOP

Gum Elastic Bougie-guided Insertion of the ProSealT Laryngeal Mask Airway Is Superior to the Digital and Introducer Tool Techniques
Joseph Brimacombe, M.D.; Christian Keller, M.D.; Dana Vosoba Judd, R.N.
Anesthesiology 2004; 100(1):25-29

Background: The authors compare three techniques for insertion of the ProSealT laryngeal mask airway.
Methods: Two hundred forty healthy patients aged 18-80 yr were randomly allocated for ProSealT laryngeal mask airway insertion using the digital, introducer tool (IT), or gum elastic bougie (GEB)-guided techniques. The digital and IT techniques were performed according to the manufacturer's instructions. The GEB-guided technique involved priming the drain tube with the GEB, placing the GEB in the esophagus under direct vision, and inserting the ProSealT laryngeal mask airway using the digital technique with the GEB as a guide. Failed insertion was defined by any of the following criteria: (1) failed pharyngeal placement; (2) malposition (air leaks, negative tap test results, or failed gastric tube insertion if pharyngeal placement was successful); and (3) ineffective ventilation (maximum expired tidal volume < 8 ml/kg or end-tidal carbon dioxide > 45 mmHg if correctly positioned). Any visible or occult blood was noted. Sore throat, dysphonia, and dysphagia were assessed 18-24 h postoperatively.
Results: Insertion was more frequently successful with the GEB-guided technique at the first attempt (GEB, 100%; digital, 88%; IT, 84%; both P < 0.001), but success after three attempts was similar (GEB, 100%; digital, 99%; IT, 98%). The time taken to successful placement was similar among groups at the first attempt but was shorter for the GEB-technique after three attempts (GEB, 25 ± 14 s; digital, 33 ± 19 s; IT, 37 ± 25 s; both: P < 0.003). There were no differences in the frequency of visible blood, but occult blood occurred less frequently with the GEB-guided technique (GEB, 12%; digital, 29%; IT, 31%; both: P < 0.02) but was similar among techniques if insertion was successful at the first attempt. There were no differences in postoperative airway morbidity.
Conclusion: The GEB-guided insertion technique is more frequently successful than the digital or IT techniques. The authors suggest that the GEB-guided technique may be a useful backup technique for when the digital and IT techniques fail.

Sodium Bisulfite: Scapegoat for Chloroprocaine Neurotoxicity?
Masahiko Taniguchi, M.D., Ph.D.; Andrew W. Bollen, D.V.M., M.D.; Kenneth Drasner, M.D.
Anesthesiology 2004; 100(1):85-91

Background: Neurologic deficits after apparent intrathecal injection of 3% Nesacaine-CE intended for epidural administration created concern about the potential toxicity of chloroprocaine and the preservative sodium bisulfite. Although bisulfite-free formulations of chloroprocaine were subsequently introduced into clinical practice, the relative toxicities of this anesthetic and preservative were never clearly established. The current studies used a relevant functional and histologic model to investigate the intrathecal neurotoxicity of these two compounds.
Methods: In the first experiment, rats implanted with intrathecal catheters were given one of two commercially available solutions of chloroprocaine, one of which contained sodium bisulfite; control animals received saline. Animals were assessed for sensory impairment 7 days after administration using the tail-flick test and were killed to obtain histologic specimens to quantify nerve injury. In the second experiment, identical methodology was used to investigate the effects of freshly prepared solutions of chloroprocaine, chloroprocaine with sodium bisulfite, sodium bisulfite, and saline.
Results: The two experiments yielded similar results. In experiment 1, tail-flick latencies and nerve injury scores after administration of plain chloroprocaine were significantly greater than those of chloroprocaine containing bisulfite. Injury scores for animals receiving chloroprocaine with bisulfite were elevated compared with those for animals given saline. In experiment 2, animals receiving plain chloroprocaine developed elevations in tail-flick latencies and nerve injury scores that were significantly greater than those for all other groups. Nerve injury scores with chloroprocaine containing bisulfite were greater than with saline or bisulfite alone. Tail-flick latencies and nerve injury scores with bisulfite alone were similar to those with saline.
Conclusions: Clinical deficits associated with unintentional intrathecal injection of chloroprocaine likely resulted from a direct effect of the anesthetic, not the preservative. The data also suggest that bisulfite can reduce neurotoxic damage induced by intrathecal local anesthetic.

Influence of Lumbosacral Cerebrospinal Fluid Density, Velocity, and Volume on Extent and Duration of Plain Bupivacaine Spinal Anesthesia
Hideyuki Higuchi, M.D.; Jyun-ichi Hirata, M.D.; Yushi Adachi, M.D.; Tomiei Kazama, M.D.
Anesthesiology 2004; 100(1):106-114

Background: The current study was designed to investigate the influence of lumbosacral cerebrospinal fluid (CSF) density, velocity, and volume on the extent and duration of plain bupivacaine spinal anesthesia.
Methods: Forty-one patients scheduled to undergo orthopedic surgery with spinal block were enrolled. Lumbosacral CSF volumes were calculated from low thoracic, lumbar, and sacral axial magnetic resonance images. CSF velocity at the L3-L4 level was derived from phase-contrast magnetic resonance images. Spinal anesthesia was performed in the lateral decubitus position. CSF (2 ml) was sampled to measure CSF density before injection of 3 ml plain bupivacaine (0.5%). Statistical correlation coefficients (p) between CSF characteristics and measurements of spinal anesthesia were assessed by Spearman rank correlation. In addition, stepwise multiple linear regression models were used to select important predictors of measures of spinal anesthesia.
Results: There was a significant correlation between CSF density and peak sensory block level ( p = 0.33, P = 0.034). Lumbosacral CSF volume inversely correlated with peak sensory block level ( p = -0.65, P < 0.0001) and positively correlated with onset time of complete motor block ( p = 0.42, P = 0.008). CSF volume also inversely correlated with time required for regression of the sensory block to L1 ( p = -0.35, P = 0.026) and L2 ( p = -0.33, P = 0.039). There was a significant inverse correlation between peak diastolic CSF velocity and duration of motor blockade ( p = -0.44, P = 0.005). Multiple regression analysis revealed that weight and CSF volume significantly contributed to the peak sensory block level ( R² = 0.46).
Conclusions: These findings indicate that CSF density and volume influence the spread of spinal anesthesia with plain bupivacaine and that CSF volume also influences the duration of spinal anesthesia. CSF velocity might also influence the duration of plain bupivacaine spinal anesthesia.

Diplopia: A Complication of Dural Puncture (REVIEW)
Isuta Nishio, M.D., Ph.D.; Brian A. Williams, M.D., M.B.A.; John P. Williams, M.D.
Anesthesiology 2004; 100(1):158-164

Diplopia can occur after dural puncture, although it is not widely recognized. This review summarizes previous case reports and discusses the presentation of diplopia and its clinical implications.

PUB MED - TOP

Inpatient hospital admission and death after outpatient surgery in elderly patients: importance of patient and system characteristics and location of care.
Fleisher LA, Pasternak LR, Herbert R, Anderson GF.
Arch Surg. 2004 Jan; 139(1): 67-72

HYPOTHESIS: Surgery at different outpatient care locations in the higher-risk elderly (age >65 years) population is associated with similar rates of inpatient hospital admission and death.
DESIGN: Claims analysis of patients undergoing 16 different surgical procedures in a nationally representative (5%) sample of Medicare beneficiaries for the years 1994 through 1999.
SETTING: Hospital-based outpatient centers, freestanding ambulatory surgery centers (ASCs), and physicians' office facilities.
PATIENTS: Medicare beneficiaries older than 65 years.
MAIN OUTCOME MEASURES: Rate of death, emergency department risk, and admission to an inpatient hospital within 7 days of outpatient surgery.
RESULTS: We studied 564,267 outpatient surgical procedures: 360,780 at an outpatient hospital, 175,288 at an ASC, and 28,199 at a physician's office. There were no deaths the day of surgery at a physician's office, 4 deaths the day of surgery at an ASC (2.3 per 100,000 outpatient procedures), and 9 deaths the day of surgery at an outpatient hospital (2.5 per 100,000 outpatient procedures). The 7-day mortality rate was 35 per 100,000 outpatient procedures at a physician's office, 25 per 100,000 outpatient procedures at an ASC, and 50 per 100,000 outpatient procedures at an outpatient hospital. The rate of admission to an inpatient hospital within 7 days of outpatient surgery was 9.08 per 1000 outpatient procedures at a physician's office, 8.41 per 1000 outpatient procedures at an ASC, and 21 per 1000 outpatient procedures at an outpatient hospital. In multivariate models, more advanced age, prior inpatient hospital admission within 6 months, surgical performance at a physician's office or outpatient hospital, and invasiveness of surgery identified those patients who were at increased risk of inpatient hospital admission or death within 7 days of surgery at an outpatient facility.
CONCLUSION: This study represents an initial effort to demonstrate the risk associated with outpatient surgery in a large, diverse population of elderly individuals.

Sleeping characteristics of adults undergoing outpatient elective surgery: a cohort study.
Kain ZN, Caldwell-Andrews AA.
J Clin Anesth. 2003 Nov;15(7):505-9

To describe sleeping patterns of adults before and after outpatient surgery. Observational cohort study. Outpatient surgical facility127 consenting adults, including 92 surgery patients and 35 community controls. Participants' sleep was measured for two days before and 2 days after outpatient surgery. Sleep was measured using actigraphy; additional measurements were made of anxiety (STAI), pain and energy (VAS), recovery (PHRI), and sleep history. Approximately 23% of patients experienced clinically significant sleep impairment after surgery, a more difficult recovery, increased pain, and lower energy. In contrast, only 2.9% of the community control group experienced clinically significant sleep impairment during the same time period. Also, patients in the surgery group experienced significantly more True Wake Time postoperatively than did control patients (p = 0.029). The surgery group also experienced more Night Awakenings >5 minutes than the control group (p = 0.006), but not more overall Night Awakenings (p = 0.106). Finally, of the patients in the surgery group, those who had higher state anxiety in the holding area also had more difficulty sleeping over the 4-day monitoring period (True Sleep Time was lower, 352 +/- 187 vs. 229 +/- 225, p = 0.009).A moderate proportion of adults experience postoperative sleeping problems.

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