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Perioperative complications in obese patients: A thesis on risk reducing strategies
Örebro University, School of Medical Sciences.
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aspiration of gastric content and delayed or failed intubation are the leading causes of anesthesia-related mortality and morbidity. In the recovery period, airway obstruction with subsequent hypoxia is a relatively common cause of morbidity, and is highly associated to the amount of opioids administered, especially in obese patients.

The overall aim of this thesis was to study these risk factors for airway complications and postoperative hypoxia in obese patients, and to evaluate possible strategies for their prevention.

In Study I, intubation times and incidence of failed intubation in obese patients were compared between direct laryngoscopy and videolaryngoscopy with the Stortz® C-MAC™. In Studies II and III, the effect of esmolol vs. remifentanil on the esophageal junction, and the possible analgesic properties of low-dose esmolol vs. placebo were evaluated using high-resolution manometry and the cold pressor test, respectively. Finally, in Study IV, the possible opioid-sparing effect of esmolol after laparoscopic gastric bypass surgery was evaluated.

The use of videlaryngoscopy did not shorten intubation times, however appeared to reduce the incidence of failed intubation. Our results also show that esmolol has a favorable profile, compared to remifentanil, with regard to the protection against passive regurgitation and aspiration of gastric content. No analgesic effect of low-dose esmolol was however demonstrated. The intraoperative administration of esmolol instead of remifentanil also did not reduce the requirement of morphine for treatment of post-operative pain.

The use of Stortz® C-MAC™ may be recommended for intubation of obese patients. Further studies are however required to clarify the possible role of esmolol in anesthesia.

Place, publisher, year, edition, pages
Örebro: Örebro University , 2017. , p. 74
Series
Örebro Studies in Medicine, ISSN 1652-4063 ; 167
Keywords [en]
Intubation time, videolaryngoscopy, obesity, esophagogastric junction, remifentanil, esmolol, high-resolution manometry, pulmonary aspiration, postoperative pain, postoperative opioid-sparing
National Category
Surgery
Identifiers
URN: urn:nbn:se:oru:diva-59411ISBN: 978-91-7529-215-1 (print)OAI: oai:DiVA.org:oru-59411DiVA, id: diva2:1136947
Public defence
2017-11-24, Örebro universitet Campus USÖ, hörsal C2, Södra Grev Rosengatan 32, Örebro, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2017-11-06Bibliographically approved
List of papers
1. Time-to-intubation in obese patients: A randomized study comparing direct laryngoscopy and videolaryngoscopy in experienced anaesthetists
Open this publication in new window or tab >>Time-to-intubation in obese patients: A randomized study comparing direct laryngoscopy and videolaryngoscopy in experienced anaesthetists
Show others...
2017 (English)In: Minerva Anestesiologica, ISSN 0375-9393, E-ISSN 1827-1596, Vol. 83, no 9, p. 906-913Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Airway management may be difficult in obese patients. Moreover, during prolonged intubation, oxygen desaturation develops rapidly. Videolaryngoscopy improves the view of the larynx, and the Storz® C-MACTM has been shown to be superior to other videolaryngoscopes in terms of intubation time in obese patients. However, no effort has been made to compare the Storz® C-MACTM with direct laryngoscopy. The aim of the study was to evaluate if the use of Storz® C-MACTM may reduce intubation time when compared to direct laryngoscopy (classic Macintosh® blade).

METHODS: eighty patients with body mass index > 35kg/m2 were randomized to orotracheal intubation using either Macintosh® laryngoscope, or the Storz® C-MACTM with the standard Macintosh blade. Patients had no previous history of a difficult airway. Time- to-intubation (TTI) was defined as the time from the moment anaesthetist took the laryngoscope until end-tidal carbon dioxide was detected.

RESULTS: no significant difference in TTI could be demonstrated between the two devices tested (mean difference -1.7s (95% CI -6.9 to 3.5s). All patients in the videolaryngoscopy group were successfully intubated with the allocated device, whereas five patients in the direct laryngoscopy group required an alternative device for successful intubation. No significant difference regarding the subjective difficulty of intubation and postoperative sore throat between groups was demonstrated.

CONCLUSION: in obese patients the airway may be secured equally fast using direct laryngoscopy (Macintosh®) and with videolaryngoscopy using the Stortz® C-MACTM. The risk for failed intubation, however, appears to be greater with direct laryngoscopy, especially in male obese patients.

Place, publisher, year, edition, pages
Edizioni Minerva Medica, 2017
Keywords
Laryngoscopy; Obesity; Intubation
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
urn:nbn:se:oru:diva-57350 (URN)10.23736/S0375-9393.17.11740-2 (DOI)000413240600005 ()28358178 (PubMedID)2-s2.0-85029081376 (Scopus ID)
Note

Funding Agency:

Research Fund of the Örebro County Council, Örebro, Sweden 

Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2018-07-31Bibliographically approved
2. Effects of Esmolol on the Esophagogastric Junction: A Double-Blind, Randomized, Crossover Study on 14 Healthy Volunteers
Open this publication in new window or tab >>Effects of Esmolol on the Esophagogastric Junction: A Double-Blind, Randomized, Crossover Study on 14 Healthy Volunteers
Show others...
2017 (English)In: Anesthesia and Analgesia, ISSN 0003-2999, E-ISSN 1526-7598, Vol. 125, no 4, p. 1184-1190Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Passive regurgitation may occur throughout the perioperative period, increasing the risk for pulmonary aspiration and postoperative pulmonary complications. Hypnotics and opioids, especially remifentanil, that are used during anesthesia have been shown to decrease the pressure in the esophagogastric junction (EGJ), that otherwise acts as a barrier against passive regurgitation of gastric contents. Esmolol, usually used to counteract tachycardia and hypertension, has been shown to possess properties useful during general anesthesia. Like remifentanil, the beta-1-adrenoreceptor antagonist may be used to attenuate the stress reaction to tracheal intubation and to modify perioperative anesthetic requirements. It may also reduce the need for opioids in the postoperative period. Its action on the EGJ is however unknown. The aim of this trial was to compare the effects of esmolol and remifentanil on EGJ pressures in healthy volunteers, when administrated as single drugs.

METHODS: Measurements of EGJ pressures were made in 14 healthy volunteers using high resolution solid-state manometry. Interventions were administered in a randomized sequence and consisted of esmolol that was given IV as a bolus dose of 1 mg/kg followed by an infusion of 10 mu g.kg(-1).minute(-1) over 15 minutes, and remifentanil with target-controlled infusion of 4 ng/mL over 15 minutes. Interventions were separated by a 20-minute washout period. Analyses of EGJ pressures were performed at baseline, and during drug administration at 2 (T2) and 15 minutes (T15). The primary outcome was the inspiratory EGJ augmentation, while the inspiratory and expiratory EGJ pressures were secondary outcomes.

RESULTS: There was no effect on inspiratory EGJ augmentation when comparing remifentanil and esmolol (mean difference -4.0 mm Hg [-9.7 to 1.7]; P = .15). In contrast, remifentanil significantly decreased both inspiratory and expiratory pressures compared to esmolol (-12.2 [-18.6 to 5.7]; P = .003 and 8.0 [-13.3 to 2.8]; P = .006).

CONCLUSIONS: Esmolol, compared with remifentanil, does not affect EGJ function. This may be an advantage regarding passive regurgitation and esmolol may thus have a role to play in anesthesia where maintenance of EGJ barrier function is of outmost importance.

Place, publisher, year, edition, pages
Philadelphia, USA: Lippincott Williams & Wilkins, 2017
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:oru:diva-61347 (URN)10.1213/ANE.0000000000002339 (DOI)000411423300017 ()28763358 (PubMedID)2-s2.0-85030770015 (Scopus ID)
Note

Funding Agency:

Research Fund of the Örebro County Council

Available from: 2017-10-09 Created: 2017-10-09 Last updated: 2018-08-06Bibliographically approved
3. Does the β-receptor antagonist esmolol have analgesic effects?: A randomised placebo-controlled cross-over study on healthy volunteers undergoing the cold pressor test
Open this publication in new window or tab >>Does the β-receptor antagonist esmolol have analgesic effects?: A randomised placebo-controlled cross-over study on healthy volunteers undergoing the cold pressor test
2018 (English)In: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 35, no 3, p. 165-172Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Esmolol may attenuate the sympathetic response to pain and reduce postoperative opioid consumption. It is not clear whether esmolol has an analgesic effect per se.

OBJECTIVES: The aim of this study was to evaluate the analgesic effect of esmolol in the absence of anaesthetics and opioids. We tested the hypothesis that esmolol would reduce the maximum pain intensity perceived during the cold pressor test (CPT) by 2 points on a 0 to 10 numeric pain rating scale (NRS) compared to placebo.

DESIGN: Randomised, placebo-controlled cross-over study.

SETTING: Postoperative recovery area, Örebro University Hospital. Study period, November 2013 to February 2014.

PARTICIPANTS: Fourteen healthy volunteers. Exclusion criteria included ongoing medication, pregnancy and breastfeeding and participation in other medical trials.

INTERVENTIONS: At separate study sessions, participants received interventions: esmolol (0.7 mg kg bolus over 1 min followed by infusion at 10 μg kg min); 0.9% normal saline bolus then remifentanil infusion at 0.2 μg kg min and 0.9% normal saline bolus and infusion according to a random sequence. All infusions were administered over 30 min.

MAIN OUTCOME MEASURES: Perceived maximum pain intensity score, pain tolerance and haemodynamic changes during CPT, and occurrence of side-effects to interventions compared to placebo, respectively.

RESULTS: Esmolol did not reduce perceived pain intensity or pain tolerance during the CPT. The NRS-max score was similar for esmolol, 8.5 (±1.4) and placebo, 8.4 (±1.3). The mean difference was 0.1 [95% confidence interval (-1.2 to 1.4)], P value equal to 0.83. Remifentanil significantly reduced NRS-max scores, 5.4 (±2.1) compared to placebo, [mean difference -3.1 (95% confidence interval (-4.4 to -1.8)), P < 0.001]. Side-effects were seen with remifentanil but not with esmolol.

CONCLUSION: No direct analgesic effect of esmolol could be demonstrated in the present study. The postoperative opioid-sparing effect demonstrated in previous studies, could therefore be secondary to other factors such as avoidance of opioid-induced hyperalgesia, synergy with coadministered opioids or altered pharmacokinetics of those drugs.

TRIAL REGISTRATION: European clinical trials database, https://eudract.ema.europa.eu/, EudraCT no. 2011-005780-24.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins, 2018
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:oru:diva-62086 (URN)10.1097/EJA.0000000000000711 (DOI)000430786800003 ()28922338 (PubMedID)2-s2.0-85042412590 (Scopus ID)
Note

Funding Agency:

Medical Research Fund, Örebro County Council, Örebro, Sweden

Available from: 2017-11-01 Created: 2017-11-01 Last updated: 2018-08-16Bibliographically approved
4. The effect of intraoperative esmolol infusion compared to remifentanil on opiaterequirement after laparoscopic gastric bypass surgery: a randomised pilot study
Open this publication in new window or tab >>The effect of intraoperative esmolol infusion compared to remifentanil on opiaterequirement after laparoscopic gastric bypass surgery: a randomised pilot study
(English)Manuscript (preprint) (Other academic)
National Category
Surgery
Identifiers
urn:nbn:se:oru:diva-62089 (URN)
Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2017-11-02Bibliographically approved

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