Gastroesophageal reflux and aspiration of gastric contents in anesthetic practice

The effect of class 3 obesity on the functionality of supraglottic airway devices: a historical cohort analysis with propensity score matching

PURPOSE

Supraglottic airway devices (SGAs) have been increasingly used as a primary airway in patients undergoing anesthesia as an alternative to endotracheal tubes. Second-generation devices have expanded their applicability to include uses in patients with obesity. Nevertheless, there is limited evidence of SGA suitability for patients with class 3 obesity (body mass index [BMI] ≥ 40 kg·m-2). As such, we compared rates of SGA functionality between patients with class 3 obesity and patients without class 3 obesity undergoing general anesthesia.

METHODS

We performed a propensity score matching analysis using inverse probability of treatment weighting to compare the functionality of SGAs in adult patients with class 3 obesity vs without class 3 obesity. These patients underwent surgery at a hospital in Queensland, Australia from November 2017 to September 2020 and had a SGA inserted as part of their anesthetic care. All data were collected from patients' electronic medical records. We included 321 patients in the cohort with class 3 obesity and 471 in the cohort without class 3 obesity (control/comparison). The estimated effect of class 3 obesity on SGAs was calculated using adjusted odds ratios (AORs) with their 95% confidence intervals (CIs).

RESULTS

The overall weighted prevalence of nonfunctional SGAs was 3.2%, with a significantly higher rate in the class 3 obesity cohort compared with the control cohort (4.7% vs 2.1%) (P = 0.04). This adjusted analysis illustrates that class 3 obesity was associated with an almost four times higher odds of a nonfunctional SGA (odds ratio [OR], 2.3; 95% CI, 1.0 to 5.1; AOR, 3.9; 95% CI, 1.4 to 10.6) than patients without class 3 obesity.

CONCLUSION

Patients with class 3 obesity (BMI ≥ 40 kg·m-2) had greater than three-fold odds of nonfunctional intraoperative SGAs than patients without class 3 obesity.

Ultrasound assessment of gastric contents and volume in patients undergoing endoscopic endonasal transsphenoidal surgery: a prospective observational study

Intraoperative ingestion of blood, cerebrospinal fluid, and irrigation fluid can lead to an increase in gastric volume, resulting in the potential risk of aspiration in patients after endoscopic endonasal transsphenoidal surgery (EETS). In this prospective observational study, we aimed to assess the volume of gastric contents in patients undergoing this neurosurgical procedure using ultrasound, and to determine the factors associated with volume change. Eighty-two patients diagnosed with pituitary adenoma were recruited consecutively. Semi-quantitative (Perlas scores: 0, 1 and 2) and quantitative (cross-sectional area, CSA) ultrasound assessments of the gastric antrum were performed immediately before and after surgery in the semi-recumbent and semi-recumbent right-lateral positions. Seven (8.5%) patients had antrum scores from preoperative grade 0 to postoperative grade 2; nine (11%) patients had antrum scores from preoperative grade 0 to postoperative grade 1. The mean ± standard deviation (SD) of increased gastric volume was 71.0 ± 33.1 mL and 236.5 ± 32.4 mL in postoperative grade 1 and 2 groups, respectively. Subgroup analysis showed that 11 (13.4%) patients (4 in grade 1 and all in grade 2) had postoperative estimated gastric volume > 1.5 mL kg^-1 (mean ± SD 3.08 ± 1.67, range 1.51-5.01 mL kg^-1). Logistic regression analysis revealed that older age, diabetes mellitus, and long surgical duration were independent risk factors for significant volume change (all P < 0.05). Our results showed a significant increase in gastric volume in some patients who underwent EETS. Bedside ultrasound measurements of gastric volume can be used to assess the postoperative aspiration risk, particularly in older diabetic patients with a longer surgical duration.

[Is pre-oxygenation with high-flow nasal oxygen safe? randomized control trial of 56 cases of elderly patients during induction of general anesthesia with endotracheal intubation]

OBJECTIVE

To evaluate the safety of preoxygenation with high-flow nasal oxygenation in elderly patients during induction of general anesthesia with endotracheal intubation.

METHODS

Fifty-six elderly patients without difficult airway were randomized equally into high-flow nasal oxygen group (HF group) and conventional mask oxygen group (M group). Preoxygenation was performed for 5 min before induction of general anesthesia and endotracheal intubation. Oxygenation was maintained during laryngoscopy in HF group, and ventilation lasted until laryngoscopy in M group. For all the patients, the general data, cross-sectional area (CSA) of the gastric antrum measured by ultrasonography, arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂) and arterial oxygen saturation (cSO₂) were recorded before preoxygenation (T1), at 5 min of preoxygenation (T2) and immediately after intubation (T3). The safety time of asphyxia, intubation time, times of mask ventilation and postoperative complications were compared between the two groups.

RESULTS

The general data were comparable between the two groups. After 5 min of preoxygenation, PaO₂ and cSO₂ were significantly increased in both groups, and PaO₂ was significantly higher in HF group than in M group (F=118.108 vs 9.511, P < 0.05). Both PaO₂ and cSO₂ decreased after intubation, but PaO₂ decreased more slowly in HF group and still remained higher than that at T1; cSO₂ decreased significantly in M group to a lower level than that at T1. Compared with those in M group, the patients in HF group showed a significantly longer safety time of asphyxia (t=5.305, P < 0.05) with fewer times of mask ventilation (χ²= 6.720, P < 0.05). PaCO₂ increased after intubation in both groups but was comparable between the two groups (F=3.138, P > 0.05).

CONCLUSION

High-flow nasal oxygen is safe, simple and effective for pre-oxygenation, which, as compared with the conventional oxygen mask, improves arterial oxygen partial pressure and prolongs the safety time of asphyxia to ensure the safety of airway management during induction of general anesthesia in elderly patients with endotracheal intubation.

Real-Time Ultrasound Detection of Left Paratracheal Esophagus on Air Entry into the Gastric Antrum in the Induction Period of General Anesthesia: A Prospective, Randomized Study

Background

Positive-pressure ventilation (PPV) delivered via a facemask during anesthesia induction can result in gastric content being inhaled into the lungs. We hypothesized that the real-time ultrasound left paratracheal esophagus monitoring could more effectively reduce air entry into the stomach than real-time ultrasound monitoring of the gastric antrum (GA).

Methods

Patients were divided into two groups: study (S; n=30) and control (C; n=30) groups. During the induction of general anesthesia, mask ventilation adopts a pressure control mode. The initial ventilation pressure of both groups was 15 cmH₂O. Before anesthesia induction, an ultrasonic probe was used to monitor the cross-sectional area (CSA) of the GA and the presence of gas in the stomach. During and after anesthesia induction, group S used a high-frequency ultrasound probe to observe the entry of air from the left paratracheal esophagus into the GA. The ventilation pressure was gradually reduced over time until no esophageal air was found. In group C, the ventilatory pressure was set maintained at 15 cmH₂O and the CSA of the GA and air intake were monitored using an ultrasonic probe.

Results

Before and after PPV, the CSA of the GA in group S decreased (P<0.001), whereas the CSA in group C increased (P=0.002). The GA CSA in group C after PPV was larger than in group S after PPV (P=0.002). The proportion of patients who experienced intragastric air intake in group S (23.3%) was significantly lower than that in group C (66.7) (P=0.001).

Conclusion

Compared with ultrasound monitoring of the GA, real-time ultrasound detection of LPEOAE into the GA during anesthesia induction was more effective, more sensitive, significantly reduced the prevalence of intragastric air intake, and provided sufficient tidal volume and oxygen for patients.

Effect of positive end-expiratory pressure on gastric insufflation during induction of anaesthesia when using pressure-controlled ventilation via a face mask: A randomised controlled trial

BACKGROUND

Face mask ventilation (FMV) during induction of anaesthesia is associated with risk of gastric insufflation that may lead to gastric regurgitation and pulmonary aspiration. A continuous positive airway pressure (CPAP) has been shown to reduce gastric regurgitation. We therefore hypothesised that CPAP followed by FMV with positive end-expiratory pressure (PEEP) during induction of anaesthesia would reduce the risk of gastric insufflation.

OBJECTIVE

The primary aim was to compare the incidence of gastric insufflation during FMV with a fixed PEEP level or zero PEEP (ZEEP) after anaesthesia induction. A secondary aim was to investigate the effects of FMV with or without PEEP on upper oesophageal sphincter (UES), oesophageal body and lower oesophageal sphincter (LES) pressures.

DESIGN

A randomised controlled trial.

SETTING

Single centre, Department of Anaesthesia and Intensive Care, Örebro University Hospital, Sweden.

PARTICIPANTS

Thirty healthy volunteers.

INTERVENTIONS

Pre-oxygenation without or with CPAP 10 cmH₂O, followed by pressure-controlled FMV with either ZEEP or PEEP 10 cmH₂O after anaesthesia induction.

MAIN OUTCOME MEASURES

A combined impedance/manometry catheter was used to detect the presence of gas and to measure oesophageal pressures. The primary outcome measure was the cumulative incidence of gastric insufflation, defined as a sudden anterograde increase in impedance of more than 1 kΩ over the LES. Secondary outcome measures were UES, oesophageal body and LES pressures.

RESULTS

The cumulative incidence of gastric insufflation related to peak inspiratory pressure (PIP), was significantly higher in the PEEP group compared with the ZEEP group (log-rank test P < 0.01). When PIP reached 30 cmH₂O, 13 out of 15 in the PEEP group compared with five out of 15 had shown gastric insufflation. There was a significant reduction of oesophageal sphincter pressures within groups comparing pre-oxygenation to after anaesthesia induction, but there were no significant differences in oesophageal sphincter pressures related to the level of PEEP.

CONCLUSION

Contrary to the primary hypothesis, with increasing PIP the tested PEEP level did not protect against but facilitated gastric insufflation during FMV. This result suggests that PEEP should be used with caution after anaesthesia induction during FMV, whereas CPAP during pre-oxygenation seems to be safe.

TRIAL REGISTRATION

ClinicalTrials.gov, identifier: NCT02238691.

Preoperative Assessment of Ultrasonographic Measurement of Antral Area for Gastric Content

BACKGROUND Pulmonary aspiration of the gastric contents is a serious perioperative complication. The aim of this study was to evaluate the efficacy of portable ultrasonography in the preoperative evaluation of the gastric contents of patients. The secondary aim was to examine the relationship between gastric antrum cross-sectional area and age and body mass index (BMI). MATERIAL AND METHODS This single-center, prospective, cross-sectional study included 120 patients who underwent surgery. Measurements the gastric antral cross-sectional areas and quantitative and qualitative measurements of the stomach were taken by ultrasonography guidance in all patients. RESULTS With the patient in a supine position, the mean gastric antrum cross-sectional area was found to be 3.4±2.43 cm² (range, 0.79-17.3 cm²). As the number of hours of fasting increased, the gastric antral cross-sectional area statistically significantly decreased (P<0.05). Increased age and BMI values were determined to increase the gastric antrum cross-sectional area in a linear correlation; r=0.209, P<0.05 and r=0.252, P=0.05, respectively. It was determined that 20.8% of the patients exceeded the high-risk stomach antral cutoff cross-sectional area that was defined as 340 mm2 in patients fasting for at least 8 hours. CONCLUSIONS It was determined that bedside ultrasonography is a useful, non-invasive tool in the determination of gastric content and volume. A significant proportion of surgical patients may not present with an empty stomach despite the recommended fasting protocols.

Preoperative assessment of gastric contents and volume using bedside ultrasound in adult patients: A prospective, observational, correlation study

Background and Aims

Pulmonary aspiration of gastric contents is a serious complication of anaesthesia. The aim of this study was to determine, with the help of ultrasound, the gastric volume and content in fasted patients presenting for elective surgeries and correlate the results with fasting times and co-morbidities of the patients.

Methods

The study was conducted in 100 adult patients presenting for elective surgery. A preoperative bedside gastric ultrasound scan was done in supine and right lateral position. Gastric contents were noted, and gastric volume was calculated at the level of the gastric antrum. Gastric volume was estimated by measuring antral cross-sectional area (CSA) and using a mathematical model. Gastric volume in the right lateral decubitus (RLD) position was taken as the final reading. Analysis of variance and Student's t-test were done for statistical significance and P < 0.05 was considered statistically significant.

Results

Six out of 100 patients had solid gastric contents and 16 had >1.5 ml/kg clear liquids, although they had been fasting between 10 and 15 hours. Patients suffering from diabetes and chronic kidney disease had statistically significant increase in CSA in both supine and RLD. We also found increase in estimated gastric volume as the BMI of the patients increased.

Conclusion

Our study showed that fasting for more than 6-10 hours does not guarantee an empty stomach. Those with co-morbidities like diabetes mellitus, obesity and chronic kidney disease (CKD) appear more prone to have unsafe gastric contents.

Gastrointestinal endoscopy under sedation is associated with pneumonia in older inpatients-results of a retrospective case-control study

Background and aims

Apparent aspiration is a notable adverse event during gastrointestinal endoscopy under sedation (GIES), but data about inapparent aspiration are scarce. Generally, particularly older patients are at higher risk of suffering from adverse events.

Objective

The objective of this article is to determine the risk of pneumonia, lower respiratory tract infection (LRI) and systemic inflammatory activation after GIES, especially in patients of at least 65 years.

Methods

The retrospective case-control study included 250 patients undergoing GIES and assigned age-, gender- and time of performance-matched controls without invasive procedure or sedation (ratio 1:1).

Results

On day 3 patients of advanced age presented with both pneumonia and LRI more often (2.6 vs. 0.0%, p = 0.041 and 7.8 vs. 2.5%, p = 0.034, respectively). In general, several inflammatory parameters increased significantly after GIES (i.e. white blood cell count (increase of ≥ 25%) 18.6 vs. 6.9%, p < 0.001), leading to more frequent antibiotic treatment (6.8 vs. 1.6%, p = 0.004). The effects were less pronounced on day 7.

Conclusions

Patients of advanced age carry an increased risk of pneumonia and LRI after GIES. Patients are generally more likely to feature inflammation and to receive antibiotic treatment.

Evaluation of operating room reverse Trendelenburg positioning and its effect on postoperative hypoxemia, aspiration, and length of stay: a retrospective study of consecutive patients

Background

In 2014, this group published an investigation of surgical patients from 2012 who had substantial rates of postoperative hypoxemia (POH) and perioperative pulmonary aspiration (POPA). Therefore, we investigated whether intraoperative reverse Trendelenburg positioning (RTP) decreases POH and POPA rates.

Methods

Consecutive ASA I–IV surgical patients who had preoperative pulmonary stability requiring general anesthesia with endotracheal intubation were evaluated. Using pulse oximetry, hypoxemia was documented intraoperatively and during the 48 h following PACU discharge. POPA was the presence of a pulmonary infiltrate with hypoxemia. In early 2015, a multifaceted effort was undertaken to enhance anesthesiologist and operating nurse awareness of RTP to potentially decrease POH and POPA rates. Analyses included (1) combining 2012 and 2015 cohorts to assess risk conditions, (2) comparing post-campaign 2015 (increased RTP) and 2012 cohorts, and (3) comparing 2015 patients with audit-documented RTP during surgery to the other 2015 patients.

Results

Combining the 500 patients in 2012 with the 1000 in 2015 showed that POH had increased mortality (2.3%), compared to no POH (0.2%; p = 0.0004). POH had increased postoperative length of stay (LOS) (4.6 days), compared to no POH (2.0 days; p < 0.0001). POPA had increased mortality (7.7%) and LOS (8.8 days), compared to no POPA (0.4%; p = 0.0004; 2.3 days; p < 0.0001). Open aortic, cranial, laparotomy, and neck procedures had greater POH (41.3%) and LOS (4.0 days), compared to other procedures (16.3%; p < 0.0001; 2.2 days; p < 0.0001). Glycopyrrolate on induction had lower POH (17.4%) and LOS (1.9 days), compared to no glycopyrrolate (21.6%; p = 0.0849; 2.7 days; p < 0.0001). POH was lower (18.1%) in 2015, than in 2012 (25.6%; p = 0.0007). POPA was lower with RTP in 2015 (0.6%), than in 2012 (4.8%; p = 0.0088). For the 2015 patients, LOS was lower with audit-documented RTP (2.2 days), compared to other patients (2.7 days; p = 0.0246).

Conclusions

These findings are only hypothesis-generating. A randomized clinical trial is needed to confirm whether RTP has an inverse association with POH and POPA, and if RTP and glycopyrrolate are associated with improved outcomes.

Trial registration

ClinicalTrials.gov, NCT02984657

I-Gel is a suitable alternative to endotracheal tubes in the laparoscopic pneumoperitoneum and trendelenburg position

Background

The use of supraglottic airway devices (SADs) in surgeries with laparoscopic pneumoperitoneum and Trendelenburg (LPT) positioning is controversial due to concerns about insufficient pulmonary ventilation and aspiration. In this prospective, randomized-controlled trial, we evaluated whether the i-gel, a new second generation SAD, provides an effective alternative to an endotracheal tube (ETT) by comparing respiratory parameters and perioperative respiratory complications in non-obese patients.

Methods

In a randomized controlled trial, forty anesthetized patients with ASA I-II were divided into equally sized i-gel and ETT groups. We evaluated the respiratory parameters in the supine and LPT position in comparison between the two groups. The leak fraction was our primary outcome, which was defined as the leak volume divided by the inspired tidal volume. The leak volume was the difference between the inspired and expired tidal volumes. We also monitored pulmonary aspiration and respiratory complications during the perioperative period.

Results

In the LPT position, there were no differences in the leak fraction (median [IQR]) between the i-gel and ETT groups (6.20[3.49] vs 6.38[3.71] %, P = 0.883). In the i-gel group, notably less leakage was observed in the LPT position than in the supine position (median [IQR]: 7.01[3.73] %). This phenomenon was not observed in the ETT group. The rate of postoperative sore throat was also significantly lower in the i-gel group than in the ETT group (3/17 vs 9/11). No vomitus nor any signs associated with aspiration were noted in our patients after extubation in the follow-up prior to discharge.

Conclusions

The i-gel provides a suitable alternative to an ETT for surgeries with LPT positioning in non-obese patients.

Trial registration

Registered at Clinicaltrials.gov NCT02462915, registered on 1 June 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-016-0291-1) contains supplementary material, which is available to authorized users.

Post-operative pulmonary complications after non-cardiothoracic surgery

Post-operative pulmonary complications (PPCs) occur in 5–10% of patients undergoing non-thoracic surgery and in 22% of high risk patients. PPCs are broadly defined as conditions affecting the respiratory tract that can adversely influence clinical course of the patient after surgery. Prior risk stratification, risk reduction strategies, performing short duration and/or minimally invasive surgery and use of anaesthetic technique of combined regional with general anaesthesia can reduce the incidence of PPCs. Atelectasis is the main cause of PPCs. Atelectasis can be prevented or treated by adequate analgesia, incentive spirometry (IS), deep breathing exercises, continuous positive airway pressure, mobilisation of secretions and early ambulation. Pre-operative treatment of IS is more effective. The main reason for post-operative pneumonia is aspiration along the channels formed by longitudinal folds in the high volume, low pressure polyvinyl chloride cuffs of the endotracheal tubes. Use of tapered cuff, polyurethane cuffs and selective rather than the routine use of nasogastric tube can decrease chances of aspiration. Acute lung injury is the most serious PPC which may prove fatal.

Effect of hypertonic saline treatment on the inflammatory response after hydrochloric acid-induced lung injury in pigs

OBJECTIVES

Hypertonic saline has been proposed to modulate the inflammatory cascade in certain experimental conditions, including pulmonary inflammation caused by inhaled gastric contents. The present study aimed to assess the potential anti-inflammatory effects of administering a single intravenous dose of 7.5% hypertonic saline in an experimental model of acute lung injury induced by hydrochloric acid.

METHODS

Thirty-two pigs were anesthetized and randomly allocated into the following four groups: Sham, which received anesthesia and were observed; HS, which received intravenous 7.5% hypertonic saline solution (4 ml/kg); acute lung injury, which were subjected to acute lung injury with intratracheal hydrochloric acid; and acute lung injury + hypertonic saline, which were subjected to acute lung injury with hydrochloric acid and treated with hypertonic saline. Hemodynamic and ventilatory parameters were recorded over four hours. Subsequently, bronchoalveolar lavage samples were collected at the end of the observation period to measure cytokine levels using an oxidative burst analysis, and lung tissue was collected for a histological analysis.

RESULTS

Hydrochloric acid instillation caused marked changes in respiratory mechanics as well as blood gas and lung parenchyma parameters. Despite the absence of a significant difference between the acute lung injury and acute lung injury + hypertonic saline groups, the acute lung injury animals presented higher neutrophil and tumor necrosis factor alpha (TNF-α), interleukin (IL)-6 and IL-8 levels in the bronchoalveolar lavage analysis. The histopathological analysis revealed pulmonary edema, congestion and alveolar collapse in both groups; however, the differences between groups were not significant. Despite the lower cytokine and neutrophil levels observed in the acute lung injury + hypertonic saline group, significant differences were not observed among the treated and non-treated groups.

CONCLUSIONS

Hypertonic saline infusion after intratracheal hydrochloric acid instillation does not have an effect on inflammatory biomarkers or respiratory gas exchange.

Perioperative hypoxemia is common with horizontal positioning during general anesthesia and is associated with major adverse outcomes: a retrospective study of consecutive patients

Background

Reported perioperative pulmonary aspiration (POPA) rates have substantial variation. Perioperative hypoxemia (POH), a manifestation of POPA, has been infrequently studied beyond the PACU, for patients undergoing a diverse array of surgical procedures.

Methods

Consecutive adult patients with ASA I-IV and pre-operative pulmonary stability who underwent a surgical procedure requiring general anesthesia were investigated. Using pulse oximetry, POH was documented in the operating room and during the 48 hours following PACU discharge. POPA was the presence of an acute pulmonary infiltrate with POH.

Results

The 500 consecutive, eligible patients had operative body-positions of prone 13%, decubitus 8%, sitting 1%, and supine/lithotomy 78%, with standard practice of horizontal recumbency. POH was found in 150 (30%) patients. Post-operative stay with POH was 3.7 ± 4.7 days and without POH was 1.7 ± 2.3 days (p < 0.0001). POH rate varied from 14% to 58% among 11 of 12 operative procedure-categories. Conditions independently associated with POH (p < 0.05) were acute trauma, BMI, ASA level, glycopyrrolate administration, and duration of surgery. POPA occurred in 24 (4.8%) patients with higher mortality (8.3%), when compared to no POPA (0.2%; p = 0.0065). Post-operative stay was greater with POPA (7.7 ± 5.7 days), when compared to no POPA (2.0 ± 2.9 days; p = 0.0001). Conditions independently associated with POPA (p < 0.05) were cranial procedure, ASA level, and duration of surgery. POPA, acute trauma, duration of surgery, and inability to extubate in the OR were independently associated with post-operative stay (p < 0.05). POH, gastric dysmotility, acute trauma, cranial procedure, emergency procedure, and duration of surgery had independent correlations with post-operative length of stay (p < 0.05).

Conclusions

Adult surgical patients undergoing general anesthesia with horizontal recumbency have substantial POH and POPA rates. Hospital mortality was greater with POPA and post-operative stay was increased for POH and POPA. POH rates were noteworthy for virtually all categories of operative procedures and POH and POPA were independent predictors of post-operative length of stay. A study is needed to determine if modest reverse-Trendelenburg positioning during general anesthesia has a relationship with reduced POH and POPA rates.

Airway pepsin levels in otherwise healthy surgical patients receiving general anesthesia with endotracheal intubation

BACKGROUND

Airway pepsin has been increasingly used as a potentially sensitive and quantifiable biomarker for gastric-to-pulmonary aspiration, despite lack of validation in normal control subjects. This study attempts to define normal levels of airway pepsin in adults and distinguish between pepsin A (exclusive to stomach) and pepsin C (which can be expressed by pneumocytes).

METHODS

We performed a prospective study of 51 otherwise healthy adult patients undergoing elective extremity orthopedic surgery at a single tertiary-care academic medical center. Lower airway samples were obtained immediately following endotracheal intubation and just prior to extubation. Total pepsin and pepsin A concentrations were directly measured by an enzymatic activity assay, and pepsin C was subsequently derived. Pepsinogen/pepsin C was confirmed by Western blot analyses. Baseline characteristics were secondarily compared.

RESULTS

In all, 11 (22%; 95% CI = 9.9%-33%) had detectable airway pepsin concentrations. All 11 positive specimens had pepsin C, without any detectable pepsin A. Pepsinogen/pepsin C was confirmed by Western blot analyses. In a multivariate logistic regression, men were more likely to have airway pepsin (OR, 12.71, P = .029).

CONCLUSIONS

Enzymatically active pepsin C, but not the gastric-specific pepsin A, is frequently detected in the lower airways of patients who otherwise have no risk for aspiration. This suggests that nonspecific pepsin assays should be used and interpreted with caution as a biomarker of gastropulmonary aspiration, as pepsinogen C potentially expressed from pneumocytes may be detected in airway samples.

A randomized trial to identify optimal precurarizing dose of rocuronium to avoid precurarization-induced neuromuscular block

PURPOSE

The aim of this study was to examine the safe precurarizing dose of rocuronium required to avoid neuromuscular block after precurarization.

METHODS

Twenty-four female patients were randomly allocated into two groups of 12 patients each. General anesthesia was induced and maintained with remifentanil and propofol, and a laryngeal mask was inserted without the aid of a neuromuscular blocking agent. Patients were randomized to receive either 0.03 or 0.06 mg/kg rocuronium as a precurarizing dose. Neuromuscular block was monitored using acceleromyographic train-of-four (TOF) of the adductor pollicis muscle. Three minutes after the precurarization, all patients received suxamethonium 1.5 mg/kg and were graded on severity of fasciculations.

RESULTS

The average TOF ratio was kept above 0.9 even 3 min after precurarization with 0.03 mg/kg rocuronium. In contrast, in patients who received 0.06 mg/kg rocuronium, the ratios significantly decreased to 0.72 (0.14) [mean (SD), P < 0.004] and 0.68 (0.18) (P < 0.006) 2 min and 3 min after the precurarization, respectively. No visible muscle movement was observed following suxamethonium injection, except that one patient who received 0.03 mg/kg rocuronium showed very fine muscle movements of the fingertips.

CONCLUSION

Rocuronium at 0.06 mg/kg is an overdose for precurarization. The results of the present study demonstrate that a safe and effective precurarizing dose of rocuronium is 0.03 mg/kg.

Effectiveness of the timing principle with high-dose rocuronium during rapid sequence induction with lidocaine, remifentanil and propofol

PURPOSE

The main purpose of this study was to examine the effectiveness of the timing principle with 1 mg kg(-1) rocuronium for rapid sequence intubation. As secondary outcomes, propofol and lidocaine with or without remifentanil were examined to note their effects on the cardiovascular responses to laryngoscopy and intubation.

METHODS

Thirty patients were randomly allocated to one of two groups of 15 patients each: a lidocaine-treated group (L) and a lidocaine/remifentanil-treated group (LR). Thirty seconds after lidocaine 1 mg kg(-1) with or without infusion of remifentanil 1 microg kg(-1) min(-1), all patients received a bolus of rocuronium 1 mg kg(-1). Shortly afterwards, patients were given propofol 2-2.5 mg kg(-1). Intubating conditions and cardiovascular responses were observed 60 s after rocuronium. The time to spontaneous recovery of visible train-of-four (TOF) counts of 4 was observed at the thumb during 1.0-1.5% end-tidal sevoflurane and remifentanil anesthesia.

RESULTS

All patients had excellent or good intubating conditions. Hypertension and tachycardia during laryngoscopy were well prevented in group LR, whereas they were significantly observed in group L. The times to reappearance of TOF counts of 4 were comparable in all groups [mean (SD); 63.6 (8.6) min in group L and 63.5 (11.6) min in group LR].

CONCLUSION

Application of the timing principle with 1 mg kg(-1) rocuronium is beneficial for rapid tracheal intubation. Co-administered lidocaine, remifentanil and propofol can definitely suppress cardiovascular responses during laryngoscopy and intubation.

Hyperphosphatemia after sodium phosphate laxatives in low risk patients: prospective study

AIM

To establish the frequency of hyperphosphatemia following the administration of sodium phosphate laxatives in low-risk patients.

METHODS

One hundred consecutive ASA I-II individuals aged 35-74 years, who were undergoing colonic cleansing with oral sodium phosphate (OSP) before colonoscopy were recruited for this prospective study.

EXCLUSION CRITERIA

congestive heart failure, chronic kidney disease, diabetes, liver cirrhosis, intestinal obstruction, decreased bowel motility, increased bowel permeability, and hyperparathyroidism. The day before colonoscopy, all the participants entered a 24-h period of diet that consisted of 4 L of clear fluids with sugar or honey and 90 mL (60 g) of OSP in two 45-mL doses, 5 h apart. Serum phosphate was measured before and after the administration of the laxative.

RESULTS

The main demographic data (mean +/- SD) were: age, 58.9 +/- 8.4 years; height, 163.8 +/- 8.6 cm; weight, 71 +/- 13 kg; body mass index, 26 +/- 4; women, 66%. Serum phosphate increased from 3.74 +/- 0.56 to 5.58 +/- 1.1 mg/dL, which surpassed the normal value (2.5-4.5 mg/dL) in 87% of the patients. The highest serum phosphate was 9.6 mg/dL. Urea and creatinine remained within normal limits. Post-treatment OSP serum phosphate concentration correlated inversely with glomerular filtration rate (P < 0.007, R(2) = 0.0755), total body water (P < 0.001, R(2) = 0.156) and weight (P < 0.013, R(2) = 0.0635).

CONCLUSION

In low-risk, well-hydrated patients, the standard dose of OSP-laxative-induced hyperphosphatemia is related to body weight.

Risk of death after emergency repair of abdominal wall hernias. Still waiting for improvement

PURPOSE

The precise importance of factors affecting morbidity and mortality in patients with complicated abdominal wall hernias undergoing emergency surgical repair has been not completely elucidated.

PATIENTS AND METHODS

A retrospective multicentric study of all patients (n = 402) with abdominal wall hernia who underwent urgent operations over 1-year period was conducted in ten hospitals. Logistic regression analysis was used to evaluate variables that affect morbidity and mortality.

RESULTS

Thirty-five percent of patients had inguinal hernia, 22% femoral hernia, 20% umbilical hernia, and 15% incisional hernia. Mesh repair was used in 92.5% of cases. Intestinal resection was required in 49 patients. Perioperative complications occurred in 130 patients, and 18 patients died (mortality rate 4.5%). Complications and mortality rate were significantly higher in the group of intestinal resection. Patients older than 70 years also showed more complications, required intestinal resection more frequently, and had a higher mortality rate than younger patients. In the logistic regression analysis, age over 70 years, intestinal resection, and American Society of Anesthesiologists (ASA) III/IV class emerged as independent predictors of a poor outcome. Based in our results, we propose a simple schema to calculate risk of death in these patients.

CONCLUSION

Using multivariate logistic regression analysis, probabilities of death after complicated abdominal wall hernia surgery are increased in patients with: age over 70 years, high ASA class, and associated intestinal resection. Guidelines should be developed to improve prognosis in these patients.

Acute pulmonary capillary leak syndrome during elective surgery under general anesthesia

A 75-year-old previously healthy man presented for elective resection of rectal cancer under general anesthesia. Six days before the operation, he had a high-grade fever, and elevated leukocyte count and C-reactive protein concentration, but this was resolved by an intravenous antibiotic. His condition was well controlled before the operation. Soon after the operation started, severe hypoxemia emerged, with low arterial pressure. Fiberoptic bronchoscopy demonstrated a massive amount of plasma-like edema fluid; the total amount of suctioned fluid was approximately 800 ml at the end of the surgery. This acute pulmonary edema appeared to be due to increased permeability rather than pulmonary congestion as indicated by chest radiography, pulmonary artery occlusion pressure, echocardiogram, and the protein-rich edema fluid. Elevated concentrations of the proinflammatory cytokines, interleukin (IL)-6 and IL-8, in both plasma and the pulmonary edema fluid, suggested a possible role of systemic and pulmonary inflammation in the development of this acute pulmonary capillary leak. According to the "two-hit" hypothesis, the bacterial infection preceding the operation may have primed the immune cells, and the following surgical stress may have then triggered rapid progression of acute respiratory distress syndrome. We should keep in mind that, especially following sepsis, sudden massive pulmonary capillary leak can occur during elective surgery, even though the patient's condition is well controlled.

Effects of preanesthetic administration of morphine on gastroesophageal reflux and regurgitation during anesthesia in dogs

OBJECTIVE

To determine the effect of morphine administered prior to anesthesia on the incidence of gastroesophageal reflux (GER) in dogs during the subsequent anesthetic episode.

ANIMALS

90 dogs (30 dogs/group).

PROCEDURE

The randomized prospective clinical study included healthy dogs with no history of vomiting. Dogs were scheduled to undergo elective orthopedic surgery. Food was withheld for (mean+/-SD) 17.8+/-4.1 hours prior to induction of anesthesia. The anesthetic protocol included acepromazine maleate, thiopental, and isoflurane. Dogs were randomly selected to receive morphine at various dosages (0, 0.22, or 1.10 mg/kg, IM) concurrent with acepromazine administration prior to induction of anesthesia. A sensor-tipped catheter was used to measure esophageal pH, and GER was defined as a decrease in pH to < 4 or an increase to > 7.5.

RESULTS

40 dogs had acidic reflux, and 1 had biliary reflux. Proportions of dogs with GER were 8 of 30 (27%), 15 of 30 (50%), and 18 of 30 (60%) for morphine dosages of 0, 0.22, and 1.10 mg/kg, respectively. Mean duration of GER was 91.4+/-56.8 minutes. There was no significant association between GER and age, weight, vomiting after preanesthetic medication, administration of antimicrobials, or start of surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Most healthy dogs vomit after a large dose of morphine, but vomiting does not increase the likelihood of GER during the subsequent anesthetic episode. Administration of morphine prior to anesthesia substantially increases the incidence of GER during the subsequent anesthetic episode.