Preoperative pregabalin does not reduce propofol ED50: a randomized controlled trial

Background

In many studies, gabapentinoids, such as pregabalin, have been shown to reduce preoperative anxiety. This anxiolysis is often accompanied by sedation, one of the most frequent side effects of pregabalin. We hypothesized that pregabalin taken preoperatively could reduce propofol requirements for induction of general anesthesia.

Methods

A randomized double-blind placebo-controlled trial was conducted after approval by the local ethics committee. Fifty women aged 18-40 yr, American Anesthesiologists Society physical status I and II, and scheduled to undergo elective laparoscopic gynecologic procedures were enrolled after written consent. Treatment group patients were given pregabalin 150 mg po one hour before surgery while patients in the control group received a placebo. The primary outcome was the propofol dose required to achieve a targeted anesthetic depth in 50% of the population, i.e., effective dose (ED)₅₀. The ED₅₀ was estimated using Dixon’s up-and-down methodology. The targeted anesthetic depth was defined based on predetermined entropy monitoring values (State Entropy [SE] < 50 and Response Entropy [RE]-SE < 10). As a secondary outcome, we tested if pregabalin reduced pre-induction anxiety levels which were measured on a 0-100 scale.

Results

The propofol ED₅₀ was not statistically different between the pregabalin group (mean 1.33 mg·kg^?1; 95% confidence interval [CI] 1.23 to 1.43) vs the placebo group (mean 1.37 mg·kg^?1; 95% CI 1.28 to 1.46); P = 0.19. Also, pre-induction anxiety level was not different between groups (median 31; interquartile range [IQR] [10-52] vs median 42; IQR [4-71], respectively; P = 0.41).

Conclusions

Preoperative pregabalin does not reduce propofol requirements in a population of healthy young women undergoing laparoscopic gynecologic procedures. This study failed to show a pre-induction anxiolytic effect of pregabalin in such a population. This trial was registered at www.clinicaltrials.gov (NCT01158859).     

Oropharyngeal leak pressure with the laryngeal mask airway Supreme™ at different intracuff pressures: a randomized controlled trial

Background

A higher oropharyngeal leak pressure (OLP) is a marker of efficacy and safety when using laryngeal mask airway devices. The new disposable laryngeal mask airway (LMA?) Supreme? has lower OLP compared with the LMA ProSeal?. Increased intracuff pressure of laryngeal mask airway devices may improve OLP but may result in more postoperative pharyngolaryngeal adverse events. This study was designed to compare the OLP of the LMA Supreme at varying intracuff pressures.

Methods

One hundred and twenty-three patients were divided randomly into three groups. General anesthesia was standardized using a propofol-fentanyl induction and desflurane in air-oxygen for maintenance. Intracuff pressures of the LMA Supreme were adjusted to 80 cm H₂O, 60 cm H₂O, and 40 cm H₂O according to group allocation. The primary outcome was OLP. Secondary outcomes included postoperative pharyngolaryngeal adverse events and the satisfaction scores of patients and anesthesiologists. The OLP was compared amongst groups using analysis of variance with Bonferroni correction. All reported P values are two-sided.

Results

The OLP with an intracuff pressure of 80 cm H₂O was significantly higher compared with 60 cm H₂O and 40 cm H₂O (26 [6] vs 20 [6] vs 18 [5] cm H₂O, respectively; P < 0.001). The incidence of postoperative pharyngolaryngeal adverse events (P = 0.6), patient satisfaction scores (P = 0.2), and anesthesiologist satisfaction scores (P = 0.8) were comparable amongst the three groups.

Conclusion

An intracuff pressure of 80 cm H₂O with the LMA Supreme is associated with a higher OLP compared with 60 cm H₂O or 40 cm H₂O without a greater incidence of postoperative pharyngolaryngeal adverse events. For a superior glottic seal when using the LMA Supreme, we recommend intracuff pressures up to 80 cm H₂O.     

Residual paralysis: a real problem or did we invent a new disease?

Purpose

Over the past three decades, many studies have shown a high proportion of patients in the recovery room with residual neuromuscular blockade after anesthesia. The purpose of this Continuing Professional Development module is to present the physiological consequences of residual paralysis, estimate the extent of the problem, and suggest solutions to prevent its occurrence.

Principal findings

Residual paralysis is defined as a train-of-four ratio (TOFR) < 0.9 at the adductor pollicis. While tidal volume and, to a lesser extent, vital capacity are well preserved as the intensity of blockade increases, the probability of airway obstruction, impaired swallowing, and pulmonary aspiration increases markedly as TOFR decreases. In recent studies, incidences of residual paralysis from 4-57% have been reported, but surveys indicate that anesthesiologists estimate the incidence of the problem at 1% or less. The decision to administer neostigmine or sugammadex should be based on the degree of spontaneous recovery at the adductor pollicis muscle (thumb), not on recovery at the corrugator supercilii (eyebrow). The most important drawback of neostigmine is its inability to reverse profound blockade, which is a consequence of its ceiling effect. When spontaneous recovery reaches the point where TOFR > 0.4 or four equal twitch responses are seen, reduced doses of neostigmine may be given. The dose of sugammadex required in a given situation depends on the intensity of blockade.

Conclusion

Careful monitoring and delaying the administration of neostigmine until four twitches are observed at the adductor pollicis can decrease the incidence of residual paralysis. The clinical and pharmacoeconomic effects of unrestricted sugammadex use are unknown at this time.     

The Impacts of Super Obesity Versus Morbid Obesity on Respiratory Mechanics and Simple Hemodynamic Parameters During Bariatric Surgery

Background

This study was designed to determine the impact of the degree of obesity on respiratory mechanics and simple hemodynamic parameters at laparoscopic bariatric surgery.

Methods

The patients were divided into two groups, each of which included 24 patients (a morbidly obese group and a super obese group) undergoing laparoscopic bariatric surgery. Dynamic respiratory compliance, respiratory resistance, and peak inspiratory pressures were measured at four time points: 10 min after anesthesia induction (T1: induction), 10 min after pneumoperitoneum (T2: pneumoperitoneum), 10 min after terminating pneumoperitoneum (T3: end-pneumoperitoneum), and before extubation (T4: extubation). The systolic, diastolic, and mean arterial pressures and the heart rate values were measured noninvasively in T0 (10 min before operation).

Results

Obesity was found to cause a statistically significant increase in respiratory resistance and a peak inspiratory pressure and a decrease in dynamic respiratory compliance. In the morbidly obese group, the lowest dynamic respiratory compliance was 37?±?12 mL/cm H₂O, but it was 33?±?13 mL/cm H₂O in the super obese group. The systolic pressure, diastolic pressure, and mean arterial pressure were found to decrease significantly in both groups.

Conclusions

Morbid obesity and super obesity have negative effects on hemodynamics and respiratory mechanics.     

Arthroscopic shoulder surgery under general anesthesia with brachial plexus block

Objective

Changes in respiratory parameters and pulmonary function tests were evaluated after shoulder arthroscopic surgery with brachial plexus block (BPB). The purpose of this study was to identify the mechanism of respiratory dysfunction after this type of surgery.

Methods

Patients undergoing arthroscopic rotator cuff repair under general anesthesia (GA) with BPB were enrolled in the arthroscopy group (n?=?30) while those undergoing open reduction of a clavicle or humerus fracture under GA were enrolled in the control group (n?=?30). Forced vital capacity (FVC) and forced expiratory volume 1 s (FEV₁) were measured at the outpatient clinic stage (#1) before (#2) and 20 min after BPB (#3) and 1 h after extubation (#4). Respiratory variable measurements along with the cuff leak test were performed 5 min after surgical positioning (T1) and at the start of skin closure (T2). Respiratory discomfort was evaluated after extubation. The upper airway diameters and soft tissue depth of chest wall were also measured by ultrasonography at stages #3 and #4.

Results

Static compliance decreased significantly at T2 in the arthroscopy group (50?±?11 at T1 vs. 44?±?9 ml/cm H₂O at T2, p?=0.035) but not in the control group. The incidence of positive cuff leak tests at T2 was significantly higher in the arthroscopy group than in the control group (47% in the arthroscopy group vs. 17% in controls, p?=0.010). While FEV₁ and FVC remained stable at stages #1 and #2, FVC and FEV₁ decreased at stages #3 and #4 only in the arthroscopy group (FVC in arthroscopy group, #2: 3.26?±?0.77 l; #3: 2.55?±?0.63 l, p?=0.015 vs. #2; #4: 2.66?±?0.41 l, p?=0.040 vs. #2). The subglottic diameter decreased at #4 in the arthroscopy group, while no changes occurred in the control group (0.70?±?0.21 cm vs. 0.85?±?0.23 cm in the arthroscopy and control groups, respectively, p?=0.011). Depth of skin to pleura increased at both intercostal spaces 1–2 and 3–4 in the arthroscopy group. There were three cases of hypoxia (S_pO₂?<?95%) with room air in the arthroscopy group while none occurred in the controls.

Conclusion

Shoulder arthroscopic surgery under GA with BPB induced both restrictive and obstructive pathologies. It is important to maintain a high level of awareness for the potential negative respiratory effects of this surgery especially for subjects with pre-existing cardiopulmonary disease. The measurements in this study would be useful to monitor the risk of respiratory dysfunction in these patients.     

Funktionelle Ergebnisse nach Laservaporisation der Prostata mit dem KTP-Laser

Background

Treatment for bladder outlet obstruction (BOO) caused by benign prostatic hyperplasia (BPH) impairs the quality of life. The potassium tintanyl phosphate (KTP) vaporisation of the prostate offers promising modalities in treatment of BOO. We prospectively determined the impact of KTP-lasertherapy on voiding function, quality of life and sexual function.

Patients and methods

So far a total of n=123 patients complaining of syptomatic BPH were treated with an 80 watt Laser. N= 40 of them agreed to participate in the study and were evaluated prospectively. Preoperative pressure-flow-studies verified significant bladder outlet obstruction in all cases. Disease specific quality of life and sexual function were assessed using the International Prostate Symptom Score (IPSS) and International Inventory of Erectile Function (IIEF). Three months after treatment follow-up video-urodynamics were carried out to determine changements in pressure flow and bladder function.

Results

All patients showed significant improvement after a hospital stay of 4,9 days. The maximum flow rate increased from 9,1 ml/sec preoperatively to 20,2 ml/sec and the amount of residual urine decreased from 98 ml preoperatively to 17 ml immediately after removal of the catheter. Urodynamics after the follow up period showed that the maximum urinary flow improved from 9.7 ml/s preoperatively to 17,6 ml/s and the volume of residual urine decreased from a median of 127.5 ml preoperatively to 45ml postoperatively. The IPSS and IIEF decreased from a median of 20,4 preoperatively to 8,16 and from a median of 14 preoperatively to 12,7 respectively. The pressure-flow study verified the desobstruction and showed a decline in detrusor pressure at maximum flow from 76,66 cm H₂O to 33,79 cm H₂O. The urethral opening pressure sank from 75.86 cm H₂O preoperatively to 37,51 cm H₂O postoperatively.

Conclusion

The potassium tintanyl phosphate (KTP) vaporisation of the prostate is a promising new method in the treatment of benign prostatic hyperplasia as shown by the data. Beside its low perioperativ and postoperative morbidity due to a high hemostatic property it offers a good tissue debulking effect.     

Pre-operative inspiratory muscle training preserves postoperative inspiratory muscle strength following major abdominal surgery �C a randomised pilot study

INTRODUCTION

The aim of this pilot study was to assess the effect of pre-operative inspiratory muscle training (IMT) on respiratory variables in patients undergoing major abdominal surgery.

PATIENTS AND METHODS

Respiratory muscle strength (maximum inspiratory [MIP] and expiratory [MEP] mouth pressure) and pulmonary functions were measured at least 2 weeks before surgery in 80 patients awaiting major abdominal surgery. Patients were then allocated randomly to one of four groups (Group A, control; Group B, deep breathing exercises; Group C, incentive spirometry; Group D, specific IMT). Patients in groups B, C and D were asked to train twice daily, each session lasting 15 min, for at least 2 weeks up to the day before surgery. Outcome measurements were made immediately pre-operatively and postop-eratively.

RESULTS

In groups A, B and C, MIP did not increase from baseline to pre-operative assessments. In group D, MIP increased from 51.5 cmH₂O (median) pre-training to 68.5 cmH₂O (median) post-training pre-operatively (P < 0.01). Postoperatively, groups A, B and C showed a fall in MIP from baseline (P < 0.01, P < 0.01) and P = 0.06, respectively). No such significant reduction in postoperative MIP was seen in group D (P = 0.36).

CONCLUSIONS

Pre-operative specific IMT improves MIP pre-operatively and preserves it postoperatively. Further studies are required to establish if this is associated with reduced pulmonary complications.     

Sugammadex Allows Fast-Track Bariatric Surgery

Background

Morbidly obese (MO) patients are at increased risk for postoperative anesthesia-related complications. We evaluated the role of sugammadex versus neostigmine in the quality of recovery from profound rocuronium-induced neuromuscular blockade (NMB) in patients with morbid obesity.

Methods

We studied 40 female MO patients who received desflurane and remifentanil anesthesia for laparoscopic removal of adjustable gastric banding. NMB was achieved with rocuronium. At the end of the surgical procedure, complete reversal of NMB was obtained with sugammadex (SUG group, n?=?20) or neostigmine plus atropine (NEO group, n?=?20) in the presence of profound NMB.

Results

No difference in surgical time or anesthetic drugs was found between the groups. Anesthesia time was significantly greater in the NEO group than in the SUG group (95?±?21 vs. 47.9?±?6.4 min, p?<?0.0001), which was mainly due to a longer time to reach a train-of-four ratio (TOFR)?≥?0.9 in the NEO group (48.6?±?18 vs. 3.1?±?1.3 min, p?<?0.0001) during reversal of profound NMB. Upon admission to the postanesthesia care unit, level of SpO₂ (p?=?0.018), TOFR (p?<?0.0001), ability to swallow (p?=?0.0027), and ability to get into bed independently (p?=?0.022) were better in the SUG group than in the NEO group. Patients in the SUG group were discharged to the surgical ward earlier than patients in the NEO group were (p?=?0.013).

Conclusions

Sugammadex allowed a safer and faster recovery from profound rocuronium-induced NMB than neostigmine did in patients with MO. Sugammadex may play an important role in fast-track bariatric anesthesia     

Contribution of the nasal passage to face mask ventilation: a prospective blinded randomized crossover trial

Background

Previous studies have shown that the nasal passage plays an important role in manual face mask ventilation, but this has yet to be quantitatively assessed. We conducted a prospective randomized crossover clinical trial to compare the change in pressure-controlled face mask tidal volume with and without nasal airway occlusion.

Method

Female patients undergoing elective surgery under general anesthesia served as study subjects. Patients were randomly assigned to face mask ventilation beginning either with or without nasal passage occlusion (achieved with a swimmer’s nose clip), followed by removal or application of the nose clip, respectively. After standardized induction of general anesthesia and muscle paralysis, a tight-fitting face mask was applied to each patient, and tidal volume was measured by the anesthesia machine during pressure-controlled ventilation (10, 15, 20 cm H₂O; 8 breaths·min^?1; inspiratory:expiratory ratio 1:2).

Results

The median [interquartile range] tidal volume was lower with vs without nasal passage occlusion at 10 cm H₂O inspiratory pressure (100 [55-134] mL vs 300 [230-328] mL, respectively; median difference (MD), 200 mL; 95% confidence interval (CI), 157 to 229; P < 0.001), 15 cm H₂O inspiratory pressure (190 [120-230] mL vs 520 [420-593] mL, respectively; MD, 340 mL; 95% CI, 257 to 395; P < 0.001), and 20 cm H₂O inspiratory pressure (270 [215-390] mL vs 790 [713-823] mL, respectively; MD, 520 mL; 95% CI, 390 to 582; P < 0.001).

Conclusion

Nasal passage obstruction considerably reduces tidal volume achieved during face mask ventilation. In some patients, it may be advantageous to relieve nasal airway obstruction for effective face mask ventilation.

Trial registration

UMIN Clinical Trials Registry, number UMIN000022184. Registered 2 May 2016.

     

Maximum urethral closure pressure in women: normative data and evaluation as a diagnostic test

Introduction and hypothesis

Our goal was to identify correlates of maximum urethral closure pressure (MUCP) and MUCP as a diagnostic test for stress urinary incontinence (SUI).

Methods

This study was a retrospective review of women with non-neurological referrals for urinary incontinence between1995 and 2006.

Results

We studied the characteristics of 8,644 women who underwent urodynamics for non-neurological referrals. Mean MUCP was 48?cm?H₂O in urodynamic stress incontinence (USI), 50?cm?H₂O in mixed urinary incontinence (MUI), 65?cm?H₂O in detrusor overactivity incontinence (DOI) and 67?cm?H₂O for continent women . Age and MUCP were negatively correlated in all groups. Multiple regression analysis showed lower levels of MUCP in women with USI who also had previous hysterectomy or anti-incontinence surgery or who were in an older age group. Previous anti-incontinence surgery and older age were risk factors for lower MUCP in women with MUI and DOI. Receiver operator curves did not show MUCP to have utility as a diagnostic test despite age and parity stratification. MUCP?<?20?cm?H₂O showed a sensitivity of 5?% and specificity of 98?% in diagnosing USI.

Conclusions

MUCP failed to meet the criteria for a diagnostic test. Women with USI and MUI have lower MUCP than women with DOI and continent women in each decade of life. MUCP decreases with age.     

Efficacy and safety of artificial pneumothorax under two-lung ventilation in thoracoscopic esophagectomy for esophageal cancer in the prone position

Background

Thoracoscopic esophagectomy for esophageal cancer performed using two-lung ventilation in the prone position has many advantages, such as convenient anesthesia induction and maintenance, and good oxygenation. We examined the safety of surgery and anesthetic management by following chronological changes in intraoperative respiration and hemodynamics.

Methods

We focused on the most recent and consecutive 14 cases of thoracoscopic esophagectomy for esophageal cancer in the prone position performed from November 2010 until recently. We measured the following items by use of FloTrac system : cardiac index (CI), central venous pressure (CVP), mean arterial pressure, partial pressure of oxygen in arterial blood (PaO₂), partial pressure of carbon dioxide in arterial blood (PaCO₂), peak airway pressure (APmax), and tidal volume.

Results

No major changes were observed in CI, systolic blood pressure, and TV after the start of pneumothorax (statically not significant). Conversely, CVP increased immediately after pneumothorax (p < 0.05) and decreased almost to its original level thereafter. The mean APmax value was 18–20 cm H₂O [mean increase, 4.2 cm H₂O; (p < 0.05)]. The mean P/F ratio and mean PaCO₂ were 244.4 and 48.3 mmHg, respectively, during artificial pneumothorax.

Conclusion

No excessive increases in airway pressure or clear circulatory depressions were observed because of artificial pneumothorax under two-lung ventilation in thoracoscopic esophagectomy for esophageal cancer in the prone position. These results suggest that artificial pneumothorax under two-lung ventilation is beneficial for maintaining stable hemodynamics and oxygenation in thoracoscopic esophagectomy in prone position.     

Alterations in respiratory mechanics after laparoscopic and open surgical procedures

Objective

To compare the effects of laparoscopic and open surgical procedures on postoperative strength and respiratory mechanics.

Design

Prospective cohort study.

Setting

Adult university hospital.

Participants

Fifty-one women aged 21 to 62 years scheduled to undergo elective cholecystectomy or hysterectomy (or related procedures), otherwise in good health.

Intervention

Open or laparoscopic cholecystectomy or hysterectomy (or related procedures).

Main Outcome Measures

Maximum voluntary handgrip strength (HGS), forced vital capacity (VC), forced expiratory volume in 1 second (FEV₁), and maximal inspiratory pressure (MIP) were each measured preoperatively and on the first postoperative morning. A visual analogue pain scale score was evaluated in relation to performance of the postoperative strength and respiratory measurements.

Results

VC, FEV₁ and MIP, but not HGS, were decreased after surgery. Postoperative VC, FEV₁ and MIP were lower after open procedures than after laparoscopic procedures and after cholecystectomy than after hysterectomy (all p < 0.001). Pain scores were lower after laparoscopic than after open procedures (p < 0.005) and could account in part for differences in postoperative respiratory mechanics.

Conclusions

Cholecystectomy and hysterectomy do not result in generalized muscle weakness, unlike more major abdominal procedures. Postoperative alterations in respiratory mechanics are related to the site of the surgery, the use of an open versus a laparoscopic approach and postoperative pain.     

Sevoflurane and isoflurane impair edrophonium reversal of vecuronium-induced neuromuscular block

Purpose

A dose-response relationship study for edrophonium to examine the modification of volatile anaesthetics on reversal of vecuronium block.

Methods

One hundred and twenty ASA (I–II) patients were anaesthetized with sevoflurane, isoflurane (I minimum alveolar anaesthetic concentration [MAC] end-tidal concentration), or fentanyl-diazepam anaesthesia, in combination with 66% nitrous oxide (n = 40 for each group). The evoked electromyogram (EMG) response of the abductor digiti minimi was monitored at 20 sec intervals following train-of-four (TOF) stimulation of the ulnar nerve. The initial neuromuscular block was produced by vecuronium 100 μg · kg^?1. When the amplitude of the first response (T₁) had spontaneously recovered to 10% of the control, edrophonium (0, 125, 400, 700 or 1000 μg · kg^?1; eight patients each) was randomly administered, and the ratio of the fourth TOF to the first response (TOFR ) was monitored at one minute intervals for 10 min.

Results

Sevoflurane and isoflurane impaired the edrophonium-assisted TOFR recovery in an edrophonium dose and time dependent manner. The dose-response curves at 10 min exhibited a greater shift to the right in the sevoflurane and isoflurane groups than in the fentanyl-diazepam-nitrous oxide group (P < 0.05). Higher ED₅₀ values (the edrophonium dose required to obtain TOFR value of 50%) in the sevoflurane (> 1000 μg · kg^?1) and isoflurane groups (851 · μg · kg^?1) were observed than in the fentanyl-diazepam-nitrous oxide group (339 μg · kg^?1) (P < 0.05).

Conclusion

One MAC sevoflurane and isoflurane anaesthesia impair edrophonium reversal of vecuronium block to a similar degree.     

Usability and performance characteristics of the pediatric air-Q® intubating laryngeal airway

Purpose

The air-Q® intubating laryngeal airway (ILA) is a supraglottic device (SGD) designed specifically to function as both a primary airway and a bridging device and conduit for fibreoptic intubation in difficult airway scenarios. This observational study evaluated the usability and performance characteristics of pediatric air-Q ILA sizes 1.0, 1.5, 2.0, and 2.5 when used as a primary airway.

Methods

One hundred ten children, American Society of Anesthesiologists physical status I-III and undergoing elective surgery, received a weight-appropriate air-Q ILA following induction of anesthesia. The evaluation criteria included ease of insertion, quality of ventilation, presence of gastric insufflation, oropharyngeal leak pressures (OLPs) and maximum tidal volumes (V_T max) in five different head positions, and fibreoptic view of the glottis.

Results

For sizes 1.0, 1.5, 2.0, and 2.5, the median [P25,P75] neutral OLPs (cm H₂O) were 23.0 [20.0,30.0], 16.5 [15.0,20.8], 14.0 [10.0,17.8], and 14.0 [11.3,16.8], respectively. The median [P25,P75] neutral V_T max values (mL·kg^?1) were 17.4 [14.3,19.7], 20.3 [16.8,25.5], 17.8 [14.5,22.1], and 14.0 [11.6,16.0], respectively. Median [P25,P75] ease of insertion scores (0-10; 0 = easiest ever, 10 = most difficult ever) were 1 [1,2], 2 [2,3], 2 [1,2.8], and 2 [2,3] respectively. Ventilation was adequate in 108/110 cases, and a fibreoptic view of the vocal cords was obtained in 102/110 cases.

Conclusions

The air-Q ILA functions acceptably as a primary SGD in infants and children. The OLPs are lower than published values for the ProSeal laryngeal mask airway (LMA ProSeal?), the current pediatric SGD of choice, but adequate tidal volumes are readily achievable. The fibreoptic views of the glottis portend well for fibreoptic intubation through the device. (This trial was registered at clinicaltrials.gov number, NCT00885911).     

Recurarization after sugammadex reversal in an obese patient

Purpose

We report a case that involved immediate postoperative respiratory failure necessitating tracheal intubation, which was possibly related to recurarization after sugammadex reversal.

Clinical findings

A 54-yr-old woman weighing 115-kg was scheduled for laparoscopic repair of abdominal dehiscence under general anesthesia. Muscle relaxation was induced and maintained with rocuronium (170 mg iv total dose). At the end of the 170-min procedure, two twitches were visualized after supramaximal train-of-four (TOF) stimulation at the adductor pollicis muscle, and the patient’s central core temperature was 35.6°C. Sugammadex 200 mg iv (1.74 mg·kg^?1) was administered. With the patient fully awake, a TOF ratio 0.9 was obtained five minutes later. The tracheal tube was then removed, and the patient was transferred to the postanesthesia care unit. Ten minutes later, the patient presented respiratory failure necessitating tracheal intubation and sedation with propofol. One TOF response only was visualized at the adductor pollicis muscle. Another dose of sugammadex 200 mg iv was administered. Forty-five minutes later, the patient was fully awake and her trachea was extubated after repeated measures of the TOF ratio (≥ 0.9) at the adductor pollicis muscle. The patient fully recovered without sequelae, further complication, or prolonged hospital stay.

Conclusion

Shortly after tracheal extubation, an obese patient experienced respiratory failure necessitating tracheal intubation and an additional dose of sugammadex. This occurred despite initial reversal of neuromuscular blockade with an appropriate dose of sugammadex 2 mg·kg^?1 iv given at two responses to TOF stimulation.     

Intraoperative Ventilation of Morbidly Obese Patients Guided by Transpulmonary Pressure

Background

Bariatric surgery has proven a successful approach in the treatment of morbid obesity and its concomitant diseases such as diabetes mellitus and arterial hypertension. Aiming for optimal management of this challenging patient cohort, tailored concepts directly guided by individual patient physiology may outperform standardized care. Implying esophageal pressure measurement and electrical impedance tomography—increasingly applied monitoring approaches to individually adjust mechanical ventilation in challenging circumstances like acute respiratory distress syndrome (ARDS) and intraabdominal hypertension—we compared our institutions standard ventilator regimen with an individually adjusted positive end expiratory pressure (PEEP) level aiming for a positive transpulmonary pressure (P _L) throughout the respiratory cycle.

Methods

After obtaining written informed consent, 37 patients scheduled for elective bariatric surgery were studied during mechanical ventilation in reverse Trendelenburg position. Before and after installation of capnoperitoneum, PEEP levels were gradually raised from a standard value of 10 cm H₂O until a P _L of 0 +/? 1 cm H₂O was reached. Changes in ventilation were monitored by electrical impedance tomography (EIT) and arterial blood gases (ABGs) were obtained at the end of surgery and 5 and 60 min after extubation, respectively.

Results

To achieve the goal of a transpulmonary pressure (P _L) of 0 cm H₂O at end expiration, PEEP levels of 16.7 cm H₂O (95% KI 15.6–18.1) before and 23.8 cm H₂O (95% KI 19.6–40.4) during capnoperitoneum were necessary. EIT measurements confirmed an optimal PEEP level between 10 and 15 cm H₂O before and 20 and 25 cm H₂O during capnoperitoneum, respectively. Intra- and postoperative oxygenation did not change significantly.

Conclusion

Patients during laparoscopic bariatric surgery require high levels of PEEP to maintain a positive transpulmonary pressure throughout the respiratory cycle. EIT monitoring allows for non-invasive monitoring of increasing PEEP demand during capnoperitoneum. Individually adjusted PEEP levels did not result in improved postoperative oxygenation.

     

Prediction of pulmonary function after lobectomy

Aim-Background

Lung cancer is the most common cause of cancer death in both men and women in our country. It has been estimated that there will be 7,000 lung cancer deaths every year in Greece. However, many patients with bronchogenic carcinoma also have coexistent obstructive lung disease. In these patients, preoperative prediction of functional status after lung resection is mandatory. The aim of our study was to determine the effect of lobectomy on postoperative spirometric lung function.

Methods

Seventy-two patients underwent spirometric pulmonary tests preoperatively, and at three and six months after surgery. The predicted postoperative forced vital capacity (FVC) and forced expiratory volume in the first second (FEV₁) were calculated using the following formula suggested by Juhl and Frost.

Results

The functional percentage loss at six months for lobectomies was 7.34% for FVC and 7.72% for FEV₁ respectively. The linear regression analysis derived from the correlation between predicted and measured FEV₁ revealed the following equation: FEV ₁ POSTOP = 0.00211+0.896660 X FEV ₁ PREOP.

Conclusions

We conclude that our formula is a reliable method for predicting postoperative respiratory function of the patients with lung cancer.     

Risikofaktoren bei Patienten mit zweizeitigem Thoraxverschluss nach Korrektur eines angeborenen Herzfehlers

Background

Primary sternal closure after cardiac operations in infants with congenital heart defects can lead to hemodynamic instability due to cardiac dilation and increased inotrope dependency. The alternative comprises secondary sternal closure (SSC).

Patients and methods

We performed a retrospective study on 43 neonates and infants, who were operated for congenital heart defects with the use of cardiopulmonary bypass (CPB) in our clinic between January 1994 and September 2003. In these infants SSC was indicated. The age difference at the time of operation was 48.4 months (0.03 months to 48.43 months), the weight difference varied from 1.0 kg to 12.8 kg (median 3.7 kg). The average operation time was 377.9 min (45 min to 670 min), during which CPB was used on average for 221.1 min (31 min to 521 min). In 34 (79 %) infants the sternum was left open primarily, while in the other 9 (21 %) patients the thorax was reopened secondarily on the same day as the operation. In order to makeshift close the thorax, an EPIGARD^® membrane was used in 31 cases (72.1 %) and in the other 12 patients (27.9 %) a SILASTIC^® membrane was used.

Results

6 patients (14 %) died before SSC. In the other three the thorax was closed secondarily; however they succumbed postoperatively to multi-organ failure. In three patients superficial thoracic wound infections occurred. There was no correlation detected between weight, CPB time and mortality. We found a positive correlation between epinephrine- dose 60 minutes after the end of CPB and the interval to final sternal closure. The central venous pressure (CVP) of the 9 patients who died were between 9 and 20 cm H₂O (median =15 cm H₂O). The CVP of the 34 survivors was between 2 and 28 cm H₂O (median = 10 cm H₂O), p<0.007. 77.8 % of patients who had deceased had an oxygen partial pressure below normal 60 minutes after the end of CPB. In addition, the median of 39.1 mmHg was much lower compared to the survivors (median = 199 mmHg).

Conclusion

SSC is not a routine procedure and is associated with a low infection risk. Higher epinephrine dependency 60 minutes after the end of CPB prolongs the time until final sternal closure. Patients with a CVP over 15 cm H₂O 30 minutes after CPB and with oxygen partial pressure below 95 mmHg at 60 minutes after CPB have a worse postoperative prognosis.     

A comparison of the Supreme™ laryngeal mask airway with the Proseal™ laryngeal mask airway in anesthetized paralyzed adult patients: a randomized crossover study

Purpose

The Supreme? laryngeal mask airway (SLMA) is a new single-use advanced form of the Proseal? laryngeal mask airway (PLMA). This study tested the hypothesis that the SLMA is equally as effective as the PLMA as a supraglottic ventilatory device in anesthetized paralyzed adult patients.

Methods

Size 4 SLMAs and PLMAs were compared in a randomized crossover study involving 60 patients aged 21-75 yr and American Society of Anesthesiologists physical status I and II. Once the patients were anesthetized and paralyzed, the SLMA and the PLMA were inserted into each patient in random order. The primary outcome measure was the laryngeal seal pressure (LSP) at an intracuff pressure of 60 cm H₂O. Secondary outcome measures included the ease of inserting the laryngeal mask airway devices (LMADs) and the fibreoptic position of the airway tube.

Results

There was no statistically significant difference in LSP between the SLMA and the PLMA. The mean LSP was 19.6 ± 5.8 cm H₂O and 20.9 ± 6.7 cm H₂O for the SLMA and the PLMA, respectively. There was a similarity between the SLMA and the PLMA regarding the number of attempts required and the duration for insertion. However, fibreoptic positioning was better with the PLMA than with the SLMA (P < 0.0001).

Conclusion

The clinical performance of the SLMA as a ventilatory device is comparable with that of the PLMA, as illustrated by the similar LSPs. The inferior position of the SLMA airway tube compared with that of the PLMA does not affect its ease of ventilation.     

Intrarenal pressures remain low with placement of a dual lumen catheter for retrograde irrigation to induce renal hypothermia

Objective

To determine whether placement of a 10 French dual lumen catheter produces a low-pressure collecting system during retrograde irrigation to induce renal hypothermia. Indication for the study is as a potential adjunct for partial nephrectomy.

Methods

Ex vivo porcine kidneys underwent harvest, and a ureteral catheter (either single lumen or dual lumen) was placed in the ureter within the renal pelvis. Pressure measurements (n?=?1,080) were recorded at 1-s intervals. Irrigant flow rates were initiated at gravity and subsequently increased at 10?cc/min increments to a maximum of 100?cc/min.

Results

During retrograde infusion without a dual lumen catheter, every 10?cc/min rate increase resulted in an 8?cm H₂O rise in intrarenal pressure. The maximum flow rate obtained was 20?cc/min before urinary extravasation or intrarenal drainage occurred. Maximum pressure obtained before urinary extravasation or collecting system perforation was 16?cm?H₂O. Placement of a dual lumen catheter within the renal pelvis allowed intrarenal pressures to remain less than 5?cm?H₂O (when infusion rates <80?cc/min). The maximum flow rate while maintaining pressures <20?cm H₂O was 90?cc/min. Flow rates above 100?cc/min resulted in urinary extravasation. The maximal flow rate that is safe for collecting systems with a dual lumen catheter is 80?cc/min, and without a dual lumen catheter rates greater than 20?cc/min resulted in collecting system perforations.

Conclusion

Using an ex vivo porcine model, application of a 10 French ureteral dual lumen catheter produced adequate retrograde drainage that resulted in low intrarenal pressures at high infusion rates (up to 80?cc/min).