Reproducible determination of transpulmonary pressures.

Oesophageal pressures, as measured in an oesophageal balloon catheter, are a validated substitute for pleural pressures. Transpulmonary pressures, indispensable to improve our understanding of ventilatory physiology, are therefore typically calculated as the difference between airway and oesophageal pressures. The oesophageal pressure signal, however, features a superimposed oscillation due to cardiac motion, not representative for pleural pressure. Additionally, oesophageal contractions or surgical manipulation can alter the signal. In practice, transpulmonary pressures are therefore manually determined from the pressure-time graphic by visual inspection of the waves and averaging a limited number of samples. We suggest an approach to extract the end-expiratory transpulmonary pressure from the raw monitoring data.•Our approach reproducibly determines end-expiratory transpulmonary pressures at a given level of set positive end-expiratory pressure at the ventilator.•Our approach ignores surgical disturbance and cardiac oscillations in the oesophageal pressure signal.

Effect of body weight on upper airway findings and treatment outcome in children with obstructive sleep apnea.

OBJECTIVE/BACKGROUND: Surgical interventions for obstructive sleep apnea (OSA) are less effective in obese than in normal-weight children. However, the mechanisms that underpin this relationship are not fully understood. Therefore, this study aimed to explore how body weight influences upper airway collapse and treatment outcome in children with OSA. METHODS: We conducted a retrospective analysis of prospectively collected data on polysomnography, drug-induced sleep endoscopy (DISE), and treatment outcome in otherwise healthy children with OSA. Associations between body mass index (BMI) z-score and upper airway collapse during DISE were assessed using logistic regression modelling. Treatment success was defined as obstructive apnea-hypopnea index (oAHI) < 5 events/hour and cure as oAHI < 2 events/hour with obstructive apnea index < 1 event/hour. RESULTS: A total of 139 children were included [median (Q1─Q3); age 4.5 (3.1─8.4) years; BMI z-score 0.3 (-0.8 to 1.4); oAHI 10.8 (6.8─18.0) events/hour]. Twenty-five of them were overweight and 21 were obese. After adjusting for age and history of upper airway surgery, BMI z-score was significantly correlated with circumferential upper airway collapse during DISE (odds ratio 1.67; 95% confidence interval 1.12─2.65; P = 0.011). Outcome of DISE-directed treatment was similar in normal-weight (success: 91.4%; cure: 78.5%), overweight (success: 88.0%; cure: 80.0%), and obese (success: 90.5%; cure: 76.5%) children. Children with circumferential collapse responded better to continuous positive airway pressure than to (adeno)tonsillectomy. CONCLUSION: Increasing body weight is associated with circumferential upper airway collapse during DISE and, accordingly, may require treatment strategies other than (adeno)tonsillectomy.

A prospective randomized double-blind trial of the efficacy of a bilateral lumbar erector spinae block on the 24h morphine consumption after posterior lumbar inter-body fusion surgery.

BACKGROUND: Spine surgery is associated with considerable postoperative pain and can be challenging to treat. A loco-regional technique suitable for spine surgery should cover the dorsal root of the spinal nerves at the levels where surgery is performed. The erector spinae block is a loco-regional technique with promising results and was recently described at the thoracic level. There are no randomized trials of this technique on a lumbar level. This study tests the hypothesis that the 24-h postoperative morphine consumption is significantly lower in patients undergoing posterior lumbar inter-body fusion surgery with a lumbar erector spinae (LUMBES) block when compared with a sham block. METHODS: This prospective randomized double-blind multicenter study will randomly allocate 80 adult patients undergoing elective posterior lumbar inter-body fusion surgery during general anesthesia to one of two groups as follows: (1) bilateral erector spinae block (20 mL 0.25% levobupivacaine) or (2) bilateral sham block (20 mL NaCl 0.9%). Our primary endpoint is 24-h postoperative morphine consumption. Secondary endpoints include 72-h morphine consumption, intraoperative sufentanil dosage, postoperative pain scores at regular time intervals both at rest and during movement, time to first postoperative mobilization, and the Quality of Recovery 40 survey score. DISCUSSION: The LUMBES trial is a pragmatic clinical study that will provide evidence of whether a bilateral lumbar erector spinae block is effective in reducing 24-h postoperative morphine consumption in patients undergoing lumbar inter-body fusion surgery. If this hypothesis is confirmed, this finding could contribute to more widespread implementation of this technique. TRIAL REGISTRATION: Local ethics committee B300201837508, ClinicalTrials.gov identifier: NCT03825198 . Registered on 31 Jan 2019.

Pain assessment by pupil dilation reflex in response to noxious stimulation in anaesthetized adults.

BACKGROUND: In response to noxious stimulation, pupillary dilation reflex (PDR) occurs even in anaesthetized patients. The aim of the study was to evaluate the ability of pupillometry with an automated increasing stimulus intensity to monitor intraoperative opioid administration. METHODS: Thirty-four patients undergoing elective surgery were enrolled. Induction by propofol anaesthesia was increased progressively until the sedation depth criteria (SeD) were attained. Subsequently, a first dynamic pupil measurement was performed by applying standardized nociceptive stimulation (SNS). A second PDR evaluation was performed when remifentanil reached a target effect-site concentration. Automated infrared pupillometry was used to determine PDR during nociceptive stimulations generating a unique pupillary pain index (PPI). Vital signs were measured. RESULTS: After opioid administration, anaesthetized patients required a higher stimulation intensity (57.43 mA vs 32.29 mA, P < .0005). Pupil variation in response to the nociceptive stimulations was significantly reduced after opioid administration (8 mm vs 28 mm, P < .0005). The PPI score decreased after analgesic treatment (8 vs 2, P < .0005), corresponding to a 30% decrease. The elicitation of PDR by nociceptive stimulation was performed without changes in vital signs before (HR 76 vs 74/min, P = .09; SBP 123 vs 113 mm Hg, P = .001) and after opioid administration (HR 63 vs 62/min, P = .4; SBP 98.66 vs 93.77 mm Hg, P = .032). CONCLUSIONS: During propofol anaesthesia, pupillometry with the possibility of low-intensity standardized noxious stimulation via PPI protocol can be used for PDR assessment in response to remifentanil administration.

Drug-induced sedation endoscopy in surgically naïve infants and children with obstructive sleep apnea: impact on treatment decision and outcome.

PURPOSE: Adenotonsillectomy (AT) is the first-line treatment for obstructive sleep apnea (OSA) in children irrespective of clinical upper airway (UA) findings. We aimed to investigate whether drug-induced sedation endoscopy (DISE) changes treatment decision and outcome in otherwise healthy children and infants with OSA. METHODS: Retrospective analysis of prospectively collected data on polysomnography, DISE, and treatment in surgically naïve, otherwise healthy infants (n = 34) and children (n = 75) with OSA. Treatment success is defined as post-treatment obstructive apnea/hypopnea index (oAHI) < 5 h-5-1, and cure is defined as oAHI < 2 h-1. RESULTS: Based upon UA findings during DISE, AT was performed in 22 infants and 57 children. oAHI improved from 16.5 h-1 (8.1-28.3) to 0.8 h-1 (0.3-4.2) (p = 0.01) in infants and from 28.6 h-1 (23.4-34.9) to 0.7 h-1 (0.4-1.8) (p < 0.001) in children. AT was successful in 84.2% of infants and 91.4% of children. A cure was obtained in 68.4% of infants and 78.7% of children. DISE changed the treatment decision in 1/3rd of infants and 1/4th of children, and they did not undergo AT. In the non-AT group, isolated adenoidectomy/tonsillectomy or non-surgical treatment was successful in 86.6% of children and in 100% of infants. Cure was achieved in 66.6% of children and 75% of infants. CONCLUSIONS: DISE performed in otherwise healthy and surgically naïve infants and children with OSA altered the therapeutic decision making in up to 1/3rd to 1/4th of the cases and resulted in comparable treatment outcomes as standard treatment by AT. The present data suggest that DISE may provide individually tailored treatment of OSA in otherwise healthy infants and children.

Drug-induced sedation endoscopy in pediatric obstructive sleep apnea syndrome.

AIM: To describe the pattern of upper airway (UA) obstruction during drug-induced sedation endoscopy (DISE) and to evaluate the outcome of DISE-directed treatment. METHODS: Prospective study of DISE in surgically naive obstructive sleep apnea syndrome (OSAS) children without syndromic comorbidity or craniofacial abnormalities. Treatment was individually tailored according to UA findings during DISE and polysomnographic data. Reported values are median (lower-upper quartile). RESULTS: Thirty-seven children aged 4.1 years (2.1-6.0), with body mass index z-score 0.3 (-0.9 to 0.9), and obstructive apnea-hypopnea index (oAHI) 9.0/h (6.1-19.3) were included. Adenotonsillar obstruction was found in 33 cases (89%) as an isolated entity or as part of a multi-level obstruction. These children were treated with adenotonsillectomy (n = 28), adenoidectomy (n = 3), or tonsillectomy (n = 2). The remaining four patients received non-surgical treatment. Pre-postoperative polysomnographic data in 22 patients showed a significant improvement in oAHI from 8.6/h (6.7-20.7) to 1.0/h (0.6-2.0) (P = 0.001). Only two of these 22 children had residual OSAS (oAHI ≥ 5/h), indicating a success rate of 91%. CONCLUSIONS: Based on UA findings during DISE, a non-surgical treatment was proposed for 11% of children. A 91% success rate was obtained in those treated with (adeno)tonsillectomy. These data suggest that DISE may be helpful to identify patients most likely to benefit from UA surgery.

Life-threatening macroglossia after posterior fossa surgery: a surgical positioning problem?

A 55-year-old woman was operated in the lateral park bench position with significant neck flexion and oral packing. Macroglossia was noticed immediately postoperatively after endotracheal extubation. The patient was reintubated for 13 days and subsequently required a tracheostoma. After the placement of the tracheostoma and the removal of the endotracheal tube, the congestion of the tongue decreased markedly within 24 hours. Macroglossia is a rare complication following posterior fossa procedures with few cases reported so far. It can cause airway obstruction, which could be a life-threatening complication, and it therefore requires prompt treatment. The aetiology of postoperative macroglossia remains uncertain and has been attributed to arterial, venous and lymphatic compression, mechanical compression, or neurogenic causes. This article describes new insights into aetiology and also describes preventive measures and possible treatment.

Outcome of sleep endoscopy in obstructive sleep apnoea: the Antwerp experience.

OBJECTIVES: Snoring and obstructive sleep apnoea (OSA) result from upper airway (UA) collapse during sleep. Sleep endoscopy is a dynamic evaluation of the UA that can be used to determine the site(s) of collapse during respiratory events. This study evaluates the feasibility and outcome of sleep endoscopy in patients with OSA, compares the findings with the literature, and reviews the therapeutic advice given to patients. METHODOLOGY: A retrospective analysis was conducted of the data for 70 OSA patients in whom UA surgery was considered. Sleep endoscopy was performed after IV administration of midazolam and propofol. The UA was visualised and assessed for the location of UA flutter, narrowing or collapse. Feasibility and safety were evaluated retrospectively. Outcome data were described as type and pattern of flutter and/or collapse. Treatment advice given to the patients was reviewed. RESULTS: Sleep endoscopy showed monolevel palatal collapse in 31.9%, monolevel tongue/hypopharyngeal collapse in 27.8% and multilevel collapse in 31.9% of patients. In 5.6% of patients, no collapse was found. In all patients except 2, reliable assessment proved possible of the site(s) of obstruction. No side effects were reported. CONCLUSION: Sleep endoscopy is feasible and safe in daily practice when sedation is performed by an anaesthesiologist and can be used to locate the site of collapse in the UA. Sleep endoscopy findings in our study sample, as well as in the literature, differ according to the content of the study sample and the method of sedation. Treatment advice may differ from sleep endoscopy findings since other factors such as age and patient preferences need to be considered.

Target-controlled infusion of rocuronium in infants, children, and adults: a comparison of the pharmacokinetic and pharmacodynamic relationship.

UNLABELLED: Target-controlled infusion (TCI) of rocuronium can be used to maintain a stable blood concentration (Cp). At steady-state, the pharmacokinetics (PK) are compensated for by TCI, and a stable effect can be observed. The theoretical Cp may represent effect-site concentration (EC). We used the EC-effect relationship to study pharmacodynamics (PD) in infants, children, and adults. After giving their written, informed consent, 14 infants, 23 children, and 21 adults scheduled for elective surgical procedures received 3 to 6 ascending Cp targets of TCI rocuronium according to PD data. Just before each increase of TCI, venous blood samples were taken to measure Cp. Neuromuscular block was evaluated acceleromyographically. Individual effect data and measured Cp were fitted to the Hill equation. Maximum block during TCI targets-1000, 1300, and 1600 ng/mL-was smaller in children in comparison with infants and adults. The concentration in the effect compartment associated with a 50% drug effect (EC(50)) was significantly smaller in infants (mean [SD]) (652 [215] ng/mL) than in adults (954 [276] ng/mL) and was the largest in children (1200 [295] ng/mL). Calculated mean EC(90) values were 1705, 2230, and 2035 ng/mL, respectively, in infants, children, and adults. TCI rocuronium established steady-state PK/PD at different TCI targets and allowed us to define PK/PD relationships in a standardized way. Steady-state TCI rocuronium revealed the most potency of rocuronium in infants and the least in children. IMPLICATIONS: Target-controlled infusion (TCI) of rocuronium in infants, children, and adults was used to analyze the pharmacokinetic/pharmacodynamic relationship. Steady-state TCI rocuronium revealed the most potency of rocuronium in infants and the least in children.

Target controlled infusion of rocuronium: analysis of effect data to select a pharmacokinetic model.

BACKGROUND: We aimed to evaluate whether area under the curve (AUC) analysis of pharmacodynamic data can be used to compare pharmacokinetic models taken from the literature, during a target controlled infusion (TCI) of rocuronium. METHODS: Seventy-two patients scheduled for orthopaedic surgery received a TCI of rocuronium (Stanpump) based on one of four pharmacokinetic models: those described by Szenohradszky, Alvarez-Gomez, Wierda, and Cooper. The resulting theoretical plasma concentration versus time curve was calculated for all patients based on all four pharmacokinetic models. Predicted effect versus time curves were calculated following the pharmacokinetic-pharmacodynamic link model (Sheiner and colleagues). Neuromuscular block was evaluated acceleromyographically. The difference between the area under the observed effect (AUC(OE)) and predicted effect (AUC(PE)) versus time curves was used for comparison. RESULTS: AUC(PE )differed significantly from AUC(OE) in the Szenohradszky and Alvarez-Gomez models, both with the reference link-pharmacodynamic data and with altered link-pharmacodynamic variables. AUC(PE )and AUC(OE) were comparable for the Wierda and Cooper models. The mean AUC(OE) was 25.1 (SD 11.9)% block x h. AUC(PE)-AUC(OE) was significantly larger in the Szenohradszky model when compared with all other pharmacokinetic models. This difference remained when link or pharmacodynamic variables were modified. The smallest AUC(PE)-AUC(OE) difference was found with the Wierda model. CONCLUSION: It was possible to use AUC analysis for identification of the pharmacokinetic model that best predicted the pharmacodynamic characteristics of our patients.

Lethal complications after tonsillectomy.

Lethal complications after tonsillectomy. Two cases of serious complications after paediatric tonsillectomy, that were referred to our department, resulted in death, one due to massive haemorrhage and one due to hyponatremia. Thanks to early recognition and adequate treatment, two other cases could be successfully treated. The literature on serious complications after tonsillectomy was critically reviewed. Guidelines on peri- and postoperative fluid management are given. Vascular anatomy of the tonsillar region is reviewed. Location and treatment policy on severe haemorrhages are discussed.

Target controlled infusion of remifentanil and propofol for cesarean section in a patient with multivalvular disease and severe pulmonary hypertension.

A 36 year old parturient with known valvular heart disease was admitted with respiratory distress and fatigue after 35 weeks of pregnancy. Echocardiography revealed severe tricuspid regurgitation, mitral stenosis and aortic valve insufficiency. Following clinical examination and insertion of a radial and pulmonary artery catheter it was decided to perform a Caesarean Section. The pulmonary artery pressure upon arrival in the operating theatre was 105/50 mm Hg whereas cardiac output was 3.5 l/min. Induction of anesthesia was performed with a target controlled infusion of remifentanil and propofol combined with rocuronium bromide. Haemodynamic variables remained very stable during and after intubation. The lungs of the apnoeic baby were manually ventilated until spontaneous respiration began at 1 minute post delivery. Apgar scores were 3, 7 and 9 after 1, 5 and 10 minutes respectively. Umbilical artery pH was 7.29. The patient's haemodynamic status gradually improved over the following few days. Two months following delivery she underwent unevenful valvular surgery.

Hyperbaric oxygen (HBO) as useful, adjunctive therapeutic modality in compartment syndrome.

The authors describe a compartment syndrome progressively developed after a long-term surgical procedure, with a patient positioned in supine position with calf rest, who was successfully treated with hyperbaric oxygenation. This approach saved the patient from a more invasive therapeutic intervention.

Small-dose hyperbaric versus plain bupivacaine during spinal anesthesia for cesarean section.

UNLABELLED: In a double-blind, randomized trial, 98 parturients undergoing cesarean section received either hyperbaric or plain bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural procedure. To prevent hypotension, 1000 mL of lactated Ringer's solution, 500 mL of hydroxyethyl starch 6%, and ephedrine 5 mg were administered i.v. The height of the block was equal in both groups, but more patients in the plain group had blocks that were either too high or too low (P < 0.01). The number of patients requiring epidural supplementation was equal in both groups. Strict criteria were used to treat hypotension. The overall incidence of systolic blood pressure (<90 mm Hg) was 13%, whereas it was more pronounced in the plain group (21% vs 6% in the hyperbaric group, P < 0.05), which required more ephedrine (P < 0.05) and in which a greater incidence of nausea was noticed (P < 0.05). We conclude that the use of a small dose of intrathecal bupivacaine combined with sufentanil plus our described preloading regimen resulted in a lower incidence of hypotension. Further, we conclude that the use of hyperbaric bupivacaine in this manner provides a more reliable block and a lower incidence of hypotension than plain bupivacaine. IMPLICATIONS: A small dose of hyperbaric bupivacaine 0.5% combined with sufentanil used intrathecally during cesarean section offered a more reliable cephalad spread of the spinal block than the glucose-free combination, which was reflected in a lower incidence of hypotension and nausea.

Potentiation of sufentanil by clonidine in PCEA with or without basal infusion.

Sufentanil or a sufentanil-clonidine combination was evaluated to determine whether the basal rate in patient-controlled epidural analgesia (PCEA) might affect the daily consumption, quality of analgesia or incidence of side effects. Following Caesarean section delivery, 60 patients were randomly assigned to receive one of the four following PCA regimens (15 patients per group) for the relief of post-operative pain by the epidural route: sufentanil 2 micrograms mL-1 in 0.9% NaCl, demand dose 5 micrograms i.e. 2.5 mL, (group S+ with, group S without an infusion at 2.5 mL hr-1) or sufentanil 2 micrograms mL-1 + clonidine 3 micrograms mL-1, demand dose 5 micrograms sufentanil + 7.5 micrograms clonidine i.e. 2.5 mL (group SC+ with and SC without an infusion of 2.5 ml hr-1). The other PCA settings (Bard I PCA pump) were a lock out of interval of 10 min and a 1 h limit of 20 micrograms sufentanil and 30 micrograms clonidine i.e. 10 mL. The parameters measured were the analgesic drug consumption and number of dose demands during the first 24 h, pain scores at 6 h intervals, side effects and quality of sleep. The concurrent infusion increased the dose requirements regardless of the content of the syringe. Consumption of sufentanil was the highest in those patients receiving the plain solution with a basal infusion. Clonidine addition reduced the dose requirements but only significantly in those receiving the background infusion. Patients treated with the mixture tended to reach lower pain scores than those receiving sufentanil only without basal rate. Patients receiving the mixture with basal rate requested significantly fewer additional demands compared with the three other groups, but this did not influence the quality of sleep. Since side effects were more frequently registered in the patients in this group, it was concluded that the optimum regimen was the sufentanil-clonidine combination but with deletion of the basal rate.