Frank Dette

Forced needle advancement during needle-nerve contact in a porcine model: histological outcome.

BACKGROUND: In this study, we determined whether needle advancement during needle-nerve contact (forced needle-nerve contact) is associated with a higher risk of nerve injury compared with needle-nerve contact without needle advancement (nonforced needle-nerve contact). METHODS: In 8 anesthetized pigs, the brachial plexus nerves underwent forced (0.15 Newton) or nonforced (0.0 Newton) needle-nerve contact without nerve penetration. The grade of nerve injury was histologically assessed using an objective score ranging from 0 (no injury) to 4 (severe injury). RESULTS: Sixty-nine nerves, including controls, were examined. Histology revealed a significant difference between forced and nonforced needle-nerve contact (median [interquartile range] 3 [2–4] vs 2 [1–2]; P = 0.004). Myelin damage and intraneural hematoma occurred only after forced needle-nerve contact. CONCLUSIONS: The severity of structural nerve injury after needle-nerve contact was directly related to force exposure via needle advancement.

The influence of perioperative oxygen concentration on postoperative lung function in moderately obese adults.

Background and objective Obesity aggravates the negative effects of general anaesthesia and surgery on the respiratory system, resulting in decreased functional residual capacity and expiratory reserve volume, and increased atelectasis and ventilation/perfusion (Va/Q) mismatch. High-inspired oxygen concentrations also promote atelectasis. This study compares the effects of perioperative inspired low-oxygen and high-oxygen concentrations on postoperative lung function and pulse oximetry values in moderately obese patients (BMI 25–35). Methods We prospectively studied 142 overweight patients, BMI 25–35, undergoing minor peripheral surgery; they were randomly allocated to receive either low-inspired or high-inspired oxygen concentrations during general anaesthesia. Premedication, general anaesthesia and respiratory patterns were standardized. Arterial oxygen saturation (pulse oximetry) was measured on air breathing. Inspiratory and expiratory lung functions were measured preoperatively (baseline) and at 10 min, 0.5, 2 and 24 h after extubation with the patient supine, in a 30° head-up position. The two groups were compared using repeated-measure analysis of variance and t-test analysis. Results The low-inspired oxygen group had significantly better arterial saturation during the first 24 h (P < 0.01). Mid-expiratory flow 25 values indicating small airway collapse were significantly better in the low-oxygen group at all measurements (P < 0.05). Conclusion We conclude that postoperative lung function and arterial saturation is better preserved by a low-oxygen strategy, although it is not clear whether this has clinical relevance for the prevention of postoperative pulmonary complications.

A comparison of desflurane versus propofol: the effects on early postoperative lung function in overweight patients.

BACKGROUND: In this study, we evaluated the influence of propofol versus desflurane anesthesia in overweight patients on postoperative lung function and pulse oximetry values. METHODS: We prospectively studied 134 patients with body mass indices of 25 to 35 kg/m2 undergoing minor peripheral surgery lasting 40 to 120 minutes. Patients were randomly assigned to receive propofol (total IV anesthesia) or desflurane anesthesia via a tracheal tube targeting bispectral index values of 40 to 60. Premedication, adjuvant drug usage, and ventilation were standardized. We measured oxyhemoglobin saturation and lung function preoperatively (baseline), and at 10 minutes, 0.5 hour, 2 hours, and 24 hours after tracheal extubation. All values were measured with the patient supine, in a 30° head-up position. Changes from preoperative baseline values were first analyzed for the impact of body mass index and type of anesthesia using univariate methods, followed by linear regression and multivariate analysis of variance. RESULTS: Within the first 2 hours after surgery, the propofol group displayed lower oxyhemoglobin saturation (at 2 hours, mean ± SD, 93.8% ± 2.0% vs 94.6% ± 2.1%; P < 0.007) and lung function (forced vital capacity, forced expiratory volume exhaled in 1 second [FEV1], peak expiratory flow, midexpiratory flow [MEF], forced inspiratory vital capacity, and peak inspiratory flow; between 11% and 20% larger reduction from baseline in the propofol group, all P < 0.001) compared with the desflurane group. Even 24 hours after surgery, FEV1, peak expiratory flow, MEF, forced inspiratory vital capacity, and peak inspiratory flow were reduced more in the propofol group (all P < 0.01). At 2 hours after extubation, increasing obesity was associated with decreasing FEV1 and MEF in patients anesthetized with propofol but not desflurane (P < 0.01). CONCLUSION: We conclude that, for superficial surgical procedures of up to 120 minutes, maintenance of anesthesia with propofol impairs early postoperative lung function and pulse oximetry values more than with desflurane. Furthermore, increasing obesity decreases pulmonary function at 2 hours after propofol anesthesia but not after desflurane anesthesia.

Short term non-invasive ventilation post-surgery improves arterial blood-gases in obese subjects compared to supplemental oxygen delivery - a randomized controlled trial

BackgroundIn the immediate postoperative period, obese patients are more likely to exhibit hypoxaemia due to atelectasis and impaired respiratory mechanics, changes which can be attenuated by non-invasive ventilation (NIV). The aim of the study was to evaluate the duration of any effects of early initiation of short term pressure support NIV vs. traditional oxygen delivery via venturi mask in obese patients during their stay in the PACU.MethodsAfter ethics committee approval and informed consent, we prospectively studied 60 obese patients (BMI 30-45) undergoing minor peripheral surgery. Half were randomly assigned to receive short term NIV during their PACU stay, while the others received routine treatment (supplemental oxygen via venturi mask). Premedication, general anaesthesia and respiratory settings were standardized. We measured arterial oxygen saturation by pulse oximetry and blood gas analysis on air breathing. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 1 h, 2 h, 6 h and 24 h after extubation, with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P < 0.05.ResultsThere were no differences at the first assessment. During the PACU stay, pulmonary function in the NIV group was significantly better than in the controls (p < 0.0001). Blood gases and the alveolar to arterial oxygen partial pressure difference were also better (p < 0.03), but with the addition that overall improvements are of questionable clinical relevance. These effects persisted for at least 24 hours after surgery (p < 0.05).ConclusionEarly initiation of short term NIV during in the PACU promotes more rapid recovery of postoperative lung function and oxygenation in the obese. The effect lasted 24 hours after discontinuation of NIV. Patient selection is necessary in order to establish clinically relevant improvements.Trial Registration#DRKS00000751; http://www.germanctr.de

Occurrence of Rapid Eye Movement Sleep Deprivation After Surgery Under Regional Anesthesia

BACKGROUND:Sleep disturbances after general surgery have been described. In this study, we assessed rapid eye movement (REM) sleep in patients undergoing knee replacement surgery using a regional anesthetic technique. METHODS:Ambulatory polysomnography (PSG) was performed on 3 nights: the night before surgery (PSG1), the first night after surgery (PSG2), and the fifth postoperative night (PSG3). Postoperative analgesia was maintained with peripheral nerve catheters for the first 3 days and with oral opioids thereafter. In addition, nonsteroidal antiinflammatory drugs were administered. Postoperative pain was monitored using a visual analog scale. RESULTS:PSG was performed in 12 patients, 6 men and 6 women, with a mean age of 61 (±12) years. REM sleep was reduced from PSG1 (median 16.4%) to PSG2 (median 6.3%; P = 0.02). The Hodges-Lehmann estimate for the median reduction is −7.8% (95% confidence interval −14.8% to −0.7%). During PSG3, significantly more REM sleep was detected (median 15.4%) compared with PSG2 (P = 0.01). The Hodges-Lehmann estimate for this median increase is 10.0% (95% confidence interval 1.7%–25.3%). CONCLUSION:Postoperative reduction of REM sleep also occurs after surgery and regional anesthesia.

Changes in cerebral oxygen saturation following prone positioning for orthopaedic surgery under general anaesthesia: a prospective observational study.

BACKGROUND Prone positioning is often necessary in orthopaedic surgery. The prone position, however, may result in impaired cerebral venous drainage with a subsequent reduction in cerebral perfusion. As a consequence, cerebral hypoxia may occur with the potential for neurological impairment. OBJECTIVE We assessed the changes in cerebral oxygen saturation with near-infrared spectroscopy using two different monitors after positioning the patient from supine to prone. DESIGN Prospective observational study. SETTING Primary Care University Hospital, from May 2010 to February 2011. PARTICIPANTS Forty patients undergoing general anaesthetic procedures, of which 35 completed the investigation. Similar measurements were done in 35 volunteers, who were studied while awake. INTERVENTIONS Near-infrared spectroscopy was measured throughout anaesthesia using INVOS (a trend monitor using two infrared wavelengths) for one hemisphere and FORE-SIGHT (a monitor using four wavelengths of laser light to calculate absolute oxygen saturation) for the other hemisphere in an alternate randomisation pattern. OUTCOME MEASUREMENTS The primary outcome was a change in cerebral oxygen saturation of more than 5% during prone positioning. A comparison with the changes obtained in awake volunteers following similar positioning was also made. RESULTS Cerebral oxygen saturation increased during prone positioning with INVOS 0.032% per minute (P < 0.01) and with FORE-SIGHT 0.032% per minute (P < 0.01) in anaesthetised patients. Awake volunteers showed an increase of 0.171% per minute (INVOS) and 0.082% per minute (FORE-SIGHT) during prone positioning. Comparison of INVOS with FORE-SIGHT showed a good association, with a gradient of 0.80% per 1% change (P < 0.01). CONCLUSION Both monitors detected a small increase in cerebral oxygen saturation of less than 5% in patients undergoing orthopaedic surgery in the prone position and in awake volunteers. This small increase is of limited clinical relevance and prone positioning may be regarded as safe in terms of the maintenance of cerebral oxygen saturation. TRIAL REGISTRATION clinicaltrials.gov identifier: NCT01275898.

Impact of regional femoral nerve block during general anesthesia for hip arthoplasty on blood pressure, heart rate and pain control: A randomized controlled study

BACKGROUND Adequate pain management is essential for preventing hemodynamic instability which can affect the perfusion of vital organs during the perioperative period, particularly in geriatric patients. For hip arthroplasty, peripheral nerve block is frequently used, limiting the adverse effects of opioid and non-opioid analgesics. OBJECTIVE The aim was to survey the impact of a supplementary single shot femoral nerve block (FNB) on hemodynamic stability and pain level. METHODS After registration at German Clinical Trial Register (DRKS-ID): DRKS00000752. and Ethics Committee approval (University Hospital of Marburg), 80 patients who underwent elective hip surgery were included. Half of them were randomly assigned to receive a FNB followed by general anesthesia; a control group received only general anesthesia as standard procedure (STD). Blood pressure and heart rate were measured and recorded every five minutes during surgery and stay at the postanesthesia care unit (PACU). RESULTS Fifty-two patients were included for statistical analysis. The FNB group had significantly lower systolic blood pressures during and after surgery and lower diastolic blood pressure postoperatively, heart rate, as well as opioid and non-steroidal anti-inflammatory consumption. CONCLUSIONS Femoral nerve block improved perioperative hemodynamic stability mostly likely attributable to an overall reduced sympathico adrenergic tone.

Langzeitregistrierung von Atemgeräuschen im Schlaf bei Patienten mit chronischer Sinusitis

BACKGROUND AND PURPOSE Nocturnal worsening of respiration in patients with chronic sinusitis is most likely induced by creeping of mucus from the parasinuses down to the pharynx. The aim of this study was to document respiratory symptoms such as deglutition, wheezing and cough in patients with chronic sinusitis using long-term recording of respiratory sounds. PATIENTS AND METHODS According to the CORSA (computerized respiratory sound analysis) criteria, long-term recording of respiratory sounds was performed in 20 patients with chronic sinusitis. RESULTS Wheezing was detected in 30%, (excessive) cough was found in 40%. Deglutition was measured with a frequency of ten per hour. CONCLUSION Long-term recording of respiratory sounds is a practical and noninvasive method for the documentation of clinical symptoms like wheezing, coughing and deglutition during sleep.ZusammenfassungHintergrund und Ziel:Eine waagerechte Körperposition begünstigt bei Patienten mit chronischer Sinusitis ein nächtliches Abfließen von Schleim und Sekret über den Oropharynx. Dies kann zu einer häufig nur während der Nachtstunden auftretenden respiratorischen Symptomatik wie Giemen, Husten und Atemnot führen, die in dieser Studie dokumentiert werden sollte.Patienten und Methodik:Im Rahmen einer Pilotstudie wurde bei 20 volljährigen Patienten mit chronischer Sinusitis eine nächtliche Langzeitregistrierung von Atemgeräuschen in Analogie zu den CORSA-Kriterien („computerized respiratory sound analysis“) durchgeführt.Ergebnisse:In 30% der Fälle (sechs Patienten) konnte Giemen, in 40% (acht Patienten) teils exzessives Husten dokumentiert werden. Schlucken wurde mit einer Häufigkeit von zehn Schluckereignissen pro Stunde detektiert.Schlussfolgerung:Die Langzeitregistrierung von Atemgeräuschen kann zur Objektivierung nächtlicher Symptome wie Giemen, Husten oder Luftnot einen wichtigen Beitrag leisten.AbstractBackground and Purpose:Nocturnal worsening of respiration in patients with chronic sinusitis is most likely induced by creeping of mucus from the parasinuses down to the pharynx. The aim of this study was to document respiratory symptoms such as deglutition, wheezing and cough in patients with chronic sinusitis using long-term recording of respiratory sounds.Patients and Methods:According to the CORSA (computerized respiratory sound analysis) criteria, long-term recording of respiratory sounds was performed in 20 patients with chronic sinusitis.Results:Wheezing was detected in 30%, (excessive) cough was found in 40%. Deglutition was measured with a frequency of ten per hour.Conclusion:Long-term recording of respiratory sounds is a practical and noninvasive method for the documentation of clinical symptoms like wheezing, coughing and deglutition during sleep.

Risk of interrupting nocturnal nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnea

Patients with obstructive sleep apnea are at risk of respiratory and cardiovascular complications (e.g. hypoxia, hypertensive crisis, cardiac ischemia and arrhythmias) as a result of airway callapse during the perioperative period. Therefore it is essential that the nasal continuous airway pressure (nCPAP-therapy) be maintained during that time. Such patients and the medical staff should be aware of this problem.