Hubert J. Schmitt

Difficult intubation in acromegalic patients: incidence and predictability.

Background Previous studies have suggested that the incidence of difficult intubation in acromegalic patients is higher than in normal patients. However, these studies were retrospective and did not include preoperative assessment of the airways. The aims of this study were to determine the incidence of difficult intubation and to assess the usefulness of preoperative tests in predicting difficult laryngoscopy. Methods One hundred twenty-eight consenting acromegalic patients requiring general anesthesia and tracheal intubation were studied. Preoperatively, Mallampati classification, thyromental distance, and head and neck movement were determined in each patient. After induction of anesthesia and muscle paralysis, laryngoscopic grade was assessed during direct laryngoscopy; Cormack and Lehane grade III or IV were classified as difficult. The association of individual airway assessment with laryngeal view was evaluated using the Fisher exact test. Predictors of difficult laryngoscopy were evaluated by calculating their sensitivity and specificity. Results Laryngoscopy was difficult (grade III) in 33 of 128 patients (26%). Application of external laryngeal pressure improved laryngeal visualization to grade II in 20 of these 33 patients. In the remaining 13 patients (10%), intubation was difficult (more than two attempts, blade change, use of gum-elastic bougie). Mallampati classes 3 and 4 were significantly related to laryngoscopy grade III (Fisher exact test, P = 0.001). Conclusions The incidence of difficult laryngoscopy and intubation in acromegalic patients is higher than in normal patients. Preoperative Mallampati scores of 3 and 4 were of value in predicting difficult laryngoscopy. Nevertheless, even this test will miss a significant number of patients with a difficult airway.

Onset and duration of rocuronium-induced neuromuscular blockade in patients with Duchenne muscular dystrophy.

Background: In patients with Duchenne muscular dystrophy (DMD) the response to nondepolarizing muscle relaxants is scarcely documented and conflicting. The current study was conducted to determine the time to peak effect and the time for complete spontaneous recovery after a single dose of 0.6 mg/kg of rocuronium in patients with DMD. Methods: Twenty-four patients (12 with DMD, 12 controls, aged 10–16 yr) were studied. All patients were anesthetized with propofol and fentanyl/remifentanil. Neuromuscular transmission was monitored by acceleromyography. After induction all patients received a single dose of 0.6 mg/kg of rocuronium. The complete time course of onset and spontaneous recovery were recorded Results: Significant (P < 0.01) increase in the onset times to 95% neuromuscular block was observed in DMD patients (median, 203 s; range, 90–420 s) compared with controls (median, 90 s; range, 60–195 s). The time between rocuronium administration and recovery of first twitch of the train-of-four to 90% was significantly (P < 0.01) prolonged in DMD compared with controls (median, 132 min; range, 61–209 min versus 39 min; 22–55 min). The recovery index was also significantly prolonged in the DMD group compared with controls (median, 28 min, range, 15–70 min versus 8 min; 3–14 min). Conclusions: The most striking and surprising result of this study is the delayed onset of blockade in DMD after a standard dose of rocuronium. This effect should be kept in mind in situations when a rapid airway protection is necessary in DMD patients. The documented very long recovery from rocuronium-induced block emphasizes the need for careful assessment of neuromuscular function in DMD patients.

Venous Air Emboli Occur During Release of Positive End-expiratory Pressure and Repositioning After Sitting Position Surgery

We studied the effect of positive end-expiratory pressure (PEEP) release and positioning on the occurrence of venous air embolism (VAE). Eighteen consecutive patients (8 women, 10 men; ASA grade I–III) undergoing neurosurgery in the sitting position were studied. After induction of anesthesia ventilation was controlled with a PEEP of 5 cm H2O in an oxygen-air gas mixture. A transesophageal echocardiographic (TEE) probe was inserted. Preoperatively, a patent foramen ovale was excluded in all patients. TEE monitoring was performed during surgery, during PEEP release at the end of surgery with the patient still in the sitting position, and during change of the patient position into the supine position. The severity of VAE was differentiated as follows: grade 1 = only microbubbles; grade 2 = microbubbles and decrease of end-tidal carbon dioxide partial pressure (Petco2) by more than 1.5 mm Hg; grade 3 = microbubbles combined with a decrease of Petco2 by more than 1.5 mm Hg, and a decrease of mean arterial blood pressure by at least 20 mm Hg. During surgery, VAE with a grade of 1, 2 or 3 occurred in 7, 4, and 2 patients, respectively. After PEEP release, VAE of grades 1, 2, and 3 were observed in 7, 2, and 1 patients, respectively. During repositioning from sitting to supine position, VAE of grades 1, 2, and 3 was observed in 6, 1, and 1 patients, respectively. The patient with VAE grade 3 needed inotropic support until 2 h after surgery to maintain sufficient blood pressure. No patient showed any sign of paradoxical arterial embolism or cardiac dysfunction. We conclude that VAE occurs not only during surgery in the sitting position, but also with release of PEEP and during repositioning to the supine position.

Intramuscular versus surface electromyography of the diaphragm for determining neuromuscular blockade.

We determined the neuromuscular blockade of 0.2 mg · kg−1 mivacurium at the diaphragm by using two new methods of electromyographic (EMG) monitoring and compared it with acceleromyography of the orbicularis oculi (OO) and the corrugator supercilii (CS) muscle. After the induction of anesthesia in 15 patients undergoing gynecologic laparoscopic surgery, evoked EMG responses at the diaphragm were obtained by using skin electrodes at the back of the patient, placed lateral to T12/L1 or L1/L2, and a laparoscopically applied wire electrode inserted into the dorsolateral portion of the diaphragm. Acceleromyography at the right OO and the left CS was performed. The facial and phrenic nerves were stimulated transcutaneously (onset: every 10 s, offset: every 15 s, single twitch stimulation). Lag and onset time, peak effect, and clinical duration (time to reach 75% of control value and time to reach 90% of control value) were measured and the results were compared by using analysis of variance;P < 0.05 showed significant difference. Pearson’s correlation test and the Bland-Altman test were used to compare the two diaphragmatic monitoring methods. Mean peak effects of >98% were reached at all sites. Onset times at diaphragm (skin, IM) were significantly (P < 0.005) shorter than at the CS or OO (100 ± 14 s and 98 ± 16 s vs 147 ± 39 s, 185 ± 38 s) without being statistically different between OO and CS. There was a good correlation of lag, onset time, time to reach 75% of control value, and time to reach 90% of control value (r = 0.8, 0.9, 0.8, and 0.75;P < 0.01) between the two diaphragmatic methods. Mean difference and limits of agreements are −2 ± 15 s, 1 ± 21 s, −1 ± 2.3 min, and −2 ± 3.4 min. We showed a shorter onset and clinical duration at the diaphragm in comparison with CS and OO. Two methods of EMG of the diaphragm correlated well and showed good comparability. The novel method of surface diaphragmatic EMG at the patient’s back may be useful during routine clinical anesthesia. Implications The novel method of monitoring the diaphragmatic neuromuscular blockade (NMB) at the patient’s back showed good correlation and good comparability with the IM NMB derived from an endoscopically inserted wire electrode and might be clinically used. The simultaneous determination of the NMB at the orbicularis oculi and the corrugator supercilii muscle did not show that either of these muscles was a good indicator of the diaphragmatic response.

Effect of Humidified and Heated CO2 During Gynecologic Laparoscopic Surgery on Analgesic Requirements and Postoperative Pain

STUDY OBJECTIVE To determine the effect of humidified and heated CO(2) for pneumoperitoneum during laparoscopic surgery on analgesic requirements, postoperative pain, and patient satisfaction. DESIGN Prospective, randomized, double-blind, controlled study (Canadian Task Force classification I). SETTING University hospital. PATIENTS Ninety consecutive women scheduled for gynecologic laparoscopic surgery. INTERVENTION Operative laparoscopic management of adnexa surgery or adhesiolysis. MEASUREMENTS AND MAIN RESULTS Thirty consecutive patients were randomized into each study group. Group I received humidified, heated gas; group II dry, heated gas; and group III (control group) standard dry, cold gas. No significant difference in intraoperative and postoperative analgesic requirements or postoperative pain score between group I and group II was found. There was even a tendency (not significant) toward less pain and higher postoperative satisfaction in patients in the control group. Therefore, the evaluation was stopped after 53 patients. CONCLUSION The use of humidified, heated gas did not reduce postoperative pain or intraoperative analgesic requirements and is thus not preferable to standard dry, cold gas in gynecologic laparoscopic surgery.

Rocuronium 0.3 mg·kg−1 (ED95) induces a normal peak effect but an altered time course of neuromuscular block in patients with Duchenne's muscular dystrophy

Background:  In patients with Duchennes muscular dystrophy (DMD) recovery from neuromuscular block is delayed. It has been assumed that this is because of a higher potency of muscle relaxants in this patient cohort. We determined the peak effect, and the time course of action of rocuronium 0.3 mg·kg−1 (ED95) in DMD patients.

Anaesthetic management in patients with Duchenne muscular dystrophy undergoing orthopaedic surgery: a review of 232 cases.

Context Patients with Duchenne muscular dystrophy are at increased risk of some anaesthesia-related hazards such as rhabdomyolysis, fever and hyperkalaemia. Objectives To evaluate the management of anaesthesia in patients with Duchenne muscular dystrophy, including preoperative evaluation, intraoperative performance, critical events and postoperative care. Design We performed a retrospective case review study of anaesthesia in patients with Duchenne muscular dystrophy covering the period between April 2000 and December 2008. Patients 91 Duchenne patients undergoing 232 general anaesthetics for orthopaedic surgical interventions. Setting University hospital. Results Anaesthesia was performed using propofol, opioids and, if required, a non-depolarising muscle relaxant. Eight difficult direct laryngoscopies were reported. All patients undergoing spinal fusion surgery received transfusion of homologous blood products and required postoperative invasive ventilatory support for an average of 19 h. There was no severe anaesthesia-related complication and no case of unexplained fever or rhabdomyolysis. Conclusion This retrospective survey confirms clinical experience that total intravenous anaesthesia can be used safely in Duchenne patients without major concern. Further prospective studies are necessary to establish evidence-based clinical guidelines for daily practice.

Onset and duration of mivacurium‐induced neuromuscular blockade in children with Charcot–Marie–Tooth disease. A case series with five children

Background:  The Charcot–Marie–Tooth (CMT) disorders are a group of hereditary motor and sensory neuropathies characterized clinically by peripheral muscle wasting and weakness. We hypothesized that unknown involvement of the muscle used for monitoring neuromuscular block may account for the conflicting reports about the effect of nondepolarizing neuromuscular agents in these patients. The aim of this study was to compare onset and recovery from mivacurium‐induced neuromuscular block on the adductor pollicis and orbicularis oculi muscles.

The detrimental role of colloidal volume substitutes in severe ovarian hyperstimulation syndrome: a case report

Although, the mechanisms for the development of ovarian hyperstimulation syndrome (OHSS) are still not clear, the symptoms usually correlate with the levels of serum estradiol and ovarian enlargement. We report a case, where the clinical course was unusually prolonged. When menstrual bleeding had already occurred, serum estradiol was less than 10 pg/ml and the ovaries were almost normal in size, the patient developed pleural effusion and a significant alteration in blood-coagulation. This was most likely caused by an over-infusion of hydroxyethyl starch (HES) over 10 days. The pleural effusion contained high levels of HES, reaching 74% of the plasma concentration as measured by a novel method after acidic hydrolysis of HES. Carbohydrates as dextran and HES are well known to interact with the blood-coagulation system. Increase capillary permeability, typical of OHSS, leads to loss of colloidal substances into the third space, where HES is slowly degraded and osmotic pressure is high. This might prolong and aggravate the urine of OHSS.

Influence of disease progression on the neuromuscular blocking effect of mivacurium in children and adolescents with Duchenne muscular dystrophy.

Background:Studies with nondepolarizing neuromuscular blocking agents showed a delayed onset and prolonged recovery in patients with Duchenne muscular dystrophy. The objective of this study was to investigate if these alterations depend on disease progression. Methods:The authors studied 11 children (6–9 yr) with moderate Duchenne muscular dystrophy, 11 adolescents (12–16 yr) with advanced Duchenne muscular dystrophy, and 2 age-matched control groups of 8 patients each (5–9 and 10–17 yr). Anesthesia was performed with propofol and remifentanil. Patients received a single intravenous dose of 0.2 mg/kg mivacurium. Neuromuscular transmission was monitored by acceleromyography. The time course of neuromuscular blockade was characterized by the onset time and the times to different levels of recovery. Results:Onset and duration of neuromuscular blockade were significantly prolonged in adolescent Duchenne muscular dystrophy patients (onset time, 4.0 min; recovery index, 12.3 min; median), as compared with Duchenne muscular dystrophy children (onset time, 2.3 min; recovery index, 6.8 min), and also as compared with young controls (onset time, 2.0 min; recovery index, 4.4 min) and adolescent controls (onset time, 2.5 min; recovery index, 4.8 min). Within the Duchenne muscular dystrophy patients, onset time and recovery index increased significantly with age. In the control group, age had no effect. Conclusions:The neuromuscular blocking effects of mivacurium showed a significant age dependency in Duchenne muscular dystrophy patients, which was most probably caused by the progression of the disease.