Ultrasonographic Assessment of Bladder Volumes in Children Undergoing Penile Surgery: Does the Type of Anesthesia Matter?

BACKGROUND: There are scant data reporting postoperative ultrasonographically measured bladder volumes in children undergoing penile surgery. STUDY QUESTION: We studied the effect of various anesthesia techniques on return of micturition after penile surgery in children, using ultrasonographically measured bladder volumes. DATA SOURCES: Ultrasonographically measured postvoiding residual bladder volumes indexed to age-appropriate capacity, and time elapsed between the end of surgery and spontaneous voiding after pediatric circumcision, distal hypospadias repair, or repair of urethrocutaneous fistula, were studied. STUDY DESIGN: Children between 4 months and 12 years were randomized to caudal block, intravenous (IV) fentanyl or penile block, in association with inhaled general anesthesia. Bladder volumes were measured before surgery and immediately after voiding for the first time. Time to first postsurgery void was also recorded. RESULTS: Thirty-one children completed all assessments; 12 underwent caudal block, 9 IV fentanyl anesthesia, and 7 were given penile block. The mean first postvoid bladder residual volumes were highest in the caudal and lowest in the penile block children (27.5 vs. 17.3 mL, P = 0.003). The time elapsing between the end of surgery and first voiding was the longest in the fentanyl group compared with caudal and penile blocks (232, 178, 150 minutes, respectively, P = 0.02). CONCLUSIONS: None of the anesthetic techniques provoked postoperative urinary retention after minor penile surgery in children. The penile block appears superior to caudal block or to IV fentanyl-based anesthesia with regard to postoperative recovery of normal micturition.

Blood Flow Versus Hematocrit in Optimization of Oxygen Transfer to Tissue During Fluid Resuscitation.

The effectiveness of fluid resuscitation regimens in hemorrhagic trauma is assessed based on its ability to increase oxygen concentration in tissue. Fluid resuscitation using both crystalloids and colloids fluids, creates a dilemma due to its opposing effects on oxygen transfer. It increases blood flow thereby augmenting oxygen transport but it also dilutes the blood simultaneously and reduces oxygen concentration thereby reducing oxygen transport. In this work we have studied these two opposing effects of fluid therapy on oxygen delivery to tissue. A mathematical model of oxygen diffusion from capillaries to tissue and its distribution in tissue was developed and integrated into a previously developed hemodynamic model. The capillary-tissue model was based on the Krogh structure. Compared to other models, fewer simplifying assumptions were made leading to different boundary conditions and less constraints, especially regarding capillary oxygen content at its venous end. Results showed that oxygen content in blood is the dominant factor in oxygen transport to tissue and its effect is greater than the effect of flow. The integration of the capillary/tissue model with the hemodynamic model that links administered fluids with flow and blood dilution indicated that fluid resuscitation may reduce oxygen transport to tissue.

Opiates do not violate the viability and proliferative activity of human articular chondrocytes.

Articular cartilage injuries present a challenge for the clinician. Autologous chondrocyte implantation embedded in scaffolds are used to treat cartilage defects with favorable outcomes. Autologous serum is often used as a medium for chondrocyte cell culture during the proliferation phase of the process of such products. A previous report showed that opiate analgesics (fentanyl, alfentanil and diamorphine) in the sera have a significant inhibitory effect on chondrocyte proliferation. In order to determine if opiates in serum inhibit chondrocyte proliferation, twenty two patients who underwent knee arthroscopy and were anesthetized with either fentanyl or remifentanil were studied. Blood was drawn before and during opiate administration and up to 2 h after its discontinuation. The sera were used as medium for in vitro proliferation of both cryopreserved and freshly isolated chondrocytes, and the number and viability of cells were measured. There was no difference in the yield or cell viability between the serum samples of patients anesthetized with fentanyl when either fresh or cryopreserved human articular chondrocytes (hACs) were used. Some non-significant reduction in the yield of cells was observed in the serum samples of patients anesthetized with remifentanil when fresh hAC were used. We conclude that Fentanyl in human autologous serum does not inhibit in vitro hAC proliferation. Remifentanil may show minimal inhibitory effect on in vitro fresh hAC proliferation.

[Patient dissatisfaction following prolonged stay in the post-anesthesia care unit due to unavailable ward bed in a tertiary hospital].

OBJECTIVES: The present study aimed to evaluate subjective reactions of post-surgery and anesthesia patients who stay in post-anesthesia care units (PACU) longer than necessary medically, due to administrative causes. METHODS: We interviewed consenting postoperative patients during an 18-month period. All patients who remained in the PACU twice our obligatory PACU length of stay (> 4 hours) due to lack of an available bed in the appropriate hospital ward, were interviewed at the time of discharge. The study group consisted of those who remained > 4 hours after surgery and a control group of patients who were discharged within 4 hours. The questions were chosen from different sources, including generic and condition-specific questionnaires. RESULTS: A total of 67 patients stayed > 4 hours and 63 < 4 hours. The overall mean PACU length of stay for the former was 14.23 +/- 5.77 hours (range 1.5-30 hours). No significant differences were found between the groups in terms of age, gender, surgical time or postoperative pain visual analogue scale. Irritability due to lack of independence were statistically higher, and satisfaction rates were lower in patients who stayed > 12 hours compared to those who were discharged after 4-12 hours (P < 0.05). CONCLUSIONS: Overcrowded wards may lead to significant delays in discharge from the PACU. Prolonged stay in the PACU requires attention, both from the administrative and the medical standpoints, because it may irritate the patient. Patients' irate behavior may distract the medical staff from effectively performing their duties and interferes with optimal medical care in the PACU.

Changes in end-tidal carbon dioxide due to gastric perforation during pneumoperitoneum in the rat.

BACKGROUND: Carbon dioxide is the most widely used gas to establish pneumoperitoneum during laparoscopic surgery. Gastrointestinal trauma may occur during the peritoneal insufflation or during the operative phase itself. Early diagnosis of these injuries is critical. OBJECTIVES: To assess changes in end-tidal carbon dioxide (ETCO2) following gastric perforation during pneumoperitoneum in the rat. METHODS: Wistar rats were anesthetized, tracheotomized and mechanically ventilated with fixed minute volume. Each animal underwent a 1 cm abdominal longitudinal incision. A 0.3 x 0.3 cm cross-incision of the stomach was performed in the perforation group but not in the controls (n = 10/group) and the abdomen was closed in both groups. After stabilization, CO2-induced pneumoperitoneum was established at 0, 5, 8 and 12 mmHg for 20 min periods consecutively, each followed by complete pressure relief for 5 min. RESULTS: Ventilatory pressure increased in both groups when pneumoperitoneal pressure 5 mmHg was applied, but more so in the perforated stomach group (P = 0.003). ETCO2 increased in both groups during the experiment, but less so in the perforated group (P = 0.04). It then returned to near baseline values during pressure annulation in all perforated animals but only following the 0 and 5 mmHg periods in the controls. CONCLUSIONS: When subjected to pneumoperitoneum, ETCO2 was lower in rats with a perforated stomach than in those with an intact stomach. An abrupt decrease in ETCO2 during laparoscopy may signal gastric perforation.

CobraPLA Insertion by anesthetists and non-anesthetists wearing unconventional protective gear: a prospective study in humans.

BACKGROUND: The threat of a mass casualty unconventional attack has challenged the medical community to devise means for providing rapid and reliable emergent airway control under chaotic conditions by inexperienced medical personnel dressed in self protective gear. Since endotracheal intubation may not be feasible under those conditions, other extraglottic devices should be considered. We assessed the performance of anesthesia and non-anesthesia residents in inserting the CobraPLA, a supraglottic airway device, on consecutive anesthetized patients, to assess its potential use under simulated conditions. MATERIAL/METHODS: Anesthesia and non-anesthesia residents wearing either surgical scrubs or complete anti-chemical gear inserted the CobraPLA in anesthetized patients. If post-trial positive pressure ventilation via the CobraPLA was unsuccessful, an LMA or endotracheal tube was inserted in its stead. RESULTS: It took anesthesia residents 57+/-23 sec and 43+/-13 sec (P<0.05) to place the CobraPLA while wearing anti-chemical gear and surgical scrubs, respectively. Non-anesthesia residents wearing anti-chemical gear performed worse than anesthetists in their first insertion (73+/-9 sec, P<0.05), but after the brief training period they performed as well as their colleagues anesthetists (58+/-10 sec, P=NS). Post-trial, twenty-one CobraPLA (42%) leaked, preventing adequate positive-pressure ventilation: 13 devices (26% of the total) required replacements. CONCLUSIONS: Anti-chemical protective gear slowed the insertion of the CobraPLA by anesthetists, and more so by other residents inexperienced in airway management. In 26% of the cases CobraPLA was inadequate for positive pressure ventilation.

An evaluation of general and spinal anesthesia techniques for prostate brachytherapy in a day surgery setting.

We evaluated four anesthetic techniques for transperineal brachytherapy of the prostate in a day-surgery setting: general anesthesia with either fentanyl and propofol total IV anesthesia (TIVA) or with fentanyl, thiopental, and isoflurane (F-P-I), versus spinal block using 5 mg of 0.5% large-dose spinal hyperbaric bupivacaine (LDS) or 2.5 mg of 0.5% hyperbaric bupivacaine plus fentanyl 25 mug small-dose spinal (SDS). Operating room time was shorter in the general anesthesia groups. TIVA patients voided earlier (103 +/- 41 min) than F-P-I patients (131 +/- 65 min), SDS (126 +/- 55 min), and LDS patients (169 +/- 65 min; P < 0.05 TIVA versus all groups and between spinal groups). TIVA patients were discharged earlier (119 +/- 42 min) than F-P-I patients (160 +/- 69 min) and SDS or LDS patients (132 +/- 53 and 186 +/- 72 min, respectively; P < 0.05 versus all groups and between the spinal groups). There were no intergroup differences regarding postanesthesia nausea or vomiting, pain score, return to normal function at home, or overall satisfaction. Whereas all four techniques are suitable for this procedure, TIVA provides the earliest voiding and consequently fastest discharge. Between spinal techniques, the SDS technique requires more intraoperative sedation but provides earlier voiding and consequently earlier discharge. TIVA, general anesthesia with isoflurane and fentanyl, and two spinal techniques (5 mg of bupivacaine 0.5% or 2.5 mg of bupivacaine 0.5% plus 25 mug of fentanyl) are suitable techniques for transperineal brachytherapy in the day-surgery setting. TIVA allows for earliest voiding and therefore fastest discharge home. Spinal block with 2.5 mg of bupivacaine plus 25 mug of fentanyl provides earlier voiding and consequently earlier discharge than 5 mg of bupivacaine alone.

Antichemical protective gear prolongs time to successful airway management: a randomized, crossover study in humans.

BACKGROUND: Airway management is the first step in resuscitation. The extraordinary conditions in mass casualty situations impose special difficulties in airway management, even for experienced caregivers. The authors evaluated whether wearing surgical attire or antichemical protective gear made any difference in anesthetists' success of airway control with either an endotracheal tube or a laryngeal mask airway. METHODS: Fifteen anesthetists with 2-5 yr of residency and wearing either full antichemical protective gear or surgical attire intubated or inserted laryngeal masks in 60 anesthetized patients. The study was performed in a prospective, randomized, crossover manner. The duration of intubation/insertion was measured from the time the device was grasped to the time a normal capnography recording was obtained. RESULTS: Endotracheal tubes were introduced significantly (P < 0.01) faster when the anesthetist wore surgical attire (31 +/- 7 vs. 54 +/- 24 s for protective gear), but the mean times necessary to successfully insert laryngeal masks were similar (44 +/- 20 s for surgical attire vs. 39 +/- 11 s for protective gear). Neither performance failure nor incidences of hypoxemia were recorded. CONCLUSIONS: This first report in humans shows to what extent anesthetists' wearing of antichemical protective gear slows the time to intubate but not to insert a laryngeal mask airway compared with wearing surgical attire. Laryngeal mask airway insertion is faster than tracheal intubation when wearing protective gear, indicating its advantage for airway management when anesthetists wear antichemical protective gear. If chances for rapid and successful tracheal intubation under such chaotic conditions are poor, laryngeal mask airway insertion is a viable choice for airway management until a proper secured airway is obtainable.

Laryngeal mask airway insertion by anesthetists and nonanesthetists wearing unconventional protective gear: a prospective, randomized, crossover study in humans.

BACKGROUND: Mass casualty situations impose special difficulties in airway management, even for experienced caregivers. The laryngeal mask airway is part of the difficult airway algorithm. The authors evaluated the success rate and the time to secure airways by mask by anesthetists, surgeons, and novices when wearing either surgical attire or full antichemical protective gear that included butyl rubber gloves and a filtering antigas mask. METHODS: Twenty anesthetists and 22 surgeons with 2-5 yr of residency inserted a laryngeal mask airway in 84 anesthetized patients, and 6 novices repetitively inserted masks in 57 patients under both conditions in a prospective, randomized, crossover manner. The duration of insertion was measured from the time the device was first grasped until a normal capnography recording was obtained. RESULTS: Anesthetists needed 39 +/- 14 s to insert the masks when wearing surgical attire and 40 +/- 12 s with protective gear. In contrast, surgery residents needed 64 +/- 40 and 102 +/- 40 s (P = 0.0001), respectively. Anesthetists inserted masks in a single attempt, whereas the surgeons needed up to four attempts with no hypoxia or failure associated. The initial attire-wearing novices' insertions took as long as the surgeons'; three of them then reached the mean performance time of the anesthetists after four (protective gear) and two (surgical attire) trials, with only one occurrence of hypoxia and a failure rate similar to that of the surgeons. CONCLUSIONS: Anesthesia residents insert laryngeal mask airways at a similar speed when wearing surgical attire or limiting antichemical protective gear and two to three times faster than surgical residents or novices wearing either outfit. Novices initially perform at the level of surgical residents, but their learning curve was quick under both conditions.

Flumazenil attenuates development of tolerance to diazepam after chronic treatment of mice with either isoflurane or diazepam.

UNLABELLED: In an effort to clarify the mechanism of action of isoflurane, we studied the effect of flumazenil on mice chronically treated with isoflurane or diazepam. Mice were pretreated with diazepam, isoflurane, or saline, with and without flumazenil. After 2 wk, responses to isoflurane and diazepam were assessed, and central benzodiazepine receptor (CBR) binding characteristics were assayed. Mice pretreated with isoflurane failed the horizontal wire test at a larger isoflurane concentration (0.5%) compared with saline-pretreated mice (0.4%) (P < 0.05). These differences did not occur when flumazenil was added to the pretreatment. After the administration of diazepam, 20% of diazepam- and 11% of isoflurane-pretreated mice failed the horizontal wire test, versus 50% and 44% when flumazenil was added to either drug (P < 0.002) and 80% and 100% in the saline and saline plus flumazenil-treated mice. The increased CBR density due to flumazenil was attenuated by the coadministration of isoflurane or diazepam. Flumazenil attenuated the development of tolerance to diazepam after chronic treatment with diazepam or isoflurane and attenuated the development of tolerance to isoflurane. Isoflurane, like diazepam, attenuated the effect of flumazenil on CBR ligand binding. These findings suggest that isoflurane shares a mechanism of action with diazepam, probably via the gamma-aminobutyric acid system, most probably the CBR. IMPLICATIONS: Flumazenil attenuates the development of tolerance to isoflurane and diazepam after chronic isoflurane pretreatment. Isoflurane, like diazepam, attenuates the increase in central benzodiazepine receptor (CBR) density caused by flumazenil. These findings suggest that isoflurane and diazepam share a mechanism of action, most probably via the gamma-aminobutyric acid system and the CBR.

Halothane, isoflurane, and fentanyl increase the minimally effective defibrillation threshold of an implantable cardioverter defibrillator: first report in humans.

UNLABELLED: Placing an implantable cardioverter defibrillator (ICD) involves the induction of ventricular fibrillation, whereupon the minimally effective defibrillation energy threshold (DFT) is determined. We evaluated the effects of 0.7% halothane, 1% isoflurane, or 1.5 micro g/kg of IV fentanyl during N(2)O/oxygen-based general anesthesia (GA) or those of subcutaneous 1.5% lidocaine plus IV 0.35 mg/kg of propofol on the DFT during ICD implantation in humans (n = 20 per group). Thirty minutes after the first set of DFT measurements under such conditions, the inhaled anesthetics were withdrawn, and all three GA groups received fentanyl 1 microg/kg IV (second set). A third set was taken 30 min later, before the GA patients awakened and when only N(2)O/oxygen was delivered for GA. The lidocaine plus propofol patients were given the same IV propofol bolus 1 min before each fibrillation/defibrillation trial and at the same time points as the three GA groups. The first DFTs were 16.1 +/- 2.2 J (halothane), 17.7 +/- 2.7 J (isoflurane), 16.4 +/- 2.9 J (fentanyl), and 12.9 +/- 3.8 J (lidocaine plus propofol) (P = 0.01). The second set of DFTs were significantly lower than the first sets for the halothane (P = 0.01) and isoflurane (P = 0.02), but not the fentanyl or lidocaine plus propofol, regimens. The third DFTs were significantly (P < 0.01) lower than the first ones for the three GA groups, but not for the lidocaine plus propofol patients. Thus, halothane, isoflurane, and fentanyl increased DFT values during ICD implantation in humans, whereas lidocaine plus intermittent small-dose IV propofol minimized these thresholds. IMPLICATIONS: Halothane, isoflurane, and IV fentanyl added to N(2)O/oxygen-based general anesthesia similarly increase minimal defibrillation threshold energy requirements (DFT) during cardioverter defibrillator implantation in humans. Subcutaneous lidocaine plus intermittent small-dose IV propofol minimizes DFT compared with these general anesthetics while providing equal patient satisfaction.