Cengiz Karsli

Cerebrovascular carbon dioxide reactivity in children anaesthetized with propofol

Background: Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anaesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in paediatric patients. To determine the effects of propofol on carbon dioxide cerebrovascular reactivity in children, middle cerebral artery blood flow velocity was measured at different levels of endtidal (PECO2) by transcranial Doppler sonography.

Hemodynamic and Respiratory Effects of Pediatric Urological Retroperitoneal Laparoscopic Surgery: A Prospective Study

PURPOSE Our understanding of the effects of retroperitoneal CO(2) insufflation on cardiopulmonary variables in children remains limited. This study was designed to investigate prospectively the effect of CO(2) insufflation in a pediatric population undergoing retroperitoneal laparoscopic surgery. MATERIALS AND METHODS We prospectively evaluated a consecutive series of patients enrolled between July 2003 and August 2004. Anesthesia was administered following a standardized protocol. Data collection included respiratory rate, PAP, O(2) saturation, ETCO(2), HR, MAP, electrocardiogram and insufflation pressure. All variables were recorded before, during and after CO(2) insufflation at regular intervals of 1 to 2 minutes, with up to 23 measurements recorded for each period. RESULTS A total of 18 participants were recruited. Mean +/- SD for age and weight were 79.4 +/- 53.2 months and 26.7 +/- 15.5 kg, respectively. Mean retroperitoneal CO(2) insufflation pressure was kept at 12 mm Hg. Significant differences (p <0.05) in average ETCO(2), PAP and MAP were noted after CO(2) insufflation compared to baseline (pre-pneumoretroperitoneum) values. HR and temperature did not change. At completion of the laparoscopic intervention physiological variables exhibited a trend to return to baseline values. CONCLUSIONS This prospective study documents significant changes in systemic hemodynamic variables that seem to be directly associated with the insufflation of CO(2) during pediatric retroperitoneal laparoscopic surgery. This ongoing evaluation confirms the effect of laparoscopic urological surgery and CO(2) insufflation on cardiopulmonary function in children.

The effect of sevoflurane on cerebral blood flow velocity in children

Background:  Sevoflurane is a suitable agent for neuroanesthesia in adult patients. In children, cerebrovascular carbon dioxide reactivity is maintained during hypo‐ and normocapnia under sevoflurane anesthesia. To determine the effects of sevoflurane on middle cerebral artery blood flow velocity (Vmca) in neurologically normal children, Vmca was measured both at different MAC values and at one MAC over a specified time period, using transcranial Doppler sonography.

The effect of nitrous oxide on cerebrovascular reactivity to carbon dioxide in children during propofol anesthesia.

Nitrous oxide (N2O) increases cerebral blood flow when used alone and in combination with propofol. We investigated the effects of N2O on cerebrovascular CO2 reactivity (CCO2R) during propofol anesthesia in 10 healthy children undergoing elective urological surgery. Anesthesia consisted of a steady-state propofol infusion and a continuous caudal epidural block. A transcranial Doppler probe was used to measure middle cerebral artery blood flow velocity. Randomization determined the sequence order of N2O (N2O/air or air/N2O) and end-tidal (ET)co2 concentration (25, 35, 45, and 55 mm Hg) using an exogenous source of CO2. At steady state, three sets of measurements of middle cerebral artery blood flow velocity, mean arterial blood pressure, and heart rate were recorded. A linear preservation of CCO2R was observed above 35 mm Hg of ETco2, irrespective of N2O. A decrease in CCO2R to 1.4%–1.9% per millimeters of mercury was seen in the hypocapnic range (ETco2 25–35 mm Hg) with both air and N2O. We conclude that N2O does not affect CCO2R during propofol anesthesia in children. When preservation of CCO2R is required, the combination of N2O with propofol anesthesia in children would seem suitable. The cerebral vasoconstriction caused by propofol would imply that hyperventilation to ETco2 values less than 35 mm Hg may not be required because no further reduction in cerebral blood flow velocity would be achieved.

The effect of nitrous oxide on cerebral blood flow velocity in children anesthetized with propofol.

Background: Propofol for maintenance of anesthesia by continuous infusion is gaining popularity for use in pediatric patients. Nitrous oxide (N2O) has been shown to increase cerebral blood flow velocity (CBFV) in both children and adults. To determine the effects of N2O on middle cerebral artery blood flow velocity (Vmca) during propofol anesthesia in children, Vmca was measured with and without N2O using transcranial Doppler (TCD) sonography.

The effect of remifentanil on cerebral blood flow velocity in children anesthetized with propofol

Background : Cerebrovascular stability and rapid anesthetic emergence are desirable features of a neuroanesthetic regimen. In this randomized crossover study the effect of a low‐dose remifentanil infusion on cerebral blood flow velocity (CBFV) in children anesthetized with propofol was evaluated.

Fentanyl is more effective than remifentanil at preventing increases in cerebral blood flow velocity during intubation in children.

PurposeControlling the cerebral and systemic hemodynamic responses to laryngoscopy and tracheal intubation may play a role in determining clinical outcome in pediatric neurosurgical patients. This study compared the effects of remifentanil and fentanyl on cerebral blood flow velocity (CBFV) and hemodynamic profile during laryngoscopy and tracheal intubation in children under sevoflurane anesthesia.MethodsSixty healthy children aged two to six years undergoing dental surgery under general anesthesia were enrolled. Each child was randomly assigned to receive a remifentanil or fentanyl infusion, at a rate of 0.75, 1.0, or 1.5 μg·kg−1·min−1 after induction of anesthesia with 2% sevoflurane. Middle cerebral artery blood flow velocity was measured by transcranial Doppler (TCD) sonography Once a baseline set of hemodynamic variables and TCD measurements were recorded, the opioid infusion was started. Measurements were taken at two-minute intervals, starting four minutes prior to laryngoscopy until four minutes following naso-tracheal intubation.ResultsRemifentanil caused a more significant decrease in mean arterial pressure and CBFV prior to tracheal intubation than did fentanyl (P < 0.001). During laryngoscopy and for two minutes following tracheal intubation, CBFV increased in all remifentanil groups (P < 0.05), whereas it remained stable in all fentanyl groups.ConclusionThis study suggests that fentanyl was more effective than remifentanil at preventing increases in CBFV during and immediately following laryngoscopy and tracheal intubation in children undergoing sevoflurane anesthesia. Fentanyl also seemed to provide a more stable hemodynamic profile prior to laryngoscopy and tracheal intubation when compared to remifentanil.RésuméObjectifLe contrôle des réponses hémodynamiques cérébrale et générale à la laryngoscope et à l’intubation trachéale peut influencer de façon déterminante l’évolution clinique des enfants de neurochirurgie. La présente étude a comparé les effets du rémifentanil et du fentanyl sur la vitesse du flux sanguin cérébral (VFSC) et sur le profil hémodynamique pendant la laryngoscopie et l’intubation trachéale chez des enfants soumis à une anesthésie au sévoflurane.MéthodeSoixante enfants en bonne santé devant subir une intervention dentaire sous anesthésie générale ont été choisis pour l’étude. Chaque enfant a été assigné au hasard pour recevoir une perfusion de rémifentanil ou de fentanyl selon une vitesse de 0,75, 1,0 ou 1,5 μg·kg−1·min−1, après l’induction de l’anesthésie avec du sévoflurane à 2 %. La vitesse circulatoire de l’artère cérébrale moyenne a été mesurée par Doppler transcrânien (DTC). La perfusion a commencé après la réalisation des mesures de base des variables hémodynamiques et du DTC. Les mesures ont été prises aux deux minutes, en commençant quatre minutes avant la laryngoscopie jusqu’à quatre minutes après l’intubation nasotrachéale.RésultatsAvant l’intubation trachéale, le rémifentanil, comparé au fentanyl, a causé une baisse plus importante de la pression de l’artère moyenne et de la VFSC (P < 0,001). Pendant la laryngoscopie et pendant deux minutes après l’intubation trachéale, la VFSC a augmenté avec le rémifentanil (P < 0,05) alors qu’elle est demeurée stable avec le fentanyl.ConclusionCette étude montre que le fentanyl a été plus efficace que le rémifentanil à prévenir des hausses de la VFSC pendant et immédiatement après la laryngoscopie et l’intubation trachéale chez des enfants sous anesthésie avec du sévoflurane. Le fentanyl, comparativement au rémifentanil, semble fournir aussi un profil hémodynamique plus stable avant la laryngoscopie et l’intubation trachéale.

The cerebrovascular response to hypocapnia in children receiving propofol.

Hypocapnia is used to treat acute increases in intracranial pressure during neurosurgery. Cerebrovascular reactivity to carbon dioxide (CCO2R) is preserved above 35 mm Hg ETco2 in children during propofol anesthesia; however, a plateau effect has been suggested below 35 mm Hg. To further delineate this phenomenon, we measured CCO2R by transcranial Doppler (TCD) sonography over small increments in ETco2 in 27 healthy children. Anesthesia comprised a standardized propofol infusion and a caudal epidural block. A TCD probe was placed to measure middle cerebral artery blood flow velocity (Vmca). ETco2 was adjusted between 24 and 40 mm Hg at 1–2 mm Hg increments using an exogenous source of CO2. There was an exponential relationship between ETco2 and Vmca above an ETco2 value of 30 mm Hg (r = 0.82). However, Vmca did not change with ETco2 less than 30 mm Hg (r = 0.06). There were no significant changes in heart rate or arterial blood pressure. We conclude that when contemplating methods to decrease brain volume and intracranial pressure, hyperventilation to ETco2 values less than 30 mm Hg may not be necessary in children receiving propofol, as no further reduction in cerebral blood flow velocity will be achieved.

Technique of Lung Isolation for Whole Lung Lavage in a Child with Pulmonary Alveolar Proteinosis

airway in most cases. Nevertheless, even newly developed types of laryngeal masks (as the LMA-STM) may be cause for the obstruction of the laryngeal inlet when the mask displaces laryngeal cartilages medially, narrowing the laryngeal inlet. This is the first report of this phenomenon of medialization in a LMA-STM. Because laryngeal masks are important backup devices in the management of difficult airways, this infrequent cause of a laryngeal mask failure must be made known. Strategies to handle laryngeal mask failures might be included in the algorithms for difficult airway management, and backup strategies for the “backup device” laryngeal mask should be considered.

Cerebral blood flow velocity in children anaesthetized with desflurane.

Background: Desflurane allows for rapid emergence and changes in depth of anaesthesia which makes it especially suitable for neuroanaesthesia. This study was designed to determine the effects of different desflurane concentrations on cerebral blood flow velocity (CBFV) in healthy children.