Markku Paloheimo

Hyaluronidase as an adjuvant in bupivacaine-lidocaine mixture for retrobulbar/peribulbar block

Hyaluronidase 7.5 IU/mL added to the local anesthetic improves peribulbar block, but smaller concentrations have not been shown to be effective. In this prospective, double-blinded study, 714 consecutive ocular surgery patients were randomized into three groups: no hyaluronidase (n = 241), hyaluronidase 3.75 IU/mL (n = 244), and hyaluronidase 7.5 IU/mL (n = 229). Retrobulbar/peribulbar block was performed with two injections of a 1:1 mixture of bupivacaine 0.75% and lidocaine 2%, 6–8 mL. Patient data were collected on demographics, initial volume of local anesthetic, need for supplementary block, and akinesia of the anesthetized eye. When hyaluronidase was used (3.75 or 7.5 IU/mL), the initial block was sufficient and the anesthetized eye was akinetic significantly more often than in the group without hyaluronidase. The hyaluronidase groups (3.75 and 7.5 IU/mL) did not differ significantly in any respect. We conclude that the addition of hyaluronidase 3.75 or 7.5 IU/mL improved the success of the initial retrobulbar/peribulbar block and akinesia and reduced the need for supplementary block. Implications We conclude that the addition of hyaluronidase 3.75 or 7.5 IU/mL improved the success of the initial retrobulbar/peribulbar block and akinesia and reduced the need for supplementary block.

Effect of pain on autonomic nervous system indices derived from photoplethysmography in healthy volunteers

BACKGROUND Photoplethysmographic pulse wave amplitude (PPGA) and heart rate (HR) can be used to measure cold, nociception-induced autonomic responses, or both. The aim of our study was to correlate the intensity of experimental pain to changes in physiological variables reflecting the autonomic nervous system response to pain. METHODS PPGA, HR, and subjective measurements of pain intensity were measured in 29 healthy male volunteers during two heat stimuli (43°C and 48°C) and the cold pressor test (CPT). Surgical pleth index (SPI), autonomic nervous system state (ANSS), and ANSS index (ANSSi) were calculated using PPGA and HR. RESULTS Pain intensity scores increased on the average by 1.6, 3.5, and 8.1 for the 43°C, 48°C, and CPT stimuli, respectively. The pain intensity scores for all three stimuli groups were significantly different from each other (P<0.001). All three stimuli changed HR, PPGA, SPI, ANSS, and ANSSi values significantly from their respective baseline values (P<0.001 for all). Heat stimuli-induced pain intensity did not correlate with the magnitude of the respective changes in HR, PPGA, SPI, ANSS, and ANSSi. CPT-induced pain intensity correlated with the magnitude of the respective changes in HR, PPGA, SPI, ANSS, and ANSSi. PPGA, ANSSi, ANSS, and SPI differentiated between heat and cold stimuli-induced pain. CONCLUSIONS All three thermal stimuli produced a significant change in photoplethysmograph-derived parameters. All photoplethysmograph-derived parameters appear to be suitable to study autonomic nervous system activation.

Measurement of surgical stress in anaesthetized children

BACKGROUND The surgical stress index (SSI), derived from a combination of heart rate (HR) and photoplethysmographic amplitude (PPGA) time series, is a novel method for continuous monitoring of intraoperative stress and has been validated in adults. The applicability of SSI and its constituents to monitoring children has not been previously evaluated. METHODS In this controlled trial, 22 anaesthetized patients, aged 4-17 yr, undergoing strabismus surgery were randomized into two groups, Group LL and Group BSS. Patients in Group LL received topical conjunctival anaesthesia with a 1:1 mixture of lidocaine 2% and levobupivacaine 0.75%, and patients in Group BSS received balanced salt solution. RESULTS Endotracheal intubation (n=22) increased median (range) SSI from 39.2 (22.6-55.6) to 53.6 (35.8-63.3) (P<0.001), decreased PPGA from 5.62 (2.79-9.69) to 5.27 (2.59-7.54)% (P=0.001), and increased the difference of response entropy (RE) and state entropy (SE) of frontal biopotentials (RE-SE) from 3.1 (0.06-9.1) to 5.7 (0.6-9.4) (P=0.01). Conventional haemodynamic variables also increased, median (range) HR from 72.9 (56.7-113.8) to 84.2 (60.4-124.8) beats min(-1) (P<0.001), and systolic non-invasive arterial pressure (S-NIBP) from 87 (78-143) to 103 (79-125) (P=0.007). When 3 min baseline before surgery was compared with 12 min of surgery, median (range) SSI increased from 43.3 (31.2-58.0) to 49.9 (39.3-57.2) (P=0.042) vs from 46.6 (26.8-57.8) to 52.1 (31.7-60.1) (P=0.024) and PPGA decreased from 6.60 (3.10-8.24) to 5.80 (3.03-7.65)% (P<0.001) vs from 5.51 (3.25-9.84) to 5.06 (3.08-8.99)% (P=0.042), in Groups LL and BSS, respectively, but SSI or other indicators did not differ significantly between the groups. CONCLUSIONS SSI, PPGA, HR, NIBP, RE, and RE-SE detect autonomic responses to nociceptive stimuli in anaesthetized children undergoing strabismus surgery.

Converting to topical anesthesia in cataract surgery.

PURPOSE To evaluate the complications and difficulties encountered by surgeons converting from paraocular to topical anesthesia in cataract surgery and to evaluate patient pain and satisfaction with each procedure. SETTING Department of Ophthalmology, Helsinki University Central Hospital, Helsinki, Finland. METHODS Three hundred eyes of 245 consecutive patients were prospectively assigned by permuted block-restricted randomization to receive topical (bupivacaine 0.75%) (Group 1; n = 136) or paraocular (Group 2; n = 163) anesthesia. The intraoperative conditions were judged by the surgeon. A numerical scale (0 to 10) was used to assess the degree of pain during administration of anesthesia, during surgery, and 1 and 24 hours postoperatively. Outcome measures were the number of complications and adverse events registered perioperatively and 4 months postoperatively as well as Snellen visual acuity and surgically induced astigmatism (SIA) measured 1 week and 4 months after surgery. RESULTS The success of posterior chamber intraocular lens (IOL) implantation through a self-sealing clear corneal incision was very high (99.3% and 96.9% in Groups 1 and 2, respectively). One case (0.7%) in the topical group required vitrectomy and implantation of an anterior chamber IOL. Anesthesia-related difficulties were reported in about 40% of patients in Group 1 and 4% in Group 2 (P < .001). Supplemental paraocular anesthesia was required in 4 cases (2.9%) in the topical group. Sedative/analgesic medication given perioperatively was required significantly more often in Group 1 (13.2%) than in Group 2 (2.4%) (P < .01). Significantly more pain during surgery (P < .001) and 1 hour after surgery (P < .001) was reported in the topical group. In Group 1 69.9% and in Group 2 93.3% reported no pain during surgery (P < .001). Chemosis (1.8%), subconjunctival hemorrhage (1.2%), and periorbital hematoma (1.2%) were seen only in the paraocular group. Perioperatively, no severe complications occurred in Group 1 and the number of adverse events was less than in Group 2. Postoperatively, 2 cases of endophthalmitis developed in the topical group and none in the paraocular group. There was no between-group difference in outcome measures; a visual acuity of 20/40 or better was found in 87.8% of eyes in Group 1 and 84.9% in Group 2 4 months postoperatively, and the percentages of eyes with SIAs within 1.0 diopter of preoperative values were similar (78.6% and 73.3%, respectively). Patient preference for topical anesthesia appeared to be higher than for paraocular anesthesia. CONCLUSION Paraocular anesthesia gave better analgesia than topical, but topical anesthesia provided acceptable analgesia during surgery and showed that intraocular procedures can be performed without akinesia. The surgeon converting to topical anesthesia may expect slight difficulty in 40% of cases and more severe difficulty in 7%. Surgically related complications were similar with both methods.

Autonomic nervous system state: the effect of general anaesthesia and bilateral tonsillectomy after unilateral infiltration of lidocaine

BACKGROUND Autonomic nervous system (ANS) sensitively responds to intraoperative stress. Several indices characterizing the state and responses of autonomic signs to nociceptive stimuli have been introduced. This study evaluated the behaviour of ANS descriptors after induction, before and during tracheal intubation, and during bilateral tonsillectomies after random and blinded unilateral infiltration of lidocaine 1% until emergence from anaesthesia. METHODS Twelve patients undergoing bilateral tonsillectomy were anaesthetized with fentanyl and propofol (induction) and sevoflurane (maintenance). All patients were monitored throughout anaesthesia for middle finger temperature, non-invasive arterial pressure, heart rate (HR) and pulse rate (PR), state entropy (SE) and response entropy (RE), and surgical pleth index (SPI). New parameters complementing the above and characterizing the ANS state (ANSS) and responses are pulse-to-pulse interval (PPI), pulse plethysmographic amplitude (PPGA), ANSS, and an index based on maximal ANSS for the subject (ANSSI). Serial data were stored as 10 s averages into a laptop computer. RESULTS Anaesthesia induction was associated with an increase in finger temperature to >30 degrees C within 10 min, whereas PPGA increased to their maximum levels within 5 min. Laryngoscopy and intubation were associated with transient autonomic responses in most patients. All autonomic signs indicated statistically significant sympathetic activation during saline-infiltrated tonsillectomies when compared with lidocaine-infiltrated sides (P<0001). Hypnotic measures (SE and RE) and finger temperatures did not differ between the sides. CONCLUSIONS HR, PPI, PPGA, ANSS, ANSSI, SPI, and RE-SE detect autonomic responses to nociceptive stimuli and differentiate between tonsillectomies on locally anaesthetized tonsils from controls.

A rapid increase in the inspired concentration of desflurane is not associated with epileptiform encephalogram.

The large inspired concentration of sevoflurane (S) during mask induction of anesthesia can induce epileptiform electroencephalogram (EEG) associated with tachycardia. Tachycardia is also seen when the concentration of desflurane (D) is abruptly increased. It is not known whether this is associated with epileptiform EEG similar to S. We studied EEG and heart rate (HR) during rapidly increased concentrations of S or D in 31 females during the postintubation period of anesthesia. Anesthesia was induced with propofol and remifentanil, and the tracheas were intubated. Patients were randomized to receive either S or D in nitrous oxide-oxygen mixture after intubation, at a small dose first. After 10 min, S or D vaporizer was advanced to the highest reading of the vaporizer (7% for S, 18% for D) for 5 min. HR and EEG were recorded. Epileptiform EEG activity was recorded in eight of 15 patients in group S and in none in group D (P < 0.05). HR increased in both groups. In group S, HR increased gradually and the highest HR value was 84 bpm at 5 min after the increase in sevoflurane concentration. In group D, HR increased to 93 bpm 2 min after the increase in desflurane concentration (no significant difference, S versus D). A rapid increase in the concentration of S frequently induces epileptiform EEG during normoventilation. Tachycardia during increasing concentrations of D is not associated with epileptiform EEG.

Monitoring of the inspired and end-tidal oxygen, carbon dioxide, and nitrous oxide concentrations: clinical applications during anesthesia and recovery

Respiratory oxygen, carbon dioxide, and nitrous oxide concentrations were recorded in 20 patients breath-by-breath during general anesthesia and early recovery, using the Cardiocap multiparameter monitor. Several approved maneuvers were performed to demonstrate the usefulness of endtidal oxygen measurement. “Oxygrams” provided by the fast paramagnetic oxygen sensor confirmed the capnometric information in the diagnosis of hypoventilation, apnea, and disconnections. In one patient, the alarm for inspiratory oxygen concentration, set at 18%, appeared to prevent alveolar hypoxia and low arterial saturation from occurring when oxygen instead of nitrous oxide was turned off. Low end-tidal oxygen levels revealed inadequate fresh gas oxygen supplementation while low flow circuits were closed. During manual hypoventilation at the end of anesthesia, the inspiratory-expiratory oxygen difference increased almost twofold while end-tidal carbon dioxide increased by only 30%. Changes in nitrous oxide concentration often complemented oxygen-related information obtained in our observations. In the recovery room, a decrease in end-tidal oxygen concentration preceded low pulse oximetry readings. Therefore, it is suggested that all three gases should be monitored continuously to prevent mishaps related to insufficient ventilation and inappropriate gas concentrations during anesthesia and immediate recovery.

Orbicular muscle akinesia in regional ophthalmic anaesthesia with pH-adjusted bupivacaine: effects of hyaluronidase and epinephrine.

The success rate and duration of lid akinesia after adding hyaluronidase and / or epinephrine to pH-adjusted bupivacaine was examined in a double-blind fashion in patients undergoing cataract surgery under local anaesthesia. A two-injection-site technique was used. For globe akinesia all patients (n = 120) received an inferolateral intraconal injection (3 ml) of pH-adjusted bupivacaine 0.75% and hyaluronidase. Lid akinesia was obtained with a medial extraconal injection (3.5 ml) of alkalinized bupivacaine with or without an adjunct. The patients were randomized to four groups as follows: a medial injection of plain bupivacaine (n = 31), with added hyaluronidase (n = 30), with added epinephrine (n = 29) or with both epinephrine and hyaluronidase (n = 30). The final solutions had a p H of 6.7. Lid akinesia was supplemented with periosteal injections if needed. The degree of akinesia from clinical assessment was graded from 0–2 and also measured with electromyography at ten minute intervals for 30 min after surgery, and three hours after the block. The least satisfactory result (P < 0.01) and shortest duration of the lid block (P < 0.05) was obtained with plain pH-adjusted bupivacaine. No differences in the success rate or duration of the block among the other groups were seen. The duration of the block was longer in the epinephrine groups than in the two other groups (P < 0.01) and longer in the epinephrine and hyaluronidase group than in the group receiving only hyaluronidase (P < 0.05). We conclude that the best initial results and longest duration of blocks were shown in the groups receiving epinephrine or epinephrine and hyaluronidase.RésuméCette étude à double insu évalue le taux de succès et la durée de l’akinésie de la paupière après l’ajout d’hyaluronidase et/ ou d’épinéphrine à la bupivacaine à pH ajusté chez des patients soumis à une chirurgie de la cataracte sous anesthésie locale. Une technique à deux sites d’injections est préconisée. Pour l’anesthésie du globe oculaire, tous les patients (n = 120) reçoivent une injection inférolatérale dans le cône musculaire (3 ml) d’une solution à pH ajusté de bupivacaine 0,75% et d’hyaluronidase. L’akinésie palpébrale est obtenue par une injection médiane hors du cône (3,5 ml) de bupivacaine alcalinisée avec ou sans ajout. Les patients sont randomisés de la façon suivante en quatre groupes: injection médiane de bupivacaïne simple (n = 31), avec hyaluronidase (n = 30), avec ajout d’épinéphrine (n = 29) ou épinéphrine associée à l’hyaluronidase (n = 30). Le pH final de chaque solution est ajusté à 6,7. L’akinésie palpébrale est supplémentée par des injections pèriostées au besoin. Le degré d’akinésie est coté de 0–2 et mesuré à l’électromyographie à des intervalles de dix minutes pour 30 minutes, après la chirurgie et trois heures après le bloc. Le résultat le moins satisfaisant (P < 0,01) et la durée la plus courte du bloc palpébral (P < 0,05) survient avec la bupivacaine simple à pH ajusté. Pour le taux de succès ou la durée du bloc, on ne trouve pas de différences entre les autres groupes. La durée du bloc est plus longue dans le groupe épinéphrine que dans les deux autres groupes (P < 0,01) et plus longue dans le groupe épinéphrine-hyaluronidase que dans le groupe ne recevant que de l’hyaluronidase (P < 0,05). Nous concluons que les meilleurs résultats initiaux et les plus longues durées d’action se retrouvent dans les groupes recevant de l’épinéphrine ou de l’épinéphrine associée à l’hyaluronidase.

Inspiratory end-tidal oxygen content difference: a sensitive indicator of hypoventilation

The effect of progressive hypoventilation on end-tidal gas concentrations and corresponding partial pressures in arterial blood was studied in anesthetized pigs. Oxygen, CO2, and nitrous oxide concentrations were measured continuously with fast infrared and paramagnetic sensors as ventilation was decreased gradually in 12.5% increments at 5-min intervals. Samples for blood gas determinations were obtained at 3 min after each respirator adjustment. An increasing difference between inspiratory and end-tidal oxygen concentrations (FIO2 — PetO2) was the most sensitive indicator of hypoventilation and exceeded the sensitivity of end-tidal CO2. Decreasing PetO2 was followed by a decrease in PaO2, but no detectable change in arterial oxygen saturation until the ventilation was decreased to 37% of the initial value. The rapidly decreasing alveolar oxygen was replaced by nitrous oxide, and a sudden drop in ventilation was characterized by a change in the end-tidal values of all the three gases and peaked waveforms. Thus, PetO2 and FiO2 — PetO2 are sensitive and valuable indicators of adequate ventilation and appropriate oxygen supply.

Periocular anaesthesia: Technique, effectiveness and complications with special reference to postoperative ptosis

Abstract. The effectiveness of periocular anaesthesia and its complications were examined in 100 successive cataract operations. The patients were divided into 3 groups according to the duration of ocular compression with an Autopressor® device after administration of periocular anaesthesia. In the control group, no compression was used (C‐0, n = 36 patients). In the other two groups, compression was used for 10 (C‐10, n = 32) and for 20 (C‐20, n = 32) min. No differences in globe or orbicular akinesia were found between the groups. At 10 min, immobilisation of the globe in different directions was attained in 60.1–84.5% of the patients. Compression for an additional 10 min did not significantly improve the akinesia. In contrast, the hitherto undescribed loss of light perception increased with time: 15 patients at 10 min and 22 at 20 min were unable to see light. Chemosis and haematomas in the upper eyelid occurred more often in C‐0 than in the other 2 groups. One day postoperatively the average palpebral aperture was smaller in C‐0 than in the other two groups. The frequent postoperative ptosis (74.3% on the 1st day) decreased rapidly, but on postoperative day 7, 9 patients still had ptosis. In only one patient was ptosis still recognizable at 6 weeks postoperatively. No serious complications occurred. This study demonstrates that periocular anaesthesia with ocular compression is a suitable method for cataract surgery.