Robotic navigation to subcortical neural tissue for intracellular electrophysiology in vivo.

In vivo studies of neurophysiology using the whole cell patch-clamp technique enable exquisite access to both intracellular dynamics and cytosol of cells in the living brain but are underrepresented in deep subcortical nuclei because of fouling of the sensitive electrode tip. We have developed an autonomous method to navigate electrodes around obstacles such as blood vessels after identifying them as a source of contamination during regional pipette localization (RPL) in vivo. In mice, robotic navigation prevented fouling of the electrode tip, increasing RPL success probability 3 mm below the pial surface to 82% (n = 72/88) over traditional, linear localization (25%, n = 24/95), and resulted in high-quality thalamic whole cell recordings with average access resistance (32.0 MΩ) and resting membrane potential (-62.9 mV) similar to cortical recordings in isoflurane-anesthetized mice. Whole cell yield improved from 1% (n = 1/95) to 10% (n = 9/88) when robotic navigation was used during RPL. This method opens the door to whole cell studies in deep subcortical nuclei, including multimodal cell typing and studies of long-range circuits.NEW & NOTEWORTHY This work represents an automated method for accessing subcortical neural tissue for intracellular electrophysiology in vivo. We have implemented a novel algorithm to detect obstructions during regional pipette localization and move around them while minimizing lateral displacement within brain tissue. This approach leverages computer control of pressure, manipulator position, and impedance measurements to create a closed-loop platform for pipette navigation in vivo. This technique enables whole cell patching studies to be performed throughout the living brain.

Cleaning patch-clamp pipettes for immediate reuse.

Patch-clamp recording has enabled single-cell electrical, morphological and genetic studies at unparalleled resolution. Yet it remains a laborious and low-throughput technique, making it largely impractical for large-scale measurements such as cell type and connectivity characterization of neurons in the brain. Specifically, the technique is critically limited by the ubiquitous practice of manually replacing patch-clamp pipettes after each recording. To circumvent this limitation, we developed a simple, fast, and automated method for cleaning glass pipette electrodes that enables their reuse within one minute. By immersing pipette tips into Alconox, a commercially-available detergent, followed by rinsing, we were able to reuse pipettes 10 times with no degradation in signal fidelity, in experimental preparations ranging from human embryonic kidney cells to neurons in culture, slices, and in vivo. Undetectable trace amounts of Alconox remaining in the pipette after cleaning did not affect ion channel pharmacology. We demonstrate the utility of pipette cleaning by developing the first robot to perform sequential patch-clamp recordings in cell culture and in vivo without a human operator.

Patient puzzle. Use systematic assessment to detect & correct patient conditions.

Medic 27 responds to a report of a fall victim at 27 West Pinnacle Lane. En route, the crew learns from dispatch that the patient fell approximately 25 feet from the roof of a three-story structure onto the roof of an adjacent garage. The caller reports the patient "going in and out of consciousness." The EMS crew requests the dispatch of a rescue unit and ladder company to assist on scene and the placement of a medical helicopter on standby. On scene, the patient's wife reports her husband accidentally disturbed a hornets' nest as he secured a weather vane to the top of the family home. She says the hornets stung her husband repeatedly. In his attempt to avoid the stings, his movements jarred the ladder, causing him to fall to the roof below. As you walk to the side of the patient's home, his wife adds that her husband has a cardiac condition and now complains of chest pain and trouble breathing. You wonder what you'll find when you reach the victim. Is he a medical patient with traumatic injuries or a trauma patient with medical complications?

Effectiveness of interactive videodisc instruction for the continuing education of paramedics.

OBJECTIVES: To evaluate the effectiveness of interactive videodisc (IVD) instruction of paramedics through the use of computer analysis of trip sheets. DESIGN/SETTING: Prospective, controlled, in an urban 9-1-1, paramedic, emergency medical services (EMS) system with total call volume of 62,000/year; 15,000 advanced life support (ALS). INTERVENTIONS: All 150 paramedics in the system received eight hours of IVD instruction covering five subject areas: 1) airway; 2) head/cervical trauma; 3) chest; 4) shock; and 5) cardiac arrest. Trip sheets from 9,943 runs in the pre-IVD period were subjected to computer analysis, and a compliance score was generated using previously developed algorithms that assigned a weight to each omission and commission. After a nine-month IVD training period, 4,303 cases were collected and analyzed in the post-IVD period. Statistical analyses were made using "Student's" t-test and Chi-square with alpha set at 0.05. EXCLUSIONS: Only those records of adult patients who fit one of the five protocols were eligible for computer analysis. Of the 9,943 cases in the pre-IVD group, 480 (4.8%) were excluded, all due to inadequate data recording by the paramedics. A statistically similar portion, 233 (5.4%) of the 4,303 post-IVD instruction cases were excluded (p = .15). RESULTS: Overall the mean compliance score of the pre-IVD group was 0.65 +/- 0.19 (+/- SD). The post-IVD group score was 0.65 +/- 0.19 (p = 0.99). Analysis of scores for each algorithm also showed no significant differences. This study had an observed power of .94 to detect a difference in compliance as small as 0.030. CONCLUSION: Eight hours of IVD instruction did not result in improved paramedic performance as judged by computer analysis of trip sheets.

Effectiveness of interactive videodisc instruction for the continuing education of paramedics.

OBJECTIVES: To evaluate the effectiveness of interactive videodisc (IVD) instruction of paramedics through the use of computer analysis of trip sheets. DESIGN/SETTING: Prospective, controlled, in an urban 9-1-1, paramedic, emergency medical services (EMS) system with total call volume of 62,000/year; 15,000 advanced life support (ALS). INTERVENTIONS: All 150 paramedics in the system received eight hours of IVD instruction covering five subject areas: 1) airway; 2) head/cervical trauma; 3) chest; 4) shock; and 5) cardiac arrest. Trip sheets from 9,943 runs in the pre-IVD period were subjected to computer analysis, and a compliance score was generated using previously developed algorithms that assigned a weight to each omission and commission. After a nine-month IVD training period, 4,303 cases were collected and analyzed in the post-IVD period. Statistical analyses were made using "Student's" t-test and Chi-square with alpha set at 0.05. EXCLUSIONS: Only those records of adult patients who fit one of the five protocols were eligible for computer analysis. Of the 9,943 cases in the pre-IVD group, 480 (4.8%) were excluded, all due to inadequate data recording by the paramedics. A statistically similar portion, 233 (5.4%) of the 4,303 post-IVD instruction cases were excluded (p = .15). RESULTS: Overall the mean compliance score of the pre-IVD group was 0.65 +/-0.19 (+/-SD). The post-IVD group score was 0.65 +/-0.19 (p = 0.99). Analysis of scores for each algorithm also showed no significant differences. This study had an observed power of .94 to detect a difference in compliance as small as 0.030. CONCLUSION: (ABSTRACT TRUNCATED AT 250 WORDS)

Use of a lighted stylet to confirm correct endotracheal tube placement.

Despite the fact that endotracheal intubation is a skill essential for clinicians of varied specialties, the procedure is not without risk, especially when practiced in an emergency setting, particularly the field environment. Of all complications, none is more serious than unrecognized esophageal intubation. Clinical experience with a method of guided orotracheal intubation using a rigid-wire lighted stylet prompted us to develop a technique to confirm correct intratracheal placement of an endotracheal tube using a new flexible lighted stylet designed for nasotracheal intubation. Endotracheal tubes were placed under direct vision at three sites in the upper airway of five unembalmed human cadavers: esophagus (20 cm from the teeth), trachea (20 cm from the teeth) and the right or left pyriform fossa. Thirty-five volunteer intubators were asked to identify tube placement using the transilluminated glow from the flexible nasotracheal lighted stylet. A total of 168 placements were made in 40 trials. Only one of 56 intratracheal placements was misidentified as esophageal. Of 112 extratracheal placements (esophagus or pyriform fossa), one was misidentified as intratracheal. The level of experience or training bore no relationship to the ability of the intubator to identify correct placement. We conclude from the study that this technique is a rapid and reliable method of confirming correct placement of endotracheal tubes. The use of this method could reduce, if not eliminate, unrecognized esophageal intubation in the field, emergency department, the critical care unit, and the operating room.

Patient-controlled inhalational analgesia in prehospital care: a study of side-effects and feasibility.

A clinical trial of a 50:50 mixture of nitrous oxide and oxygen for pain relief was carried out to determine the feasibility of its use in a field setting and the side-effects produced by this sedative/analgesic. The gas mixture was delivered from a single-tank system using a demand-valve apparatus which was triggered by the patient's inspiratory effort. This "patient-controlled" sedation/analgesia was provided to 1243 patients over a period of 18 months. Of the 1201 patients evaluated, 20.6% reported minor side-effects consisting of nausea or vomiting (5.7%), dizziness or lightheadedness (10.3%), excitement (3.7%), and numbness (0.3%). Ninety-one (7.6%) patients became drowsy or fell into a light sleep but all were readily aroused by verbal command. All retained the ability to cough or swallow on command. No consistent or clinically adverse changes were found in BP or pulse rates. The trial supports the concept that this agent is a promising sedative/analgesic for the relief of mild to moderate pain and anxiety. Because of its safety, it is particularly suited to use in prehospital emergency care.