key: cord-0682644-ija9oa2f authors: Hoffman, Henry T.; Walsh, Jarrett E.; Pratt, Alessandra; Miller, Robert M.; Schwalje, Adam; Stegall, Helen R.; Nonnenmann, Matt title: Laser plume containment during flexible transnasal laryngoscopy date: 2021-02-05 journal: Laryngoscope Investig Otolaryngol DOI: 10.1002/lio2.526 sha: 31b3b0bd3e2ee7c62cb3f160b8e5bfa275257b29 doc_id: 682644 cord_uid: ija9oa2f OBJECTIVE: To evaluate a negative pressure microenvironment designed to contain laser plume during flexible transnasal laryngoscopy. METHODS: The Negative Pressure Face Shield (NPFS) was previously reported as well tolerated with initial use on 30 patients. Diagnostic transnasal laryngoscopy was performed on an additional 108 consecutive patients who were evaluated by questionnaires and sequential pulse oximetry. Further study addressed operative transnasal potassium‐titanyl‐phosphate (KTP) laser laryngoscopy with biopsy done on four patients employing the NPFS. RESULTS: The previously described NPFS version 3 (v.3), a transparent acrylic barrier with two anterior instrumentation ports, was modified by repositioning the side suction port closer to the level of the nose and deepening the lateral sides, squaring off the lower projection. A post‐procedure questionnaire employing a 5‐point Likert scale ranging from no symptoms (rating of 1) to intolerable (rating of 5) identified excellent patient tolerance of the new design (v.4), among 22 patients evaluated and similar in the comparison to the 116 patients using version 3. Among the 138 patients analyzed, only one patient rated the experience as greater than “mild claustrophobia.” 100% of patients answered either “none” or “mild” to the pain and shortness of breath questions. The NPFS (v.4) was then successfully used in four patients for laser laryngoscopy with biopsy of laryngeal papilloma (3/4) and hemorrhagic polyp (1/4). Post‐procedure questionnaire identified no shortness of breath (4/4), no claustrophobia (4/4), no pain (4/4) and no significant changes in pulse oximetry during use. CONCLUSION: Extensive experience in performing diagnostic laryngoscopy with the NPFS directed design changes leading to successful use for transnasal flexible laser laryngoscopy with biopsy in a negative pressure microenvironment. LEVEL OF EVIDENCE: Level 2b (Cohort Study). High energy surgical devices such as laser and electrocautery produce plumes that contain cardiotoxic and carcinogenic aerosols as well as viable viral contaminants. [1] [2] [3] [4] [5] Efforts to control spread of these substances include recommendations from the Centers for Disease Control and Prevention (CDC) to limit dispersion through use of smoke evacuators containing a suction unit. 6 Concern about risk of viral transmission associated with aerosol generating procedures (AGPs) has been amplified during the COVID pandemic to intensify efforts to limit dissemination of surgically produced aerosols. 7 Serban et al recently identified that use of filtrations systems "will probably remain a routine also in the future" and that "the effect of COVID-19 pandemic will be most probably a progress in the safety regulations". 8 An umbrella emergency use authorization (EUA) was provided by the U.S. Food and Drug Administration (FDA) May 1, 2020 for use of passive protective barrier enclosures (without negative pressure) when performing aerosol producing medical procedures on patients at risk for infection with SARS-CoV-2 in health care settings. This authorization was revoked by the FDA August 20, 2020 due to studies leading to the conclusion there was lack of efficacy and a potential for adverse events. [9] [10] [11] FDA authorization remains viable for protective enclosures employing suction to create a negative pressure. In a letter (August 21, 2020) to health care providers the FDA identified "If electing to use a protective barrier enclosure for additional protection during aerosolizing procedures by HCPs, FDA recommends the use of devices that incorporate negative pressure". 12 FDA support (EUA) remains (as of October 4, 2020) for several devices for use "when performing airway-related medical procedures" as barriers to isolate the patient within a negative pressure environment maintained by continuous suction. 13, 14 The Negative Pressure Face Shield (NPFS) is a protective enclosure employing suction to create a negative pressure microenvironment previously reported to permit diagnostic flexible transnasal laryngoscopy with a high level of patient tolerance. 15 We present additional experience with the NPFS and subsequent minor modifications to the original design permitting study during operative flexible transnasal laryngoscopy with biopsy and laser ablation. The local institutional review board (IRB) directed and approved the clinical evaluation of the NPFS. All methods were in full accordance with the principles set out by the World Medical Association Declaration of Helsinki. A special IRB approved written consent was obtained from each patient who participated in the study and was supplemented by a second additional approved written consent for those selected patients whose images were depicted in figures. Testing of multiple prototypes led to development of the NPFS version 3 (v.3) made of 0.2 00 (5 mm) thick acrylic. This NPFS is a transparent 9 00 × 10.5 00 rectangular device with a depth of 3.5 00 and an inferior stabilization flange used to engage a clamp on a camera stand (Matthews Hollywood Century 40 00 S Stand for Grip Arm Kit, Adorama Inc., New York, New York) for positioning in front of the patient. The three openings in the NPFS were smoothed and sealed to ensure that these areas would not harbor unwanted particulate matter. These openings included two separate 1 /4-in. (6.35 mm) access ports in the lower midline of the face shield and a 5/16-in. (7.94 mm) suction port on the mid-lateral surface. The initial design, version 3 was modified to version 4 to deepen the box and place the suction at a lower level closer to the nose and mouth. The added depth was provided to not only increase the distance of the patient from the front of the shield, but also to assess potential use of the lower flange of the box as a chin rest (Figures 1 and 2 ). Institutional approval was granted August 11, 2020 to use the NPFS clinically in a non-research mode. Following this date, all subsequent use of the NPFS for diagnostic laryngoscopy was done off-study. Operative transnasal laryngoscopies were continued on-study leading to a consecutive series of transnasal flexible laryngoscopy with KTP laser and biopsy on four patients between August 19 to September 23. As previously reported, a sterilization wrap (Halyard H100 sterilization wrap, O&M Halyard Inc., Alpharetta, Georgia) was fashioned as a cylinder and secured to the NPFS with tape circumferentially. 15 The wrap was adapted to drape over the patient's head as a hood to create a closed environment by drawing the lower aspect of the drape loosely around the patient either by using a 3 to 4 ft length of umbilical tie (white twill ½ in., 36-yard roll, Horn Textile Inc., Titusville, Pennsylvania) or, as was more common practice later in the study, tucking the drape into the patient's shirt without use of twill tape ( In all 4 cases treated with laser laryngoscopy the patients were premedicated with a drying agent either by orally with 1 mg glycopyrrolate with sips of water 1 ½ hours preoperatively (3 patients) or with 0.2 mg glycopyrrolate IV 1 hour preoperatively (1 patient). 30 to 45 minutes before the procedure bilateral superior laryngeal nerve blocks were performed with 1 cc of 2% lidocaine with 1:100000 epinephrine administered to each side (2 cc total) employing dental carpules. 17 Immediately before the procedure topical nasal decongestion and anesthesia was administered employing 4% lidocaine with 1% phenylephrine spray. Final topical anesthesia to the larynx was performed with delivery of~2 cc of 4% lidocaine directly to the larynx through a 25-gauge sclerotherapy needle (Interject Sclerotherapy Needle Catheter 25 g × 240 cm Boston Scientific, Marlborough, Massachusetts) in the channel of the laryngoscope. Mild sedation (1-2 mg of IV versed) was administered in two of the four operative cases as per the patients request with postoperative affirmation from both patients that they tolerated the procedure well and did not feel the sedation had been necessary. As has been previously practiced, the transnasal laser laryngoscopy was done with KTP laser settings of 30 watts, 15 ms pulses, and 2 pulses per second for each case. 18 Total dose delivered for the hem- Overall tolerability was analyzed by dichotomizing the Likert scale such that values of (1) none or (2) slight were considered to be "well tolerated" and other values (3-5) were considered "not well tolerated". This cutoff was determined a priori to define acceptable tolerance. The Clopper-Pearson procedure was used to construct confidence intervals for the true tolerability rate on each of the three factors. To compare tolerability between the two devices (NPFS v.3 vs NPFS v.4), a stricter tolerability threshold was applied such that only values of (1) were considered well tolerated, as preliminary data showed all subjects meeting the a priori threshold. Fisher's exact test was used to determine if there were significant differences in the stricter tolerability proportion between groups. Observed tolerability and 95% confidence intervals for the proportion of subjects that would report the procedure as tolerable on each of the three factors identifies consistency in reported effect for the subgroups of subjects on Version 3 and 4 ( Table 3 ). In the previously reported group of 30 subjects, 100% reported meeting the tolerability threshold on all three factors and with high confidence that the true tolerability rate is above 88% (Figure 6 ). In the subsequent subjects evaluated on Version 3, there was one subject reporting less than "well tolerated" claustrophobia (considered moderate claustrophobia-not severe or intolerable), with high confidence that the true tolerability rate for claustrophobia is above 93%. For shortness of breath and pain, all subjects reported these factors as well tolerated and we have high confidence that the true well tolerated rate is above 95% on these two factors. In comparing the stricter tolerability threshold (none vs any intolerance) between the three groups, the Fisher's exact P-values were .4094, .2102, and .5484 for claustrophobia, shortness of breath, and pain, respectively. These results indicate no significant differences in the strict interpretation of "well tolerated" between the three groups. "not a big deal; it was all right; didn't bother me any more than the other way you did it." "I am claustrophobic, but I didn't feel claustrophobic in there." "It was quick and easy, and I felt safe." "I can't believe anybody would be claustrophobic in that." "pretty neat; very safe; caught all that sneeze." The additional depth provided to the NPFS v.4 permitted use of the lower shelf to serve as a place for the patient to deposit the facial tissue given to them at the end of the case when they could blow their nose and clean their face in a closed environment (Supporting Information 2, Data S1-video and protocol). The inferior shelf was initially trialed for use as a chin rest. It was rapidly identified that complete immobiliza- supplement, Video S1, also available https://youtu.be/uCopxWgje_U) (Supporting Information 3, Data S1-protocol). "experience was fine, I was awake but had no worries about it." "it wasn't as bad as I thought it was going to be worst part was pushing the probe through the nose, but that wasn't bad either." "kind of like how you are better positioned; it was fine, no big deal; only negative was nose running." Instrumentation through the anterior port in the NPFS v.4 was readily performed without additional difficulty compared to previous use in the pre-COVID era when done without the NPFS. The support provided to the flexible laryngoscope as it is passed through the anterior port offered further stability in performing the procedure. The COVID pandemic has stimulated development of novel strategies to limit spread of SARS-CoV-2 that are applicable to control of other surgically generated toxic and infectious aerosols. 22, 23 CDC-supported recommendation from the National Institute for Occupational Safety and Health (NIOSH) (accessed October 9, 2020) directs "a smoke evacuator or room suction hose nozzle inlet must be kept within 2 in. of the surgical site to effectively capture airborne contaminants generated by these surgical devices." 6 These NISOH recommendations cite a single article (Smith et al 24 ) in which CO 2 laser plume dispersion was assessed leading to the additional assertion that if the smoke evacuation system were turned off for even a short period, high concentrations of fume would result that could lead to exposure. 24 These investigators suggested that the suction must be functioning during the entire time the laser is in operation and ideally maintained on for an additional 20 to 30 seconds after the laser is turned off. Our practice in limiting plume dispersion in the past had been to maintain suction on the channeled laryngoscope as much as possible during active lasing with hopes that process would decrease exposure of the laser plume not only to health care workers but also the patient. We continue this practice now supplemented by the additional control of the laser plume employing the NPFS. Publications addressing flexible transnasal laser laryngoscopy in the pre-COVID era identify many excellent discussions about technical aspects of the procedure, but generally do not address suction control in detail. 25 Prior to the COVID-era, reports were vague about limiting exposure to laser plume with general comments such as recommendations to use "proper smoke evacuation" and the more specific "after the procedure, surgeons kept on their masks for 10 minutes to clear the fumes from the surgical room." 26 The importance of containing laser plume expands beyond that of limiting exposure to viral infection. 5 Although the carcinogenic and cardiotoxic effects of laser plume remain theoretical in the absence of epidemiologic evidence, there is indirect evidence for the negative impact of environmental exposure to these substances. For example, a survey of nurses exposed to surgical plume identified respiratory conditions to be twice as prevalent among them when compared to the general population. 27 F I G U R E 6 Tolerability responses by prototype version and factor splitting out previously reported version 3 group Protection from aerosol by mask wearing is established as a helpful health policy, but an incomplete method to limit exposure to viral spread. [28] [29] [30] The misconception by many that surgical masks termed "laser masks" provided adequate protection has been modified in identifying that most toxic metabolites and viral particles are <5 μm and not adequately filtered by these masks. 31 Adaptations to the previously described NPFS v.3 permitted successful treatment of 4 patients with KTP laser. This operative use of the NPFS v. 4 was performed without additional difficulty and added confidence to the containment of aerosol. Research addressing dissemination of laser combustion byproducts has included a specific focus identifying infectious bioaerosol containing human papillomavirus (HPV). 32 A "Triological Society Best Practices" review questioned the infectivity of laser plumes containing HPV but concluded that-unlike the less effective use of commercially available filters and masks-"evacuation of plume from the surgical field is likely an effective strategy to prevent viral contamination". 31 Shortcomings to our study include the lack of data identifying successful containment of bioaerosol through use of the NPFS. The Negative Pressure Face Shield, initially designed to limit exposure to bioaerosols, was adapted with minor modifications to permit its application in efforts to contain laser plume during awake flexible transnasal laryngoscopy. Surgical procedures were readily accomplished with a high level of patient tolerance. 3-2018: American National Standard for Safe Use of Lasers in Health Care CDC NIOSH Control of Smoke for Laser/Electric Surgical Procedures DHHS (NIOSH) Publication Number 96-128 Risk of virus contamination through surgical smoke during minimally invasive surgery: a systematic review of the literature on a neglected issue reviewed in the COVID-19 pandemic era Infectivity of murine papillomavirus in the surgical byproducts of treated tail warts How should we safely handle surgical smoke? Laryngoscope Publication Number 96-128. 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