The penny dropped earlier today as I was listening to some of my favorite songs on my wonderful Marshall portable speaker (above, mission control for boj).
Since forever I've had the speaker near my laptop where it's helped pump up the volume when my MacBook Pro's [not all that bad] internal speakers aren't enough.
Anyhoo, I was about to put it on the right side of my computer where I always site it since the hearing in my right ear is much better than that in my left, a fact I was finally able to document objectively using Apple's AirPods Pro hearing test.
I mean, I've known for many, many years — since I was a kid — that if it was noisy for whatever reason when and where I wanted to go to sleep, I needed to put my right side down into the pillow with my left up uncovered.
But my brain suddenly jumped the usual rails and switched: I thought to myself, "If the hearing in my right ear is better, I should put the speaker on the left side of the computer because my right ear will perceive it as plenty loud while my diminished left ear gets the full blast.
Fantastic: much better sound this way, it's like I got an additional speaker and I'm listening in stereo.
Bottom line: you can teach a geriatric near-brain-dead retired anesthesiologist who breathed far too much unscavenged waste gas during his 38 years in the O.R. new tricks.
A couple questions and an observation:
ReplyDeleteIs waste gas actually a problem?
Are there ways to capture it? And then where does it go?
(I'm picturing a sort of kitchen range hood, but cleaner.)
Did you ever notice any effect on you at the time?
One of my ears is lacking in high-frequency sensitivity, and I use your pillow trick.
I use good headphones for serious music listening more than speakers nowdays,
opposite of the effect you get with your one speaker.
Both ears sound "normal" to me, probably just because I am used to the difference.
But maybe my hearing loss isn't as severe as yours.
NOTE: I BEGAN MY ANESTHESIOLOGY RESIDENCY IN 1977
ReplyDeleteQ. Is waste gas actually a problem?
From Perplexity Pro:
Unscavenged waste anesthetic gas absolutely was an issue historically, and it is still a recognized occupational and environmental concern today, but modern scavenging systems, ventilation standards, and monitoring have drastically reduced typical exposure in well‑run facilities.[osha +2]
Early era: when it was unscavenged
Before the late 1960s–1970s, most operating rooms, dental offices, and veterinary suites vented anesthetic gas straight into the room air with no dedicated scavenging. Nitrous oxide and early halogenated agents (e.g., halothane) often leaked from breathing circuits, masks, and valves, so staff could work all day in a low‑grade anesthetic “fog.”[cdc +2]
By the late 1960s and early 1970s, epidemiologic studies reported higher rates of headaches, fatigue, and possibly spontaneous abortions and congenital anomalies among exposed OR personnel, which raised alarms even though later re‑analysis found major methodological flaws and no clear causal link at modern “trace” levels. This research, plus growing occupational‑health awareness, pushed regulators and professional groups toward formal exposure limits and engineering controls.[digitalcommons.usf +2]
Regulatory response in the 1970s
In 1977 NIOSH issued a landmark criteria document on occupational exposure to waste anesthetic gases and vapors, recommending exposure limits of about 2 ppm for halogenated agents and 25 ppm for nitrous oxide during anesthetic administration. The same guidance laid out control measures: dedicated scavenging systems, good maintenance of anesthesia machines, leak testing, and room ventilation standards.[stacks.cdc +3]
OSHA and NIOSH subsequently described unscavenged or poorly scavenged waste anesthetic gases as a potential cause of adverse neurologic and reproductive effects, particularly before widespread adoption of scavenging and modern OR ventilation. In that period it was common to have no active scavenger, minimal monitoring, and reliance on general room ventilation, which was later recognized as inadequate.[ehs.msu +2]
How it was dealt with historically
ReplyDeleteFrom roughly the 1970s onward, control efforts followed classic industrial‑hygiene hierarchy:
• Engineering controls: Hospitals began installing dedicated anesthetic gas scavenging systems (AGSS) that connect to anesthesia machines and vent excess gas outside the building instead of into the OR. First‑generation negative‑pressure systems originated in the UK but some designs were phased out because unstable suction could interfere with the anesthesia machine.[sciencedirect +2]
• Room ventilation: ORs moved toward higher air‑exchange rates and directional airflow to dilute and remove waste anesthetic gases that escaped the circuit and scavenger.[osha +1]
• Work‑practice changes: Staff were taught not to turn on nitrous oxide or vaporizers until the circuit was connected, to shut them off promptly when not in use, and to avoid deliberately emptying reservoir bags into the room. Mask fit, minimizing mask‑only anesthesia, and proper filling of vaporizers became standard training points.[cdc +1]
• Monitoring and maintenance: Facilities introduced routine leak‑testing and preventive maintenance of anesthesia machines, along with periodic air monitoring to verify that waste gas concentrations stayed below recommended levels.[digitalcommons.usf +2]
By the late 20th century, prospective studies in modern, scavenged ORs generally did not show a causal relationship between trace exposure levels and adverse health outcomes, reinforcing that the key was keeping levels low with these controls.[pubmed.ncbi.nlm.nih]
Current practice and remaining issues
Today, in human hospitals, stand‑alone surgical centers, and many dental and veterinary practices, dedicated scavenging systems are considered standard of care for inhaled anesthesia. An AGSS uses active suction or passive venting to collect waste gas from the anesthesia machine or wall outlet and discharge it safely outside; general building ventilation is explicitly not considered sufficient on its own. Institutions are expected to have formal “waste anesthetic gas programs” that combine scavenging, work practices, regular equipment checks, and training.[ors.nih +6]
However, unscavenged or poorly scavenged waste gas can still be a problem in some settings:
• Smaller or older facilities, dental operatories, and animal research labs sometimes rely on partial or passive controls, which can allow higher room concentrations if practices are poor.[sedationsystems +1]
• NIOSH and OSHA still estimate that hundreds of thousands of health‑care workers may be exposed to some level of waste gases, so they emphasize ongoing monitoring and training.[youtube +1]
• Even with good scavenging, virtually all excess volatile agent and nitrous oxide vented from the system goes into the outdoor atmosphere, where it contributes to greenhouse effects; current initiatives focus on lowering fresh gas flows and choosing lower‑impact agents to reduce this environmental load.[asahq +1]
So historically, yes: truly unscavenged waste anesthetic gas was common and was viewed as an occupational hazard once people started measuring it, leading to the scavenging and ventilation standards that are routine now. Today the main focus is preventing localized failures (leaky circuits, bad practices, older suites) and reducing the broader environmental footprint of the gases that are deliberately vented outside.[amcaremed +6]
Q. Are there ways to capture it? And then where does it go? (I'm picturing a sort of kitchen range hood, but cleaner.)
A. See above
Q. Did you ever notice any effect on you at the time?
A. Never