(Hypothetical case)

You are called to the PACU to review a patient, who despite face mask oxygen has saturations of only 88%. She is a woman in her 50s who has just undergone a 3 hour laparoscopic hysterectomy for endometrial cancer. She has a BMI of 48, has been a smoker for 30 years, and had a chest infection 3 weeks ago. When she walked into the hospital earlier this morning she was breathing relatively normally. She had a long period of time when we she was steeply head down, there was a pneumoperitoneum of gas pushing on her lung bases and we were positively ventilating her with the anaesthetist choosing what gas mixture, pressures and ventilation modes they used. What has happened during this operation and anaesthetic that now she has serious respiratory dysfunction here only a few hours later in PACU?

Are there any strategies that we could have employed intraoperatively to try and minimise or avoid postoperative respiratory problems like this?

Join Lloyd and I as we discuss this thorny issue which is not uncommon in gynaecological patients having laparoscopic and open abdominal surgery.

Part 1: We discuss post pulmonary dysfunction and consensus statements on the topic.

Part 2: We talk about practical intraoperative & postoperative strategies you might consider to try and protect the lungs and prevent any problems.

"Lloyd's Recipe"

Check the patient's oxygen sats whilst supine - pre induction (use to plan target sats intra & post)

Individualise FiO2 for pre-oxygenation and not necessarily 100% for most (usually 80%)

Have the APL valve at around 5cm H20 when preoxygenating

Head-up / ramped (to maintain FRC)

Recruitment manoeuvre after intubation and before pneumoperitoneum - use a machine technique not hand recruitment.

Start with a PEEP 5-8cm H20, individualise during the case - may need higher whilst head down and pneumoperitoneum.

Small Tidal Volumes (TV) 5-8ml/kg of ideal body weight - (obese patients don't get bigger TV's)

Keep FiO2 < 0.4

I:E ratio 1:1

If disconnection - repeat recruitment maneouvre

At emergence / extubation - sitting upright, don't disconnect to suction ETT, recruit again if laparoscopic procedure or obese.

Routinely use NM monitoring - ensure TOFR >0.95

Don't use 100% O2, Aim FiO2 < 0.8

If breathing on manual ventilation setting have APL valve at 5-10 to maintain PEEP

Squeeze bag as extubating

Immediately post extubation place face mask with APL still at 5-10

Be cautious / avoid excessive opioids that will suppress respiratory drive in PACU

References

A systematic review and consensus definitions for standardised end-points in perioperative medicine: pulmonary complications BJA 2018 May 120(5)

Postoperative pulmonary complications BJA: British Journal of Anaesthesia, Volume 118, Issue 3, March 2017,

Perioperative interventions for prevention of postoperative pulmonary complications: systematic review and meta-analysis BMJ 2020; 368

Lung-protective ventilation for the surgical patient: international expert panel-based consensus recommendations BJA 2019 Dec;123(6)